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Home My WebLink AboutAPA2657FINAL REPORT JUNE 1985 DOCUMENT No.2657 VOLUME 4-APPENDIX E FIELD MEMORANDUM SURVEY OF EXPERIENCE IN OPERATING HYDROELECTRIC PROJECTS IN COLD REGIONS -Alaska Power Authority ==~:-.:~.__-__.,--, o~#:\=~~&@©@ .TNA JOINT VENTURE FEDERAL ENERGY'REGULATORY COMMISSION PROJECT No.7114 SUSITNA HYDROELECTRIC PROJECT r $l ,f ,l R..····.0 SUSITNA HYDROELECTRIC PROJECT SURVEY OF EXPERIENCE IN OPERATING HYDROELECTRIC PROJECTS IN COLD REGIONS VOLUME 4 -APPENDIX E FIELD MEMORANDUM OF VISIT BY H.W.COLEMAN BRITISH COLUMBIA HYDRO (VANCOUVER) AND PEACE RIVER TOWN AND SUPPLEMENTARY MATERIAL Prepared by Harza-Ebasco Susitna Joint Venture Prepared for Alaska Power Authority Final Report June 1985 Document No.2657 Susitna File No.42.2.5 ---rt\ \\:-\-;;1 S oS~ FL\'1;!- ,-c:::r- \110-2f.oJ ARLIS -~-"-------- Alaska Resources Library &Information Senrices lUlchorage,Alaska I I ~ I NOTICE ANY QUESTIONS OR COMMENTS CONCERNING THIS REPORT SHOULD BE DIRECTED TO THE ALASKA POWER AUTHORITY SUSITNA PROJECT OFFICE ARLIS Alaska Resources Library &Information Services Pulchorage,AJaska ce SUSITNA JOINT VENTURE :- : LOCATION TO FROM MEMORANDUM Chicago Office FGD.AEA,MPS, H.W.Coleman DATE April 20,1984 NUMBER SUBJECT Winter Power Operations B.C.Hydro-Peace River Experience Intrl:>duction Durilo.g the week of April 2,1984,HWC and Wayne Dyok attented the Third International Specialty Conference on Cold Regions Engineering in Edmonton,Alberta to add to background design information for Susitna.My ~omments regarding the conference papers are included in a separate memo.In addition to the conference,we gathered additional information regarding B.C.Hydro's winter power operation,particularly the Portage Mountain Development (PMD), and its effect on downstream river ice ~n the vicinity of Peace River Town (PRT),Alberta.Reference 1 gives a good summary description of the freeze-up event of January,1982,which has focused attention on the flooding potential of fluctuating power flows with an ice covered river. Conclusions My conclusions regarding the effect of Portage Mountain Development on Peace River ice conditions,based on discussions with B.C. Hydro and Alberta Environment personnel,and other are as follows: - 1.lPreeze-up staging of the order of several meters can result from consolidation of an ice front following flow fluctuations from a load following power plant. -2.~rhis consolidation and associated staging can extend over a range of 100-150 km. The most important aspect of the freeze-up staging is flow surge from water released from storage under a backwater profile foll~wing consolidation of an ice front,resulting in unsteady flows which may be 1.5-2.0 times the steady flow. Such consolidations occur naturally to some extent,but are I:onsiderably more frequent and of greater magnitude with the higher winter power flows,and particularly if flow is fluctuated. The generally accepted procedure for operation in the vicinity of a sensitive area,is to maintain steady,high power discharge while the ice front is passing thru the area.Once the front is l~ell upstream,and a competent cover has developed,which period 3 • I"- co M I"-coCry 0 4 .00 LO LO I"- M M 5. - ---------~_..",.,-,----------'-------.,,--------------------~ RIA"ilASCO SUSJTNA JOINT VENTURE MEMORANDUM LOCATION TO FROM Chicago Office FGD,AEA,MPS,HHC,WEL H.W.Coleman DATE April 20,1984 NUMBER Page Two SUBJECT _--:;W;;-i---..n_t_e-;;r:;---;;P_o_w_e-;;;:r_O-,p,-e_r-=a~t:-i","-o_n....:s-=-__-:-- B.C.Hydro-Peace River Experience may be 1-2 weeks depending on the air temperatures,load following operations can resume.The ice front is always subject to consolidation,but the sensitive area will be safe if the front is far enough b lstream. up 6.Break-up consolidation and jamming is much less controllable. Factors other than power releases can be more important,such as development of intervening flow from snowmelt,effect of tributaries,and rate of warming of air temperatures. 7.On the Peace River,the procedure on break-up seems to be to provide high,fluctuating flows as far as possible in non- sensitive areas.When approaching a sensitive area,it is desirable to reduce flow and hold steady until the front is downstream of the sensitive area. 8.For Sustina,our basic problem is that we don't have a specific sensitive area,but rather the entire "river more or less,since the fishery is the primary environmental concern. Visit to Peace River Town I visited PRT on April 3,1984 in order to see the river ice conditions first-hand and talk to Alberta Environment personnel in PRT,who monitor the river ice conditions on a daily basis. Reference 2 shows photos of the river ice conditions in PRT and for a distance of about 25 km upstream on April 3,1984.The ice front on this day was near Dunvegan Bridge,about 100 km upstream of PRT.The front was retreating gradually with warm air temperatures and little intervening flow.I talked briefly with Jim Amirault of Alberta Enviroment in PRT.His staff monitors ice front location and ice conditions in general.When the ice front is advancing or retreating thru town,the central office in Edmonton takes over the monitoring effort.Gordon Fonstad of the Edmonton office has been in charge of this program in recent years. Amirault emphasized the importance of the Smoky River,which enters the Peace about 6 km upstream of town.If the Smoky breaks up prior to the Peace,jamming will occur in town.(Reference 3, p.15).This occurred in 1979 and raised ice levels within 0.3 meters of the top of dikes at that time.The dikes were subsequently raised about 1 meter.High break-up stages occurred in 1973 and 1974 also (Reference 3,p.17),but dikes were not overtopped since they had been raised following a very large summer flood in 1972. ;;;; - ,- ·-IlJI"flA,ICO SUSITNA JOINT VENTURE MEMORANDUM SUBJECT .,__....W;:-i_n...-t_e....r~P......-::o:-:w:-e--:;:;r---:o~p:-e-:--r-,;a.-:t..-::i-=o-:n:-s"'"""==~~ B.C.Hydro-Peace River Experience In fact,all high stages prior to 1982 resulted from break-up. The January 1982 event was the first problem which occurred on freeze-up. H.W.Coleman Page Three-I : i ,.... I [,.- ..... LOCATION TO FROM Chicago Office FGD,AEA,MPS,liHC,WEL DATE .-::A:£p:...:r:...:i=-I~.;:.2...:.0....?,--=1:..;9_8;;..4 _ NUMBER _ - - ..... ..... - Following the early January,1982 freeze-up event in PRT,B.C.Hydro releases were held very uniform at about 1700 m3 /s (about 90%of capacity)for the next two weeks,per request of Alberta Environment (Reference 4,p.5).On January 20,B.C.Hydro returned to its normal load following operation,with dis§harge varying daily from as high as 1900 m 3 /sec to as low as 900 m Isec (Reference 4, Figure 1).The gauge reading at Peace River showed almost no response to the daily flow fluctuation. Basement flooding in PRT was reported as early as January 9,1982. However,because power demand was high,and an attempt was being made to "set"'the ice cover,releases from B.C.Hydro were not decreased (Reference 4,p.6).Consequently,groundwater levels in West PRT maintained at flood levels until early March,after B.C.Hydro releases were decreased to about 1000 ~/s in late February.In late March,B.C.Hydro increased flows again and flooding occurred again in PRT until the river ice broke up in late April • Because of the massive amount of ice in the consolidated cover from the January,1982 event,break-up was considered a potential problem in PRT.Mitigative measures included plowed lanes in the ice with sand and salt to weaken the ice at desired locations and pre-blasting in jam key areas.The break-up turned out to be very mild,primarily melt-out in place,because of a dry fall and cool spring which prevented a build-up of river flow before break-up. In addition,B.C.Hydro releases were maintained nearly constant for 1 week prior to break-up in PRT. After talking with Amirault,I toured the river around town,and drove up river about 25 km to Shaftsbury Ferry.The river was ice coverd generallY,with a few areas of weak ice and a few small open leads.The ice level in town appeared to be 5-6 meters below the top of dikes.The ice was generally rough and broken up from consolidation.The river at surface level was generally 500-600 meters wide,excluding islands,and of the order of 5 meters deep.The ice was probably up to 2 meters thick.My general impression from looking at the river ice condition and stage,was that break-up flooding this year will be no problem.However, it has been demonstrated many times that break-up predictions are notoriously unreliable. C:f))SUS/TNA JO/NT VENTURE - I.OCATION TO FROM MEMORANDUM Chicago Office FGD,AEA,MPS,HHC,WEL R.W.Coleman DATE April 20,1984 NUMBER Page Four SUBJECT _--:W:-i-::;n_t_e-::r=--p-:-o_w_e--:r=-_O....'P__e_r=a--:t:-i_o_n_s-=-__--:-- B.C.Hydro-Peace River Experience Visit to B.C.Hydro,Vancouver On Thursday,AprilS,Wayne Dyok and I flew from Edmonton to Vancouver to discuss winter power operation and enviromental aspects common to B.C.projects and Susitna. We met with C.V.Kartha and Les Parmly of the Hydrology Section. They are in charge of monitoring river conditions at the various B.C.Hydro projects. Parmly described the Peace River as follows:The river originates in the Rocky Mountains in B.C.and flows easterly to Peace River Town, Alberta,a distance of about 500 km.From Peace River Town,it flows north and then east to vicinity of Lake Athabasca in Northeastern Alberta,another 500-600 km.From here it joins other rivers,ultimately the Mackenzie River,and drains to the Beaufort Sea.The river is generally wide and flat sloped,with intermittent narrow canyon sections.In 1972,the Portage Mountain Development (PHD),located about 400 km upstream of PRT,was completed.In 1979,the Peace Canyon Dam,about 20 km downstream of PHD,with much smaller storage and no reregulation capacity,was completed. rS The PHD supplies about 35%of the total sykem load and Mica about 25%(Reference 5).PHD is the primarily load following plant because treaty committments to the U.S.preclude Mica from large flow fluctuations.Therefore,it is critically important to the B.C.system for PHD to load follow in the winter. Under pre-project conditions,the ice cover advanced upriver,and with some intermitttent bridging,eventually covered the entire river length.With PMD,the ice generally bridges well downstream of PRT at Fort Vermillion,and advances upriver to vicinity of the Alberta-B.C.border,about 175 km downstream of PMD.The furthest upstream progression with PHD has been to the town of Taylor,B.C., about 125 km downstream of PMD,in 1974 and 1979. PMD has a selective withdrawal intake with two levels.Drawdown is up to 100 feet.Release temperatures in winter are generally 2-3°C. 53 .... I-i l IfIIAIlJI"IIAICO SUSITNA JOINT VENTURE MEMORANDUM 1'.' LOCATION TO FROM Chicago Office FGD.AEA,MPS,HBC,WEL B.W.Coleman DATE April 20,1984 NUMBER _ Page Five """ .- - ....' - SUBJECT __---"1Y~i~n~t<.:e::..:.r~P_:o~w~e...!:r:_...:O~p~e:...!r:..la~t..:!i~o!..Jn!oUZ.s _ B.C.Hydro-Peace River Experience B:C.Hydro has developed a river ice computer model over the years for use on the Peace and other rivers.Their model is the result of work done by LaSalle Lab on the Liard and MacKenzie Rivers,and other improvements based on Syl Petryks work on the Peace.The main concern of E"C,Hydro on the Peace seems to have been the freeze-up jam induced flooding around Taylor,B.C.in 1974 and 1979.The event in 1979 was extensively monitored and modelled by B.C.Hydro (Reference £). The freeze-up jams at Taylor,B.C.are induced by the flow fluctuations at PMD,when the ice front is in the vicinity of Taylor.The situation is similar at Peace River Town (PRT).The difference is that the problem at PRT has generally been during break-up,whereas break-up has not been a problem in B.C. Parntly and Kartha con'firmed the influence of the Smoky River on PRT problems.If the Smoky breaks-up first,jams will develop at the confluence with possible flooding in PRT.B.C.Hydro recognizes that operation control is necessary at PMD during passage of the ice front thru sensitive areas during freeze-up.Their approach is to "set" the cover in place at relatively high uniform flows.After this,they can fluctuate load as required with no negative effects. On break-up,the preferred procedure is to try to induce the Peace to break-up in PRT prior to the Smoky.To accomplish this~PHD should be fluctuated as much as possible as long as the ice front is well upstream of PRT.When the break-up front nears PRT,PHD flow should be minimized and held steady until the front moves thru PRT. Following this,PHD can resume normal operation • In }{arch,1982,Acres conducted ice flexure tests on the Peace River for the Canadian Electrical Association.These test consisted of flOl~fluctuations at Peace Canyon over a 6 day period,with measurements of open-water stage fluctuations,and under-ice stage fluc~tuations downstream of the ice front.Results are shown in Reference 7.These studies demonstrate the following: 1.The open-water stage fluctuations propagate downstream without significant attenuation. MEMORANDUM LOCATION TO FROM Chicago Office FGD,AEA,MPS,HHC,WEL H.W.Coleman DATE April 20!1984 NUMBER Page Six SUBJECT Winter Power Operations B.C.Hydro-Peace River Experience 2.The ice front retreat (meltout)at Clayhurst Ferry was probably encouraged by the flow fluctuation. 3.The ice-water surface at Dunvegan and PRT responds to fluctuation,but the rapid fluctuations are dampened. cover floats up and down without substantial break-up areas,except for shore-fast ice. the flow The ice in these We were also shown photo records taken during river ice reconnaissance flights for the past 4-5 years.These records are similar to the R&M documentation for the Susitna.We were supplied with a copy of the 1981-82 and 1982-83 Ice Observation Reports prepared by B.C.Hydro (References 8 and 9).These reports include observers diaries, meteorological data,miscellaneous ice/water levels and ice front progression rates. Meeting with Alberta Environment,Edmonton On April 6,1984,I visited with Gordon Fonstad of Alberta Environment in Edmonton.He supplied me with three reports (References 3,10 and II)in addition to the 1981-82 Ice Observation Report he sent previously (Reference 4).We discussed the various ice events on the Peace River since he has been in charge of the Alberta Environment effort for several years.He was responsible for the mitigative efforts in preparation for break-up in 1982.It is interesting that following the severe consolidation event in January 1982,the spring break-up was uneventful.In fact,Fonstad indicated that the ice weakening efforts in PRT probably had little to do with the mild break-up.It was primarily lack of rapid flow build-up from smowmelt. Fonstad also pointed out that the 1983 break-up was different from previous years.Usually,the Peace breaks-up and moves thru PRT, followed by the Smoky break-up.In a few years,the Smoky broke up first,causing jams in PRT.However,in 1983,a partial meltout occurred in PRT,followed by break-up of the Smoky,and then break-up of the Peace.No significant stage increase occurred in PRT.- - r Z~iii 1IIlleG SUSITNA JOINT VENTURE MEMORANDUMrIF'" 1 l. LOCATION Chicago Office DATE Apr i 1 2 0,1 9 84 TO FGD,AEA,MPS,BBC,WEL.._------=---......;;.----'------'-------NUMBER _ FROM H.W.Coleman Page Seven I- I .~ .- - - ""'" SUBJECT _--.,W....i_n,..-t_e....r..--....P;-o_w_e-:;:;r:--O_p~e_r.a:;-t:;--i_o_n:-s--;:;.........__=-:;_B.C.Hydro-Peace River Experience The 1982-83 Alberta Enviroment report includes a summary of break-up stage increases in PRT since .1960.This summary shows a clear increase in high break-up stage frequency with project compared to pre-project (3 events to 1).However,it is interesting that all four events had accompanying high flow rates in the Peace River and 3 out of 4 events had high flow rates in the Smoky during break-up.In other words,the break-up event in PRT is probably related more to snowmelt interflow than to PMD operation. Ff)nstad also described other rivers in Alberta where monitoring programs of winter flow conditions are in progress.In particular, the Athabasca River break-up jams cause flooding in the City of Fort McMurray,Alberta (Referenc~11).This problem is apparently unrelated to any hydro operation. Fonstad also mentioned a problem on the North Saskatchewan River, downstream of the Trans Alta Utilities Corporation,Bighorn Dam and on the Red Deer River downstream of Dickson Dam.Be gave me a rf~ference in Calgary who can probably supply more information. Fonstad thought that Manitoba Hydro probably can supply information 011 the Nelson River and Churchill River (Rerefence /Z ). Fonstad confirmed much of the information I already had.He reiterated that while hydro operation can be a problem in cold regions,it is being controlled in Canada by careful operation at critical times.He did mention that our situation on the Susitna, where the major impact is fisheries over a significant portion of the river,will be more difficult since the problem is not localized, as has been the Canadian experierice. H.W Coleman H'~C/mmg - - .- REFERENCE 1 1 J I 1 -20- 1 1 I I I J 1 1 J 1 J D i \I I . analysis are J.D.Allen,L. L.Douglas.C.J.Kopec,and G.M.Pawluk. This paper ia preaented with the permiasion of ARCO AlaskA,Inc.and the Prudhoe Bay Unit Co-Owners. Reference: ProcGedings:Cold Regions EI1g1naerirtG Specially Conference,April 4-6.1984 Canadian Society for Civil Engineering Montreal,Quebec. FREEZE-UP FLOOD STAGES ASSOCIATED WITH FLUCTUATING RESERVOIR RELEASES REFERENCES Kinney,T.e.,Santana,B.W.,Hawkins,D.H.,Long,E.L.,Yarmak,Jr. E.1983.Foundation stabilization of central gas injection facilities, Prudhoe Bay,Alaska.Proceedings of the Fourth International Permafrost Conference,National Academy Press,Washington,D.C.,pp.618~622. Long,E.L.1963.The Long thermopile.Proceedings of the First International Permafrost Conference,National Academy of Science,Washing- ton,D.C.,pp.487-491. Sanger,F.J.1969.Foundations of structures in cold regions. U.S.Army Cold Regions Research Engineering Laboratory Monograph III-C4. Hanover,N.H. Yarmak,Jr.E.1983.Some considerations regarding the design of two phllse liquid/vapor convection type passive refrigeration systems. Proceedings of the Fourth International Permafrost Conference.National Academy Press,Washington,D.C. 248 C.R.Neill,Northwest Hydraulic Consultants Ltd., 4823 -99 Street,Edmonton,Alberta,T6E 4Yl D.O.Andres,Alberta Research Council, 4445 Calgary Trail south, Edmonton,Alberta.T6H 5R7 ABSTRACT Recent studies for hydropower development in northern Canada have given much attention to the potential effects of flow regulation on the winter regime of rivers,inclUding levels and thicknesses of ice accumulations during freeze-up and breakup.Generally,increased flows during freeze-up result in higher,thicker ice covers in early winter.Fluctuating flows may detrimentally affect the stability of ice covers,particularly in the period just after freeze-up. Abnormally high ice-pack levelS occurred at Peace River town in early January 1982,associated with a partiCUlar COmbination of weather conditions and fluctuating releases 400 km upstream.The water levels resulting from consolidation of a fresh accumulation type of ice cover almost overtopped flood dikes that had been constructed some ten years ear lier.Ana lysis indicates that the phenomena were associated with an unusual combination of a thin ice cover formed rapidly in late December and a succession of discharge fluctuationll over the Christmas-New Year period.Using field observations of water levels and ice thicknesses,it has been possible to reconstruct an approximate history of the chain of events and to analyze the phenomena in terms of river ice mechanics. INTRODUCTION The Town of Peace River is located on the banks of the Peace River in nor thern Alberta,approximately 400 km below a hydroelectric development completed by British Columbia Hydro and Power Authority in 1972 (Figure 1).RegUlation of the river by Bennett Dam has increased winter flows at Peace River town to approximately 4 times previoull natural flows,and has considerably altered ice conditions in the river.Our ing a late freeze-up per iod at the beginning of January 1982,coincident with notable fluctuations in power demand and plant releases over the holiday period,record high freeze-up levels occurred at the town.The purpose of this paper is to describe the sequence of events and to analyze the ice levels in terms of present understanding of river ice hydraulics. 249 2 J Figure 21 View Upstream Towards Highway and Railway Bridgea,February 1983. .........•...: ....,..~ ,~~t.r ....··~, ~.., • -"1 -.;.' 4'":'............,..... -.:If, -. ~~.,.st f'~~jJ_llR\"'~~_,~_. .~jfti_~I~'·'~~~L ,~.::~~~~~-;'~'~..:.~~:"::.~.,~;;_:.····i.~··;-.~~.>-f:~~~. "t.:.........:!.__.......,~..• -"!'~.".:4.,._".. ......• •';\..,6,':..11 o 30 60 !IIIk., I I I , Figure 1:Location Map BACKGROUND The possibility of flooding due to ioe jamming during breakup has always been present at Peace River town.Since completion of the up- stream works in 1972,however,freeze-up levels and winter ice levels have been noticeably higher than before.Also,higher breakup levels than any previously recorded were experienced in 1973,1974 and 1979. After the 1979 breakup exper ience,dikes buil t to protect the lower parts of the town against aunmer flooda were raised by approximately 1 m to provide for ice-related flooda.Freeze-up levels experienced in January 1982 were several metres higher than any previously experi- enced,and almoat reached the record breakup level of 1979 (Figure 2). Bet",een 1972 and 1982 aeveral studiea were made of ice problems at Peace River (Nuttall,1974,Andres,1975,1978;Acres,1980;Carson and Lavender,1980,Davies et aI,1981).Some of these studies were directed mainly to breakup conditions;othera considered freeze-up and winter levels associated both "'ith present conditions and with a con- templated future power project at Dunvegan,approximately 100 km up- stream (Figure 11.In the study by Acres (1980),a computer simula- tion program was used to predict water and ice levels at Peace River town for various operating scenarios of the Dunvegan proposal.Field investigationa were conducted in the winter of 1979-80 to assist the simulations.Another reported study (Keenhan et aI,1982)WllS concerned with freeze-up conditions at Taylor,approximately 300 km upstream of Peace River town. The question of effec ts of hydroelectr ic projects on river ice conditions haa received much attention elaewhere in Canada in recent years,eapecially in connection with northern developments like the Churchill-Nelson system in Manitoba,the James Bay project in Quebec, and a contemplated development in northern British Columbia which would impact on the Liard-Mackenzie River system all the way to the Beaufort Sea.These projects are referred to in papers by Hopper et al (1978),Michel and Drouin (1981),and Parkinson (1982).Several organizations have developed comPJter programs which aim to simulate 250 251 1 J J J i ).1 1 1 1 4 I I J I 1 )]1 1 5 1 } ice formation,transport,freeze-up,thickening,and breakup on a more or less continuous basis,taking into account both thermal and hydro- mechanical processes.(Most numer ical models odginate in par t from t.he St.Liiwi:CIICe ai~~t'at:ud!.~3 ::€pcrted by Per!s!!t et al (1966),,) These models have been applied to aSsess the impact of future develop- ments by calibrating with natural data and predicting with altered hydrologic and thermal regimes.Considerable uncertainty exists,how- ever,about the formulation of many elements of the ice regime,as discussed by Clement and Petryk (1980),Calkins (1981)and Michel (19831.It is therefore important to analyze experiences such as that described herein. HYDROLOGIC AND MErEOROLOGIC FACTORS The Peace River has been gauged at Peace River town since 1915, with a gap from 1932 to 1957.The mean flow is approltimately 1800 m3/s.Winter flows under natural conditions were mostly in the range of 200 to 500 m3 /s,but onder regulated conditions since 1972 have ranged mostly from 1000 to 2000 m3 /s (Figure 31. The river is located at the bottom of a deep postglaclal valley with narrow fragmentary terraces.At bankfull conditions the channel ",idth is aboot 550 m and the depth about 8 m.The slope is approxi- mately 0.35 In/km.The bed is of gravel,overlying shale at approxi- mately 5 m depth.Banks are of gravel overlain by silt,with rock outcrops where the channel abuts the valley walls. Under natural conditions freeze-up usually occurred in early Novenber,and breakup in late April.Under recent regulated condi- tlons freeze-up is delayed until December,or even early January as in 1981-82.Mean January temperature is approximately -200 C.As in other regulated northern rivers,the ice cover forms by upstream pro- gression of arrested ice floes in a process involving both juxtaposi- tion and shoving.In the Janoary 1982 event,a thin ice cover that had formed through the town only a few days earlier,consolidated abruptly by shoving from upstream and rose to an abnormally high level. S~UENCE OF EVENTS DECEMBER 1981 -JANUARY 1982 ,.. I \Flow Prior to l¥"W.A.C.Bennett Dam I 1\ I \,...... "1/'l Estimated Flow as Regulated bV Dam /1\V ~.J. ~I ...... ",~-ro--'-r--... V , iii....... E III ~ 10.r: lil is c::: m ~ >~ ~ 8000 6000 4000 2000 o J F M A M J J A SON 0 Month An approximate sequence of discharges,water levels and air temperatures for the period December 15,1981 to February 5,1982 is illustrated in Figure 4.An ice Cover began to form on the lower river early in December.but because of relatively mild weather in mid-December did not reach Peace River town until January 2nd,when the water level rose abruptly by 2.8 m at a discharge of approximately 1800 m3/s and a temperature of about -300 e.Within the next few days,the temperature dropped to nearly -40OC and the discharges dropped to below 1000 m3/s as the effect of the New Year holiday on reservoir releases communicated itself down river.A thin cover therefore progressed upstream very rapidly.By January 5th the head of the COver had reached a point 88 km upstream,where water levels rOSe 3.8 m at a discharge of 1200 m3/s.The head of the cover had progressed upstream at a more or less constant rate of 0.30 mis, regardless of fluctuations in discharge during this perioda • Between Peace River and Dunvegan the average rise in stage associated with the ice cover formation was 3.3 m.With an average channel width of 500 m and a measured celerity of 0.30 mis,near ly 500 m3/s of flow was therefore being continuously abstracted into storage,probably reducing the discharge at Peace River to a minimum of about 500 m3/s on January 4th.This caused the stage to drop about 1.1 m (Figure 4)from the peak aSSociated with ice COver forma- tion. On January 7th,after the ice cover had progressed some distance upstream of Dunvegan,rapid increases in discharge resulting from I Figure 31 Monthly River Flows Downstream of Peace River 252 a PerSonal Communication,R.Carson,Acres ConSUlting Services Ltd. 253 6 7 On January 8th,12 hours after the peak at Peace River,the head of the cover was observed to be only 40 km upstream of Peace River, r eadvancing upstream a tar ate of 0.18 m/s b •This rate was rna in- tained at least until January 10th.Between then and January 14th the cover advanced very slowly,probably due to warmer temperatures (Figure 4).On January 14th it resumed progression upstream at a rate of 0.18 mis,and the head passed Dunvegan again in the night of January 15th-16th.with a discharge of about 1700 m3/s and a mean daily temperature of -25OC,the local stage rise at Dunvegan was 4.7 m. MEASUREMENTS OF ICE COVEll AND HYDRAULIC C""RACTERISTICS If a stage rise of say 4.0 m was typical of the second ice front advance between Peace River and Dunvegan,the diversion of flow into stora~e,for a celerity of 0.18 mis,would have been about 360 m Is.The almost constant water level at Peace River from January 10th to 31st suggests that the loss to storage was more or less constant over that period,since outflows from Bennett Dam were maintained at about 1700 m3 /s.The flow at Peace River would then have been about 1340 m3/s.A Water Survey of Canada measurement on February 2nd (Figure 4)more or less confirms this interpretation. 2400 2200 2000 1110O W :0 1800 ~.. 1400 ~.200 1000 800 fiOO "-=W'I.r Ley.l ••'eece River Oallgll Outllow "am Bennlltt D'm_f lagUed 3 DlyA /\.....--......--------------......I \(-....-",- I I --\ I \ /WSC Mee,u,e",en'\ \,1 \l/)I \.Di.che<gell Peece Ri,e'Geuge,•'-V -_.'".~_..-- 319 318 311 ¥318 "315.2I 3.4 w 313 312 311 310 As soon as possible after the consolidation of January 7th,high- water marks,water levels,and ice thicknesses were recorded.I\.high water profile and the existing water level profile were obtained on January 13th,and ice thickness measurements were obtained over the following week.Due to the very cold conditions and the rough ice,a full coverage of ice thickness measurements could not be made.How- ever,these data were later augmented by measuring the thicknesses of shear walls as revealed during breakup in April 1982 (Figure 5).Februerv 30 125 Me.n Oeily Ai,bmper'"Jr' ,---••P\lIece RivlH Aifpon 25 30'5 W ~20 Ilecl\mber 1981 Jenuery 1982 ~~-ll/1 -N ~-30 I--40 1111111 15 20 F{gure 4:Sequence of Water LevelS,Discharges and Temperatures,December 1981 to February 1982 resumption of normal power output at Bennett Dam a day or two earlier were followed by a massive consolidation and thickening of the new ice cover.A 9-m high jam formed 14 km below Dunvegan.but failed after about 2 hours.I\.surge of ice and water then moved downstream (FOnstad,1982),reaching Peace lliver at 10:30 p.m.(Figure 4).The stage rose abruptly by about 3.5 m to an elevation of 318.15 m,some 3.4 m above the previous stable ice cover and only 1.5 m below the top of the flood protection dikes.Within 2 hours of the peak the stage had dropped by 0.60 m,and after about 36 hours it had dropped a further 1.15 m to an elevation of 316.4 m,where it remained more or less constant for the rest of January.Later aerial inspection indi- cated that noticeable consolidation of the ice surface extended to about 10 km downstream of Peace River. The winter measurements indicated a relatively consistent thick- ness below water level of from 3.8 to 4.2 m,although in some loca- tions the value was as low as 2.3 m.The cover appeared to be formed primarily from frazil slush in which were embedded ice floes originat- ing from broken border ice and frozen crusts of frazll pans.The border ice ranged from 0.5 to 1.0 m in thickness and the frozel'crusts were in the order of 0.3 m thick.The maximum ice height along the bank was from 0.9 to 1.5 m above the January 13th water level and more or less corresponded to the maximum water level associated with the ice cover consolidation.The perceived average ice surface on the day of survey was generally from 0.2 to 0.6 m above the water levell where shear lines were evident,ice had pushed up at least 1.6 m above the water level. b Personal Communication,R.Carson,Acres Consulting Services Ltd. ?~....255 J J J .J J J I J 1 1 1 1 1 J 1 I i -I 8 9 UI.. I: !.. ~ III 41 :£ ~ '0 41.. II 8 ii III :! >. '0 :J.. III II I ~ I • I . I• i !i i I I !!IjII1-! III IIIIJW I' \, ,..:;;...,~~'~::~~ir::'4:J Figure 5:Shear Walls Indicating Ice Thickness,April 1982 open-water hydraulic characteristics were evaluated from thirteen channel crosS sections and thalweg profiles surveyed in the summer of 1982.These indicate that upstream of Bewley Island (Fiqure 6)the channel is relatively uniform.Both the bed and water surface have a mean slope of 0.32 m/km (Figure 71.The water surface slope with ice cover also parallels the bed slope,as do highwater marks frolR the flood wave that accompanied ice cover consolidation.When measured ice thicknesses are plotted on the profile,the mean line for the ice/water interface also has the same slope.This suqqests that more or less uni form flow prevailed for all three measured conditions. Averaqe hydraulic characteristics as analyzed for the surveyed open-water and steady ice cover conditions are summarized in Table 1. and typical channel cross sections are illustrated in Fiqure 8. Ice thickness measurements were also made at breakup following the passage of the ice front.when many of the exposed shear walls were still intact (Figure 5).Most of the shear walls were about 4 m thick.The reliability of these measuteme..ts is not as g~eat as for the winter measurements.but they generally substantiate the latter. 256 257 10 I 11 Table 1:Summary of surveyed Average Channel Characteristics ~1on108.• 1340 b 555 2040 (below ice) 3.9 1.95 0.62 4.0 c 0.043 d(Compoaite) Ice Cover (Late January 1992) '" at.I I !.',,•••D ••_ DI*I.nce'ml 1 J...-..:..~.1.~ j w· J'" i: J 0.032 d 1270 a 520 U50 2.9 2.9 0.94 Open Channel (Summer 1982) ...,,~IIIIE...IldDnD.li lOw'CflatdofSupIRtI'li«UJ1l ... Measured at Peace River,less Smoky River inflow. Reservoir releases less abstractions to storage from ice front progression • Mean submerged thickness for reach. computed with a water surface slope of 0.32 m/km. _D •_•_ .~.~ 6ed1on.11.., _lOll ...._W...l......=J ~_._-w..l.......--,.1'.i_ ....IItMnW••L.....~ -WM.l......~l:l.lm _ I!..., ,.~ *•-•--••-_I", c d ... Discharge,Q (rolls) Top width,W (m~ Flow Area,A (m ) Mean Depth,h (m) Hydraulic Radius,R,Ro 1m) Mean Velocity,V (m/s) Submerged Ice Thickness,t s (m) Manning Roughness nb,no Character istic Notes:II ~-b j J ... )'" i .11 J," j .t: M ~ j 1ft C... ID ~........ owo.. tI- .... ~.... B.... J ~ .1 II: ~ .!! III;1 J I IL '15 fI !...q: Iii ~ 'IS I :::l rl .1 l:I 0 ~ 1llP!'8 ZAMII.-/ ....1tDpt·8 W'tN -.."tWIJOIIl ePlIII*'"~"OflO.UO:) --UJfI'J ItIUlII!3I'W 'fl -- I i, If IJl I Iri I I I i 1/ +I j+ 1/+~ +I i I I t) ~l I I J i -- - ~ I -/j I .i :~ :1: ~~ •I <9;.J _1 '0 ..! I !i ..!II I !I IiI ~!, , ,~',I ,~'! , ,~' ,! ,~!' , ,~~ IWI UOll81\813 :l\lep08!) ·fH ••++ I i i l:i I i .§'.!~I I .r !SUII .!!~!~. j I!~"0 }I i I Figure 9:Selected Cross Sections 258 I 259 I f .1 I J ~..I i 1 -1 -.]1 1 1 1 i j I 1 I 12 1] ANALYSIS 2100 ml/s,which agrees reasonably well with the maximum discharge as estimated above from hydraUlic considerations. Ice Cover Stability The terms on the left-hand s ide represent the shear force per unit length on the bottom of the cover plus the downstream component of the weight of the cover.The terms on the right-hand side repre- sent the resistance of the cover due to internal fr iction plus the resistance due to cohesion. (11 WRifgs +WtrigS .rpi (l-Si)9t2 +2Cit where W is the s,tream width,Ri is the hydraUlic radius associated with the ice cove[J e,the density of water,g is the acceleration of gravity,S is the channel slope,t is,the ice thickneSl'I1 Pi il'l the density of ice,1"-is a dimensionless coefficient of internal friction*,si is the specific gravity of ice,and Ci il'l a cohesion parameter as discussed below. Thickening of a river ice cover can occur in two ways:(i)by hydrodynamic instability at the advancing edge of the cover,whereby arriving ice floes,are carried underneath the edge,and (ll)by mechanical instability within the cover,Whereby hydraulic forces cause it to consolidate and thicken.From the nature of the events observed on January 7th,it is apparent that the second case applies. Various equatioos have been presented for analysis of this type of condition.That by Uzuner and Kennedy (1974)can be written in modified form as: r ..12.5 SW(l +Ri/0.92t)/t ~..Co(l-p)where Co is Uzuner and kennedy's -shear strel'ls coefficient-and p is porosity. 12) With regard to the COhesion parameter Ci in Equat ion Il),it is important to note that the equation was developed for an uncongealed aCcumulation of ice floes where Ci represents a -soil mechanics- type of cohesive strength as in the Coulomb-Mohr relationships,and not a shear strength of solid ice.The rationale for using Equation 11)to analyze the Peace River consolidation is that the thin surface freeZing,estimated from observations to have been about 0.3 m thick, is'assumed to have been effectively destroyed by fleXing of the cover under the action of surges and unsteady flow.If,as suggested by Beltaos (1978),Ci is taken as approximately 100 Pa,the cohesion term is then much less than the friction term and can be neglected. With f..1000 kg/m3 ,Pi ..920 kg/ml ,9 ..9.8 mjs 2,and si .. 0.92,Equation ,(1)can be reduced tOI • Discharge Variations The discharge at the peak stage cannot be determined reliably from the gauge height records because the thickness and the roughness of the ice cover are unkown.However,if it is assumed that thickness and roughness remained constant between the peak of January 7th and the thickness measurements of late January,then the peak discharge can be estimated from the measured highwater marks as recorded and the overall roughness under ice cover as shown in Table 1.Using the same composite roughness of 0.043 and a measured mean depth of 4.9 m,the peak discharge of January 7th was estimated to be 2000 m3/s on the basis of steady uniform flow.This is somewhat larger than the routed release from Bennett Dam,estimated at approximately 1600 m3 /s (Figure 4). The extremely rapid stage rise suggests that both the discharge and ice thickness were increasing during this per iad.However,wi th- out knowing how either variable changed,the exact time of maximum ice thickness or peak discharge cannot be determined.It seems reasonable to assume that the maximum thickness was achieved a t the peak gauge height and that this also defines the time of maximum discharge. Following,the peak stage the ice thickness remained constant,and the reduction in stage was due to a reduction in discharge. Following the failure of the jam downstream of Dunvegan on January 7th,approximately 100 km of river ice was consolidated into a length of about 50 km.Factors contr ibuting to the subsequent high stage rise at Peace River include the initial surge of water from the failure of the jam,the increased dischar.;le due to release from channel storage,and the increased ice thicknesses within the con- solidated length.It is believed that the major flow increase during the consolidation was due to release from channel storage as the length of ice-covered river was shortened.The augmented discharge also transported the broken ice and was responsible for the increased thickness of the accumulation. A crude approximation of the peak discharge can also be made by considering the conservation of volume during the consolidation.It can be estimated that approximately 1 m depth of stored water was released from the 60 km of river upstream of the consolidation, producing an inflow of 33 x 10 6 mJ into the 40 km immediately upstream of Peace niver.Within this 40 km,the additional roughness of the thickened ice cover increased the depth of flow by about 0.3 m, which reduced the additional volume passing Peace River to about 27 x 10 6 m3 •Gauge records suggest it is reasonable to assume that the flood wave lasted from 8 to 12 hours,corresponding to an increase in discharge of from 600 to 900 m3 /s.This,when added to a 1200 m3 /s base flow,results in a peak discharge estimate of 1800 to 260 261 14 To apply Equation [21,tbe bydraulic radius Ri associated witb the ice cover is computed from, (3)Ri/Ab =(ni/n b)3/2 wbere ice tougbness ni ..(2no 3/2 -nb 3/2)2/3 tbe Ice Alberta Dam on River. Andres,D.O.,1978.Effects of tbe Dunvegan Regime of tbe Peace River at tbe TOwn of Peace Environment,Edmonton. Beltaos,S.,1978.Field Investigations of River Ice Jams.Pro- ceedings IAHR Symposium on Ice problems,Part II,Lulea,Sweden, pp.357-371. Andres,D.n.,1975.Ice Breakup Observations and Mitigation at tbe TOwn of Peace River,April 1975.Alberta Environment,Edmonton. Acres Consulting Services Ltd.,1980.Dunvegan Power Project, Peace River ice study.Report to Energy Resources COnservation Board, Calgary. 15 REFERENCES Ri +Rb ..2Roand Applied to tbe Peace River consolidation witb nb ..0.032,no ..0.043,and tberefore ni ..0.053,Ri is found to be 3.3 m.Equa- tion (2)then gives an internal fr iction coefficient jA"0 .93 for a total ice thickness of 4.3 m.This is witbin the normal range of values of )A computed for breakup jams (Beltaos,1978),wbicb suggests tbat massive consolidations occur so rapidly tbat tbe e Hects of downward freezing can be neglected in estimating levels and tbicknesses. Fonstad,G.D.and Quazi,M.E.,1982.Peace River 1981/1982 Ice Observation Report.Alberta Environment,Edmonton,Alberta. Michel,B.and Drouin,M.,1981.Courbes de Remous sous les Couverts de Glace de La Grande Riviere.Canadian Journal of Civil Engineering,Vol.8,No.3,pp.351-363. carson,R.K.and Lavender,S.T.,1980.A Discharge/water LeVel Relationsbip for Ice Cover Stability.proc.Worksbop on Hydraulic Resistance of River Ice,Burlington,Environment Canada,pp.112-115. Northern Britisb Calkins,D.J.,1981,Ice/Hydraulic Processes in Riversl An Assessment of Current Technology.Report to ColUmbia Hydro and Power Authority. Clement,F.and Petryk,S.,1980.Limitations to Numerical Modelling of Ice 1n Rivers.proc.Workshop on Hydraulic Resistance of River Ice,Burlington,'Environment Canada,pp.243-262. Davies,L.B.,Deeprose,R.K.and Hunt,H.M.,1981.Observations and Report on River Ice Conditions in tbe Peace River Basin 1978-79. Joint Task Force of 'B.C.Hydro,Alberta Environment,and B.C.Environ- ment. Hopper,H.R.,Simonsen,C.P.S.and Poulier,W.J.S.,1978. Cburcbill River Diversion,Burntwood River Waterway:Studies to Evaluate Winter Regime.Canadian Journal of Civil Engineering, Vol.5,No.4,pp.586-594. Keenban,T.,Panu,U.S.and Kartba,V,C.,1982.Analysis of Freeze-up tce Jams on tbe Peace River near Taylor,B.C.Canadian Journal of Civil Engineering,Vol.9,No.2,pp.176-188. (1)The unusually high ice accumulation stage at Peace River on January 7-8,1982 resulted wben a rapid increase in discbarge broke up and consolidated a thin new ice cover,tbat bad formed quickly very late in the seaSon under very low temperatures. CONCLUSIONS (2)The ice cover consolidation led to accumulation tbicknesses of some 4 m over a considerable lengtb of river,and was accompanied by a flood wave as water was released from storage in tbe back- water zone at tbe bead of tbe previously advancing cover. (3)Analysis of steady conditions as observed a week or two after tbe abrupt consolidation indicated an overall hydraulic rougbness of 0.043.The rougbness of tbe underside of tbe ice cover was estimated as approximately 0.053.Applied to tbe peak stage conditions of January 7tb,tbis yielded an estimate for tbe peak discharge at Peace River of 2000 m3/s,approximately 50 percent greater tban immediately preceding discbarges. (4)Analysis of tbe bydranechanical stability of tbe consolidated cover,neglecting cobesion,indicates an internal friction coef- ficient ]A of approximately 0.9,similar to values reported for ice jams under breakUp conditions. (5)It is believed that tbe information presented herein constitutes an interesting documentation of a severe freeze-up accumulation associated witb strong discbarge fluctuations,providing reason- able definition of bydromecbanic parameters witbout tbe need for manipulation of botb tbickness and rougbness. 2 p '1l 263 J I 1 _!J J J I 1 I I 1 1 I 1 j J ]]i !'I r·~----- p~rkin50n;F.E ••1982.water Temperature Observations During Breakup on the Liard-Mackenz ie River System.proc.workshop on Hydaulics of Ice-Covered Rivers.Edmonton,National Research council of Canada.pp.261-290. TWO-DIMENSIONAL SIMULATION OF FREEZING AND THAWING IN SOILS H.P.Thomas.Senior Project Engineer, Woodwsrd-Clyde Consultants Anchorage.Alaska R.G.Tart,Jr ••Geotechnical Manager Woodward-Clyde Consultsnts Anchorage,Alaska l'Reierence:--""'Iproceedings'Cold RegIon.Engineering Speclelly Conference,April 4-6,1984 ~!'_~~~~!~So~!,~y lor ClYil Enginee"nglMVlln'l::'IJi.QuuuI;Je.J Field Data with Theories on Ice submitted for publication to 16 Michel.B.,1983.Comparison of Cover progression in Large Rivers. Canadian Journal of Civil Engineering. Nuttall.J.B.,19}4.Ice Breakup at Peace River.1914.Report to Alberta Environment.Edmonton. pariset.E.,Hausser.R.and Gagnon.A••1966.Formation of Ice Covers and Ice Jams in Rivers.Journal of Hydraulics Division ASCE, November,pp.1-24. ABSTRACT ACKNOWLEDGEMENTS The fi rst author'II connection with the Peace River incident was through a brie f investigative study commiss ioned by River Engineer ing Branch of Alberta Environment in February 1982.and conducted in cooperation with Messrs.M.E.Quazi and G.D.Fbnstad of that branch. The second author's involvement was through the Alberta cooperative Program in Transportation and Surface wster Engineer ing. operated by Alberta Research council in cooperation with provincial departments of Environment and Transportation and the University of Alberta.Field data were obtained by staff of the Civil Engineering oepartment.Alberta Research Council. Uzuner.M.S.and Kennedy,J.F ••1916. Ice Jams.Journal of Hydraulics Division 1383. Theoretical Model of River ASCE.September,pp.1365- Phase change produces some of the most drsmatic volume and strength change effects on soils in cold regions.Numerical solution techniques! provide powerful tools for analysis of resl-world hest flow problema.Inlourengineeringpractice,we have found a two-dimensional finite-element' computer program called "DOT"(Determination of Temperature)to be particularly usefuL Capabilities of the program include an ability tOI handle transient as well as steady-state problems.arbitrary geometries, inhomogeneous materials and non-uniform initial temperature distributions. Example applications of the DOT progrsm described in the psper include calculation of thawing around a warm pipeline in permafrost.thawing around warm oil wells in permafrost (including the influence of a convection surface).and frost penetration as a result of placement of gravel fill in shallow seawater on the arctic coast.Limited data are presented comparing predicted and measured thaw for one of the examples. INTRODUCTION AND BACKGROUND Phase change produces some of the most dramatic volume and strength change effects on soils in cold regions (see Andersland and Anderson 1978; Johnston 1981).Thawing of initially-frozen soils results from an increase in the soil temperature.This increase can result from (1)a ourface disturbance such as stripping or compression of the tundra insulating layer,placement of a gravel pad,or concentration of surface runoff (thermal erosion),or (2)introduction of a heat source such as a warm pipeline.This thawing is accompanied by soil consolidation (expulsion of excess pore water)and a decrease in soil shear strength. The amount of soil thaw strain increases with soil ice content and soil shear strength is least before excess pore pressures have had an opportunity to dissipate. Foundation settlement over the depth of thaw. reduced during permafrost potential failure surfaces is calculated by integrating the thaw strain Foundation bearing capacity may be greatly thaw as is available resistance to sliding on in sloping ground. 264 265 - - - -! - REFERENCE 2 /"l I • ,~ I , ~- 0 1 C' ~,...,~ 1 4-! ~ i I ",,...-,. )1 J fil J ~!L•1,,!t:- i 1i ~,~~... t' ~~•{ t..,,1., I I i I ~ r .~ 'f' i r Ai• r i ..rm'fiI'$ f I r• .- • ,-"""• ".. ;. ;",.•ttl.'- e • Z ~ .I 0 U • • ... FORT McMURRAY ICE STUDY LOCATION PLAN o ., T£ltltlTO •COIIONATION H T '"H '" • • I'l z FIGURE ________._w,.~-----_ - Ir- l __\..:":c ~. i .... F"'-'>. --I ~,., ,- - .... ~._-,.-...../ PC-Ace-I</J/~/L .:I AI'-"- "... - "..."~ ."~ .c:-; -' Rltlc/!-76 4U U A;?~84 IF='i !--. , I ~ 1 \ ·;-- '- .,......~,.--~-_...-...- RIve-A- f/6i'rcr RI tJ e:-I€. .:I AI'''8"1 -REFERENCE 3 i~ , .....I .; i J I , i I .'.~i i. t ..... { northwest hydraulic consultants ltd. EVALUATION OF 1982 RIVER ICE CONDITIONS AT PEACE RIVER Prepared for: River Engineering Branch Technical Services Division Alberta Environment Prepared by: Northwest Hydraulic Consultants Ltd. May 1982 l,~ \~ \ ! I..A. L L .~ nort hwest hydraulic consultants ltd. ABSTRACT The report is based on an evaluation of river freeze-up conditions at Peace River in January 1982,when record high levels were experienced,and on an assessment of potential high stages during 1982 spring break-up, conducted before the fact. It is concluded that high freeze-up stages were caused by a combination of late freeze-up due to a warm December and severe fluctuations in releases from Bennett Dam over the Christmas-New Year period.It is considered that there is,a potential for high break-up stages comparable with ,those of other recent high years,but that oVlertopping of the town dikes is unlikely. (i) northwest hydraulic consultants ltd. CREDITS AND ACKNOWLEDGMENTS The report was prepared by C.R.Neill,P.Eng. with assistance in analysis from W.Rozeboom,P.Eng. Acknowledgments are expressed to Messrs. G.D.Fonstad and M.E.Quazi of Alberta Environment, Mr ..D.D.Andres of Alberta Research Council,Dr.R.Gerard of the University of Alberta,and Mr.S.T.Lavender and Mr.Rob Carson of Acres Consulting Services for their cooperation in providing documents,comments and advice. .. -,L L i .[~. \ " ,~" .- ,... - northwest hydraulic consultants ltd. 1.INTRODUCTION 1,.1 Objectives In February 1982 River Engineering Branch of Alberta Environment requested Northwest Hydraulic Consultants to investigate and report on river ice conditions at Peace River,investigations to be done in cooperation with River Engineering and Alberta Research engineers.Specifically, investigations were to be directed to causes of high freeze-up stages,potential break-Up problems,and feasible remedial measures to mitigate the latter. A brief progress report covering results of freeze- up investigations was submitted on 10 March,and a letter report cover ing break-up projections and recommendations followed on 22 March.The present report documents more fUlly and extends the material in these preliminary reports.It was submitted in draft form in April and finalized with minor revisions in May 1982. 1.2 Statement of Problems The possibility of flooding due to ice-jamming at break-up has always been present at Peace River town. Since completion of Bennett Dam and Schrumm hydro- elE~ctric plant by B.C.Hydro in 1972,winter discharges in the Peace River have been greatly increased,resulting in delayed freeze-up,higher winter ice levels and greater quantities of ice,and apparently increased frequency of high levels at break-up.Higher break-up levels than any previously recorded occurred in 1973,1974 and 1979. I I I I I I I I I I I I I 1 I , I northwest hydraulic consultants ltd. Following a high summer flood in 1972,dikes were built to protect the lower parts of the town against open- water flood events.After the 1979 break-up,the dikes were raised by approximately 0.9 m. In early January 1982,unprecedented high freeze-up levels occurred 'when an initial ice cover only a few days old consolidated abruptly through the town.The dikes were not overtopped,but subsurface seepage caused basement flooding.Releases from Bennett Dam were sUbsequently cut back by agreement in order to reduce seepage problems f and ice levels fell accordingly. Con -n arose over possible overtopping of the dikes dur6.spring break-up in April 1982. 1.3 Previous Studies Reviewed River ice problems at Peace River have been the subject of several studies and reports since completion of Bennett Dam.In order to understand and analyze the causes of the 1982 conditions,previous documents provided by River Engineering Branch and others were reviewed. Brief notes on these are given below in chronological order:detailed references are given in Section 5. Nuttall,1974.In March 1974 Dr.J.B.Nuttall of the University of Alberta analyzed break-up flood potential and recommended local mitigative measures. The report,prepared in July 1974,covers pre- break-up investigations and actual occurrences, discusses the effectiveness of mi tigative measures, and recommends future measures. - 1·.1- [.J.. l~ I !~, Il •- - - .. northwest hydraulic consultants ltd. 3 Andres,1975.Relatively high freeze-up levels were experienced in January 1975,and local mitigative measures were again taken,but break-up proved uneventful.The report analyzes conditions in considerable detail and attempts to develop predictive relationships for maximum brea~-up stage. Doyle,1978.The Peace River ice-jam observations reported were too far downstream of Peace River town to be relevant in the present context. Andres,1978.The effects of a proposed hydro- electric peaking plant at Dunvegan were analyzed with respect to ice conditions downstream.The report predicts likely positions of the ice front,freeze-up levels as a function of discharge,and fluctuations in ice cover level.It is concluded that there would be no adverse effects at break-up at Peace River,and that the proposed project might be operated so as to reduce present break-up levels. Acres,1980.This study also analyzed effects of the projected Dunvegan development in detail,and reported the results of field investigations in the winter of 1979 -1980.A computer simulation program was used to predict water and ice levels at Peace River for various operating scenarios. Carson and Lavender,1980.A short paper based on part of the above-mentioned Acres study presents a consolidated stage-discharge plot for Peace River under open water and ice conditions,including both freeze-up and break-up data • ...._------------------------------- I northwest hydraulic consultants ltd. I 4 1.4 Consultations With Others In addition to these previously released documents, we reviewed a preliminary draft report by G.D.Fonstad of River Engineering Branch covering the freeze-up events of January 1982. Davies,Deeprose and Hunt,1981.A Joint Alberta-B.C.Task Force was formed to observe, analyze and make recommendations on ice-related hazards at Peace River and their control by flow adjustments at Bennett Dam.The 1981 report, covering the 1978 -79 season,summarizes observa- tions,analyzes the high 1979 break-up levels,and discusses possibilities for ice-jam prediction. ".-';'.',J.. River are quoted here in metres above heights above Water Survey of Canada 304.8 m.Discharges are quoted in Levels at Peace Geodetic Datum.For gauge zero,deduct m3 /s. 1.5 Units and Datums Discussions were held with Mr.G.D.Fonstad of River Engineer ing Branch,Mr.D.D.Andres of Alberta Research Council (formerly of River Engineering Branch),Dr.R. Gerard of the University of Alberta,and Mr.S.T.Lavender of Acres ConSUlting Services,to clarify previous interpretations,compare evaluations and discuss recommendations.These discussions were of great value in developing the conclusions and recommendations of this report. , I I I ~ 1.'.1I 11 I I I :1 'I 11 I 'I I I " 1 J I It: f· 'j r- -,J.., northwest hydraulic consultants ltd. 13 2.4 Inferred Causes-of -High Freeze-Up-Levels warm December combined -with releases from Bennett Dam had freeze-over at Peace River until In considering the hydraulic causes of freeze-up water levels of 7 B January following points appear most significant: -'1- ..L, i.- ·L ...).- l i 1 .A relatively relatively high delayed complete 1 January ,or so. the 1982, high the -.~ ....- - .••- .' .. .- 2.Very cold weather in the first few days of January enabled an initial thin accumulation cover of frazil pans to advance rapidly upstream to the vicini ty of Dunvegan.In the middle of this process,discharges arr iving from upstream were suddenly cut in half,then raised again over a 3-day period. The most obvious hypothesis is that the rapid increase in discharge between 4 and 7 January caused break-up and consolidation of a cover which had formed only a few days earlier and was therefore quite weak.The resulting telescop,ing of the cover over a long length of river released a large quantity of water from storage as levels dropped from an ice-cover rating to an open-water rating.This storage release produced a transient flow and stage peak on the night of 7 - 8 January. In December 1979,as reported by Acres (1980), complete freeze-over occurred at Peace Ri,ver on 24 December,and by 28 December the freeze-over northwest hydraulic consultants ltd. 14 front had advanced 44 km upstream.Between 30 December and 3 January.following a rapid increase in Bennett Dam releases from about 400 to 1200 m3 /s a day or two earlier,the ice front retreated downstream by 12 km:the cover consolidated over a length of 26 km and thickened from about 1.0 to 2.4 m where measured at a point 18 km above Peace River.This 1979 experience appears to have been quite similar to that of 1982,the main difference being that in 1979 the consolidation did not extend over such a long length and did not noticeably affect Peace River town.By the time the 1979 discharge increases arrived,the cover in the vicinity of Peace River had been in place for a longer period than in 1982 and was presumably thick and strong enough to resist consolidation. northwest hydraulic consultants ltd. 3.PROJECTION OF BREAK-UP CONDITIONS 1982 15 iJI~ I...l 3.1 Past High Break-Up'Events Based on data tabulated in the Joint Task Force report,the three highest break-up floods of record were as shown in Table 2.Reported maximum levels were 318.6, (1979),318.2 (1973)and 317.5 m (1974).The top of the dike near the Water Survey of Canada gauging station is at elevation 319.8 m approximately,that is,1.2 m above the 1979 1evel.a On a purely statistical basis,the pn)babi1i ty of attaining top-of-dike levels appears to be Examination of previous studies referred to in Section 1.3 shows that high break-up water levels associ- a1ted with ice jamming downstream of Peace River can result fJ:om various combinations of -circumstances involving flow and ice conditions in both the Peace and Smoky Rivers upstream.According to the Joint Task Force (Davies et al,1981):"If,for example,it appears that the combined discharge of the Smoky and Peace Rivers below their cc.nf1uence will exceed 90,000 cfs (2500 m3 Is)or if the Smoky River itself may contribute 40,000 cfs (1133 m3 /s) OI'more,a flood situation is assumed likely • • •It should be noted that a jam downstream • • •does not have tOI occur to cause flooding.In 1979,a jam formed at the mouth of the Smoky and when it broke,a l5-foot high flood wave resulted in water levels of approximately 1045 feet (318.5 m)at the Town of Peace River.- The 1979 level was oply about 0.3 m below the ·top of the dikes as they existed at that time,before they were raised. a ',..,. - ,~ ~- ka.i ~ ~ ~ ~ ~ lui ~-.. r- ill F"" '.~ I I I I I I I 'I I I I I I 11 j~ )1 I I I northwest hydraulic consultants ltd. 16 quite low,in the order of 1%..In those three highest years,maximum rises above 5-day pre-break-up levels ranged from 4.1 to 4.5 m.(On 27 April 1982,with Peace River ice broken through the town but Smoky River not yet broken up,water level was reported as 314.2 m.) L t- ,- 1:-\ t I\. .I.. northwest hydraulic consultants ltd. 17 TABLE 2.DATA FOR THREE HIGHEST BREAK-UP FLOODS AT PEACE RIVER Rank Date 5-day Maximum Maximum Approx. Pre-Breakup Elevation Stage Breakup Elevation a Rise Above Discharge Pre-Breakup at Peace River m m m m3 /s -- - 1 2 3 30/Apri1/79 12/Apri1/73 20/Apri1/74 314.1 313.8 313.4 318.6 318.2 317.5 4.5 4.4 4.1 4,100 2,800 3,600 Extracted from Table 1 of Joint Task Force Report (Davies et aI, 1981),and converted to metric units. a Note On 27 April 1982,with Peace River ice front downstream of the town but Smoky River not yet broken up,water elevation at the gauge was reported as 314.2 m.Th is is 1.7 lower than the elevation of the day before the break-up front passed through, reflecting the change from ice cover to open water hydraulics. northwest hydraulic consultants ltd. 18 3.2 Feasible Mitigative-Measures Mitigative measures which have been used in past years are of two types:(i)local measures to weaken the ice through the town by plowing lanes,salting,dusting and blasting:and (ii)upstream measures to reduce Peace i River discharges.Objective evidence that local measures have been successful is difficult to obtain,nevertheless these measures are not difficult to conduct and provide local reassurance that efforts are being made to reduce danger. With regard to discharges,Figure 5 shows a break-up stage-discharge diagram based on Nuttall (1974), with added data after 1974 from the Joint Task Force report.On the basis of the scatter band shown in this diagaram,a discharge of at least 3300 m3 /s is required to produce an elevation of 319.5 m.To give some margin of error,it would be desirable to be able to keep discharge to 3000 m3 /s or less:at least 1 m or so of freeboard should then be available.Use of Acres'diagram (Figure 2)leads to similar conclusions. In considering feasible restriction of Peace River discharge,the uncontrolled discharge of the Smoky River is all-important.In the three years of highest break-Up levels (1979,1973 and 1974),Smoky River discharges at Watino were about 1600,600 and 2400 m3 /s respectively.For a Smoky River discharge of say 2000 m3 /s,upstream Peace River discharge would therefore have to be restricted to about 1000 m3 /s (35,000 cfs). If B.C.Hydro release was 1000 m3 /s,local inflow 500 m3 /s,and Smoky River flow 2000 m3 /s,tQe total of 3500 m3 /s at Peace River might just reach the top of the dikes. - l~ il,- l I L i ' l- I r- northwest hydraulic consultants ltd. 19 It appears advantageous to induce Peace River break-up before Smoky River break-up.This implies that upstream Peace River flows should be kept as high as possible up to say one week before expected Smoky River break-up. 3.3 Break-up Recommendations The following summary of recommendations was contained in our letter of March 22 addressed to Mr. M.E.Quazi of River Engineering Branch. .~.. 1. 2. 3. 4. 5. Allow B.C.Hydro to :..ume normal operation as soon as practicable,to encourge break-Up progression down the Peace River.Peaking operation is probably advantageous. Develop a means of forecasting break-Up date and if possible discharge for the Smoky River. One week before expected Smoky break-Up,have hydro releases cut as low as possible. Keep monitoring break-up front,water temperature, stages and discharges. Continue local ice weakening measures to provide ice passage and discourage jamming • - - - ,~ REFERENCE 4 lr~ iF- ......! • " lCE SI.UDY PEACE RIVER 1981/32 ICE OBSERVATION REPORT .--~-'"'.'.. RIVER ENGINEERING·BRANCH Water Resou!ces'~anage·n.1ent.serVIces ~.."....:~.Technical services Division .. p. .-.",::-; :.!"~:- ":.<.-:::;-••....f ~... ./~~:".-:,~..-;..~- ". ~-. .-.:..,....'...:...._----"--~------- .:':',I' .. ~/,...' • :'Z.• ~.._:""".".--.-. -.'- -.'._. .i .:~.. i - .a ..- .. r ".. ~. .-' lp- t.... r"'"' [~ I,i ~ (po, j~ I ) " ALBERTA ENVIRONMENT WATER -RESOURCES t-1ANAGEf~ENT SERVI CES TECHNICAL SERVICES DIVISION Prepared by:G.O.Fonstad,P.Eno. Head,River Studies Section River Engineering Branch .... Submitted by:M.E.Quazi,P.Eng. Branch Head River Engineering Branch Portions of the "Alberta -B.C.Joint Task Force on Peace River Ice -Report" prepared by Alberta Environment PEACE RIVER 1981/82 ICE OBSERVATION REPORT j - November 1982 {- ~: 1 L, r- t 1 r- 't J F1, ~ i ~ jF ( .It SUt1t-1ARY This report contains the first draft of the sections of the 'Alberta -B.C.Joint Task Force on Peace River Ice l Report which were the responsibility of Alberta Environment.Other sections,written by the B.C.Ministry of the Environment and by B.C.Hydro and Power Authority,complete the report to the respective Ministers of the Environment for the two Provinces. The report summarizes the even:ts which occurred at freeze-up at Peace River Town in January of 1982.A presentation is made of the basement flooding problem which occurred in the West Peace River subdivision.An outline of the breakup preparation undertaken, .., ,.- ," including ice weakening efforts,is made.The observations of River Engi neeri ng Branch fiel d staff of the breakup of the Heart,Smoky and Peace River are presented • .Finally,a proposal for a controlled mode of operation of B.C. Hydro1s G.~1.ShrUM generating station at the HAC Bennett Dam during freeze-up at Peace River Town is included . i -[F~' , t--, {'r- ~ lpM 1 ~- I " J- ( ~ 1- ~ - SUtmARY This report contains the first draft of the sections of the 'Alberta -B.C.Joint Task Force on Peace River lee'Report which were the responsibility of Alberta Environment.Other sections,written by the B.C.Ministry of the Environment and by B.C.Hydro and Power Authority,complete the report to the respective Ministers of the Environment for the two Provinces. The report summarizes the events which occurred at freeze-up at Peace River Town in January of 1982.A presentation is made of the basement flooding problem \'/hich occurred in the \-Jest Peace River subdivision.An outl ine of the breakup preparati on undertaken, .f t- ~ """ including ice weakening efforts,is made.The observations of River Engineering Branch field staff of the breakup of the Heart,Smoky and Peace River are presented . .Finally,a proposal for a controlled mode of operation of B.C. Hydro's G.~1.ShruM generating station at the HAC Bennett Dam during freeze-up at Peace River Town is included. i L~~~ !F= ~ .J~ J. ,F"'" "i I ~. :!""'" ~r , ~- 2.0 PEACE RIVER FREEZE-UP 2 .1 General The Peace River at Peace'River TO\r1n froze up,in the 1981/82 season,in an unusual manner for the river.The initial ice cover H formed normally in early January,)(6wever,five days after the initial cover formation the river experienced a second staging due to consolidation of the ice pack.This second staging was in the order of 3.5 m,and brought the ice level to within 1.66 m of the top of the dikes in Peace River Town*.A complete record of hourly water levels at Peace River,and flow releases,uncorrected for travel time,from B.C. Hydro and Power Authority's (BCHPA)G.H.Shrum (Gr1S)generating station, for the period 24 December 1981 to 30 April 1982,is shown in Figure(s) 1. 2.2 Sequence of Events The sequence of events \"lhi ch occurred at Peace Ri ver TO\rJn duri ng the 1981/82 freeze-up period has been previously summarized bjl Northwest Hydraulic Consultants Ltd (NHCL)(1)**,based on prelil7linary data and verbal reports collected by Alberta Environment,Acres Consulting Engineering Ltd.and others.Copies of this report were distributed to BCHPA,the B.C.r·1inistry of Environment and Alberta •Note:*All reference to dike level~is made with respect to the dike across the river from the Water Survey of Canada gauging station. **!;ur.lbcrs in parentheses refer to numbered references cited following the text of this reper:. Environment.The following is a slight change to that reported sequence of events,based on an increased data base. In its analysis NHCl presented the freeze-up events in terms of BCHPA's releases from GMS,lagged three days to allow for flow through time to Peace River Town.Figure 2 shows open water flow travel times from Hudson Hope to Taylor,and fron Taylor to Peace Ri ver,based on data provided by the Alberta River Forecast Centre.Figure 3 sho\'/s these times consolidated for flow from Hudson Hope to Peace River. BCHPA's mean daily releases during the period 24 DeceMber 1981 to 7 January 1982 varied from a minimum of 800 m3 S-l to a maximum of 1777 m3 s-1 ,and had an average of 1347 m3 s-1 •Flow through times froM Figure 3 would thus be 86,46 and 41.5 hours.for the minimum,average and Maximum releases respectively.For this reason the mean daily Gr·tS releases have been plotted on Figure 4,for the period 25 December to 8 January,lagged 48 hours (instead of the 72 hours used by NHCl).Shown also are the Peace River gauge heights,based on hourly data,and Uater Survey of Canada's nlSC)preliminary mean daily flows for the gauge 07HAOOl,Peace Rivel~at Peace River.Figure 4 should be consulted while reading the following sequence of events: a.25 to 28 December 1981 The river stage at Peace River generally decreased due to decreased releases from the Gf1S plant in response to lesser power demand over the Christmas holiday.It was originally reported that the upstream progressing ice accumulation had passed through the Town of Peace River on 28 December.The absence of a significant rise in water level on this date indicates that the river was still operating in an open \'iater mode.The slight rise at approximately 0300 hours of 28 December could be due to a brief stationary period in the general ice flow,brought on by the reduction in surface area ") I. -r~ J~ L ,tr- 1F- ~- 'I'~~;1 ~c ,,\~ I; ~\ .il!:;;i 1:>- E .... 3 corresponding to the decrease in flow at Peace River fro~1500 to 913 m3 s-between 26 and 28 December.The prel iminery \;SC records for December of 1981 show lice conditi ons'for the peri od 16 to 20 December,and 27 and 28 December,but show normal,or open water,conditions for the remaining tine.The disappearance of ice conditions reflected in the USC records can be explained in terns of a wann period between 19 and 22 December,as sho\'1n in the level ing-off of accumulated degree-days of freezing shown in Figure 5. b.28 December 1981 to 1 January 1982 ----------------------------~----- The water level at Peace River rose gredually by O.B m until approximately 1700 hours on 1 January,in response to increased pm"er gencl~ation releases foll ('I\'/ing the Chri stmas break.Ai r temperatures,which had been at a mean daily value of _3 DC on 21 December,dropped to a mean of -37 DC on 1 January,with nightly lows in the order of -40 to -41 DC.Thi s caused 2.dramati c increase in the accumulation of degree-days of freezing,and initiated rapid ice production in the open river. Water levels rose 2.63 m at Peace River while the discharge in the river was in the order of 2060 to 2170 mSs-1 •Most of this increase corresponds to the normal experience of 'staging'at freeze-up,as the open water rating curve indicates a change of 0.06 m between the two discharges.This staging all7lost certainly indicates the formation of an ice cover on the river, with the corresponding increase in hydraulic resistance. Water levels at Peace River dropped 1.22 m from the staging peak on 2 January.Power releas~s at G~lS had dropped from 1777"mss-1 on 30 December to 1724 m3 s-on 31 December,and further to 798 mSs -1 on 1 Janua ry as the load demand decreased for the New Year's -holiday.LLS.C.records show the discharge at Peace River dropped from 2170 m3 s-1 on 2 January to 1010 m3 s-1 on 4 January,whi ch woul d have caused a stage reduction of 0.81 rn under open water conditions.The remaining 0.41 m of stage decrease can probably be attri buted to sr.1Dotheni n9 out of the roughness of the under si de of the ice cover as the roughness projections were me1ted off by the slightly warmer fluid flow beneath the ice. Increasing GMS releases,from 798 m'3s-1 on 1 January to 1695 mss-1 on 5 January,reflecting increased load demand following New Year's Day,caused an increase in water level at Peace River .~ ~, -.1:..!.! ~! -I J I0:'5 1 I ~ 1 ~: .. 1: Because of the potenti?l for serious flooding of the Town cf Peace River if the new ice accumulation re-ruptured and reconsolidated,BCHPA was requested to regulate their releeses from Gr~to a constant value,in order to let the ice accumulation gain strength by freezing.Accordingl)',as can be seen on Sheet 2 of Figure 1,BCHPA regulated their releases to ~n average of 1691 m3s~1 over the period of 9 to 20 January.In this same period the recorded discharges at Peace River had a mean of 1941 m3s-1 ,while the Smoky River had a QeBn discharge of 22 m3s-1,yielding a local inflo\'J between Gf.1S and Peace River of 228 m3 s-1 • The water level at Peace River dropped a further 0.41 m on 9 January before it levelled off,with minor fluctuations,until the middle of February,when a decrease in releases caused the water level to drop a further 1.33 rn (see discussion of ~Jest Peace River groundwater levels). 5 --------'1"""""------------...,.--------------------- I I I I U U U o I n q I I 1 m 'I •r I - I I!. 6 3.0 COt1t1 ITTEE ACTI VIT I ES 3.1 Uest Peace River Groundwater Flooding Uhen the water levels in the Peace River rose on the night of 7/8 January,the groundwater table in the river!s floodplain responded by rising as well.Unfortunately,no data was taken during January. Groundwater levels in West Peace River were recorded at a private well by Mr.Barry Ellis,a Town employee,from 5 February,and were subsequently tied into Geodetic Bench by the Town of Peace River.The groundwater level data has been added to Figure(s)1 in terms of corresponding gauge heights.No correction was included for river slope to transfer the levels as elevations to the WSC gauge,however,the data serves to indicate relative effects. Uhen the river level rose and stabil ized by 9/10 \.lanuary,at c gauge height between 11.5 and 12 ro,the groundwater table in Hest Peace River came up and caused flooding in a number of basements.The groundwater response to the change in river levels was reported to be relatively moderate,as it was·a matter of some b/elve days before the Town started to receive flooding complaints.As BCHPA had a fairly high power demand,and the various authorities were trying to maintain the ri ver 1eve 1 wh il e the ice cover ga i ned strength th rough freez i ng,the releases from Gr1S had to be held constant.Hence,little could be done at that time to alleviate the basement flooding problem in West Peace River. (1 ~, I . ~1 Ll~.:~ " Ll L-roo , L~] UJ L) W .-W i 1) I"- WJ F- L.1I-~j "... fI 7 The releases from Gt1S were held nearly constant for the period 8 to 20 January in order to let the ice accumulation at Peace River gain strength by freezing (Figure 1,sheets 2 and 3).Following this,the Gt1S generating station resumed its normal operations.However,the groundwater problem in ~Jest Peace River continued,as the attenuated releases from Gr1S did not cause a substantial river level change at Peace River Town. In February the basement flooding probleM was still acute.FrOM the reported depths of basement fl oodi ng it was judged that if the ri ver level could be drawn dO\'1n in the order of a metre,the flooding probler.J would abate,hence BCHPA was requested to reduce its releases.BCIIPA complied with the request and began stepping down its Gr1S releases on 16 February.The releases were stepped down from a mean discharge of 1615 rn 3 s-1 ,for the first half of February,to an average of 1030 m3 s-1 for the second half.Sheet 5 of Figure 1 shows the resulting decrease of 1.27 rn in stage at Peace River over the period 19 to 25 February.In the sar.Je period the groundwater table in \-lest Peace River dropped 0.42 m; and continued to drop a further 0.48 rn by mid March.During this period the basement flooding problem in \4est Peace River appears to have abated,though one or two hOr.Jes r.Jay sti 11 have experi enced SOMe Ini nor flooding. An increase in releases from Gf'1S on 16 r·1arch caused the river level to again increase,\'/ith a corresponding increase in groundwater levels.The data shows that the increase in flows from GUS,initiated at 0600 hours on 16 t1arch,caused the river ·levels at Peace River to i. i i II • ·'8.'."; ! II id ld i ~ j~ ~.• !a II .i···.·O1 .,Ia' i ~. J I II ..',','.;,Itil I 'j 'I...·.·'~ ~~ I I 8 increase 0.39 m starting at 2100 hours on 18 t1arch.This indicates an ice-covered flow travel timet for the ice concitions which existed,of 63 h~urs for a di scharge of approximately 1250 m3 s -1;an increase in travel time of 15.5 hours over the open water travel tiMe (Figure 3). The groundwater level increase,over the period 18 to 31 r~arch, which resulted from the 0.39 rn increase in river level,was Measured to be 0.34 m.This i~crease in groundwater level was sufficient to reinstate basement flooding in five or six homes in \'lest Peace River. The flooding persisted until the river levels decreased follo\rJing the lbreak-up'of the Peace River in late April. The data indicates that (as an initial attempt)if future occurrences of basement flooding in Hest Peace River are to be avoided, the ice-covered ri\'~r stage at Peace River should not be allo...,ed to increase above 11.0 m (Elevation 315.80 ID,or 1036.09 ft GSC). Additional data would be required to confirm or alter this value.In this respect it is recor:unended that basement elevations in \·Jest Peace River be established by the Town for all of the homes in the subdivision.Additionally,in order to.obtain better records of groundwater levels to determine the maximum river level that would not cause basement flooding,Alberta Environment has established three groundwater level recording wells ill Uest Peace,and will record the levels daily throughout the ice-covered period. , J J ] _...~..............-_......._----- 9 3.2 Breakup Preparations Because of the unusually high level at freeze-up and the perceived thickness of the ice accumulation in the reach through Peace River Towns it was thought that the thick ice would prove a barrier or blockage to the passage of the normal spring break-up front.As well s snowpacks in the river basins tributary to the Peace River above the Town were gauged as being above nonnal s which could result in above normal spring runoff. The combination of a possible blockage to the passage of the break-up front and possible high spring runoff gave every indication that an ice jams if one occurred at Peace Rivers could result in serious flooding of i, the Town.For this reason preparations for break-up were commenced in February of 1982. The Town of Peace River reviewed and updated its contingency plan for flooding situations in the Town.On '·1arch 3rd s a coordinating meeting was held in Peace River of JTlost agencies,Governments Police and the like,which could be involved in providing assistance to the Town in case of spring flooding.Following this meetings and at the recommendation of the River Engineering Branch,Alberta Environments the Town of Peace River undertook to plow a single lane on the surface of ,. the ice in preparation for other possible break-up mitigative measures. This aspect is discussed in more detail in the next section. A meeting was held between the members of the Alberta -B.C.Joint Task Force on Peace River Ices in Peace River on 25 March.At that time Alberta Environ@ent submitted a draft report to the other members of the Committees entitled 'Status Report and Proposed Ice Jam t'itigation 10 Plans,Peace River at Peace River Town ,(2).The report sunmarized preparations by the Town and others towards the anticipated breakup flooding,outlined a breakup observation plan,provided a summary of l'1itigative measures conducted in the past at Peace River,and nade aseries of recommendations regarding what should be attempted to this end in 1982.After due consideration and discussion the members of the Committee agreed to the adoption of most of the recommendations,which led to the implementation of a program of pre-break-up mitigative measures. 3.3 Ice Weakening Effort Ice weakeni ng measures,in advance of breakup,were conducted as approved by the Committee.These included lane clearing and dusting. plus preblasting in specific areas identified in previous studies as being ice jam prone. Uhen the secondary stagi ng occurred on 7/8 January the ice surface ended up as a jagged mass.The ice cover thickness,as measured by the Alberta Research Council in late January,was reported to be in the order of 1 m of solid ice,with up to 3 m of loose floes and accumulated sl ush ice beneath.The jagged surface made access and movement on the ice,for ice jam mitigation purposes,virtually impossible.It was decided to plow lanes on the ice surface,which would require the use of bulldozers,from the mouth of the Heart River to a point downstrean of the Town.This would provide dual benefits in that a passable lane would exist which could be used to access the river for other mitigative measures;and the lanes themselves could be dusted with sone dark - - -'.........-#'-.t"e -c -$' observations,if any,were carried out prior to April 16.Albel~ta Environ~ent carried out aerial inspections of the Heart River from tla~pa i ~- ~ i ~--~I·"- .1,..... 4.0 BREAKUP OBSERVATIONS 4.1 Heart River Breakup of the Heart River was uneventful this year. 18 Few 1 _~ I.. ~ i 1, ,-( "Lf ,~ to Peace River every second day from 16 April to 23 april,and daily thereafter until breakup occurred in the Peace River at Peace River Town on 26 April. All observations showed the ice in the Heart River to be virtually ~elting in place.By 19 April the river was virtually free of ice between Na~pa and the mouth of the river.There were three exceptions. The lowest kilometre of the river,between its ~outh and He tlAR ra i lway bri dge whi ch crosses the Hea rt Ri ver just above the '12 Foot Davis'Ballpark retained ice.This reach still contained both solid and fragmented ice.The ice,however,was deteriorating (candling and ~elting)rapidly due to solar radiation and thermal erosion due to the river flew.Sediments carried in the flow were,at times,being deposited on top of the ice,which woulci have accelerated the thermal deterioration processes. The ether two reaches where a complete ice cover existed were in areas where bank slides (one major,one minor)had constricted the Heart River.The minor slide had constl~ic:ted the channel width by about sm:" and held the river ice upstream of the constriction.The ice in this ~;;;::...----,~,---------"..."'''-------------''''I''.,-----~. -- 20 in place until 28 April,when it moved down and was turned downstream to occupy the space between the ice in the shear ridge across the mouth and the right bank of the Peace River.The ice in the gap plowed and blasted in the shear ridge across the mouth of the Heart did not go out at this time,however,it was evident that most of the Heart River discharge was finding its way through the gap and into the Peace River. The final dislodgement and run of the ice in the lower reach of the Heart River resulted in a stage decrease,possibly due more to the lowering of the Peace River levels following its breakup,of approximately 1.5 m. 4.2 Smoky River Few known observations of the ice conditions on the Smoky River beb:een its confluence with the Peace River and the HSC Gauge 'Sr:lOky River at Watino'were carried out prior to 16 April 1982.From 16 to 23 April Alberta Environment carried out aerial observations every second day,and daily observations from 23 to 26 April v!hen the ice on the Peace River weont out.Additional mino;ubservations were taken on 27 and 28 April,when the Smoky River was finally clear of ice. f10re detailed observations were made for the Smoky River than for the Heart.The following is il summary of the obsen.'C\tions made by Alberta Environment staff over the period 16 to 28 April. Ice on the Smoky River g.enerally darker than on the Peace River. - J~ J~ t}~ ~i., 23 ~,and appeared to be being forced between the chunks of the ice dam as the l~tter stayed virtually motionless.At first we could not tell where the fragmented ice was coming from, but after waiting for 15 -20 minutes,it became apparent that the ice was being entrained into'the river flow about 30 -40 m upstream of the toe of the jam held by the Dam.The ice was apparently being 'simply'entrained,i.e.,little to no vorticity associated with the entrainment,and passed beneath the toe of the jam and upstream half of the dam,and \:las re-emerging in the fragmented dO\'tnstream half. -The inspection was carried on up to Watino and back,with no ice except that grounded on the banks being present. -Upon arrival back at the Hanging Dam the river was virtuelly clear of ice.Only about 0.75 km of the original jam remained,as well as grounded ice along the river banks in what were the jam's shear walls.Ice continued to be forced through the Hanging DaM. The ice which had flowed through the d~m was small,and well dispersed,with no indication of reforming another jam. The jam at the mouth of the river was still in place,though was 2 - 3 krn longer.No flood threat was perceived. -The river was clear of ice to ~Jatino,except for this jar.;, the Hanging Dar.;fragments and grounded ice along the banks. Gauge Height was 1.911 m at 0900 hours HST at \latina. i.~2_~er!l The ice jam at the mouth of the Smoky had pushed through the most right-hand distributary channel (between the islands and the right bank of the Peace River)last night,leaving the heavily hUrmTlocked ice between the remaining islands and shoals'intact.. Smoky River clear of ice except for Hanging Dam and grounded ice along the banks. The Smoky River breakup was therefore an uneventful occurrence,and was basically thermal (semi -static)in nature.No flooding was experienced;and the event which usually causes problems for the Town of 24 Peace River,that is the Smoky River ice running out before the Peace River is clear of ice,did not occur.That the ice went out in a therlilal (melt)mode was attributed to the marked lack of inflow from snO\...melt,as witnessed by the gauge heights recorded at \latino • .The only event of interest was the manner in which the ice,jammed on the Hanging Dam,went out. 4.3 Peace River Observation of the location of the Peace River Breakup front was conducted by BCHPA from 17 !tarch 1982 t and was taken over (by agreement) by Alberta Environment when the breakup front reached the Dunvegan Bridge,or April 16 th in this case.The breakup front position and associated information is given in the following Table 1. The breakup 'front'could be classified as a thermal (semi-static) phenomenon,as opposed to the more dynamic breakup events characterized by the fracturing and movement of a still fairly substantial ice cover under the influence of a flood wave or general rising stage due to an increase in discharge with the commencement of the spring runoff.The thermal front was characterized by the following (moving from upstream to dO\'lnstream): a.An open lead in the ice cover,varying in width from an eighth to a quarter of the width of the river.Within this open lead were small ice floes broken off of the ~dges of the upstream ice still attached to the banks,and a small amount of debris such as t·imber deadfall.The ice floes and debris covered the open lead to less than ten percent of its area. ] d 1.I .. --------_._---------_...._..-.---- 25 ,"~ ! (~ .j ! I " .... a_ I b.At the downstream limit of the open lead was a small accumulation of jammed ice and debris,occupying a width roughly equal to the width of the open lead upstream,and varied in length from 30 to 100 rn (:!:).This small debris jam did not appear to create a significant backwater behind it. c.Ahead of the 'debris front'the ice cover was mostly intact,or more properly had not moved yet.A long,narrow a rea of ver)' dark ice,indicating rapid deterioration t preceded the debris front,and basically followed the river's thalweg.More often than not t this 'finger'of dark ice contained a number of small areas where the ice had melted out in place,and small 'floes had been detached by melt . ~I-"Ij 26 ~ i.. TABLE 1,~Peace River Breakup ,Breakup Front Position/Timing.. '".-Date Time Front(l)Progression Comments at Mile Rate ;:.\(mil est day) ~_»i 17 ~1a r 88.1 r.Jile above Clayhurst $4.5 Ferry ..\'23 t·1a r 115. 2.5 ~.25 f-1ar 120. 2.5 29 t1a r 130. 1.5 31 Mar 133.112 r.li upstream of 1.5 Peace Rivpr Town 2 Apr 136. 0.0 5 Apr 136. 3.3 8 Apr 146. 4.8 13 Apr 170.75 mi upstream of-2.5 Peace River Town 16 Apr 0900 177.5 6.53 ~19 Apr 0840 197.1 5.55 21 Apr 0830 208.2 ....6.35 23 Apr 0845 220.9 7.00 24 Apr 0820 227.9.-8.90 25 Apr 0800 236.8 6.70 """26 Apr 0600 243.5 6.12 26 Apr 1600 246.1 At Bridges in Peace ~5.16 River 27 Apr 0830 249.6 4.06 27 Apr 1500 250.7 9.33 28 Apr 0830 257.5 16.00 3 May 0940 337.5 58.10(2) 7 Hay 1035 570.0 Notes:See next Page. .... 32 Ice front at Mile 257.5 at 0830 hours,an area known as '12 - Nil e Fl ats f • The front had passed through all knO\'tn areas of ice jam initiation. i-fI 4.4 General Observations The 1982 ice breakup on the Peace River \'las nowhere near as disastrous as mid-winter data indicators pointed out that it could be. That the breakup went quietly and smoothly can be attributed,by priority,to the following: c.Controlled releases from Gr1S.And, The fi rst two poi nts are natural phenomena,Clnd hence cannot be These two alone, d.In some small neasure,to the ice weakening efforts carried out before the arrival of the breakup front. a.A cool spring which held off the snowmelt runoff until the breakup was through Peace River Town. b.A reportedly dry late summer and fall,such there was 1 ittle Moisture in the ground at freeze-up.t'\ost of the local snowmelt in spring appeared to be absorbed into the ground. however,probably contributed as much as 70 percent of the effective mitigative circu~stances which led to the uneventful breakup. controlled for purposes of ice jam -mitigation. r. ,.The controlled releases from Gr,ts by BCHPA likely added another 20 percent to the total effective mitigative effort.The constant,or very gradually varied flow releases within operating limits,prevented major stage changes in the river which could have precipitated a mOI'e dynamic breakup.One contingency allowance that was made,but never invoked, ~-_.---------,.......---------------_._--- 33 was to have the GMS releases cut back as snowmelt runoff increased,in order to maintain a fairly constant flow through Peace River Town.It is the constancy of discharge at Peace River Town which is desirable, both at breakup and at freeze-up. The remaining 10 percent of the effective mitigative measures goes to the ice weakening effort.Some comments should be made concerning the efficacy of these efforts due to the costs involved. a.to Alberta Environment -$21,751.14 (less wages etc.) b,to Peace River Town -$150,385.24 c.to BCHPA - TOTAL $ Ice thickness measurements nade during the preblasting operations showed an average decrease in ice thickness along the plowed lanes of 0.62 m (2.04.ft)from the measurements made while the lanes were being plowed,with a maximum decrease of 1.05 m.Even with this reduction, some ice thickness measurements carried out for the preblasting operation~in the period of 16 to 21 April,were in excess of 2.44 m. The plowed lanes served a second purpose,being drainage of the surface melt of the ice cover.When the winter jam (which created the ice cover)formed in January there was a certain amount of silt deposited on the ice from the flow,as well as a cel~tain amount of debris in the form of deadfall timber.As the sun angle increased into the spring,the exposed faces of the hummocked ice surface began to melt,aided by radiation absorption due to the deposited silts and debris.The melt,however,was only of the exposed ice hummocks,above the mean ice surface,and did not contribute toward general ice 1 "'"I ) .I I -- " ..I"""-: iii 34 weakening.Some of the meltwater found its way into the plowed lanes, and began to flow downstream.As well,in the numerous holes that were augered through the ice to test its thickness prior to plowing the lanes,river flow exchanged with the meltwater flow.Dependent upon the location of the lane surface with respect to the river's hydraulic grade line i.e.,r~ised above or depressed below,the ice lane flow would drop down through the auger holes,or river flow would boil up through then respectively.The flow through the holes caused enlargement through thermal erosion,many holes becoming large enough for a man to drop through,and in one or two instances large enough to drop a vehicle through.~ith fluid flow on top of the lanes as well as beneath them, thermal erosion would occur fro~both sides. The efficacy of the ice blasting downstream of Be\'Jley Island and dovmstream of Si x ~1i1 e Poi nt \."as diffi cul t to judge,as the breakup front passed through both of these areas at night.However,observation of the resulting craters before the arrival of the breakup front had sho\'1n that most of the blast debris which had fallen back into the craters had disappeared by the timE'the breakup front ardved.This can be attributed to ice floe entrainment by the river flow,and possibly to melt to a snell degree.The craters allowed sediment laden river flow onto the surface,which in turn created thernal erosion around and between the craters,and possibly some increased heat absorption through the changed surface albedo. There is a hint in the data contained in Table 1 that the ice front passed through the blasted area slightly quicker than others.See for instance the progression rates between 1500 hours on 27 April and 0830 36 have been located one-lane-spacing (38 m~)further towards Bewley Island.The breakup front continued to follow the second and third 1anes all the way down to the end of the 1anes nea r Si x t~;1e Poi nt.In this respect the thinner ice in the lanes appears to have been beneficial. The area where the most.noticeable ef-fE:cts,and possibly the r.10st noticeable success in the overall ice weakening effort was achieved,was the work conducted at the mouth (if the Heart River.There is little doubt but that the massive ice accumulation in the shear zone across the r.1outh of the He,,"~cull:~~tuted an obstruction to both fluid end ice flow from the Heart.A good portion of the ice ;n the shear zone was probably grounded to the bed of the Peace River,allowing flow from the Heart through it by percolation only.Plowing a gap through the shear zone removed the surcharge load on the r.1ean ice cover.The buoyancy of the ice remaining beneath the ice cover caused the ice to lift,Most probably through the ~echanism of plastic creep.This may have opened a sr.lall waterway through the ice in the shear zone.Subsequent blastin9 of the ice in the gap.with the charges placed at depth,appeared to cause further heave of the upper surface,and likely caused an enlargement of the waten~ay at the bottOM of the ice. ~lhen the little ice \1Jhich remained in the Heilrt.Ri ...t:r (following melt)finally moved out,it was contained against the right bank of the Peace River by the shear ridge.The Heart River flow,however,~",as o~served to be making its way through the gap.The ultimate efficacy of this work was not tested,as the Heart River neither jammed at the mouth,nor increased its discharges appreciably. ",----,'--.:-,.,.-.----,----,,-----~'.._:.---,---'----,'.'lJi-....1-"1l~~-'to ~~.11-4 11-'j;·-~l-'~-'--I ----}--.-1--:-J--..·l~··.··i-'······l__.~.·1..;..;...._ D U It J I ~fJ,..1 _~'C~.~"'...,I\..~~J."-e.-_l,..~,........r.-.'-.,,-......_ ._"'"'II'......_~-~.,..,.....A .......~. TABLE 2 Breakup Data Pe~ce River at Peace River Town Year Breakup 5-Day Pre-breakup Discharge Ouring Breakup Maximum Ice Jam Maximum Stage Increase Date Elevation*Peace River Smoky River Elevation Above Pre-breakup Elevation (m)Above Smoky River*2 Above Confluence*3 (m)(01) ~---_..--_.----- 1960 Apr 16 312.88 883.49 365.29 313.21 0.33 1961 Apr 20 311.69 1112.85 104.77 311.81 0.12 1962 Apr 16 312.30 866.50 648.46 313.94 1.64 1963 Apr 19 311.75 3381.03 1093.03 316.14 4.39 1964 Apr 19 312.33 897.64 206.15 312.15 -0.18 1965 Apr 14 311.90 1568.75 481.39 313.61 1.71 1966 1967 Apr 30 311.90 291.66 1005.25 313.40 1.50 [196B ...1969 Apr 15 311.96 475.72 94B.61 314.89 2.93 (1970 1971 Apr 19 312.48 1260.10 203.8B 313.06 0.58 1972 Apr 20 313.21 1452.65 538.02 314.86 1.65 1973 Apr 12 313.76 2273.84 515.37 318.18 4.42 1974 apr 20 313.36 2288.00 1308.24 317.51 4.15 1975 Apr 17 314.16 2174.73 69.94 314.52 0.36 1976 Apr 11 313.94 1676.36 594.65 314.34 -0.40 1977 Mar 12 312.72 767.39 66.83 311.90 -0.82 1978 Apr 15 313.18 1333.72 215.77 313.49 0.31 1979 Apr 30 314.10 2520.20 1589.99 31B.61 4.51 1980 Apr 18 311.81 651.29 387.94 313 .06 1.25 1981 1982 Apr 26 315.46 1653.00 247.00 315.94 0.48 Notes:*1 Average elevation of mean daily disch~rges at Peace River for 5 days prior to breakup,estimated from recorded water levels. *2 Peace River Dir,charge '"DischClrge at Peace River -Smoky River ni~charge at \latinn *3 Smoky River at Wntino. w 00 jF"" 1. 'j- ...J.._..i. ..(~ ·1'I-:..... ~l-.: i'!'\ 1.. 1_ "I';.l ~...! J ....-.I "- J ) I 39 5.0 PROPOSED MODE OF OPERATION FOR 1982/83 FREEZE-UP Cross sections established during the 1981/82 ice season were surveyed following breakup.,/tIowever they were not available in time to conduct any analysis towards the mode of operation of Gf1S for the freeze-up period in 1982/83.However,the limited data and observations available froM the 1981/82 season suggest a mode of operation which can be considered a first attempt at controlling the freeze-up level. First,it was noted that for this past freeze-up the rupturing of the initial ice cover was caused by increased releases from Gt'1S in response to an increased load deMand following reduction in load over the Christmas to New Year holiday season (See Figure 1,Sheet 2 of 9 or Figure 4).Figure 1,Sheet 2 of 9,shO\'ls something like a five-fold increase in releases over the period 1 to 6 January.It is now known that the release of a moderately sized ice jam,in the vicinity of Verte Island,created a slug of flow (released from storage)which contributed to the rupture of the i ni ti a1 cover in Peace Ri ver,however,thi s release was also likely due to the stepped up release~from Gr1S. The point to be made here,and in fact to the operation of any hydro generating station when the freeze-up front is passing through sensitive areas for winter flooding,is that the discharge should be held constant,or at least within reasonable limits,until the ice cover has formed and gained some internal strength through freezing.The question remains as to what would constitute the maximum desirable freeze-up level ~hrough the Town of Peace River;to allow BCHPA a -------------- 40 reasonable amount of freedom of operation in response to load deMand. and yet avoid both surface and groundwater flooding in the Town of Peace River?As groundwater flooding occurs in response to increased river levels~at a lower level than that which would cause overbank flooding, and stays for the longest time,this should be the pri~ary consideration for attenpting to control the freeze-up level.If this criteria is met, then there should be no occurrences of surface flooding due to dike overtopping from stage increases as the ice cover forms. The limited groundwater level data available shows that a Peace River ice-covered stage,for the particular cover thickness attained in 1982~of between 11 and 12 m (Elevation 315.8 to 316.8 m;1036.1 to 1039.4 ft)maintained the basement flooding condition in \·Jest Peace River until mid-February.BCHPAls releases during this period were in the order of 1690 m3 s-1 (59,689 cfs)over the period 9 to 20 Januar~1 to provide a constant discharge to let the cover gain strength;and varied from 1930 to 880 m3 s-1 (68,160 to 31,080 cfs)until 16 February when the releases were cut to in the order of 1000 m3 s-1 (35,320 cfs)in order to lessen the groundwater flooding in H~st Peace River. \lhen the Gr\S releases were reduced following 16 February the groundvlater table dropped over a peri od of 12 days so that it corresponded to a gauge height at the ~SC gauge of approximately 11.0 m. The corresponding groundwater 1evel was in the order of 10.4 m (See March 1 levels,Figure 1,Sheet 50f 9).The basenent flooding problem abated ...lith this decrease,with the exception of perhaps five homes. This suggests that the maximum allowable Peace River stage following freeze-up should be in the order of 10.0 to 10.4 m;or Elevation 314.8 I \ - - ~ f~ ":-,•-".. I t,'.~ ~J ~I :t~ 'I ' "',- I '- 41 to 315.2 m,say 315.0 m (1033.46 ft)is the maximur.l desirable river elevation.If all the basement elevations in \Jest Peace River were known,it would be a simple matter to determine the maximum allov/able river level,but they are not. The emphasis placed earlier on the particular ice cover thickness for 1982 should be noted.Different cover thicknesses,generated by the manner of freeze-up,for a constant discharge will yield different naxinum ice levels.However,as the freeze-up in January of 1982 was so unique,possibly giving an upper bound to ultimate initial cover thickness,use of the 1982 data should prove conservative.Observations from future years,hence different initial ice thicknesses,,may refine this rather crude analysis and allow BCHPA a little more flexibility ir. operations at freeze-up. An interesting,and rather unique analysis of the Peace niver freeze-up levels by Carson and Lavender (l980)(8)of Acres Consulting Services Ltd.,gives an indication of the allowable Gr,S releases, attenuated to Peace River,that would produce the rnaximun desirable ice covered level of 315.0 rn.It should be noted that while their analysis ~/as based upon leading edge stability criteria for initial ice cover formation,the figure they produced described completely (With only minor assumptions)the entire event at Peace Rivel~last year,including the secondary staging due to telescoping of the ice cover.From their -figure (see Figure 2 of Ref 1)for the above allowable river stage,the maximum value of the parameter (Q/B)2/3 should be 2,which corresponds to a discharge at Peace River Town of about 1350 m3 s-1 (47,675 cfs).At ................. 42 this point in time it is not known how much the releases from G!1S attenuate before reaching Peace River Town,therefore it is suggested that 1345 m3 s-1 (47,500 cfs)be the max;mu~constant discharge released from Gr~s to arrive at Peace River with the ice front. Figure 3 shows an open water flow travel time,for a discharge of 1345 m3 s -1,of approximately 42 hours.Therefore the foll owi ng mode of operation for GnS for the 1982/83 freeze-up period is recommended: 1.Monitor the rate of advance of the freeze-up front towards the Town of Peace River,paying attention to changes in the rate brought on by changes in atmospheric conditions,in order to be able to forecast when the freeze-up front ~lill reach Peace River Town within 48 hours.For this purpose,it is recommended that r'1ile 255 (Birch Island,just downstream of Six f1ile Point)be considered as the 'arrival'location,as the area is ice ja~ prone and could affect the Town.During this period allow BCHPA to operate Gf.1S as load deMand requires. 2.Uhen the ice front is calculated to reach 11ile 255 in 48 hours, restrict Gr1S releases to a maximum of 1345 m3 s-1 to a11o'.'l the discharge releases to arrive at Peace River coincident with the ice front.A smaller release,to conserve winter storage in Williston Lake and for conservatism due to the rough nature of the guidelines through \'/hich this estimate was made,would be acceptable,but not less than 1000 m3 s-1 •The discharge should preferably be held constant,or at most be allowed to fluctuate 42 m3 s-1 (1500 cfs),providing a release of 1345 m3 s-1 is not exceeded. 3.Closely monitor the groundwater levels in West Peace River (Alberta Environment has established three recording wells for this purpose),and if baseMent flooding becones iMmanent,reduce the releases from GflS fully realizing that it will take 48 hours to have any effect at Peace River Town. 4.As was initiated in January 1982,the ice cover fornation discharge should be held constant for a\'/hile,to al10w the ice cover to gain strength by freezing.Twelve days were allowed in January 1982,and it is recommended that a similar time be allowed this year. 5.Following the 12 day ice cover strengthening period,slowly step up base flows and peaking to nomal operations in ,~esponse to load demand.Peaking releases should ·not exceed base flows by too great an amount,though there is insufficient data to recommend limits at this time.If basement flooding begins to ,- 1- l ,- ...... ~.-•4 '..... t• ,-~f. ~ l' ,~ j -1 ~ J If'.. ~, '~ l .'~,,• ..... f J 43 be a problem,revert back to the operation on the day before the releases which bl·ought on the problem,and consider that the maximum releases until breakup. The above proposal is not as conservative as it could be, considering this will be a first attempt at setting the ice level and it aims for the maximum allowable level identified at this time.Data taken from this event should be able to refine the analysis,perhaps imposing further restrictions,or perhaps lifting some. Emergency po\rler generation requi rements through the formation and 12 day period should be made up fron other sources if possible.The Committee will have to discuss,before the need arises.the advisability of large sustained releases after the 12 day period. 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South Interior live line instructor John _Zucco,changi1llg insulotors on j()()k V transmission lure. On Vancouver Island,the regional peak of 1 256 000 kW was only slightly higher than the previous winter's peak despite the addition of 4 500 new customers,most of whom installed electric space heating.This peak would ,.-have been much higher without the positive response by Vancouver Island customers to our appeal to reduce use of electricity at peak hours. Sales of electricity in British Columbia by category of customer and percentage changes from the previous .".~year were:I>, Residiential General Bulk Other systems Year ended 31 March 1980 kW·h in millions 7612 9 136 9229 226 26203 11]'0 increase from prel'ious year 2.8 3.9 0.9 4.2 2.5 ',- 5 8838 %of total 1347 72.1 17.8 10.1 912 100 100 75 46 114 HXl.O 100.0 33.9 18.2 8.9 8.5 7.5 19.4 0.1 {).4 3.1 2416 1736 700 608 529 428 1074 7491 Installed nameplate generating capacity (leW in thousands) 26 166 1219 28295 6984 3971 13 317 7149 3491 3343 2943 7596 39250 39250 kW'h in millions Total hydroelectric Hydroelectric plants Gordon M.Shrum Mica Peace Canyon Seven Mile Kootenay Canal Bridge River Other Sources of supply: Hydroelectric generation Gordon M.Shrum Mica Kootenay Canal Peace Canyon Seven Mile Other Thermal generation Burrard Other Purchases and other transactions Requirements: Sales in B.C. Export Line loss and system use Residential General Transmission rate Other systems Total thermal Year ended %increase March 31,1982 (decrease)from kW'h in millions previous year There were no major additions to Hydro's generating capacity during the year.The total generating capacity of Hydro's plants at March 31.1982.was as follows: Total generating capacity Thermal plants Burrard Port Mann Keogh Georgia Prince Rupert Other Total requirements for electricity and sources of supply were: .capacity of existing resources. Additional capacity to serve the Island will be available in fall 1983,when the mainland- Vancouver Island 500 kV transmission connection now under construction is scheduled to start operation. A high volume of SUT- plus electricity sales to the United States resulted from fortuitous water conditions and favourable markets. Additional revenues were realized from storage arrangements with other utilities.Surplus sales in February and March 1982 were restricted because of heavy snowpacks in the U.S. Pacific Northwest. Runoff into major Hydro reservoirs during the year was above normal,pro- viding adequate hydroelectric power for supplying domestic needs in B.C.as well as sales to the U.S.As a result. system generating require- ments from the gas-fired Bur- rard thermal station near Vancouver were negligible. The Burrard plant's role is to make up shortages of energy in low water years and to provide electricity during major emergencies or if major new projects are delayed.It is a relatively expensive source of energy which is used as little as possible.Hydro is continuing to collect emission dispersion information to support appli- cation for permits under the provincial Pollution Control Act. Sales of electricity in B.C.by category of customer and percentage changes from the previous year were: Review of Operations Electric Service Revenues from electric service exceeded $1 billion for the first time,increasing 27t1Jo from the previous year to $1,1Z.~million.The increase resultl~d primarily from $233 million in sales of surplus interruptible electri- city to the United States. Sales of electricity in B.C.totalled 28295 million kW'h,an increase of 2.6070. 'The highest one-hour demand ever r('-corded on the ilntegnlted electric system - 5902000 kW -occurred on January 6,1982,up 7.80/0 from the previous year's high. At March 31,1982, Hydro was serving 1076926 electricity customers,an in- c:rease of 30780 during the year.Average annual con- sumption per residential customer was 9413 kW'h, compared with 9001 kW·h tlht year before. Approximately 7200 cus- tnmers were added on Van- c,ouver Island,about 95t1Jo of whom installed electric space heating.The Vancouver Island electric load reached a new peak of 1341 (XX)kW, up 53000 kW from the year before.Reduction in demand from tr:ansmission rate power custom(:rs,coupled with positive customer response to Hydro's appeal to curtail n()n~ess(:ntial use of electricity during e:arly evening hours, kt~pt the peak load within the - - f- { 8 = ,- " -- - - REFERENCE 6 Tnt rligt.stagE's resulted fro..,the r,ature of the ice cover progressior, whict.was typifiec by thE'forma:.ioro of freeze-u~,ice jams.Sever.jarr:s wen-ob~e"vec in the 19-tilometre reaCT.n~a"'al·"'o'-.the averao:dis:.ance betweer jarr:~bein~Z.7 kilometre~... OBSERVATION AND ANALYSIS OF FREEZE-UP ICE JAMS ON THE PEACE RIVER NEAR TAYLOR T.Keenhan l ,U.S.Panu 2 and V.C.Kartha 3 ABSTRACT Since the construction of the W.A.C.Bennett Darr.on the Peace River in British Columbia,the temperature of flow releases has been O.SoC or higher during winter months.As a result,a long reach of ice-free river persists below the da~throughout the winter.Since 1972.wnen the eighth of the ten generating units was installed at G'~j Shrum (G~S) Generating Station.raising the release capacity to 1,580 m Isec,the ice cover has advanced upstream to the Village of Taylor,located 120 kilometres downstream,in only two winters,1974 and 1979.Extensive ice measurements were carried out in 1979. Below nonmal air temperature~persisted in thE area for the month of February 1979 and the ice cover advanced to a winter rnaximurr upstream locatior,1£kilometres above thf ~ater Survt-y of Canad~(loiSC)gauge at 1aylor.Tne stage increases resu It;n~at,and upstream of Tayi or dUE:to the presence of tile ice cover produce:levels which approached the Ilia~;mur.:historic SUTmler nooe::leveh. Tr,~jams werE-observeC to fom:througr,shoves i rdC>1 vi"5 collaps~of the upstre:aT"extent of the ice cover.fOl"lTJi!tion of V,E'largest jar..withi,. the:react:involved thE-collapse of 8 f:i1omE':'r~~(l';ice-cover inte.1.£ .:ilo!!letres ane produced river stage leve1swr,icr,ove,.tc~ped ttl£:nann.. Durin9 the trlree-week period frarr 17 February tCJ f·,"""rct.lS7~v.ai th~ ice cover extended upstream of the Taylor geU~E:.the advan:e and retrea! c;f thE-cover and ice/water el evat ions were docuT;1~ntedb.\'E.C.Hydrc, personnel.By monitorin2 the ice movements at icylo r and controll;~~ to:fio~re:leases frorr G~S Generatin~S~a,io~,,,'~~~atE:freebDcrc:we~ ensured with;r,lay1or. ThE data or,ice levels and ice jams WE're pct,ne-ec ane,iClLer,uset tc as.sess the applicability of ttlree nu:nericai iCE ja::.Illudels tr ~E:a:E: Ri ver •nih paper presents "oeser;p:i on of thE i CEo jbmr.i rl~ITl!;'Cflar,i Sl! obs.erved ourin£the icE'cover advance.the.levers r~corClec:c'.troE:iCE: jams ant the results of the anaiy!is t n rcu9'~se of tn~mooel~. 1.S1'.H.I/orotecnni ca";Engi fleer,[r~p~€,r.CO"lSl.J ~tents; j~.~,~.f...·.~2.hydrOlogy En9~neer.Le.hydrc.\'arl:o~~er, I.;~';t.:.:-~'3.Su~,en'isor.Hyoro109/Senior.,Le.hydn,\'cn~o;.Jver. :(;m __,·:jf~~7t!:"!~"'1i'2~;yw.e;;~4;H!;s;.#e?$;n!e '!~';;:S'"'\'2_,!4C ;=-+YiE?SP!84 ad - - -OESCRI PTI or;OF THE 1979 I CE JAMS AND THE STUDY REACH I NTRODUCTI ON 163 Data on iCE:movement was co11ectec between the WSC gauge and the upstream terminus of th~icc cover established in February 1979.Tne analysis of ice data ~as limited to this reach.The general location and the detailed h.vOLJ':of the stud,i react,are shown on Fi9ures i and 2,respectively. B.C.Hydro has monitored ice conditions on the Peace River downstream of W.A.C.Bennett Dam since 1973 to gather data for planning and operation of hydroelectric plants.Data on river stage at freeze-up,break-up and during mid-winter have been collected annually over this period at a number of locations in British Columbia and Alberta. During February-March 1979,a series of ice jams formed in the vicinity of Taylor,producing high water levels.Ice movements were closely monitored and extensive data were collected by B.C.Hydro.The data provided an opportunity to examine various river ice simulation models and assess their applicability to Peace River. After the eighth of the ten generating units was installed3at G.M.Shrum Generating Station,raising the release capacity to 1580 m /sec in 1972, the ice cover has advanced to Taylor only twice,in 1974 and 1979. Unlike in 1979,the observations carried out during 1974 were of a qualitative nature and,therefore,were not included in the analysis. Belo~normal air temperatures persisted in the area for the montt.of ~ebrua ry 1979 and the ice cover advanced to the Water Survey of Car,adil (WSC)gauge at Taylor on 17 February.With the continuation of cold weather,the front progressed further upstrearr,to its maximum point of advance 18 kilometres above the WSC cauoe on 1 March 1979;then with the onset of milder weather,the front retreated downstream to the gauge or, E March 1979.During this period th~discharge remained relatively consta~t.Tne flows were in the order of 1450 mJ/sec. The sta'ge increase"resulting at and upstrean·,of laylor due to the presenCE:of tne ice cover produced levels whict,were exceeded only twice durin~the 35-year period of record.The open water floods of 1948 and 196!produ,ed water levels which were 1.5 and 0.£metres higher,respectively, at iaylor.Tne maximurr-freeze-up levels observed during February-March 197~are given in lable 1. The high stages resulted from the nature of the ice cover progression Which wcs typified by the formation of freeze-up ice jams. uJring the three-weel.period from 17 February to 8 March 1979 that the ice cover was upstrean of the Taylor gauge,the advance and retreat of tn:cover and iCi/water elevations were documented by B.C.Hydro personnel. Ey monitoring thf ice movements at Taylor and controlling the flow releases frot GMS Generating Station,adequate freeboard was ensured w"i thi n Taylor. ~. Including the jam located just downstream of the gauge,a total of seven freeze-up jams were observed in a 19-ki10metre reach at an average spacing of one every 2.7 kilometres.The locations and lengths of the jams are shown on Figure 2.The jams are numbered for reference.The lengths of the ice jams were typically 0.5 ki10~tres with attendant increases in stage upstream of the jam between 0.6 and 0.9 metres.Jam 5 differed in magnitude with length of 1.B kilometres and stage increase of 2.5 metres.Fo~tion conditions for Jam 5 differed from the others and are described later in the text.The locations of jam toes were at constricted channel sections where bed forms became prominent or the top width was suddenly narrowed.The toes were frequently located at the downstream ends of islands. Based on the spacing of the jams observed downstream of Jam 3.aerial observations of the channel and general knowledge of the riverbed,the locations of the jam toes upstream of Jam 3 were predicted in the field with reasonable accuracy. The regularity of the spacing of the toe locations indicated a relationshi"p between naturally occurring changes in local bed geometry,the nature of the i~e cover (i.e.strength),and backwater regimt. The freeze-up profile based on stage levels observed in the study reach. the bed profile and the open water profile are shown in Figure 3.The locations of the ice measurement points are ShOWTi or.Figure 2. The average slope of the water surface through the study reach,ba~ed on open water profiles.is 0.00040 downstrearr,of Jarr.:.:anc!0.00063 upstrearr,. Surveyed cross sections were available within the stud.y react,fro""prior studies or:open weter profiles and the locations.are shown in Figure 2. Several of the stud)reacr,cross.sections are plotte~in figure 4. leE JA~~FORMATIur.ON THE PEACE RIVER "The ice regime on the Peace River has been altered by hydroelectric.., aevelopiTJen~.ThE:regulated "linter flows are in the oraer of 1'20 II:"/sec, about five times the natural winter flow.The input of h~at to the river from the reservoir has resulted in A reach of year-round open water below the dam. Detweer.toe ~.A.C.Bennett Darn and the Town of Peace River,located in Alberta 40G kilometres downstrearr.,the flo~velocities withi~the Peace River are toe.high to allo~'fOnTiation of bani;to bank ice cover by freeze-over or growtn of shore ice.Before the development.a continuous ice cover used to form by the initial establishment of intermittent ice covers Which permittee localized upstrearr.progression and eventual forrr~tio~of a continuous cover. SinCE:hydroeiectric development,the ice cover is establiShed by the upstream progressior.o~i:single ice front or leading edge Whicr,progresses frorn downstrearr· of the Tow~of Peace Ri ver to a poi nt of maximu""advance.or upstream tern.i nus prior to the onset of milder spring weather. ""... .~. I The location of the upstream terminus during a winter is dependent on the winter severity and flow conditions.In the eight-year observation period since the winter of 1972/1973,the location of the terminus has varied between 327 and 97 kilometres below the dam. The mechanism of advance of the ice front at Taylor during 1979,as observed,is described below. The ice cover progresses through an initial consolidation or packing of the floating ice pans until it collapses as a result of the force exerted by the flow and the gravitational effect of its own weight.The collapse of the cover or "shove"produces an ice jam which bridges the river. The jam produces additional backwater and permits the progression of the cover upstream through continued packing of the incoming ice floes.The cover advances further upstream than previously due to the additional backwater until it collapses in another shove which creates a second jam upstream.The process repeats as long as there is sufficient ice supply in the river.The average spacing between the jams in the vicinity of Taylor.as noted previously.is 2.7 kilometres.All the jams within the stUdy reach except Jam 5 were formed in this u~nner. The collapse of the loosely consolidated cover of frazil pans,required to increase internal strenath,also initiates the movement of the more consol ioatec cover downstream.Durina the shoves the mass of ice moves ifi an accordion-like manner until sufficient resistance from the channel ban~s and bottom is encountered to halt the movement of the floe.The ice shoves are observed to ground on gravel bars and sides of the channel to form ice jams . The movement of th~ice cover farther downstrea~during the shoves.if extensive.can move an existing jam downstrea~.Larg~ice volumes are then releas~d.or mobilized.in the ShOVE.r~sulting in a massive jam further downstream.Jam 5 was formed in this manner when a jarr at the locatior:of Jam 6 collapsed during a shove.Five kilometres of ice collapsed into 1.8 kilometres producing a stage increase of 2.5 metres. Ice ridges 3 to 4 metres in height were observed in the middle of the cnannel.This large shove created an ice jarr which appeared t~have partially cloggeo the channel. During February-March 1979.ice·cover progressed through sUlcessive freeze-up jams on the Pea~e River near Taylor.FreEze-u~jams were also observed o~reconnaissance flights between Tavlor and the To~n of Peace Riv~r in 1979.ihouor.no detailed measurements were avai1able.the me~hanis"of ice cover progression is considered to be the same as describec above. MOG[l~lN~OF lC£JA~~ ICE-jams are ~a-:.ego"1zed by Pariset et ai (1966)into eittler "wide"or ";'arror."cnanne1 5crr::..In eo "wide"channei thE stream"ise thrust on the cover increases ~ith distance downstrearr fro~thE front edge of the cover and reaches a liffiitinc value.The ice cover thickens through successive ~hove$until its-internal resistance is equal to the sum of tM external fCiI"Ces..For "narro~'"jams the thrust is maximum at the front eogE of t~e cover ane shoves of tne cover do not occur. 165 / IOloJAICE MODEL ~..tlerE:ErD is th~effective depth,ti is the tot"1 number o~rre:lezoida1 elements ir.;;crOi!section deterr.;ined by t,~1 pcints;D i!th~averaoe deptn of thE trapezoidal elemeJ'1ts;anc J.h V,E area of ttle ira?EZO;da~ element. (1) '6~ N -=:::::::(D.t...02/3 ).L '1 i '"1£fD '"--:..-+---.----h '"(t...D.2J3 )..c:::1 1 i =1 The model has beer.developed for c rt:c.tan~lUlar channel of canst-aroi.bee slope.Since tM:Peace River cros~sections arE:nor:-rectangular \odtL changins geometry and bed sleoE:aion~tn~river,t~t aroclysis reouires c method o~transiorr.,ing the P~ilce Eivel"input ane for iT,terpretio~progra" resu1t~.10e fal1o~:in9 transforli,ct.l0L wr.ich i~used in sediment cOr.l;Jutatiom such as HEC-6 progra~to account for the:innueflce of non-rec.tanguiar eros:.!>ectior:shapes 00 transport capecit,)'wa:.usee!: A computer program dealing with both wide and narrow river ice jams has been developed at Iowa University.The program incorporates the theory of jams within "narro\\'''and "wide"channels.Ca1culations are carried out for the "narrow"conditions (Tatinclaux 1977)anc the interrlcl strength of the jare is tested by 6 force-ba1anct.If the jar.strengtr, is insufficient to withstand the forces of the flow,then the final solution h obtained b.r "wide"channel jall:theary (Uzuner anc I:ermed.y 1974). The freeze-up jams within the study reach were formed through internal collapse of the cover.and.thus.correspond to jams in a "wide"channel. The theory describin9 wide river jams has been presented by Pari set et al (1961.1966)and Uzuner and Kennedy (1974).Based on this theory. there are several computer programs for predicting the equilibrium thickness of fragmented or consolidated ice covers.In this paper. three computer programs are considered to be capable of simulating the ice jam process on the Peace River.Brief but relevant details of each of the programs (models)are given below. for the purpose of identification.the programs are referred to as IOWAICE.HEeleE.and tGLICE.each denoting the source and availability of the program. t .~--'0-._.. .-,~~.~';' j ••~~t~~~~~~;~:~i~~r~~~~~~w~ (2 ) TH::ice profile is Obtained by solving for stat;:ity at c!'"os~se~tions ir, ,"1",:l.O~s!.rear.,direct~on. 167 HEClcr MODEL wnere C i~the di~charoe at the section;C is the Chez)coe~fieie~t;E i~ tnE:stl-eall'widtr.;and H is the upstrearr.open water dectti. I-.......iro computer rnc,de1 was obtained frot:'Lalonoe,GirOl.Oarci.Letendre anG ~~so:iates ltd.inf prograrr calculates hydraulic ic:conditions for ti;;~intervals to slmulate ice conditions during the ~in~er frorr freeze- :'t'tC'b"eak-u~.Tn:prograrr.inco!,"porate~separate modules for determination c~ic~s~aoility,bac~water,anc ice generation and deposition.The model req~ires meteorolooical and cross section data.Toe prograc,which has be.;:',mod-;fi ed for U50E:or,the Peace Ri ver is deseri bed ir,cietai I by Petryk an~eoisvert (lS7E)and Petryk et al (1980), LG;.lC~r.10;:l£!. The Hydrologic Engineering Centre has modified the HEC-2 backwater model te·incorporate the "wide"river jam stability criteria as developed by Pariset et a1.The backwater capability of the progra~permits the evtluation of ice cover stability,while incorporatins downstream conditions. An advar,ugE of this model over the previously di scussed model is that H~CICE car.use natural river cross sections ~ithout the need for transformation. The results obtained from the model are transferred to the natural channel sections by locating the underside of the cover.This is done by equating the flow area,below the ice cover,of the rectangular section to the natural section.The elevation of the ice underside in the natural section is obtained from stage-area curves.The simulated thickness is retained for the natural section. ?,'dimensionless"stability diagrarr.is employee to analyze the stability of t jac at a given section.The stability diagra~is for cohesionless cover and incorporates ice characteristics as developed on tne St.Lawrence F.iver ane:the Beaut.arnois Canal.A stability functior.is computee a," a cress section for a given flo~depth and an assurnec ice cove~thickness. Tn~vc1u~ttll,;S obtained is eO;!l~ared tC'tnE:corresponding valu:frore the ":jimeris',onless'su~il ity diagran,tc.establ ish whetheY the iet:cover at !n:cn~~~section is st.able 0"not.The stabiiit,y fun:tior.is: The variation of bed geometry along the river within the Peace River limits analysis to a single cross section.The critical cross section within the reach of interest.which is considered to produce highest jam levels.is selected by trial and error for analysis.Backwater conditions from downstream are incorporated through adjustments to bed slope at the cross section.The model does not differentiate between the bed and water surface slopes. t j 1 t i ! i 1 I •I, • ',.. The model employs the dimensionless stability diagram described earlier. However.stability is also assessed for juxtaposition of floating ice blocks (Pari set et al)and by the use of lillliting flow velocities below the cover.Additionally,ice cover is established on sections with very low velocities. All three models used in the study reach assume that the ice jam is floating and does not ground;there is no cohesion within the jam;a semi~steady state flow condition exists;and that the uniform flow equation is adequate. PREPARATION OF INPUT DATA The cross sections measured in the study reach and used in the anaiysis are shown on Figure 2.The Peace River in the study reach is wide and shallow with gravel bars and secondary channels around the islands. Under ice conditions,a significant portion of the cross sectional area below the water surface is filled with floating ice or carries only a small percentage of the flow.The cross sections and flow were adjusted so that only the main channel was represented in the ice analysis. In order to simulate river stages in the study reach duE'to ice jalTliJing. ice thiCKnes$and roughness of the bed and ice cover were req~ired. Measurements of thickness of ice cover on the river coule not be made during the ice~jarr:period.Observation of ice stranded along the banks, however.revealed ice thickness generally varying between 1.5 and 2.0 metres in the study reect.except at Ja~5.lce stranded at Ja~5 was about si>.metres tnict.Since the ice cover remained within the stud)' react.for only c short period of time.the observed th;c~ne~se~wer~not considered to nave been altered by ther~~1 growth or ero~ion.However. tnf:indi reet determinet i on of ice thi cknesses by ob~ervat.'ons a 1on£tnt banks was not considered pr~eise and the observed thie~nesses are. therefore.considered to be onl.)/an indicator of the ice tr,ici:ne~se!.in the stud,}'reach. Tne determinatio~of the ice thickness and hydraulic roughness of t~ cover and bed was made by c method presented by Beltao~(1979).Tne method requires water surface elevation.bed geometry anC!the relationship of bed roughness ~ith stagf for the cross section to be analyzed.The sol~tion relies on values of ice roughness versu~thiCKness obtained by Nezhi~hDV~k,}'(j9&~)for jams created by ice'fioes and adjusted by beltac! for varyin9 bed shape. The relationship'of bed roughness to stagf:was detel"TTIinec bS backwater analysis without ice cover between the ~5[gaup~at 1ayior and a E.C. Hydro gauge iDeated ;-1/2 kilometres downstream.Open water stages at various 'flows were available at the two 9auge~fron.prior calibration work On open water bed roughness. The roughness relationship developed is (3) 166 - RE5ULTS AND DISCUSSIONS 169 where nb is the Manning's value for bed roughness;and Rb is the hydraulic radius for open water conditions. Simulations of ice!wa~eT l~vels within thE s~udy reach were madE for the singlE c;scharge of 1450 ~/sec.since flo~varia~ions were small 0 The sim~la~ed ice/water levels and thicknesses by the IOWAICE and HECleE progra~s.employing the calculated roughnes!values,are comparable to tr'E 1979 oeserved ipveh as shown on Fi~hJre 5.The lGLlCE pr·ogram rep'"od",cec.Hie 197!:progre~s ion and ret"eat of the ice cover at Tay10r fro~~hE observec ciimatic conditions.The ice levels simulated by the LG~lCt progra~exceeded thOSE observed in 1579.Tne program is being mOG,fied a~cordin?!j and the results are not availatle for presentatio~ a:this til1le. The above method was applied at five cross sections in the study reach. Of the five sections,cross sections 117 and 121 were located in the middle of a jam,cross section 115 was located at the head of a jam,and cross sections 119 and 124 were located between jams. The cross sections are plotted in Figure 4.The adjustments made to their area for ice conditions,as noted earlier,are also shown. The roughness values were.calculated using two slopes;the one obtained from the open water profile;the other obtained from the ice/water profiles observed during the 1979 ice conditions.The latter was available only at cross sections located within jams.The results of the analysis are shown in Table Z.Based on the results.the roughness values obtained for the observed ice/water slope at those sections within the jams were considered more applicable to the present study. Roughness at jam and non-jam cross sections differed consistently.The roughnes!of both the ice cover and the bed are higher for the sections located within a ja~or at the head of a jam. "lear,roughness values for jam sections were 0.058 and 0.092 for the bed and ice cover,respectively.Similarly,mea~roughness values for non- jalT,sections were 0.045 and 0.066 for the bed and ice cover.respectively. Tne jan,and oon-jam roughness values were wei ghted by thei r respecti ve lengtns to obtain mean roughness valUE for the s~udy reach.The mean rougnness values for the study reach were O.D4~and 0.072 for the bed cnd ice cover.respectively.These vi:1ue~were input to HEClCr and LGLIe:models.For the IOWAlCE simu1ation~.thE roughness values at the r~~pectivE sec:ions ~ere employed. :ne ice/water 1eveis com~uted at the measurement locations by IO~AICE and HECICE pr"9rar:s ert:dose to the observed values except at Jarr.5. ine sil!;~l'l':.ed HagH At Jar.5 giver"by boU,programs are consistently j{IWer U,CP.tne cb~ervec lie";ue5.Tni s su.ggests Ulat the "noati ng"jarr: V,eo'").el1"ot';oyeC:by betr;pr.,gnlr.!:'.is not applicable to Jam 5,and that Jar,5 rn'gnt t,av~beer,g'"oundec a5 inferred from the observations. ·, COt;:LUSJ 0::5 i~=s.ec or,thE:results of tne LGLlCr,IOIi':'JCE and HECler progrars.it ;~ concludec tr,et: HECIC~and JD~~:C~rroQra~s arE aDp;icable to tnf aficiy:is c· ice:~ater levels or,tIl€'P€cc€River.e,:c~:J·.it,tile caSE:d ',erg,: shoves e~er.:.,erierl:ec a:Jan [.LG~lCE rlrtQ~e:"':r{--:~ire~i::vdif"'cc:!..;o~~ "micr:wOLiic irr.;rOVf 1':S c.;,tlicarility 'tc "PeCE EiI.'H . Tnt:rougr:ness of tnt:iCE:cover ano bee fell"i;c:i vel,H·Ct i Dr.SIlO.;;C t>E:clE:terT"1neC hv usinG th€wete"SlIr'fcCE:SlOD~c:otSE'rl'ec unoer i~f conditior,;it er.;.Urf;satisfa:tcrj re;.ulu. 3) ln€c:~sis:cn:E.provide::b.t":r.'·,an.ir V"r.derKnar,~f th<:!-,."c r c 1 ogy Sect lor"LC hydro.in tr.€c.cli~::'·.'t"Jr c'"tnE ic€oct.e re~:J!"1H if:tbis pa~€r is a?~re:iateG. ThE.cross sectionc1 spacing employee in thE H::CICE and LG.:.1C£Dro;:rcn,s is im~ortant for sim.JlatioT,of )oc.atior.anc ;ens:tr.0"icE.jar:,;.. •Altnough the HFCICE sim~latior,produced c com~arabl€fre£zE'-u~,profile to trlat observed ~:itt,;r,the study react,.it did no~indicatE:thE:p"e~ence of th~jam:bejo~cross sectio~11~.Ic~jam~wer~simu16tec upstre~rr. of cross seetior.11:-'wr,€r~cro~s sect.ions were av oi1at,h at closer i r,ter\'il15 thar,i r,tn::dOl"lnstrec'"react.. Tot:,>:::5ur.::7,arizes the ice;/water ieve15 anc i C~tr.i ::.kness eE,'-l'htec by H~Clct ane:JOr;,t.,lCt:pro9ram ...Tr.e iCE;/weter lev~1s siw~;j;;i.ec bj tIlt: HE ~.J:~progra;.wert Ci OSf'r tt,tt:.;ob='€-t'ved 1t\,'el £.St,;-rf i c;ent.agree;iit:ri'! 0:·,i c(-tr,)Cknes se"is nn oL";.c i nee by tilt vari ous prD9"i1~:Cllie th 1 ~ espe:i.requires furthH investigation. IOWAICE simulations were made at cross sections located at the head of. or within,the ice jams.Simulations were carried out for the roughness values previously determined and the somewhat lower values suggested by Tatinclaux (1978).The simulations were made at the cross sections using the water surface slopes from the open water profile for 1450 m3/sec. Between cross sections located within the jams (117 and 121).the ice/ water surface slopes obtained from observations were also used in the analysis.The results of the simulations are shown in Table 3.The ice/water levels obtained by using the calculated roughness values were close to the observed levels.The use of different slopes (Table 3)at .the jam sections did not appreciably alter the results.Force balance calculations indicated collapse of narrow channels and that the jams were of the wide channel type. During the HECJC[simulations.it was found that the ice thickness at some of the downstrearr.cross sections had to be increased abOVE the rninimurr,stable thickness to provide sufficient backwater to attain stability at the section of interest.The ice cover thus thickened rr~y be considered to represent an ice jarr..The HECJCE freeze-up profile and location of jams arE presented in Table 4. .. .-_..~ .~~j;;: l'~1.,~~l(: •+~~'r >- ......._:..,f;o.;~...~%ji£~~~ttl~~l~~Z~~~~·j~~~~"E~~t~£~W· REFERENCES Beltaos.S.(1979):Flow Resistance of Fragmented lee Covers (lee Jams) Proceedings;Canadian Hydrology Symposium,October 1979.Vancouver. Nezhikhovskiy.R.A.(1964):Coefficients of roughness of bottom surface of slush-ice cover,Soviet Hydrology,Washington. Pariset,L,and Hausser,R.(1961):Formation and evolution of ice covers on rivers,Trans.EIC,Vol.5,No.1. Pariset,E.,Hausser,R.and Gagnon,A.(1966):Formation of ice covers and ice jams in rivers.J.Hyd.Div.,Proc.A5CE,Vol.92,No.HY6. Petryk,S.,and Boisvert,R.(1978):Simulation of Ice Conditions in Channels,Proceedings of the CSCE Specialty Conference on Computer Applications in Hydrotechnical and Municipal Engineering,May 1978. 'Toronto. ~etryl.,S .•Panu.U.S.,and Clement,F.(1980):Recent Improvements in "Numerical Mode1linc of River lee.Proc.Workshop on Hydraulic kesistance of River lee.CC1~Burlington.Ontario.23 -24 September 1980. 'T c :inc1al.o.,J.e.(lSi]):EquilibriUII,thickness of ice jam:.,....HyC::.Div., ~r~c.ASCE,Vol.103.No.HY9. lclinciau",J.e.(197B):A Short CourSE in Ice Engineering,River lee Ja~~,Univer~ity of Iowa,16 ~17 October 1970. L::!,mer,~:.S .•and Kenned}'.J.P..(19i4):Hydraulics and Mechanics of River Jc~Ja~s.IlHR Report riO.161,Universit.y of Io~;a.low". 171 - - TABLE 1 MAXIMUM FREEZE-UP LEVELS OBSERVED DURING FEBRUARY -MARCH 1979 OBSERVED IN THE ~~XIMUM WATER/ICE VJC]NITY OF LEVEL (GSC)(ITt ) Wise gauge 40~.7 Sf':9 ...407.58 Br·:10 not available Br~11 409.77 Br·~12 ,(10.38 Brt,14 412.06 B"~13 413,46 Br~15 4i13.B B~~19 415.68 B'~21 415.72 Br.2D 415.72 ..Lo(.ction~of BN are shown on Figure 2, 172 '"rJ ow r('r'lIet.i 011 rp.I1,1f rp.d duro to b Hurtil tion of r.hilnllP,1 around i"lilnrl, S 0.0006117 0.000290 O.0015R2 0.000449 0.001025 0.001220 0.000363 t (m)3.4 2.06 11,00 1.13 2.55 2.90 1.48 W(m)536.362.3 3IlS.R 355.5 287.2 287.3 477.8 Itf (m)3.112 4.203 3.207 3.571 2.464 2.485 3.124 It b (m)1.514 1.911B 1.479 1.905 1.452 1.449 1.823 h (Ill)4.626 6.195 4.liR7 5.542 3.917 3.934 4.942 v (m/s)0.5840 .64605 .89573 .7445 .6946 0.6908 0.6149 "i 0.09051 0.06868 0.09557 0.06650 0.0650 0.0890 0.06619 nb 0.05647 0.04169 0.05800 0.04373 0.05917 0.05992 0.04605 n 0.07490 0.05601 0.07892 0.05571 0.07236 0.07432 0.056620 ~l) NOlE:W =channel width,H =flow depth.Y :flow Yelocfty,S :water surface slope.t =ice cover thickness.R1 =hydraulfc radius due to fce cover, R ..hydraulic radius due bed,h -flow depth under fce cover,Y ..flowv~lor.fty under ice covp,r,nt ..Manning's roughness for underside of ice cover.nb =i1anning's rOIJ9h1'tess for bed,and no "Compos He Manni ng'5 roughness for bed and ice. '1' rI\/ll.l ? I!OIlGIIIII.SS AUO let TIfICr-NrSS VI\I.IIrS.--- 11'5 117 119 121 124 H50 1450 1450 780 to 1450 OP[N (1I1\N14rt OPE N CIfArlllf I.WI ru ICE oprrl CHANNEL OPEN CHANNEl WITH ICE OPEN CHANNEL COV£R COVER 4Ll.B 41?.4 1112.4 410.5 410.:18 410.38 406.7 !i'j'.0 3fi9.11 3°6.6 356.9 29Q.1 299.1 490.7 10.64 12.9 17.9 9.4 8.4 8.4 8.3 0.331)0.43 0.113 0.58 0.41 0.41 0.48 r.lm,:;')SI.CT inN NII,mrn Ilhr:hiln,I'1)(111 3/..) S1OJlr:'11';(1(1 WA'[ll SIIIlrl\rl HI:VATlllN !lVf1r;lllf'hyrlr,llllir W (lit) ".lrmn"trr..fnr orl'n "(n,l Wit !.(Or r I OW ',p"tr"ilm of crc,,,<;-'::I>ct.ion V (""~) [<;tlmitt.ed aYr.ritq~ hyrlrilulfr.pilrnmf1lp,rs ilnll rOlll1hness Ice covr.rp,d sectfon.. ~~ oJ. ;j .\':':~ • I ~i;. 'H-~) ",)} '\.':J ,~~:.~ ":"'.'".".'00'/ \"'f ~~~;~; ;':?X 'l~;~(l .~ 1'.',.;"J"q';';. .';~~';;" I :t~[: '.""t· ~~;f.';I~ .""'.1:.~!i:~ij ···'NtlLl!~,',", ii:'~J:'".'/,\;...;:./., iJ"·;1 !:~\)~l''ic:'··."....J·'~V~':1"';~~.:,'~, :?~?l :"'(,~ :'f:?:l ';':;'1:'':,; "':,;:"_~-1 :·~'\f.·l ·l'.;l~·rl;[.;:~,. ~..,." \.~~::'~"('''1:~tl ':";~;~ ·:~::'~"';l~lf~';\";!'~l!il.'il;;rl.rlj;'!fu···"~('.::~:.\::1f.~~:\ii~;F'"::;,v·:;}.:;}.;',,'~..,.i''.Y~W:'~f""···r..~··v~~"~J t··~.\·:~14."(~,~rt.~'~F>#lh'A '·~it~"~"'.~I~••\1'f;Jr.::\/:.:)}..:i-:.~j~r.~~t~;·~;:~.~?:.\~lj.";'.l!.~b;>:'~t);.:~{.~.~·.~:{l';;.:,./~fi\~.:I.r.'~.'H .."f:,';;')'~'J,;I "\~~j,.'.ii:!·i:t;;~rr':!\Ii',,~!.j'i"~::"'~"ljIl'1'.'.1,1-I ".··'·,~'1,,"-t.··.'·1i""~'d ,.&II·:~!·.'"'~~i" ".'·I,'~~;ir·c<.,~j~~';'~',-"".'."~;i.!1i;.t,.'"!)'I.(~~!;"'/:~;~~,." TABLE 3 ICE/WATER LEVELS (m)SIMULATED BY IOW~ICE PROGRAM 122 409.5 408.24 408.83 121 409.8 409.08 409.16 409.25 120 1l10.~409.71 410.19 117 412.1 411.24 411.77 115 413.8 412.00 412.30 112 415.2 4)~.60 414.71 '\ 409.11 Slope Observed During Ice Conditions Roughness Roughness (Tatinclau~(7anle 2) 1978) Roughness (Table 2) 174 Slope From Open Water Profile Roughness (Tatinclaux,1978) Observed levels GSC (m) Location! Cross-Section Number ,-J1t·trll"'t .....1 Ip ......"rl1,·....,".1'\..,.......' 1',1111 • ,.!.~ !.'~.' 2 .64 1.15 2.46 2.65 1.21 I.~A :l.Ilifi 0.P5 1.91 1.1A 0.61 2.01 1.59 2.49 2.11 2 2.01 2 2.0J 2 2.Jl 2.61 1.92 2 2.40 2.44 2 2.65 2 2.55 2 2,1fi l.n 1.19 2 ••" 2.~'I 1.26 1,50 2.51 O.lX 1.91 1.41 o.n 2.0~ 1.59 2.42 0.-4 0.'" 0.14 1,16 2.59 0.15 2.]I; O.~A 1.16 0.11. 2.1X ~"hlllty ("..Ieuln'''''(\""", X XTill 0,11 11.14 ".1ft O.II II.I~ O.IA 11.29 D.M o.n 1.11 1.10 ~.n O.IX n.29 0.21 11.24 I)." 0.21 O.JI 11.22 1I.2X 1I.2P 11.12 D.?_ II.JX ...,. ""hUh Iml '''''.R1. "lA.1,) ."n.~fi,,..rl .':." lnfll .•n 4'.'.'A \'llf.14 4f:.O •..,(- ~~.~'I 1~4 .6A '''A.~' 4"j~.-n;.,,,..." 214.M un.1Q 4:-1\.Clr~ )n.1R )?~.11 y;~.n 'rt"i.14 '1'\.00 "fi"M 51~.no )44 ••' '.'.11 tII ••il', A.IO ~O~, 1.lr. "."4 10.01 A.?A 11.61 1lII.~"i 10.16 11.0' R ••l ".'1. X.1I2 10.n 1I,f',. JI .•~ 111.11 A.P9 A.'" 1.10 R." 1.1. G.1I; 1.'1; t'wif"'llfl'l fa',f.h.if '~l II.'0;. n.qJl n".t; o.r.R I... O.AI n,R" n.II' 0.'" n.Rl n.n II.'ta 0,"Jr. n..."" n.RI n.61 n.II'.A n,Y'! 0.62 n.r.! II.A2 O.II I.ft(ll n"·l ".f,P •.r,:" :.14 ft"11 '1'\..."",.., I.U 7.11 7." 7." 7,H 1.ttl 1."I" ::-,'" 1.'Ott '.1.' ).u ?H I."' 7 ,•• 1.'1 ?lJ ,,r.Q 1."" I.'. Lit.. 2.). 2." 2.14 ,~,.tl.rl1~ ~"'l,,,,'II,,,,'r ..'I''e ••••,I 1'101''''~"..."'1 'OJ''r ,.,·.,..t 411 ...,~ tn",".1 .f'1I•.., "p,n;, 41 t.',,, ":." '11.11 ..I'.,'" •••."n 411.'" 414.:< 1M.11' .'1"•.11 411 ••"; ",:1." '17 .10 .1'." 41 1'...... "1'.M 41).111 ."'11,'14 ."'"I?"I ,tiM."r- ..In ..... 41".1'111 jOO,.t',.". "f I,.,·'!'" 41'·"" .'....1r, ·U",."l .II•.n. 41~." .",,'11' , -""Il'.thA,·lr""."..1 .,1 ••,""...1,.,...,.."9rol·1r ~"'I''''tn ....rr"Il ..IIt.,hl ....thlf·Irrv""11 lilt '1"'!"t ....,.,..-d'jan~I.f!.~jllPl l('IClIticn 1'1'...., 41 '.41 41 1,r.n 4111,." ......·tt ..1 11 ..... 411.'J" 411."" 417.2 • 41"11'••".1 "".,1'11 41 ',"'" .nl.... .fll'.""7 .."......... 414 .•'. 41'0,07 4",.;,., ..I··.·, "1",.lI.:1 'I·..·.·:I'!·J'."Ir"'l'·(>1",n"'l,"'..n tt~·"III .'a·e""r'I~" ----- .'''."i" 41:.A';, 11'1 •.n .tll'·,•• "1;;.71 ct·;.RI 41<.0< 41~.1~ 4'"'.71 ~I"'.."1 f-fl'"'r ',...'It,l'1':r,"','''1'1'1 ',,"':P1\'.Ij t,1'p.lI'.r. '1' 4'1 .... "1.11 4'1.1.• 417 .11 'II ~,I"il', ...'.1", .1 '.1"" 41'i,'r;, ,f''f•.1" "',..,....., 41'1. AI.ll.I' 4"',1)' "A."..'I1",..r. .I,....~ f 0"••". !':''d'''''11 'i.1i , 't.", 1.'1'1 ,'.R4 ~.f11 4.II 1.41 ~.lR 'J.,It .,"111 ~.•I '.45 'i.n1 1.0;1 7.,0; 1."" 1.1''0 11.77 1."" 5.n 14.1l ~.I:" l,tl 4 1."Ii'..' I~.·t'r. ·;1r"1 .... "I(t , 1....II.l'In 1.';II.n" I ...·.."nil 14',".11" 1.0;0."" "".,.n'1 "lr.,...,.., nr.,.on ft",.nn ""'.1111 14r,..,.M .tr ,,,."" 14 1 .".,," 14,·,.."n '.In,n;. ...·.".nn If',I1."" 14'·."" •f'·n.ftn 1Il,n .,1" 1..··"."" ""'n.n" 14"".(1#1 ,C'.n.('/" 14..n .O" "I'I"tlll ". t ...',•..., I~.O" ,,.,n.',l' """.011 .'0,M ·~.n.M •'.n.lI'l ":I'Il.nll ....n.nn 4r.n on '1nl'.f1l' 1\1.1.("1 il".fI" 11~1I.~n ".IMI."" •m.nll ~'I",nn I~n".~,., 17'11"."" ••···••'n 'i·0'·i',! , t ..11 11'',"n 1'11'1,In ,,~,.., .Imt';"m ;,,.',1.'(9 If.fft.:O" t/f.OI'" 111,1"111 ll/.R''11 In,n"" ',",n"" 11_..,nll IIA,IIi''' !....·Ii...., "·..·h·1 11'.'11'" "";.(",\1 "..1.MIi 114 onn 1111 nl111 1'1;'1.1 1 "'" "U .nnlt II '.nll"l 11".l1nn 1I11.0.Q '17 .""11 11"".01'" 11"4,if''''' I'tti.""" 1I'l1."nn 11f'l\.llIlA ',ft,""''' Ilt"l "11'1 CJ ... ~ , tiG:"i'(::~ .:.('~,"i I '~i\~4;·~~f·.:;·.{;:~.i..;.laV;i;:"~'tf ,:"'~'~j1-:::.~~i{'i:..·\,t-:~·t·~.,I '~,:1-;,~fl ',:: ....",j'.{',l~Jtn,$.'~'~I'li~~ ;;\;j '~:1i~~~ ~'~ ....\~i;~I'r.flii~ '~~~;~?it;t j,",t'i"l'u/,.·~~~·~' r'·1 i ,;e"';:'~':;i:';',~t;~'IV""'~'~~:~~i~;!l;~ til !'.!:i~';il~?{~'~~.!.~:~ li-""J\";~...,':..,II.tF~:~l~~t,~;',I,.'~;·';:):r~ ,J-"~~, i~'(1.·:L~1 t .•\1.......l }iitit\§ t,4 ~'•.1 ":~ }'~";"..;;;;~~t~ h:"",(''f.\!\/;."i~; i ....;~,i.:r:1 ~X;::~,~;;:~tl~ t.::\:"'1r:~;:i,:']f~~ '.1',i"'..'i'"'~ "-.~"'.'~:~. .~XP{~;~;' TABLE 5 COMPARISON OF SIMULATED ICE/WATER LEVELS AND THICKNESSES (m) ,LOCP.TlON OBSERVED ICE THICKNESS IOWAICE HECICE\. (CROSS SECTION)ICE/WATER (Table 2)Ice/Water Ice Ice/Water Ice LEVEL Level Thickness Level Thickness GSC (m)GSC (m) (m)(m) 124 406.7 1.48 406.7 '"2.59 122 409.5 40B.33 2.25 408.57 2.44 121 409.8 2.90 .1109.16 2.97 409.75 2.44 120 410.4 410.19 2.02 410.34 1.52 119 410.5 1.73 411.11 1.83 li7 412.1 4.00 <111.77 2.0B ~12.11 1.37 115 (13.8 3.4D ~12.3D 3.52 412.8:-2.D 112 415.2 414.71 3.54 41~.21 2.7'- r·(.'~' ;.."., I & ]: li- Ii·r...'less J .).• 1 ~ Cl: ~ z E.,..... ~C'c:v 0 ..l I wc:: ~ ~ ~ 1i7 _._-_._-_._-~~----~---------~----- N I " !-..,i !•..I•I iifI: II !I ~IOc>- c 60N ,,Ol~m "Ol•.lOll,\\,6H:8 "lOll 0 ",~, I . I ••\\ \,.,•I I,\ 0 1I'.lot')I I,I•I I 0 0 I [[II00...,•\WJ 0 ,1711a::I , t-•117 IIUJ. 0 5 1~!8 ~tlWe'5lt::;:,Vl00Z...J ~I 0 I -,I- :z •....,-,...,,.,., UJ 0 VlCl::>0 V"> <:(;)I e toO -ClJ ,c:: I U,....a::ClJ -I--I ...r (;)--'-•0...J ~C>-C s..•c:s..C-o ...., t-o ZCL0CLl6110 :;:s..0cClJ0 l- e:;.....,~<: I.i-tt'I e u::E ,l-e Vl c:I c--' i I-,.I I :::>e-o l V\,n:e 'OZl v, WJ w.:u -" 1 zc:~~ll~;l:•IZI 0 \ ...,U"l e:;-0 ~Cl I I i:3I I <:,UJe:;,,>-,E!,t= I •Vl I 6HE,,EZl "" t , I ...., I 7'=: 0 \t::~ 1 0 U"l 0 ..... t Il"'e U'lN--c 0 0'............C MJ ! I (w)'l'S'h ?~OS~N3I~~A313, (. .•.. ~."..~. -;"c uzc::::.... l? J 6~O 700 ,~ 416 [) o 416 397 402 402 , 412 a I 5S0 ~......:. -J.,.; :E: w 400 I >0c 800t=412~ z C I- ~>..., -J..... 400 411 ~IG.4 -CR~SS ~ECilOSS Dr Ft~:r R!VER ~tAf.TAYLOR,B.C. •" 20 ~ 2:t:m '".- ~ A Ice Th1c1cness .. ....N ~&n N,..ill MMN NNO 000 ~_r-_,...,... 15 ~.-...,tn""'....M l:J. A ....-":!::- 10 coen LOCI\TIONS or CROSS SECTIONS 0 0-N.-0-r- :E ~~co U)...... N N ~N 0-....... ----lee Thickness ~ D OnS[RVr:o EI SmULATEO III HEeleE l:I SmllLI\TEO BY 10141\11:£ LEGum FlGlIIU:5:FREEZE-UP PROFILES jj J I) 395 400 405 415 410 "70 ~J ..- E ~; ...l VI,..:r..., uJ...;::w 0 [Q ..;( ,}.';:Ct~I't rL~/,"5 :I: 8 I-~;>- LI.e ...l I.IJ '~1[~~",,___,--,\,:'t~.,:,l,;:::l.,~..tv,.....".0'".-.......1 - ,••_.,_.. :,:~rlt~:g,~ ;i!~;J-~At:1}~~01)11114((IJr,rrlnr~1IIYLOn (;11\1(01:HI KllOM[lRES I ..1 ..~...J ~,~.-l J REFERENCE 7 -1 i ~.Ir._:~ .. "-onE ::·0 w c>cr <l I U Vl is .0 I PEACE CANYON GENERATING STATION (km 376) MARCH 1982 4(j(J I !I I I !J I I I I J !I I I I I I I I I I I I I ! I J I!!I I !, HUDSON HOPE WATER LEVELS (km 368) I 4 D '- ..44 l- E. I r Ti "1 1 I r 1, h. I I 1 I I I I I r---"\! I ".-- I r-- I ,--r I I I I - 0-:x: c> w 42:x: w c> :>~o;c.r ~ 3 fj .- I \ i J I ~\...'-- I - - "'",""f 0'"001 I I I IU jU IU I I I ·I I I-I jl6lIIIIIIIIIII I I I I.I I I , I I J • TAYLOR WATER LEVELS (km 275) -24 E ,8 I !I I I I I I I • I I I I I I I I I !I I I !'I I I I I !I I • I I I I <oJ ~:::» ~cOL...----' .... X ~ ;:"2Z :r ALCES RIVER CLAYHURST FERRY)WATER LEVEL (km 233) MARCH IR·~E fRONT AT ClA'HURST ~ERRY MARCH lO (l·DO-ICE FRONT ..kill OOwNSTREAI.I OF ClAYHURST fERRY I ~ICE COVER MELTING AND I I ICE FRONT RETREATING I I WSC GAUGE OUDOIO 60 -E- ~~O Q I .' W X W ~"0 ,-:::» e:t' ~ )0 20 I I I I I I I I I I I I J I I I I I I I I I I I 'Y I , I I......! ,I ,!! , 70 ,iii iii I I i I Iii iii I I iii I I iii iii iii Iii \ DUNVEGAN SITE 2 ICE AND WATER LEVELS (km loo,n 3 424 iii til I i I I I I I t I I I I I I I I I I I I I I I I ";I I I I I I UI I '.,.,/'_o'¥\":';.:f/r, STATION 2-2 GROUNDED AT LOW WATER LEvEL STATION 2-3 TO Z·~ICE MOVEMENTS MATti"WATER LEVEL PATTERN CLi)SEL"f . DATA NOT CONTINUOUS DATA PLOTTED FROM APPLNDIX C.TAEl..ES C]AND C 4 Slt .~[CTIONS .'37 AND 4 2 AND fiGURe:II rOR LOCA1~ON Vl'l.;t 1.I00'[MflH "'O~ITORING S1/\1<£S ~34n III ..J. W> W ...J 3420 a:w... <1 ~ 341 a .- 341 b I I !I I I I I I I I I J I I !I I I I I I I I I !I I I '!1 . I I J TOWN OF PEACE RIVER WATER LEVELS (km 0) :f..'2~I"2)212••20IIIIIII MARCH IgeZ"Ib.~,..11 01lT1l fR·)1.!ClImMJ:::Us GAUGING R(C'lRDS WSC GAUGE 07MAODI 01l1A f'l ,}TTEl'l fROM /IF'I''(IIDIX II,T/IBLE 114 12II1(1 !.31~~ ...J W;. W ...J )I~2 0: W... '" :t 31~0 I I I I I I I I I ( I I I I I I I I I I I I I I I I I I !!!I I I l r Itj ~ .CANADIAN ELECTRICAL ASSOCIAT1C'4 [Ii] STUD".or ICE COVERS SUOJECT'VARVING WATfR l.[V(l"PHASE n JIElI'S1\.I('II[S APnrU; DISCHARGES AND WATER LEVELS FOR MID-WINTER TEST ..MARCH 1982 HUDJilJ ..... ..... REFERENCES 1- l~ I'~) lr- I , )~ I I I . I i~ 1 ( IF"'" L !.,F" ..... 19 B.C.HYDRO PEACE RIVER ICE OBSERVATIONS 1981-82 HYDROELECTRIC GENERATIONS PROJECTS DIVISION - I~ Report No.H1566 October,1982 B.C.HYDro HYmOE!ECI'RIC DESIGN DIVISICN DEVEI:DPMENl'DEP.ARJ.M:Nl''. ICE OBSER\7M:.rCNS 1981-1982 - CODBER 1982 REPORI'NO.Hl566 :""'" - !,., 1 t \ I 1 I -1 .- PEACE RIVER ICE OBSERVATION 1981-82 CONTENTS Section Synopsis 1.0 Introduction }.~ i I,1.1 1.2 Authority Study Program for 1981-82 2.0 1981-82 Field Observations r- I (.~ ) I 2.1 2.2 2.3 2.4 2.5 Field Trips 9-11 January 1982 Ice Observation 8-11 February 1982 Ice-Observation 15-23 March 1982 Ice Observation 23-27 April 1982 Ice Observation 3.0 1981-82 Ice Observations by other Agencies 3.1 Ancillary Studies 3.2 Acres Consulting Services Ltd. 3.3 Northwest Hydraulic Consultants Ltd. 3.4 Alberta Environment 3.5 Peace River task Force Appendix A -Observer's Diaries _______________________AA.....,.~==~============~~~~~ l_~ L'- l~ !.- (.- [ f~ i --- S Y i~0 PSI S Field observations of icing conditions on the Peace River were carried out by B.C.Hydro personnel during the liinter of 1981-82.This work is a continuation of the ice observation program initiated in 1972. The field conditions of the Peace River from Fort St. ,John B.C.to Peace River Alberta were observed on four helicopter trips.During these trips the quality and exten:t lof the ice formation were noted and water and/or ice levels ,and water temperature were measured at selected locations. A combination of low flows and extremely cold air temperatures from January 1 to 4,1982 resulted in a rapid upstream progression of the ice cover.Initial freeze-up at the Town of Peace River Alberta occurred on 2 January and the ice front reached Dunvegan by 6 January.An increase in flows after 4 January caused a rupture of approximately 100 miles of river ice which then consolidated into 60 miles of rough broken ice.As a result,ice/water levels at the town of Peace River rose to E1.1044.3 ft.i.e.within 4 feet of overtopping the town dykes.With the continuing cold weather the ice sheet stabilized and progressed upstream to mile 86 (measured downstream from GMS),20 miles upstream of the B.C./Alberta Border by 4 March. Tne breakup as in many of the previous years was uneventful and consisted mainly of thermal erosion of the ice cover. Tne ice broke up at the town of Peace River on 26 April. Various Provincial agencies and Engineering Consultants were also in the area to observe,study and make recommendations with respect to ice jam flooding hazards at the Town of Peace River.References have been made to those reports in the text. ~__,~,_,"4---------------------r-- "••-.-",.~,..111...-.~...~,,......~_.~..,~,..~....~.~_......!.....,,111!1..,~111111.1..~_..~.,~,•..l!I!Ie,.-.~~..~~"~_"".IIII!I..,-....~~-- - 2 - In addition,the Peace River Ice Task Force consisting of members from B.C.Ministry of Environment,B.C.Hydro and Alberta Environment met twice before breakup and recommended measures to control ice jam flooding at Peace River. A detailed description of freeze-up,ice cover progression and breakup on the Peace River is given in the diaries of the field observers,presented in this report. .] ) I I '1. ! - - - (~I .. L (,- i I. i·'- I I F'" I I. I~ - SECTION 1.0 -INTRODUCTION 1.1 AUTHORITY Under ter.ms of Item 1 of Assignment Number 47$-121 Revision 1,dated 28 February 1977,the Hydroelectric Design Division was requested to: "Provide engineering services related to ice studies and other .hyqrological studies consistent with the long-range System Plan in effect as follows: (a)Study,observe and compile data on ice regimes of the Peace River •••••••.••••••". 1.2 STUDY PROGRAM FOR 1981-82 A joint B.C.Alberta Task Force was for.med in 1974 to co-ordinate ice observations on the Peace River System in the Provinces of B.C.and Alberta.B.C.Hydro as a member of this Task Force has continued to make observations of freeze-up and break-up in the Peace River in each winter since 1974.The overall objectives for 1981-82, as for all previous years from 1974 to 1981,were as follows: 1.Continue to identify existing and potential hazards to life and property that are the results of ice conditions on the lower Peace River. 2.Continue to investigate the ice regime of the lower Peace River. a)Extent and production of ice cover b)Timing of freeze;up and break-up c)Maximum river stages. # .,~,.,"' SECTION 2.0 1981-82 FIELD OBSERVATIONS 2.1 FIELD TRIPS During the winter of 1981-82,four trips were made to the Peace River.The diaries of the field observer are appended to this text.A brief discussion 'of the field trips and the duration of the trips are given below. 2.2 9-11 JANUARY 1982 ICE OBSERVATIONS The Peace River ice broke-up unexpectedly on 8 January 1982 in the reach between mile 184 and mile 285.This resulted in rising ice/water levels at the Town of Peace River,Alberta.The objective of this trip was to observe and record this event.The observer was also to maintain liaison with Hydro's Operation's staff at the G.M.Shrum Generating Station (GMS). 2.3 8-11 FEBRUARY 1982 ICE OBSERVATIONS ~he Peace River freeze-up front was approaching the B.C.-Alberta border.Weather conditions were similiar to those of 1979 when flooding and property damage resulted in the vicinity of Taylor,B.C.The objective of this trip was to monitor the ice/water levels at selected stations established during the 1979 Survey. Ice thickness,ice jam locat~ons and water temperatures ,were measured in order to 'simulate the field conditions using a mathematical river ice model. 2.4 15-23 MARCH 1982 ICE OBSERVATIONS Canadian Elec~rical Association (CEA)had commissioned Acres Consulting Services Ltd.to carry out a study on the behaviour of ice eovers subject to large daily flow and ~evel fluctuations.Some of the field observations .... - -~ - - - .- a for this study were carried out on the Peace River, and,to assist in the study,B.C.Hydro Operations were requested to make large reductions in outflows from Peace Canyon Project over a seven-day period -March 16-22.In view of the year's high ice/water level and potential hazards it was decided that B.C.Hydro staff should monitor the ice conditions during the test period. 2.5 23-27 APRIL 1982 ICE OBSERVATIONS As in previous years a trip was scheduled to observe the break-up conditions.The breakup at the Town of Peace River occurred on the 27 April without any incident. --.-tT"' I~ .- \- iI:.. \- SpCTION 3.0 1981-82 ICE OBSERVATIONS BY OTHER AGENCIES 3.1 ANCILLARY STUDIES Besides B.C.Hydro,during the winter of 1981-82,the following groups carried out ice studies on the Peace River in the Province of Alberta,in particular,at the Town of Peace River. 3.2 ACRES CONSULTING SERVICES LIMITED Acres studied the effect of flow fluctuations on an ice sheet for the CEA. 3.3 NORTHWEST HYDRAULIC CONSULTANTS LIMITED Mr.C.R.Neill assessed the pre-breakup ice conditions and made recommendations to Alberta Environment for mitigating problems.expected during break-up at the -Town of Peace River. 3.4 ALBERTA ENVIRONMENT r- ...... - 3.5 Mr.G.Fonstad of the River Engineering Branch prepared a status report and proposed ice jam mitigation plans for the break-up at the Town of Peace River • PEACE RIVER TASK FORCE The above agencies maintained close liason with the Task Force and exchanged data.The members of the Task Force met in Victoria on the 15 of February,in Peace River on the 25 of March and in Edmonton on the 1 of June to discuss the ways of controlling ice jams at the Town.of Peace River.The members are to compile a report on River Ice Conditions in the Peace River Basin during 1981-82. l~ 1~ ,~ Jr-I ' \ - -,------ AP PEN DI X Observer's Diaries A r- I REFERENCE 9 L~ If, li J [j r-,~ 1,1 '>:....~ (.-'r- , 1l..J t.. Ir,~\ I 1._.":',:'", I~ i!; L.; i: l ...... - 16 B.C.Hydro Peace River Ice Observat;ons1982-83 Hydroelectric Generations Projects Division Report No.H1641 July,1983 I?elu'rl fr;!lWC R~C'd fi,D"Y?Lel'RJrmiy $,(./-Iydro S-Ap#'B t1 B.C.Hydro Hydroelectric Design Division Development Department Peace River Ice Observations 1982-1983 July 1983 / Prepared by:.....:.--I-~-~-u:"~~;:f;.;~:;=;;;:t.==---t ApP'roved by:__..c;;6.o::::.-'u:-:~~~~;:'~~~:::;.-.:-_~'~--:-_ Manager,Development Department ·~: '1 i .-..~~. ,i j '--]~, i :'1 ~ !- - ] -----L f~ r l.~ r ------------ Peace River Ice Observations 1982-83 Contents r L. F l' il .... ,,. r L..:-r'-·C.~j , L. Section Synopsis 1.0 Introduction 1.1 Authori ty 1.2 Study Program for 1982-83 2.0 1982-1983 Field Observations 2.1 Field Trips 2.2 12 January 1983 Ice Observations 2.3 31 January - 4 February 1983 Ice Observations 2.4 17-18 February 1983 Ice Observations 2.5 7-8 March 1983 Ice Observations 2.6 n-13 April 1983 Ice Observations 2.7 Breakup Diary Appendix A-Observer's Diaries r [- r rr- L r li L~ f- l I i t. r ' I .... - Synopsis Field observations of ice conditions along the Peace River from W.A.C.Bennett Dam to the Town of Peace River (TPR),Alberta,were carried out by B.C.Hydro personnel during the winter of 1982-83.This work is a continuation of the ice observation program initiated in 1972. Ice conditions were observed during five helicopter trips.The' quality and extent of ice fonnation were noted and water and/or ice levels and water temperatures were measured at selected locations including a test reach between Site C and the BC/Alberta border. As the ice front approached TPR,B.C.Hydro's Operations Control Department maintained outflows at or close to 47500 cfs (1345 m3/s) which resulted in a freeze-up level of 1034.25 feet (3l5.3m)G.S.C. Once the ice on the river reach upstream of TPR became competent,normal outflow fluctuations were resumed. Regardless of the relatively low accumulated freeze degree-day for the winter of 1982-83,the very low GMS/PCN outflows during this period permitted the ice front to progress to mile 63 (2 miles u/s of Site C) by March 7,the furthest upstream the ice front has progressed since regulation started in 1968. An uneventful break.up of the Peace River ice at TPR occurred when the Smoky River broke up and opened a channel past the townsite on April 21.The Peace River ice above the Smoky River broke up and passed through TPR on April 24. A detailed description of freeze-up,ice cover progression and breakup on the Peace River is given in the diaries of the field observers, presented in this report. r~ L L- (T~ ft 1- l; .,... .- • SECTION 1.0 INTRODUCTION 1.1 AUTHORITY Under terms of Item 1 of Assignment Number 482-083,dated 28 July 1982 the Hydroelectric Generation Projects Division was requested to: "Provide engineering services related to ice studies and other hydrological studies consistent with the long-range System Plan in effect as follows: (a)Study,observe and compile data on ice regimes of the Peace Ri ver "11. ·1.2 STUDY PROGRAM FOR 1982-83 A joint B.C.Alberta Task Force was formed in 1974 to co-ordinate ice observations on the Peace River System in the Provinces of B.C. and Alberta.B.C.Hydro as a member of this Task Force has continued to make observations of freeze-up and break-up in the Peace River each winter since 1974.The overall objectives for 1982-83~as for all previous years from 1974 to 1982,were as follows: 1.Continue to identify existing and potential hazards to life and property that are the results of ice conditions on the lower Peace River. 2.Continue to investigate the ice regime of the lower Peace River,tncluding: a)Extent and production of ice cover b)Timing of freeze-up and break-up c)Maximum river stages. 3.Establish a test reach from the B.C./Alberta border to Site C in order to collect data throughout the winter for the calibration of a river ice computer model being developed by the Hydrology . Section • SECTION 2.0 1982-83 FIELD OBSERVATIONS 2.1 Field Trips During the winter of 1982-83~five field trips were made to the Peace River.The diaries of the field observer are appended ~o this text.In addition a breakup diary was completed to cemp,le the data gathered by phone from the Town of Peace River,Alberta Environment~B.C.Hydro Operations and Acres Consulting Services Ltd.and from office memorandum,because the scheduled breakup field trip was cancelled.A brief discussion of the field trips and diaries is given below. 2.2 12 January 1983 Ice Observations Thls trip was scheduled to observe and record any adverse effects that ~ight occur to the newly fonned ice cover at TPR by flow reductiDns at GMS/PCN generation stations.Ice conditions of the Peace River from Fort St.John (mile 65)to TPR (mile 245)were noted ..Except for lower ice/water levels,flow reductions did not appear to have any adverse effects on the ice cover. 2.3 31 January -4 February 1983 Ice Observations The Peace River ice conditions were monitored once the ice front crossed the B.C./Alberta border~Field reconnaissance indicated that ice levels would not reach 1979 maximum freeze-up levels.Data collected included the rate of progression of the ice cover and will be used to calibrate a river ice computer model being developed by the Hydrology Section. 2.4 17-18 February 1983 Ice Observations The Peace River freeze-up front had advanced upstream of the Taylor bridge to the Old Fort area (mile 68).Ice/water levels were measured at selected stations established during the 1979 Survey. Ice thickness,ice jam locations and water temperatures were also measured for use in the calibration of the river ice computer model. 2.5 7-8 March 1983 Ice Observations The Peace River freeze-up front had advanced just upstream of the Moberly River and Site C (mile 66).Ice/water levels at the damsite area were measured. 2.6 11-13 April 1983 Ice Observation Acres Consulting Services Ltd.(ACSL)as consultants to the Canadian Electrical Association continued their study on the behaviour of ice covers subject to large daily flow and level fluctuations.At the request of ACSL,B.C.Hydro agreed to 1ncrease outflows from11°9 0 cfs (311 m3/sec)to 35,000 cfs (1000 m3/sec.)for a 2 -day per10d.The observer undertOOK a field trip to the ice front location to determine whether the increase might have some effect on ac 7el:rating the rate of retreat and also to obtain open water data 1n ~he !aylor area.The increase flow was not sufficient to have.any not1ceab1e effect on the rate of erosion or break-up ofthe1cecover.- [,"""" L fi- I l-e. 2.7 Breakup Oi ary The events prior to and during breakup atTPR are summarized. The Peace River at TPR broke up without incident on 21 April. i.."-..:- .F" ! I L~. \. ..... PR/rt Attach. .b ~~.I;./t--·~.~j~~r~~.'~---P.Rocchetti CO- l- ~l~: L r [:- L- l7- - Appendix A Observer·s Diaries - -----------,-..------------------------------------"'__00 _ - r-" I i ,..... REFERENCE 10 1....:, ~, ICE 1-' t ; 'l~ \.; RIVER ENGINEERING BRANCH Water Resources Management Services Technical Services Division AIOOrra ENVIRONMENT \ \ l SUMMARY REPORT PEACE RIVER ICE OBSERVATIONS 1982/83 ICE SEASON C /---------'- L __.-__.....--_"_-".'__.__"",:;,;.." --- / j , 5 - ,- II ----- \ ---\~.-----~--- .'' 1.....---------\ ---=:;;;;;;:..--,-_. .: ,- ~~' ! J, i j J-- r j I ....., 4 J~ ; 1~ j i- I l" ~ t 1 r-, j. i!.~.. !.. f;,_ t~~' ~~ ,. ~: --.'-. ~ ~V"atel~Resources ALBERTA DEPARTMENT OF THE ENVIRONME~T WATER RESOURCES MANAGEMENT SERVICES TECHNICAL SERVICES DIVISION Prepared by:G.D.Fonstad t P.Eng. Head River Studies Section River Engineering Branch L.A.Garner t C.E.T. Technologist River Engineering Branch Submitted by:M.E.Quazi,P.Eng . Branch Head River Engineering Branch SUMMARY REPORT PEACE RIVER ICE OBSERVATIONS 1982/83 ICE SEASON Ma rch 1984 l~' 1~ ~ f- j !-I- IF"" 1: 1 11-I:,.. .l !.¥i=1t :P"" '( ~_I :""" ,. - •"--.." .r SYNOPSIS This report contains a summary of the 1982/83 ice formation and breakup on the Peace River at the Town of Peace River.It contains a record of the freeze-up advance rate on the Peace River;a record of the mean daily temperature at the Town;as well as a record of BC Hydro and Power Authority's flow releases from the Peace Canyon facility in British Columbia;a record of river levels at the Town,and a record of groundwater levels in the West Peace River subdivision. Because of the very high freeze-up levels in the previous year,an attempt was made in 1982/83 to control the freeze-up level by controlling flow releases from Peace Canyon. The ice pack on the Peace River at Peace River formed during the night of 4/5 January,1983,at a steady discharge release from Peace Canyon of 1398.4 cubic metres per second.The approach and formation of the ice cover caused a stage increase at the Town of Peace River of 3.40 metres,reaching a maximum elevation of 315.35 metres GSC (1034.61 feet) at about 1000 hours on 5 January.The dike elevation across the river from the Water Survey of Canada gauging station is 319.8 metres. The increase in the river level caused an increase in the groundwater table level in the West Peace River subdivision.This attained a maximum elevation of 314.20 metres (l030.84 feet),which W2S about one metre below the lowest basement elevation in the subdivision . i At breakup,an as yet undocumented breakup sequence occurred,which ;s described herein.Breakup at the Town effectively occurred on 24 Apri 1.1983.No ice j amm;ng problems \'lere experi encec •ba ~;ce 11 y because breakup was a thermal process rather than a dynamic hydraul ic process. The experiment to control freeze-up levels was considered to be a success. ;i ,~ TABLE OF CONTENTS ....................................................SYNOPSIS ..••••..• TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES Section ............................... ...............'". Pace- ; iii iv iv 1. 2. Introduction F~eeze-up Observations ••••••0 ••••••••••••"••••••••·•••••••1 1 3.Groundwater Levels in West Peace River 3 .~ 4.Winter Releases and River Levels 4 5.Breakup Observations •••••••••••••••••••v •••••••lIIee ••••••••4 6.Summary ••oa •••••••OI!lO.04l0 •••0 •••••••II'.IiI'••O.00 •••••••••••••••6 ..... FIGURES iii ------'-----,.....__~_~a_....--_·_~~~-------------_ri·-------~~~-------_._---------------.,...- __-----------.......-........--....-.02>"'----.-----"""-------------'-----_ LIST OF TABLES Table No. 1 Fiaure No.n< 1 Breakup Data.Peace River at Peace River Town .•...... LI S1 OF FI GURES Description Freeze-up Front Location and Mean Daily Temperatures 7 2 (10 sheets)Discharges and Water Levels iv SUMMARY REPORT PEACE RIVER ICE OBSERVATIONS 1982/83 ICE SEASON by: t-' t~ L l- fi-- L r-1.Introduction '*Gordon D.Fonstad,P.Eng. and '* Larry A.Garner,CET When the Peace Ri ver at the Town of Peace Ri ver formed its ice cover in the 1981/82 ice season,extremely high river levels resulted. Therefore,recolmlendati ons were made to the Al berte-BC Joi nt Task Force on Peace River Ice to attempt to control the freeze-up level at Peace River during the 1982183 ice formation period.This control would be effected through manipulation of flow releases from BC Hydro and Power Authority1s Peace Canyon (PCN)facility. Suchan attempt was conducted during the 1982/83 ice formation period.This report summarizes the major observations and data collected,throughout the 1982/83 ice season,for the Peace River at the Town of Peace River. 2"Freeze-up Observations """ The first observation of the freeze-up process was provided by the RCt~P Detachment in Fort Vennil ion,wherei nit was reported that the Peace Ri ver was frozen over there by 23 November,1982.Alberta Environment commenced observations of the freeze-up front on 6 December, 1982. Observations on 6 and 9 December,1982,showed an advance rate of 22.8 miles per day,which triggered the realization that at that rate of progression,the ice front would be at the Town of Peace River (TPR)in 3.2 days.As the procedure recommended by the Joint Task Force fall owi n9 the 1981/82 ice season was to have BC Hydro hol d ,thei r discharges steady once the ice was forecasted to reach TPR within 48 hours,Be Hydro was contacted. River Engineering Branch,Technical Services Division, Alberta Environment 1 2 Be Hydro was requested by the Joi nt Task Force to hol d thei r discharge releases from PCN relatively steady in the range 14B6 to 1401 cubic metres per second (m 3 /sec;or 52,500 to 49,500 cubic feet per second (cfs)),with a target mean of 1444 m3 /sec (51,000 cfs).Hydro commenced this operation on 12 December,1982,and with only occasional variation,maintained releases within the requested range.This ~ias carried out in spite of the fact that they did not have a power load or export demand to justify these high releases. Fi gure 1,attached,shows the progress of the recorded freeze-up ice front location on the Peace River,'in terms of river miles below the WAC Bennett Dam,as well as mean dai ly temperature at the iown of Peace River.(These latter were determined by averaging the daily maximum and mi nimum temperatures recorded at the Peace Ri ver Ai rport.Subsequen: analysis has shown that this mean can be considerably different from e mean calculated using hourly temperature data,which would more accurately reflect the true mean.)Figure 2 (10 sheets)records the 3-hourly rel eases from PCN;the recorded hourly water surface el evati or. as a gauge height at the Water Survey of Canada (WSC)gauge at Peace River;and,recorded mid-day groundwater elevations (in terms of equivalent gauge height)from a recording well established in West Peace River by Alberta Environment. Unfortunately,once the steady discharge release program was esta-blished,a moderating trend in the weather slowed the ice progression rate to an average of 2.63 miles/day,as shown in Figure 1. AHerna te ly,the slow-down mi ght ha ve been due to a cha nge ;n the hydraulic characteristics in the river between different reaches.A few more years of record will be required to determine whether this was in fact the case.Local variations in advance rate,however,dictated that the steady PCN releases should remain in effect.Figure 1 shows that the ice front passed through TPR on 4/5 January,1983,which ;s substantiated by the recorded water levels at TPR,shown in Sheet 2 of Figure 2.The mean peN release over the period 1 to 5 January,1983. for which the ice cover would have set in at,was 1398.4 m3 /sec (49,380 cfs). As can be seen on Sheet 2 of Fi gure 2.the net stage increase at TPR for a relatively constant release from peN was 3.40 m from 28 December 1982 to 5 January 1983.The duration of this increase reflects the approach of the ice-staged water levels,felt at TPR because of the backwater effect from the ice covered river downstream.The effects of the approaching ice cover were first felt when it was in the order of 17.5 miles below the bridges at TPR. The peak stage attained was gauge height 10.55 m (to Elevation 315.35 m),which was about 0.5 m higher than that attained during the corresponding initial staging on 2 January 1982 (10.0 m);but was 2.80 m lower than the highest stage attained in January,1982.This higher staging level in 1981/82 had been caused by secondary staging accompanying the telescoping of the ice cover on 7/8 January. .... -, r- 1- J I. ..... " ~-.f*A i,.- I~ ...., .... 3 Be Hydro had been balancing power production due to the continued high releases from peN by cutting back on releases from their Columbia River plants.As they had to maintain certain riparian flows on the Columbia,they asked the Joint Task.Force if they could cut back on their PCN releases to allow higher flows in the Columbia.The Joint Task Force members agreed on 6 January,and the cutback to a mean release of about 1050 m3 /sec (37,000 cfs)occurred on 7 January. Figure 2 shows the peN releases,river levels and groundwater 1evel s at Peace Ri ver for the balance of the ice season.Nothi ng untoward occurred for the balance of the winter. It was judged that the first attempt at controlling the freeze-up level at TPR was successful • 3.Groundwater Levels in West Peace River During the 1981/82 ice observation period,it was ascertained that groundwater seepage problems in basements in West Peace River occurred when the stage in the river exceeded 11.0 m •••for the ice conditions prevalent that year.By contrast,the highest recorded groundvlater level for 1982/83 (of three observation wells established by Alberta Environment)was 8.0 m (Figure 2,Sheet 3,and Note to Accompany Figure 2)• The data shown in Sheets 2 and 3 of Figure 2 indicates that the groundwater table began responding to the increase in river stages within about 40 hours,and when the net increase in river stage was only in the order of 0.65 m.The groundwater level raised approximately 1.73 m in the 19 day period from 29 December 1982 to 16 January 1983.The data indicates that the groundwater level appeared to remain in the order of 1.0 to 1.5 m below the adjacent river level for the balance of the wi nter*• During the initial river staging,the rate of rise of the groundwater level increased on about 2 January,1983,when the river level was about 2.4 m higher than the groundwater level.The groundwater level continued to rise after the river staging was complete (and even as the river stage dropped following the lowering of PCN releases on 7 January),driven by the differential head between the river level and the groundwater table.The groundwater level reached an initial peak on 16 January as a result of the staging.and a second slightly higher peak on 22 January in response to a short duration increase in the river level • The recorded groundwater elevation on 22 January,1983,was Elevation 314.20 m (1030.84 ft).According to the TPR Town Engineer, the lowest basement elevation in West Peace River is Elevation 315.25 m (1034.30 ft).Thus it should be possible to set the Peace River ice *Note:These levels are subject to correction as outlined on the 'Note to Accompany Figure 2\ 4 levels at TPR approximately a metre higher than in 1982/83,though this would leave little margin for groundwater level fluctuation throughout the balance of the .winter.This metre increase should be taken fro~the gauge height following the levelling off and slight reduction in river stage caused by the roughness of the underside of the ice cover smoothening out. Because the discharge releases from PCN were reduced on 7 January, the above maximum groundwater levels are likely less than they would have been had the release of 1398.4 m3 /se (49.380 cfs)continued for another week or more.As the discharges were reduced,causing a reduction in river stage commencing in the mid-afternoon of 9 January, there was insuffi ci ent data to ascertain whether or not groundwa ter seepage problems would have occurred for the particular peN releases. 4.Winter Releases and River Levels From 21 January to 24 February.Be Hydro's power releases from PC~ were low,being in the order of 500 to 600 rn 3 /sec (l7,660 to 21,190 cfs).These were further reduced to about 450 m3 /sec (15,890 cfs)over the period 25 February to 25 t·~arch.with only a few instances of peak releases in the order of 700 m3 /sec or lower.PCNreleases were again reduced on 25/26 February to in the order of 320 to 250 m3 /sec (11,300 to 12,360 cfs)until 11 April 1983,again with isolated peak releases. - Throughout this period,the water water levels at the HSC gauge tended to drop with the reduced releases.Beginning with a gauge height of about 8.5 m.the river level dropped with successive reductions in discharge to in the order of 8.0 m,then to about 7.5 m.On 6 April the river level began to rise,with no corresponding increase in PC~ releases,hence likely reflects stepped up local inflows from snowmelt. Be Hydro stepped up their releases for 12,18 and 6 hours on 7,8 and 9 April,respectively,however these were after the river level at TPR began to rise.The total increase was about 0.75 m over the period 6 to 12 April.- 5.Breakup Observations On 11 Apri 1,BC Hydro increased the PCN re leases to about 1000 m3 /sec (35,315 cfs)for a 51 hour per;od.Thi s increase foll owed the philosophy set out by the Joint Task Force during the 1981/82 breakup period.to try and initiate breakup in the Peace River before the Smoky River broke up,as experience had shown that if the Smoky broke first it would tend to cause ice jamming problems for TPR. During the 1983 breakup,a breakup sequence occurred which,to the best of our knowledge,had not happened in the years since ice studies first commenced at TPR.In previous years,either of two breakup sequences had been noted at Peace Ri ver.One sequence was that the Smoky River has broken up first,e.g.,1979,forcing its ice into the Peace River.When this occurs,high water levels have been experienced at TPR,caused by jamming of the excessive ice in the river.In f - I i r ..- " f'ii1lI'il"$, ~" ~~ .... .- .... -- .-- - ~ - ,.... ..... 5 most years,however,the Peace River has broken up first,e.g.,1982. In this sequence a main breakup front travelled down the Peace River in an orderly fashi on,causi ng breakup in ei ther a therma 1 or dynami c manner.The Peace River ice at TPR has been cleared out through this sequence before the Smoky River broke up. In 1983,however,the Peace River opened up a narrow lead in the ice through the TPR reach,by thermal processes,before the Smoky River broke up and before the main breakup front was anywhere near TPP..The lead opened up on 14 april,some ten days before the main breakup front passed through TPR.In the intervening time it grew in both length and wi dth,such that by 24 April upwards of 80';;of the wi dth of the ri ver was clear of ice. The following summarizes the major observations made during 1983. Ri sing stages at TPR on 14 April,in response to the increased releases from peN on 11 April,caused the ice cover to flex,and areas along the lower bank-ice-hinge-lines filled with water.Concurrently, an open lead developed just below Lee Isla~d in the right hand channel around Bewely Island.The main breakup front was still well upstream, being in the order of 120 miles away.By 22 April this lead had extended upstream,coveri ng a reach from just above the mouth of the Heart River to just below Lee Island,and occupying the right hand channel around Bewely Island. The main breakup front was reported to be at Mile 124 on 12 April, retreating about 3 miles per day.By 20 April breakup had occurred at Dunvegan (Mile 182.8),with all ice floes in the river clearing Dunvegan that evening . On 21 April the lower 2.5 km of the Smoky River ice was gone,but had not shoved into the Peace River ice.Presumably the floes were entrained into the Peace River flow and carried away.Flow was breaking out onto the Peace River ice.The remainder of the Smoky River ice melted in place. A later report on 22 April had the open lead at TPR developed about 80%of the way up to the mouth of the Smoky River,and extending downstream to about Mile 250.5.At 2000 hours that day,the main breakup front was located at Mile 229.2,about one mile upstream of the Shaftsbury Ferry.The ice cover between Mile 229.2 and the mouth of the Smoky River was,however,still in place. At 1100 hours on 23 April,the ice front was located at ~1ile 232.5 (2.5 miles downstream of the Shaftsbury Ferry),and had about 1.9 miles of broken ice jammed in the river upstream of it.By 2100 hours the front had moved down to Mile 233.4,and had 1.1 miles of jarrrned ice floes behind it. On 24 April at 1000 hours the ice front was at the MacKenzie Cairn observation point (Mile 235.30),and commenced moving at 1015 hours • Progression of the front was in a similar'manner as had occurred in - - ..... ;-, 6 1982~with leads melting out ahead of the front,then the jammed ice moving down into these leads and coming to rest.The breakup front passed Mile 236.89 (Correctional Institute pumphouse)at 1340 hours,and passed Mile 240.18 at 1535 hours~with jammed ice extending upstream to Mile 237.79.The ice thickness was estimated to be in the order of 0.6 to 0.7 m. 6.Surrmary The 1982/83 ice season on the Peace River at TPR was uneventful. The ice pack built in at a level that did not cause seepage problems in -. basements in West Peace River.The manner in which the ice cover built in indicates a successful attempt at controlling freeze-up at TPR (for the meteorological conditions experienced that year). Upon reaching the open lead below the mouth of the Smoky River~the front progressed quickly.A local peak in the Peace River stage occurred at 1720 hours on 24 April ~reaching a local maximum gauge height of 8.940 Tn at the WSC gauge.By 25 April at 1500 hours ~the breakup front had progressed downstream to Mile 270,some 24 miles belo~ the Highway 2 bridge at TPR. A breakup sumnary table,including the data for 1983,is included as Table 1.As can be seen in the table,the peak river stage at 'breakup'on the Peace River at TPR on 24 April was only 0.35 m higher than the five-day average pre-breakup stage.The reason for this can be readily seen in Sheet 9 of 10 of Figure 2.The local lowering of water levels on 22 April was likely due to the enlargement of the open lead through TPR.from 23 to 24 April a rise in stage of about 1.07 m accompanied the passage of the breakup front,however,to be consistent with reporting criteria from previous years,the peak on 24 April was 0.35 Tn higher than the previous five-day average level. I ~ I ~ I I I I I r I f While the ice cover was built in at a fairly high discharge,in order to allow BC Hydro some leeway in their release operations for the balance of the winter,this leeway was not fully tested~Due to a low power demand throughout the balance of the winter,Be Hydro cut their releases to well below average. The data indicates that it may be possible to increase the level at which the ice was set in,by approximately a metre. Breakup was uneventful in 1983,the dominant process being thermal deterioration of the ice accompanied by a 'melt front'rather than a dynami c breakup front.A new breakup sequence was observed at TPR in 1983,being the melting of a substantial open lead at TPR well in advance of the approaching 'melt front'. A comprehensive set of data were collected through the 1982/83 ice season,which should greatly assist future analyses. ; I, Year Breakup 5-Day Pre-breakup Discharge During Oreakup Maximum Ice Jam naximum Stage Increase Date Elevation*l Peace River Smoky River Elevation Above Pre-breakup Elevation (m)___Above_Smoky -.BJver,~~b_ove CO,n.fLuence*3 (m)(m) I-~ I J .... )k -"-"'-.~~r---- 'll"-..J"'~l i -~i.-J ..'l J -~L'""1 -~1 -·[1 -,.'1 ~~'"''I -!"l -''1 -"J "-1-'"1-.,"t ..;l _.']..,j ----~1--'-.-I_._~....•-.-..._'._"'L.,~~......-J -.,,.--.1 ~..................... TABU 1 Breakup Data Peace River at Peace River Town - ~- - 1- I, JULY 5 10 15 20 25 AUGUST 5 10 15 20 25 SEPTtMBER 5 10 15 20,~ ClCTOSER 5 10 15 20 25 MILE S'11 ~ 2..3 A./"22. NOVEMBER 5 10 15 20 25 -- ....~... ..,....~.-.....-.............-..-.......- ~...::.::__4 _:::.... ..........I .~. ..- _..':::::'--F:tS : -':F:::;:"i':T::~>::' ._.;::::::~::~:~:.-: .....4.._.........._--......-t·-~ ......----......__...._-_- ~.:.',:;"'- 5 10 15 :!C 25 JULY 5 10 15 20 25 A.UCUST 5 10 15 20 .b SEPTtMBER :.10 15 20 25 lX:TOll:ER :.10 15 20 25 NOVEMBER 5 ]0 DEl ______._...:z:·· -...,...AJI'II!l._..)UN( t4:t r ~Ca t~t",':W''''",""...."""...,..,....-=-;~·FRi~~ilif:&~1a;,~i;;:i~~£r.1:.i~--~·_-====~ ?r.rA~:RtwAt!Ic.r.::OrtieltvA T.m;",r-~:tr6Z:/~:J. .:-~::..:-.--._.-_--_-._.....-..--- - _.:::::-~---.:-l-:::...:-. _.~ • -. -5'.10 15 20 Vi> JANUARY -.......~-~.-.-_._- 5 10 15 20 25 fEllRIJARY ;;10 IS 20 25 MARCH ;;10 15 20 25 APRIL 5 10 15 20 2S lolA,. ., i"~~ i l~ t~ 1- Note to Accompany Figure 2 - ,'- .... ,,- ...... ...... A note should be made before any reader attempts to compare groundwater 1eve 1s recorded in 1982/83 wi th those recorded in 1981/82.The data for 1981/82 was plotted by subtracting the ~lSC gauge zero elevation from the groundwater elevations to obtain an equivalent gauge height.However,this then did not include an allowance for the fact that the water levels in the river adjacent to the groundwater wells was in the order of 0.97 m higher than the river level at the WSC gauge,due to the distance between the wells and the gauge and the final longitudinal slope of the ice covered river.This resulted in a plot which showed the groundwater 1evel hi gher than the ri ver 1evel,whi ch was found not to be the case.The 1982/83 data has been corrected to incorporate this difference,hence make the river level/groundwater level data more compatible. The River Engineering Branch considers that it might have made an error of up to 0.4 m in adjusting the groundwater elevations to equivalent gauge height.Thus the plotted points in Figure 2 may be 0.4 m lower than they should be.This error will have to be verified through a more detailed calculation procedure involving the river levels recorded by Water Survey of Canada at their gauge at Peace River,plus those'recorded by Alberta Environment at the Peace River Correctional Institute. ------_.---------------==========......"".~~~-------- '""", .-;'"~.... "-;: .'::r":::•.~.';;-.~ . _.-.....-;-l -'~t ~..- .'.....*:.:;..-.. ""P:: ,£1 St.l.~~.~.+-,,"..~~ ......:..~........-----...-- ---------..--"1 =".., ----.,,"".';'~~w·.:~"':"_ . t·~~~·:7.-.~~"P"~~~----..,..".......'..---.~, '.-~::~>..-_:;;~:--~'-."":.:.r.,_...... " '...I~'-'. '-;"':::'~~'~"'_~1..,..Jt:...;...:~~.;;" -ill ·a -----.. ;t r ,- _-:".. i: --------- _~'-._~_•....a==a---_ ....,;.:..-"~:..-- •p".-:;.~~.'~.:..;!.50:-~". :..-:-..'.~ .;-.~-~4'11613 - ~"c.""_•.-"~:--'~.:.-.:'.~,. ~-~..:,;.~.'...-~:~-:;"-'-'";..,~- ..~:....'.._:~....;.. 1::"-r.o"·:-~...:;.'".:.:-~.: ....":'"-..:...~~.:;,..............- ,.'....,." - ." -;;':i::.:.-:~..;-~ '-..l.. "'='.....~. .,.K.E ~'rf~CJlrT~~••~ .-. c '"~ _. ~ ~ ~ "illililii/I - - ~ I I l. I~ - ..- ~.....".. REFERENCE 11 l~ \_.-j ICE '\,..a { RIVER ENGINEERING ·BRANCH Water Resources Management Services Technical Services Division AIb3rra ENVIRONMENT ~. \ , \, r---'~ //--.~ 1982 SPRING BREAKUP AND ~iOtlITORING REPO ". "~"".~ / ~:~\ / --.----- {~ i --- ~------.-.~ 1,.---- /' -.' 'j'f"'"---_{~--.\--..::.:.:-._-- J• ATHABASCA AND CLEARUATER RIVERS AT FORT Hd1URRAY -, L~~ -("'"" t -'""'" iF"" Ll IF"" I ~ \.. .... - . j ALBERTA DEPARTt·1ENT OF THE ENVIRONt1ENT HATER RESOURCES r·1ANAGEttENT SERVICES TECHNICAL SERVICES DIVISION Prepared by:H.Rickert,C.E.T. Technologist River Engineering Branch Submitted by:M.E.Quazi,P.Eng. Branch Head River Engineering Branch 1982 SPRING BREAKUP AND MONITORING REPORT ATHABASCA AND CLEARlJATER RIVERS AT FORT Mct1URRAY December 1982 -------.-.----,--------...-.=========".,."",.."".,..""..."".====== L~ -1L "'1.I L ... j l_ -1(.~ j L. \ 1 1 rod.. ~~1 .., L ".J. - ;,~ ".JI .J •.J FORHJARD The following report,which describes the 1982 spring breakup event at Fort Mcf'1urray,is part of a continuing research pr0Q,ram to study breakup and other ice-related phenomena on Alberta rivers.This program is carried out by the Civil Engineering DepartMent of Alberta Research Council in co-operation with Alberta Environment and Alberta Transportation,under the auspices of the Alberta Co-operative Research Program in Transportation &Surface rJater Engineering.The prime intent of this report is to document the 1982 breakup in order to facilitate future comparisons. The Athabasca River in the vicinity of Fort t1cf'1urray normally produces ice jamming during breakup.In some years severe ice jams have ca,used high water levels which resulted in extensive flooding of the lowlying areas within the City of Fort Hcrturray. In 1982,breakup at Fort HcHurray occurred on Apri 1 26.At the f1acEwan Bridge gauge a 5.25 Tn increase in stage was recorded above a pre-breakup ice surface elevation of 241.5 m G.S.C.The progression of the breakup was observed from Grand Rapi ds to Fort Mct-1urray.Uater levels were taken bebleen Little Fishery River and Poplar Island,and mi scell aneous vel oci ty measurements were taken at the f,'acEwan Bri dge. Temporary jamming was observed at five separate locations upstream of the MacEwan Bridge,and a jam lasting for approximately 3.5 hrs occurred between the HacEwan Bridge and the confluence of the Clearwater River. In addition to the data presented herein,there are numerous 35 mm color slides,additional color prints,8 mm film and newspaper accounts of the breakup available from the various co-operating agencies • ; ___•__.......--r__'----------------,r- ACKNOHlEDGEHENTS T.Ridgeway and M.Anderson of Alberta Research Council assisted in the coll ection and recordi n9 of the fi e.ld data.E.Emery (summer student)Alberta Environment assisted in the assembly and preparation of the data.The Public Works Department for the City of Fort Mcl~urray collected and suppl ied the gauge information for the Clearwater River; D.Andres,,P.Eng.of Alberta Research Council made helpful comments in the preparation for breakup and in a review of this report.G.Fonstad, P.Eng.of River Engineering Branch,Alberta Environment also reviewed th;s report. ii .I \ -, ..-f ,.J, ':',4e- l -I{,- .I l. -.~ - - , r TABLE OF CONTENTS FORE\·IARD ~............ ..; ACKNO\JL EDGEr\1ENTS ; ; TABLE OF CONTENTS a-.........................................................................................iii LIST OF FIGURES ............•...................•......•......•.•..iv LIST OF PHOTOGRAPHS .•...........••.•..••.••.•••.••.•••~••.•.••.••.v LIST OF ABBREVIAT10NS ••••••.••••••...••.•.•.....•••••••••.••••.•••vi ItlTRODUCTION.......................1 PRE-BREAKUP CONDIT10NS AND·SUMMARY •.....•..•••••••.••••••.••••••.•3 BREAKUP II -....... ...... ...... .... .... .. ..............••.. ...... ...... .. ...... .. .. ........ ...... ..............6 JAMMING AND RELEASE DOWNSTREAM OF MacEWAN BRIDGE .•••••••••••••••••8 CLEAffiJATER BREAKUP AND MON1TORING .••••••.••••••.•••••••.••••••••••10 CONCLUSIONS AND DISCUSSIONS OF THE 1982 BREAKUP .•••••••••••••••••••11 REFERENCES FIGURES PHOTOGRAPHS iii Figure No. 1 2 3 4-5 6 7 8 9 10 11 12 LIST OF FIGURES Description Location Plan -Drainage Basin Athabasca River at Fort McMurray . Maximum and Minimum Temperatures (March - April 1982) Cumulative Degree Days of Thaw (Spring 1982) Pre-breakup Reconnaissance and Jamming Locations April 26 -Breakup at Fort McMurray Jamming and Release Downstream of MacEwan Bridge (April 26) Gauge Height and Velocity Profile f1acEwan Bridge (April 26) Christina River -Clearwater River Breakup (April 27-29) Gauge Locations -Clearwater River Gauge Height Readings -Clearwater River (April 26 ...29) Highwater Mark Survey -Athabasca River iv I- i i 28. ~. I-t' ~L~ - -,- INTRODUCTION Based on 24 years of recorded data (1958-81)the average break.up date of the Athabasca Ri ver in the vi cinity of Fort Md1urray is Apri 1 Ice jamming during the break.up event is not uncommon. Between Fort McMurray and the mouth of the La Biche River (Figure I)the time of breakup deviates from the usual pattern that follows the warming trend which is typical of the area upstream of the Town of Athabasca and the more southern portions of the Athabasca River 'drainage basi n.Often,the fourteen rapi d secti ons between Athabasca and Fort McMurray break up when there is only a slight increase in discharge.In this reach,the high channel slope gives rise to larger velocities and shear stresses,which can initiate breakup well in advance of other sections of the river.When the ice in the rapid sections deteriorates, ~it moves downstream,accumulating in areas of low velocity.As the discharge increases and the ice deteriorates further,small jams move dO\·mstream,compound and alternately move,jam,and buildup again.In most years these small jams have compounded into a severe jam which can cause stage increases of 2-10 m above normal summer water levels In 1982,breakup on the Athabasca River at Fort ~~c~'urray occurred on April 26 and a maximum increase in stage of 5:25 m from a pre-break.up ice surface elevation of 241.5 m G.S.C.was recorded at the MacEwan Bridge.Temporary jamming was observed at five separate locations between Cascade Rapids and the MacEwan Bridge.A jam lasting for approximately 3.5 hrs occurred just downstream of MacEwan Bridge. Doyle (1977),Doyle and Andres (1978)and Doyle and Andres (1979) prOVide the,most recent references which document the more significant 1 2 ice jamming that has occurred in the past decade.References are also provided in earlier reports which document major ice jams which occurred in the Fort McMurray vicinity prior to 1970. - - l!.~ ) ~l ~ \l ~ 1 1 I l~ I 1- II c-. i,,.....t, r-1""-_. ii_ f"'"-- I_ i; ~. i- ll' <-,~: ~ .1. ..... . 3 PRE-BREAKUP CONDITIONS AND SUr~1ARY The following section of this report is a summary of the information collected from various agencies prior to the 1982 breakup. This information can be compared to that from previous years,and may have application towards the prediction of future breakup or other ice related phenomena associated with the Athabasca River. A summary of the relationships among discharge,air temperature, and degree days of-thaw during breakup for the Athabasca River at Fort McMurray are provided in Figures 2 -3.Additional data collected prior to breakup was recorded as outlined below: narch 9-10 (photosJ &2)-A ground and aerial reconnaissance flight of the of the Athabasca River from Crooked Rapids downstream to Suncor was made with D.Andres,Alberta Research Council.The primary purpose of the flight was to ~stablish a series of geodetic bench marks to aid in monitoring fututebreakup and ice jam flooding in the area of Fort McMurray.The following conditions were noted at that time: solid ice cover from Crooked Rapids dO\'tnstream to Suncor, accumulated precipitation since November was 78%of the normal, -average temperatures were 1.4°C above normal,and a monitoring and an observation program was set-up with WSC and ARFC. "1arch 25 -Air temper-ature and precipitation were monitored for Slave Lake,Athabasca and Fort McMurray . As of ~~arch 26 -solid ice cover remained on both Athabasca and Clearwater channels • -minimum daily temperatures remained below O°C during the night -mean daily temperature between March 19-23 =5.5 0 C• ., 4 - 4 mrn of additional precipitation since March 10,and snow on ground (SOG)=32 cm. April 1 -Based on available snow pack data,1700-2266 rn 3 jsec was predicted as the maximum flow for breakup (1:2 year flood Q =2200 rn 3 jsec). As of April 5 -solid ice cover remained -between ~1arch 26 -April 5 there was 16 hrs of thaw (DOc) -heavy snowfall between March 28 and March 31 resulted in an additional 26.2 mm of precipitation -snow on ground =52 cm -mitigative measures to induce thermal weakening of the ice cover were discussed with the City of Fort McMurray April 8:-Daily monitoring commenced on W.S.C.gauging station for the Pembina River at Jarvie,Athabasca River at Windfall and Athabasca River at Athabasca.There is no telemark reporting daily for the Athabasca River'at Fort McMurray,therefore,lead times of 7 days on the average between breakup of the Pembi na Ri ver.at Jarvie and the Athabasca Ri ver at Hondo and 2 days between the Athabasca River at Hondo and the Athabasca River at Athabasca (Andres -1981)were monitored c10sely to assist in predicting the breakup event at Fort McMurray (Photo ~'s 3 & 4)• April 14:-There were open leads developing in the rapid sections. -An additional 84 hrs of thaw (DOC)occurred since ,April 5 total =124 hrs.. -There was 24 hrs of continuous thaw (DOc)between April 12-14 April 16 (Photos 3-17)-Aerial reconnaissance was made from the Athabasca -Pembina Confluence to Fort t1ct1urray. -open leads in the rapid sections were enlarging and there was only a slight breakup of the ice cover surrounding the leads. - ;-- :tJ~ =tel -1 ,J. -1 ' '", .., !~"','i :~,,'.- i ..1 5 April 19 -An additional 82 hrs of thaw (DOc)occurred since April total =224 hrs. -continuous thaw was recorded between 0700 hrs,April 17 to 0200 hrs, April 19. -additional precipitation since April 15 =7.5 mm.Total ·precipitation since Novel':1ber =93%of the nonnal. -snow on ground was reduced to 15 em. -aeri a1 reconnaissance was pl anned for April 26 or sooner if the warming trend continued • April 25:-Blasting materials were transported and available in Fort !·1ct1urray as of April 25,1982.Blaster waiting in Peace River to be placed on stand-by in the event of a serious jam that could cause flooding to Fort McMurray. there was continuous melt since April 19. -last report of snow on ground April 21,6 em,additional precipitation =nil. -Athabasca River at Athabasca stage increased 1.2 m from April 19,1982 -April 25,1982. -breakup for the Athabasca River at Athabasca occurred between 1530 - 1800 hrs on April 24,1982. 6 BREAKUP (April 26 -Photos 19-34~37~38~40) On the morning of April 26,an aerial reconnaissance was made from Fort McMurray upstream to Grand Rapids.The toe of the main ice run had proceeded to Long Rapids by 0857 hrs (Photo 22).There was running ice from Long Rapids upstream past Grand Rapids and then as far upstream from Grand Rapids as could be observed from the air (Photo 19).At that time,from the area of the toe of the main ice run to a location described as the cabin site (Photos 26.&27),which is downstream of Cascade Rapids,the channel was free of running ice (Photos 23 &24). From the cabin site,(Photo 25),a consolidating weak ice cover extended to a point just upstream of Mountain Rapids.From upstream of Mountain Rapids,there was competent ice which extended downstream through Fort McMurray and past Tar Island. The toe of the main ice run met the head of the consolidating ice at approximately 1200 hrs.At the cabin site there were signs that previous temporary jamming had occurred prior to April 26,(Temporary Jamming Location #1,Photos 25-27).Between 1200 and 1330 hrs temporary· jamming was observed at Locations 2 &3 before the impact of the main ice run pushed into the head of the competent ice immediately upstream of ~1ounta in Rapi ds (refer to Fi gure 4-5 and Photos 28-35).Between 1330 and 1504 hrs another temporary jam developed through "1ountain Rapids as a large solid ice sheet,which covered the entire width of the channel,moved and pushed its way through the rapids (Photos 28-29). Additional jamming was not observed but from measurements of the shear walls at Locations .4 &5,it is estimated there was temporary jamming between 1504 and 1640 hrs (refer to Fi g~re 6 :-:a.nd Photos 35-36). - l.~ ,i ti i I~ , I l,eI ,I 1r- ,l l~ I 1 AI' I [ I .=- l {~ I II r'~ i I '--. --,I ,"....' t ,~l i .... .~. i_~_ 7 At 1640 hrs (Photo 37)the running ice had reached the r~acEwan Bridge piers.Additional jamming took place through the bridge and immediately upstream of the Clearwater Confluence for 3.5 hrs until it released and moved past the confluence at approximately 2030 hrs (Photo 41). 8 JAf1tUNG AND RELEASE DOWNSTREAt·'OF t1acEUAN BRIDGE (between 16:40 hrs and 20:30 hrs -April 26,1982) The maximum gauge height recorded at the MacEwan Bridge during breakup was 246.75 m G.S.C.(refer to Figure 8). As previously mentioned,the moving ice reached the MacEwan Bridge at 1640 hrs and spent approximately 3.5 hrs consolidating and building head behind it.At 1700 hrs reverse flow was observed along the left bank of the Clearwater channel at Roche Islands.The Athabasca flow was entering the upstream side of the CleanJater channel while the Clearwater flow was still passing the downstream side. Slight movement occurred in the main Athabasca channel and at 2000 hrs a spillover or release channel developed downstream of the flacEwan Bri dge,di rectly opposite the Cl earwater Confl uence (refer to Figure 7 and Photo 40).At 2030 hrs movement commenced immediately downstream of the MacEwan Bridge.The first spillover channel became blocked with competent ice in the far left channel immediately dO\·mstream of the MacEwan Bridge. Between·2030 and 2055 hrs the enti re 1eft si de of the channel released with a flow velocity of"approximately 3.5-4.5 m/sec.There were solid ice sheets tossed against one another,with water spouting and the flow turned a dark chocolate brown indicating the bed was eroding.The running ice proceeded dO\'lnstream,and from the observed shear walls,evident in Photos 61-62,there could have been temporary jamming just upstream of Poplar Island sometime after 2055 hrs. At 0800 hrs the next morni ng the stage had dropped approximately 1.5 m at the MacEwan Bridge.The Athabasca channel was open,but ] j - - - - tr!! j 1-- i l~ .I \r I I .i I f""" ! l i, I , \_.... '-. t..., ... .""'. 9 running ice was still present downstream to Tar Island and past the McKay Sri dge.Competent ;ce remained in the Athabasca Channel at the Clearwater confluence.The flow from the Clearwater River continued to pass with only a slight increase in stage and no overbank flooding along the Clearwater channel was observed. = 10 CLEARWATER BREAKUP AND SUMI·1ARY (between April 27 &29) Monitoring of the Clearwater River was continued after the Athabasca breakup,because of the remaining competent Athabasca ice at the confluence.This ice did not move during the breakup and the ice cover on the Clearwater remained intact (Photos 51-53 &55-56).Gauge readings for three established gauging sites on the Clea~Jater channel ~, were collected by the City of Fort t1c~'urray (Figures 10 -11). Based on historical data for the W.S.C.gauging station,Clearwater River at Draper (Sta.07CD001),the Clearwater at that particular location normally breaks up on the same day as the Athabasca River. On April 27,between 1500 and 1800 hrs,the stage on the Clearwater at the Waterways gauging station increased approximately 1.0 m.At that time,there was an additional accumulation of ice downstream from ~ Waterways to the confluence,indicating that breakup had occurred somewhere in the Clearwater drainage basin upstream of Fort McMurray. On April 28,an aerial reconnaissance'was made of the CleanJater 'and it was observed that the Christina River had peaked.The Christina and the Clearwater channel downstream of the Christina confluence was free of a solid ice cover.Breakup of High Hill Creek,which is a tributary to the Clearwater River located upstream of the Clearwater - Christina confluence,assisted in consolidating the accumulated Clearwater ice against the competent Athabasca ice at the confluence. During the night of April 29,the consolidated Clearwater ice which had blocked the confluence,was released along the far right side of Roche Island resulting in an open channel and thereby reducing the danger of possible flooding. '1 "'""! 1 I ! -I..•~~~I L li~ t~ t~ t~ 1}- I.·n -.:-~.. 1;.1t.. ~....tJ I ~..~~. t ', i··~1 ,i' ~.: ~..~.":~ i ., ,r- ',I t. 11 CONCLUSIONS AND DISCUSSIONS OF THE 1982 BREAKUP The below normal temperatures and additional snowfall just prior to the normal time of breakup,combined with an above average snow pack in the upper Athabasca basin,created a concern for a potentially high and rapid runoff.As well,the slowly deteriorating strength and thickness of the ice cover,with the possibility of a sudden return to below normal temperatures,placed an additional concern towards having abnorma 1 ;ce conditions.With these concerns,spring breakup on the Athabasca River near Fort McHurray was closely monitored. In comparison to previous years,Fort t1cMurray experienced an uneventful breakup in 1982.A 5.25 m increase in stage resulted in a maximum gauge height of 246.75 m G.S.C.at the t4acEwan Bridge.The maximum velocity,upon release of a temporary jam just downstream of the HacEwan Bridge,was estimated between 3.5 -4.5 m/sec. The fact that a stable jam did not occur upstream prior to the ice run reachi ng Fort McMurray,could have been the rnai n reason for an uneventful breakup.Another reason could have been the temporary jamming that did occur between the r1acEwan Bridge and the Clearwater confluence may have assisted in preventing a jam from occurring downstream of the Clearwater confluence. ,. !.... l! L~ ~,-~ \,.'r- i··.1q f~, i I Y },-, REFERENCES 1.Alberta Environment (1981 -1982):"Alberta \-Jater Supply Outlook and Snow Survey Bulletin'••Technical Services Division, April 1982. 2.Acres Consulting Services Ltd.(l980):"Fort Mc~1urray Ice Control Structure -Phase 1,Location Confirmationll ,Alberta Environment,Edmonton,Alberta. 3.Andres,D.O.(l9S0):"The Breakup Process and the Documentation of the 1978 Ice Jams on the Athabasca River at Fort Mcr1urray, Proceedings of the Workshop on Hydraulic Resistance of River lee",CCIW,Burlington,Ontario 4.Blench and Associates (1964):"Flood Protection Proposals for Fort r,'ct-1urray",Alberta Envi ronment,Edmonton,Alberta 5.Doyle,P.F.(1977):111977 Breakup and Subsequent Ice Jam at fort r4cMurray",Transportati on and Surface Water Engineeri ng Division,Alberta Research Council,Internal Report No.SHE -77/01 6.Doyle,P.F.and Andres,D.JD.(1978):111978 Breakup in the Vicinity of Fort ~1crturray and Investigation of two Athabasca River Ice Jams l ',Transportation and Surface Water Engineering Division,Alberta Research Council, Internal Report No.SWE -78/05 7.Doyle,P.F.and Andres,D.O.(1979):111979 Spring Breakt.!p and Ice Jamming on the Athabasca River near Fort t1cMurray", Transportation and Surface Water Engineering Division, Alberta Research Council,Internal Report No.SUE -79/05 8._Gerard,R.(1975):"Preliminary Observations of Spring lee Jams in Alberta ll ,Proceedings Third Annual International Symposium on Ice Problems (IAHR),Hanover,N.H.,August pp.261 273. 9.Michel,B.(1971):"\'linter Regime of Rivers and Lakes'l ,U.S.Corps of Engineers,Cold Regions Research and Engineering Laboratory,Hanover.N.H. 10.Northwest Hydraulic Consultants Ltd.(1974):"Athabasca River ~linter Ice and Spring Breakup Observations -1974 11 ,Alberta Environment,Edmonton,Alberta 11.Northwest Hydraulic Consultants Ltd.(1979):IIA Study of Flood levels and the Impact of Dikes along the Clearwater River at Fort Uct1urray",Alberta Environment,Edmonton,Alberta 12.\later Survey of Canada (1974):IIIce Thickness and Breakup Data for Selected Streams in Alberta",Calgary,Alberta -[:....1 ., ,~~ I ~ .. III FORT McMURRAY ICE STUDY LOCATJON PLAN o ~~•. '.., '\.. TERRITO •CO"'ONATION H T A H A III III n '" z FIGURE 1- lr L- r l~~c I '---: ir- ,Ic: ...,..Main Ice Run ---Competent Ice Cover Broken by Main Ice Run .........Jamming Competent Cover "(..)"!\-"..:\'-..\...I:(:: \ .'.l ,i \.\i'".L)'1 i'·.\. ~-"'.",-., \"':'"..\~(....•~: \.. SUBM'ITTED...........DESIGNED :.!~:. DATE........CHECKED . \ -.."'-"'''''''''', ""\.,. \-'.\......". "- .'-...._., 'I!-+~++~-c,,/~~~+-+:'~..."-'-'--"t"'ii --\. Cfel/' ATHABASCA BREAK UP APRIL 26,1982 APPRC)VED. DATE . DRAWN CHECKED . SCAI.E DATE SHEET 6 OF 12 DRAWING No. Attempted 'Release Competent Ice Coyer final Release Open Woter Broken Ice LEGEND J J FORT McMURRAY ICE STUDY FT.McMURRAY (lower town) :FIGURE No,7 JAMMING a.RELEASE DOWNSTREAM OF MacEWAN BRIDGE A~RIL 26,1982 ~ WSC Sto.7DAOOl/1 16 km dis of bridge ~Clorke Cr. RIVER ENGINEERING BRANCH ENVIRONMENT I, I . tr",-.. ....1 : jt- {I ~ is- ..../ L~, ,F- l-, 'I t~~.. Jrr - ~, REFERENCE 12 1.I NTRODUCTI Oil ~;~of, oc i tv '.on iter.I Limestone Generating Station will be the fifth hydroelectric sUe to be developed by Ir'.a:1itoba Hydro on the Hel son River in Northern Manitoba.Its location is sho~on figure 1.It will have a head of approximately 29 m and ten units of 126 Mil'capacity each.first power is currently planned for the fall of 198£.The general arrangement of the conpl eted structures is sho....n on figure 2. The sequence of construction activities and heights of cofferdams are goye.rned by ri ve~ice cond;t;ons wt".ich are more severe than at any of the ~rev;ously develc~ed Nelson River sites. Tn;s paper is ;ntended to fern an update of two previous papers 1,2 on tne project,~t~concentration on the description of the ice conditions ex- pe~;enced since t:o::o construction of the first stage cofferdalT•• ~~TU~AL ICE C~K~rTIONS O~THE tOKER N~LSOh RIVER ,~s described ir so:r,e o~tai'ir:tM ~"e...ioL:s :;.!pers 1 ",ice accumulatior' on the lowe:-r;eis~~,River is a p~ocess Of ice jarr progression upr-ive:-frOl:'. the Nelsof.Estua:-,;.',fe::!by iCE g!:r.Hate~if,the swift open river.In:reases in lIic:ter levels CJE to the ice accumulation are typically about 10 Ill,with some areu as IIIU::::a~g IT,allov!nOnllai Sll:rrnel"levels. ...., •j f i i•!•t t Eefer'£:tho.cllr'str:.;:!iol'i of Kettle Genera-tine:Statior"ice generatin;poten- t,ai exi ste:fro-Gull Lake to Hud!C>or.lS~y,a di stance of sOOle 230 kIT..The product;or c~e~crmous vol urnes of frnil iCE from thi s open water area causec tIn,leE ja-to prog-ess as much as 2S Illr.upstrearroof the Kettl@ site by \Ii nter '!o ene.o~a tota'of some 175 kif from Hudson Bay. ;:.fte r ~tle ;r:'ou~':"'ent Of Kea 1£Ger,erat;n;Stat ion',s fore~ay in 197C.a ~f.~l";;j~:ic.e c:>..e-..as fcrmeo 0:';tne reserve';r early every Io'inter an;:'':";.r~ e1 i:r.~"a':ec tonis c:e":,,=t.e r are,.~rcr.c.ontributinc ice to the io~r r!:,,~hes of the r~\·er.~.s a ~~~1t,the ice jalf'progression s1oW>!c c.onsicierab~."aT,: ,:..yr~:a~')er:oe::r..:;:;:c~..-s~raar.-of :rJ!~on5'Sp!'"uce sit~(S'oni!2:KIT' Co ...r.s-..rea"0';rc'::'!b=~·;,~::~r,;:S:etior.j if,tne yurs 1970 to lS7i. ...~. ::-,"....-:.;",.i c:-.-: D..'~in~'t~:!,(lri):;a~-"'!'I;!t!Q'!~of tne Lirr,~s..o:i~~~v'?1C:.':7fr,:~~S";'.:tc, 1S::~6).cO:'tstru:-:':-c.~_~!".:~·:-·~:.::e G-:n!:",a:~n~S:e:ior ~!:~.•~:~-=-:....;,t'::: its ~!'~"vtd r tiC:':::...~::':-er·;i:".?,Otrn.::ie:.in:fjJ-:'ur-~£~ft":~c,··:"'E >:"5:'c~ iCf 9~-;~:-ft":I:"l;c"';:...;;"~:,.:~:",c~Lon;Spl""'u:e.!.hercfcr':r·!',:t:.~>-:~::;-?:~:. 1't~:-~~st i7:;~\-~:~::~..~:"i':-~!......e~n!'·0:no:the i::.e jc:-t-~·;..~;:;,:."~:"': c.e-s':'.~::s:'""_':-:!:!-=::";:.,er:':1!7:'7""!"'"=e,:''':;n~:~!~.;-=::::..-:~H:'~...~ F"'" ;i .... I - r' I, ~..- ~.. ~~~~~-..-- "-~~--.~-.':3 :~~-{J ----.:# .-'""F~~~,.1 "':"2 --'.J:-',-~~J -.+._-r::~~;_ot ~~::::t:-:..~.-j -., .f -.'.,,I :fc.., ! -J ~, ";, j j ~.. 1 :J j I '... designed for open water levels (some 12 m lower than for ice conditions). and river diversion through a partly completed spillway Dr powerhouse would not have tc cope .nth pessage of large volumes of solid ice. Early in the studi es.engi neeri n9 judgement based on approximate cal cul a- tions of O:len water areas.ice generation rates.etc.indicated that year round ope~water conditions could not be expected at the limestone site after the k~oundment at long Spruce.This was confirmed by the r-esults of a detailed com~uter model which simulated the oeneration of ice as a function of open water areas and daily mean air ie~.;eratures during the winter the re~u:tion of open water areas by border ice gro~t:as-a function of river velocity and degree-days of freezing the accl.'!TIulation and stability of slush ice lit the leaaing edge of the ice ji!!' the SiJ~ercen:e of iCE at the leading edge if the l;lt'roa:;hing ~locities HE excessivf:.ane!the deposition of this ice COwr1strear.on the underside of the c::we" thE sho"~TlC:a.,~U,;'cr.enin;cf the iCE COVE~ur.de"the c~~utec hYCir-au1 ic fo~:e5 EJe;te:O~it thE l:.~:'.i!ter profilE "iI",tnt "iCE cc~e"e:::ane::thE o:>er,reaches unoer nue)'. Tn!-de:isior w!S made tha:rive-cive"sio·,durinc co.,structior.must be C~ v~seC::tc cOP'=Io~t!':ve")severe iCE conditiol'1s.Detailed hydrauhc model s::..:c:ies c"tilE ri ve"iCE conci!i orrs cu"i n;tl\£pi ant's cO:lstruct ior;wo;;rc tiler.unCie--;'Her.at Las"~1t H.vopau1 it let-orc:p..,;.ir.I'.or,treal. Cor,:;tru::tio"of the S..aoe :cofferoa::-...r,icr,e'lcicses thi area of the COf'- crete s..r::ctures (see F;"gure 3)be gar.ir,1976.ir.preparatic!"for car.pletior. of the first units ir;19:'3.The con;;!ructior,p"o:eeaeC::o'oer thr-ee su::r.,e p ~ei!SO~S -tnE u;,st.rea:-le;in 197t,thE rive ..ie;ir 1977.if,::the dowr.- s-;,:-ear le;in 19iE..ine tC1"st ..lJctior,of tnt r-es:(I"tn~;;:-oje:t has ~e·, she~\..c't,,-~,orariiy.due tc thE siowe"9·Cl"-_~c~~~a!1=fo,.e:et:-:.ricit.)'tt,u. Io~~el~EPien:e~t~tht e~rl1 tc ~1t-l~7C's. j"..,-.:~irst .~!':te·.cf:!~t:"i!cc~s:''''\ic':.ior.01'tne c~!:"e::~1e-;,Lo"; ~.:.-:.;::-'!o ~es.f -·l,.~i'~,f~,,~~~~!=r ;~;;:Ol..i:-:dte."r~£iCE:f~o~.':.r'€::';:~f::::"t."'fo ~:~:?:=.~~s~t~E:":..'·i.,..':.!'1~...-;~:£'~ar::.r.-:,;-£'~!e:·L::·!:~e-e:--.t.€':.au~E: :'J!-..'e-!-:-..-;"'e-·;~:"'~:f··::or,i ~,~1.\t"E!~~."~rif ~:~f-:'~l'"r~;'I:~:e:. ~..!;-:;.~::'€:ri:::4:c:~.\:....":~.;::;r-'e~O~~:;..1;~".':".eo:.·-.;.-=.~r..:~.\~..~...~.;!':;~ :,--::•:-;'!:'.':!oE.:'"'.:..!~s":.e:b=-~t _._;S-~Io;::~.\'f ••:~....a"~t "'e:e'" t ..•'f'-~......'.. ] .", - - - •;-- ~~~~ :L:i;.,f-'- .-l ~~ .'f.-> 1977 -l!i7E In the spring.the ice behind the cofferdam became grounded as predict- ed by tne hydraulic model studies.and there were large arus of strended ice 5 to 10 II thick..Fortunately.1:he strong fio_of ~ter past the end of the upstream leg cl eared the area wtlere c.onstruction of the river leg ~s to resume,and wri:.wes able to start late in June. Later.the ice front resumed its upstream progression and eventually reached Io1thin 2 km of the Long Spruce cofferdam before the arrival of spring.The II'taximum water level recorded that winter at the Limestone cofferdal!:was el 70.S II.whic.h correlated well with the hydrauHc model simulation of el 70.0 m.for comparable flo_conditions. During this time.an estimated volume of 70 000 000 m3 of ice passed through the 360 m wide diversion channel between the end of the c.offerdam and the south river bank.Only minor damage clue to ice 90119in9 at the corner of the cofferdam ~s incurred.The resistance of the cofferdam to damage was attributed 1Il!i nly to the surface freezi ng which had occurred prior to the arrival of the ice jam. lr ttlE s~rin~of 197E:.('.'er.though the ice did no~react:its meximu:: r:.c:.er.-:i~'ti:i ckness.consioenlble yol umes werE left stranded in the eree whe~e worl'wes to re~llmE or,the dO"'"l'1streaTi,lee of thE tofferClar..• :n~ict'de1ilye~the reSI.I::lptiof,of worl;un1;il early "July.Fortunately. th~cor.st ruct i Of,s:heoo:1e ...as reasonably fl exible in that fina 1 yeer ~n:the cbwns~T"Ei!lT.leg ",-as still torrpletec before the or:~et of winter. 1r tne fa 11 o~19i7.the Long Spruce reservoi r we s impounded.Inc es expecte:.,th~ice fron~progression in the ensuins Iointer wn markedly s1Cto1t'r than in previous years.The ..inte:o toes very mild.and the ice fl"ont cr"l.r rra:.hec thE foot of the nlpids beloa'the Limestone cofferdarr. ttiC dic not progress through the diversion cliennel.TnE Iroaximuo.,"'''ater 1eve 1 "'~s a;!prDxim~te 1)e1 65 in.or only about 5 It of st~gi n;aboYe o~e~w=:er co~Gitio~s. , I~s ! : ;. It f I ~ i "...... c...0:"',.... .~ L. r-, 1- I, l~ e~~97E.the de:.isior to ~stpor.e CO"lstructiOll of the ~il!'es~one D;ant rIa:~~':"~t=:'E:~_\If~~itc~=~;..\-c,..t~!T'1'the.ensvir.;~n~!'r'~:;~th;first C~,"31"1)'t";ro\;=~......icr,thE cc·f~er ..er,~s tl:'re::-,air,. :'I,,;"~"';":.r~:co~st~\J~~;or.o~~l"'t:t.C'·&~er'!.!'r'1 the crest 1t-,'f"l "':'!P~-PCSE- .•~n:.·:s~i"'tc=tit !p~rC::;~~C!-;EiJ',f'!"~C--e~thaT th!tra:u::ir.;:;;1~\'~·~ir~C:'ica: EC ~::n:"'..lr'oratoi 1ic Ttr:ioe'l !.es.~s..;;,e ic;i:bt7Iin:'t!"j~~..-~~:!!.foi1D~·: "......'1t ~:":e t.j.-.:;..::e"r."~'::'~~;-='::'i::~:c1 c !r"'!..\o ~rI2:t".~~.:f::':1.~C rf:':''' 't"'l~:~-!'s~c~·€'s~:~~r _•.~-~:..~,:=.:,r::.=:-~t~:t-f ~:~:.~~:11!:~~,... ~~·:'c.~-ty !.!t:•.-;-:......;.:;."'iJ~i~t 'f~:..;:t~...~::.:~..=::__:~:-~::-:-_::.!: .!-. -~<'.-, ":~:.- ...._--........." -overtopping by a metre 01"so before construction of the plant began would not likely cause any significant damage topping up by 1 to 2 m could be done later prior to the start of construction if it was proven necessary.Thus.if 1t was not neces- sary.there waul d be some savi ng in cost of the cofferdam construc- tion. The winter of 1978-1979 was colder than normal.and the ice front pro- gression more rapid than in the previous year.River flows were also quite high.averaging some 4.000 m3/s in late February.By early Karch.the leading edge of the ice cover had progressed some B to 10 km upstream of the s~te.and the resulting jaming of ice caused water levels to exceed the upstream crest of the cofferdam by about 1.6 m. The area insidE,the cofferdam rapidly filled with water.and eventually overtoppec the downstream leg.Fl 0 ....ove~the cofferdam continued for several days until the river level gradually subsided. There was no significant damage done to the cofferdi!r.-during the over- topping.Tnis good performance w!s a:tri~uted tc the frOZE!':surface 0"the coffer-dal!:..c~re~ista"t to er[!sior the ....ats-init-ially floloo'e:o...e~the crest ir,i!thin shee~aflo c"ut- e~a resis:ar.t coating of ice.over ......,~Cl'"the su:seqJe:it f10~..pass- e' :1",£fol1o...il'!~sorin;.the arE!"'-;thin the cofferd·arr.was left to drain t-~r,atu!"a,s~epage.and tOOK ur.ti1 the follo ....1n;wint.er'to recede to o~e"wilt.sr ieve1s of the river. Eett:tneu ..inters had above no nr.a 1 te'::peratures.anc the ic:e front p:"o;res~ior.stoPPI!C downstrE,i!IJ:"of the cofferdal!:.causing o::ly r.;inor in:~eese~ir ~;ter lpvel. 19::-19£~ :r,:..-'iter of 191:1 -19E2 loIas colder tt.i!::"thE t~..C D:"evic~s Vfl!rs l!llC ::lE i:!f"':.r::r"'o::"es~ior.fcllo~::t~.at C~~S75 Vf!"v cicse';.Rive~~~O..,:...:;"!'se:'!':e"~le~~1es!-:'he~1;"':,61'\c'trl~t.ea."-.c.t.!';levf~~s ~~!t:t! Eo:o~!".:-::~So apo:;:c.~r.atlo~'e th!u..~tree::Crt:~:.10.tnir sne!!:of p'=~;..~;C'.'-?:O\'e'!""thf :..:::·s-:"re:=~c!""es~to:,s!\:S'--c1 !::-:':"'~.in!\9clume of :r.~o.·!"f'1~..""':S ::.:it£:5-:.:11 l""l:Or:"i ..~·C.!t!s!"t t:"t~i~~~C:f )i?te~.evel to ~r;:1"'e~SE b,:=-fi'ac:~or o~c:me=:rE. J.;:~E:-j·iC2"~:.J~;~~y c~-the.~~~.~!"'~-....~...;~;-:-,:i!:l:E.":.:~"L~-,:!,::,Co.!nf ~c~f;~~~~is s~o~~O~F1;~-!~e - - c-,. ." 5.SU!'lKA.RT ~-: i ". f~~of i'~s. IC. l~ f ~'o.~SO\.ec.'lyrk.lt f';: L ly ~.~or ". (~ I ' [! i .[\, -.~,-C.;'. .- ,.,;" .,... , ;.i f l ~ ! f I MathE!lut1clll and physical models were used to plan the concept of river ice management for the construction period of the Limestone plant.The predic- tions of both models relative to the first stage of river diversion hIve been verified by the observations of the river behaviour s1nce the cClllple- tion of the cofferdall'..Topping up of the cofferdam by 2 m ltil1 be required before resumption of the plant construct 1on I which may be as early as the s unrner of 1982. .i _ f·~ ..... - .... REFERENCES Conditions Laboratory -. ::,',:~,:>.~;.~~);:~;,';;:~~~:;;/:·::~4-"i.:f;$~~~}~ -limestone Generating Station Hydraulic Model Studies of'lce During Diversion-.LHL717.February.1978.Lllsa'le Hydraulic ltd.,Lasalle.O'JEbec. -River ~ivers1on Durin;Construction of limEstone GenerUing Station-. 8y R.l'.Cilrson.L.P.Jonassen and L.C.Leung.Proceedings of the fourth National Hydrotechnice.l Conference.CSCE.Hay.1979. -lee Processes During Construction of Limestone Generating Station-. C.P.S.Simonsen and R.W.carson.Proceedings of the Third National Hydrotechni~al Conference.CSCE.Hay.1977. 2. 3. 1. ,:1 "'''=--~':;' :~ ,~ ;I " - "~!I ~.-.~I-.--.'.. -t I.:!".. .~ I.-~ •';I I t ! I .~l_';;.. F'" '- - - ..... j 1 I I -I '; ----U_.Q .t,...._·l_~.1 " ,,_l_,___~ 1 i I I 1 1 1 I ~'?--...---:-",1 r----.J ;.,. '.,' ; ., i .... l l'; ';1 1 :;;;!: '1'1 ';,. d' :,~. I,,: .; \, 'C1 :,' '!;; '1':;':. ". ,I :;- :':',.'1 ~.,. "j' l ':!.f~\, { t l I:. ',.I ", 1_;; ',' / !: flU PLAN..,. ~.'lOlN"·" lOeAflO"Of'PIlOJfCf LMESTONE GENERATING !JTATION J't~fllll '1l·.D .J J 1v.. I. 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RIVER GENERAL ARRANGEMENT OF COMPLETED STRUCTURES LIME STONE GENERATING STATION .J] =---~'\r-----.,~-....'...._--]/;;, \v:,r I,I~.'.1Jr'"IlII'f, u,,urE .t;"Uj'lf:l ~.~ J so,", '"'r N ], I I I, -~~_..-.._---J---...---..----.------- \"HI \' ~I, ."(......,.. ~'t, L~A'l'"IIAV ~,.'ll."'AY ,, ._-----.-.-.,.•...., ,.....c .••.,'ii'TI !IflO 0 IlJO 7'.10 ]00 400I.----l .~ftn[S ,__.---I FIGURE 2 , ~11 I,It •, I i I I I i-~·-----------·--···---. ,"I !'il ".-'''--..\I ,~-~...-----1 •'I I (.'1 ";~it!,•" ....".,t.n'·".....;,,;-"'~,:~.w ...oo.;••,''~"""""+"""'''',.•.,.,~;~~~i~~.,:"i,"'.:'...u...it4J ...,v.;i-~~.~Ii~~lli ••"*"...iI...·.,!!lflil~lli~ti.8.WF!Mnl.iW*··.si '1'·15ii .•t;;';"••~,.-,1. ,,'j ) .r ;;\j H,-, i, i;~:.t··,:, "J: ,,,',",.,:i !;~~~i· ,\.... ,.;r ~ It~~· l"",.\i'.,'\\/ f',, il,\,\~\",'". 'i·l ,,I,{- ~"t,~ ,.(~~i,:, '00too FIOURE 3 100 STAGE I OIVERSION LIMESTONE OCHER"TINO 5TAT~ oIon ]..~ '...._.'I 'Lj'~,,.';!; .' j' -~"';i!~",i'j-:..''1'.fl".~,~;t ; ,,,,,,". t'..{i '~l-i:::t:;.:: t'e-nll TIIIl ..lCt (tl""Off\.'1 .,e "~)"",'..1-.,'... ,..r.f"~1)J "'Nl'",...,,,..1 r~rr""." t ..",""~"1' .,....., n "'","T r n"r "{'II..• -_ I ....."'1"" J '\;'-'''''.....l I"RRANGf:JrNT'0' tOMPl £t£0 ST !'IUt T \JIlf ~ ..........-.....--.=-...-----.-.--.. ' "I 1 ,.,OUAi:-(,--,I I ~ l..\ "\ ~• ~ l .'-,'-'-'if'-..- -\J ------- )'.(.Nfl flo ---./1 ,.",V,..J'i"';' I ,J.L1J.J I ..;.Ii I , ,.r +c'-I.LLUJ ''"f'a tr.'(.1='J r I'I'TT,[JJ·.L I";'n"·.r i ,./'.PT"rTT":I I ! 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"'j~/. ~:\i: .t<~, l\;':-!J:\;h i~,t_.•: "I',,'.\ f'," ;\X ~•.i.,. r:', I f {: [l12.0 CROSS SECTION ,OF STAGE I COFFERDAM :-;i ('0 ,MI'FAVI(lUS F"U.Loonl\P-IlILAQ riLLo~OCI(FI\.I. ®~1.(lrE rnOTECTIO,", ...,....-.-.-----...--.--.---.---.---.-.----.----I ,~ I;,II r .'"/11 '·n·'r"',11I1 "J'I':t;"n':~QtlFNr. 1n .""1""~11111"t ,~.I ,'"f \.'I .,'I:" , ' .'1',\:t ",'~~I;ll"'h~l"~'1'~111.{'.'il.'J',t{;'J"~,~'U '\"..·..t ''''''~~''"yi!l;j1'i ~i~~:rl~'~I '!iii\.hI,,·,"",~.,·t,"I1\-1\'I'""Ll "'!!"'.I ""I "'1'1")1':/1'1"!''1';1tl ,y{....t",'I(••r;."'-j'b"'l~~,r "'Ji'''''~(',f'1.'d'l~'I I ' ,,'•",.''"I ,',,,.',"'''',',(,,'''''r,'.:'",':\,I',:.':',1,,".'~l~f~;,!"I~~·,::t··';'.f:,\II.!I·;.'i;~'I~/~'r'~{I"'f";)1::~1J(h~/;;"I''i\~"'.~\r.::~:Jflj"t.\'h .•,.,"\"t')'h'i~"I.,i',)i' '..I,~..~...""'I,.~.,",'"'''~V'I~,,'''1!'I''J'4:'I'I''i'1(1''1'1 ";~'i)'11""l'V ~t \,~t "J':'l..l.~' ....,','..',".",1 ;.',W.I.·I"I~·"·I·;"»ijf~",,"'~~*"';'j,,..i,....4il""'~I··'f,.l·'.s.·•'I'I~~"•.1\,,,ll,*II,,~~i<Il1I"'~"'WW""~'I.,j '~':;;~lualllh"*./lj'*"W Y'd"l.eiJi,ilik ii"aM 111',,*"1 1 n.,(''''''; ,..~"'r.J':~; ,"'\!~' ,:~: I~l~", 'ti~. ":~.~'.'tr··•·...f,jlo"i "l~'!: " ;; -MA'l(IMI)~"W,'JTFn WATr.n LF VFt S PO r:OIf;r [I)flY IIYMAULIC M()I"lt'L ~g Fra ..,'_'__..jI>t'J)_ ,I;'0:?'"~1"":- •'OPE"WATER • I Il'\I (o.l"""[nAlIUll Cl"lVE ~ I.' /(;"JI'lAn ~ "I I IQnl ___ .:.r.'!;I ---f.;)---,...----'- ..I ,""..--~2'"''r ~}..".,.'~,......"'.....,..-. •..\rv"ttl ;"'''¥'\(I .'r,,~...(~'","uno :~.-~~'171::- l'I~;r.'ll\nOF.:(1ll~/.) Ii i Ij IJ H /I L!.: [; .' "}:' ~ I"U' "f•• \!. I~~, !iJ~:FIGURE 4 LIMESTONE GENERATING STATION RECQRIJ(O M4MIt.UM WAfER LEVELS 1918 TO IBel ____._.HI.'.I ~\ ~ i I L_._ I: ji Iir J; i' I I J ~t .',', -,... ~. ine mcximu~nea~loss be~ween the u~s~rea~an:d~stream cofferda~le~s (see F15urt:3)o::.cu~re:;ciurin~the overtoppin~of the cofferdam in I'.arcr,1979. Tne upstree::r ..ater level was el 73.6 Jr,.the Clownstrearr,water level e1 f;c.5 IT.,..it-Ii a river flo..estimo:'ec at 4.000 te,4.300 ll'3/s •The riverbec €le~a~'ior;in tne dh'ersion ct,annel aroune the co~ferdal1'is approximate1)el :~.~:If",,-:tr,very little variation e~:her laterally or longituCl;nall,Y.The "'€S~,c:e!<t~1 in~ludi n9 ice cover at thE:u~streil!7,corner Of the cofferoar::...-oul d i.rIE~£:,;)r€h6\'t:t>eer,a~pruJdlTlctely :£.6 II"an:::at ttlt:downstre~corner a ••- ke:;::'.v by F••Carsol' Reply by P..Carson During the worlcshop presentation.it ~s mentioned that stable ice cover conditions were observed in the cofferdam opening even though the corres- ponding mean velocities were relatively higll.Also the headlosses between th~upstrear.;and doltflstream sides of the cofferdam were 9I:nerally higher than observed in the hydraulic model -prObably due to the cohesiveness in the pac~ed ice.It tftould be appreciated if the author would give a qliClnti- tative description of flow conditions in the opening .men the neadless was a meximu~between upstrearr.and downstream of the cofferdam.Specifica11y what ",es t.hedischarge,mean depth including ice cover in the o;Jenin;.and the head1 ass t.>etween tile upstru;;,.and downstream sides of the cofferGam? The author has presented a very interesting and useful paper comparing com- puted and hydraulic IlIOdel results with field data. DISCUSSION S.Petrylc,Rousseau.Sauve and Warren Inc. ':"r~r.",:".~7;~:i::.;;~IIOciel of thE:iCE p-OCes.ses s!lOJlS tr,S:.....:r tn~stren:th i-t::::;;~:f!"~en:r.-v:.~ues L..'s!:'.,tne f~rtC;ice :.tt,c~nes~4s c::r~"':E~f":'ir ~st c·~-:.n=""";\."::'"t·...sl""t:'i'r!es.."::Yf::"":!tE~eS!.tnt Si~·W-ict;cn~QC 5!"!:'-..~·€'::::.~s.':;cr:o~ 'f:"c.:~;;i:e:..,...,i:r.O:CiJ"';,at C'S':1n::C!.lr:.3:~1C:~cn5.ir;trl::,V'~!"I en:::1'f.11Ch ~:..,~~=...~!ori;:"t'!:_~L1~;'~te~d;).-:·:"',s.~"f'!.1":'tJ€:::::;,;Sf-c.t'tnt-in.:.r-ce.sin;hy:Jraulic .:-c".:..e~:::...So::~..'"-..nf S-c,t.;-;r.:;fr czi 1 :-::~~;~t~. ~~f -.:~.-:-\=l :-:.~:~:,...:;~~\~s~:c.:!1l:..:i?:c~::",.c L":~·~~::ii;:"~ri:=:'~rl:....ec:tile: :'.-=--~..::~':;7··":,::::r.:Sf"l;::\·~.!"'t:D::~:·~~;,~;,;:j,ti=:::rr!:'~t-p.:~e.~;f~~:J\-'~'r:~r;':.C).- :f :A-:·':'~i'=S ;t"':.r~t r,O"ttf~,:.~:r·~r-IE::~..er 2:.':'_::to::;,ei:-t.~s:·~~t;"a:. ~I'""••:r.£~~_:.T·!1~,::::=-~C,J;~~"t;:.:....:,"'l-::·";·:.~~~e!,c:""t ·;:-,~..:;~:et'i ...· :'.~4:i."7.::"~.-c."::1~"':::'a._'"-:-'''~.r-",i.hi :"t,.....:.•".€~. .s thE 'ice cc::.u~ulatioli tn;c~ness causec primarily by shovin5 or sl~pl€fra- zi~G~::.:~.;.:l,..:.ic!"~frcr·UPJOErn~cttl? , I I; ! ~ 1 i I I I, ,~ ,.- I .( ! ,- --__'-.,..,-'-0 •-,..,..,_ -"JCii6i S.8eltaos.Canada Centre for Inland Waters You mentioned that the ice ...,anning coefficient had to be increased ..nth ice covel"thickness in order to Rmatch"the observations.Did you have observa- tions on ice cover thickness as well as stage 01"simply stage? r:c ...:.O~:.!:!""~so~.-itt~t"~inves't"'cctior.d!~:~ibec ir trl~lts~:'!:-!!"(G.e~br:: c~·:t..•:~E:~car vo;;lI't'n:ior,"'~IC:·ratloe c~rOJCr,nen vz'ues W:-"c su:c£'ssfu' if 1~'-·r--,;:r.~1":jatici51 modt1,'in;.- - ;r·t~E low'!!~rE:a:l'~~0'"thE:river,Wt,en ttlE:slC;lf'is lIIuch less ((;.O:JG;ver- su~Q.C:;2~a:U"',estpnE:}ilne:;ve'c:.itie~a:-e low.,r,the O:'SErvet stilges .ere ~est si~~iatec wit~a~~-valuE:c&tnt iCE a:C.015 to C.DZ~.Here,tne si~ \.:'L::e:'c.~t:-';%:r!'lf.5:5 -",.!~n~::!""{'!'.t bu~n~lei:t1'1;ci:.nes~me-!sureme~ts E!"'! ro::~;r:t:'te~.tie~Ce"sitE.).'i:.r.:ver,i:;;:s obvious frO""the appearanCE c'!r,=;CE:ccv!:~(rc·;c:iye'.:o S1";:::t~.!.;.;..face.nc large pressure ridges)that i:'oie!'~i.l:.r;tr.inne'"trte!"ir ttl£.steE;l~F rEilches upstrealT.~ Reply by R.Carson The majority of the observations were stages at some 18 lo::aHons along a 120 km length of the lower ~e1son River.HOlolever.in the ..nnters lIIllen ex- ploratory drilling of the foundations at potential darn sites .ere done.ice thick-nesses were obtained at those sites.Unfortunately.measure:nent of an overall average ice thi ckness w!'\i ctl coul d permit a rigorou~Cor:lilari son to the I!\athematical simulation could not be obtained be:at:se the location of the ice/..ater interface could not be distinctly discerned.Nevertheless, the rough estimates of ice thickness.based on these measurements did sup- port the calculated values.For example.the calculated thickness at the Limestcne site lias about 9 It.The best interpretation of the dril1ing done b\~~~ito~a Hydro in 1974 suooested a thickness of 7.5~.Trois drilli~c was cone ,~rio-wir.ter at least si~weeks afte~the ice cover fonnec.Cor-sider- inc tr'e cover tlac!consoi idate~to So!'l',~e,,~ent ane IT.ay hove beer:eroded o~ s~;::r.e,so!"\e ......a~fro:,,:the no ..·t'eneatl1 ;t.th£'ct,.,.,~"risor a;·p€:c'"s rei!sor.- ~~";e.!~;tn;s a"ee,the best eS:;r"ate e&..-.~,ue o·the ic~'tt m?t:.r tne cr5-eP"\tec St!S'~~:s D.~S. ~~-::-..~~...::",-":--Gtte'!":".:~te·p-~~i·::.t t~!:ttdct.~!'s~[':4 ~..a:c~r;.,.i;~:i:~,~r"lf~~:f 5·...e';~!r~~,_....f ~:.-.:1C!":tlW 1 e-:;t!col':r~e rOl,;uh",!'!$OOE tn~c:'ve-"an~tfl-e '::"'~~~:"IS~ S":~~...::-:.t"~~.-:,:.r....·!-..wc:..;lC y~:..:co~·!r!:0·"t~~·.,..a.~e~c"~~:t c",tr~ose :,·:.·e-·-:·..~-;i..;~:-'f c=~itra~i·nf :I'\e m:J"e~t~,~~:":.:jr,o:..·;:"'~~~:'-:.:~.~f"€'~5.. -..-. ... of 1.5 wasof"IJ--value ice cover.steepest slope river.includes Limestone 1oca 1 steep reach nea I'"estua ry ttli nnest ice cover.mil dest slope the river thickest of the site ( str-ess in the ice cover to the streaill- 0.025 0.06 0.09 0.05 0.015 12.5 52.7 Kl·"Z tan'..1.5 ratio of lester-al wise stress coefficient of friction of the ice 0.18 coefficient of inter-nal strength of the ice cover (rela- ted to deve10pment of p!ssive resistance of the fragmented ice mns) .. 52.7 to 60 60 to 71.7 71.7 to 1Z0 km 0 to km 12.5 to km km km un ~ "l·tan ~ "2 Reach 1 Reach 2 Reach 3 R!'ach ~ Reach 5 Wi th reg"I"'ds to ice strength.a Pa ri set and Hausser u'sed.Where 10 cclculatin;tfle il'lte~"tl nr-e'1;,tn o~the-ice cover the Iroiithsr,atical model uses I ! -. ~-- - l''::'~~~~':Wl~~:t~Jf~~~fF">?;;'~'",,'.¥:j~~';"';~J~~~ c?-E''''~"1!;M~-~i:'~~j$ _., ..~ ,,....:-~ t.~~~"- •merE:F'CE: I.~ p' 0 ~ S t l.: maxirr_;.!r.ice str-ens;tr. Of ~i ft!::e.:;ov~ ;ce oen~i _,- lOner oens·ity (c·h.G~S2} Clcceierction of gravit~' i c-e tl'ii ckness ",-iCl:.r:of river at that iocation .. ~,. "....~' .'~~;~ f ::'"m ",,·r~€'~r r ..-nfY'"", k~'a"r .... forCe t.re'15ftr~e:~:.t.n;!"'i~'!'''':t>"nr:S C~rr e cist:n=~t st!'"~t'"71 .."'iSf s:-e~!;r:ic..~·C::t1tE!'" So.)=~!S C!~,ne-:C.:·OIl~., "lCf !r:1 c":''les~ lffL;':.f'1 o~tr·::e·:=-n~0"riwf:-fir,tn~j.)·:.::e·;~:1!-d':s:.en::£ !'·::...-:-e:er.c!'":.'~:s.e::~~~~) i -,. ;........'.i-' ~~'- "r ..- \~..~.."'_;'"":'1 ':t :':'n~'!"','0..r.f.:;'t.:";'":,;I ....~.;~.~._.:~.:.:-...:.:!':'1"0:;::c.:::"::."c':-:rir ,..:'..'':'...!!..-":::~:.~.i!.e;:.:-.,:..cit:'-::-~".:--'.-:'~.::,.• ..- .- .'. -- D.Calkins.CRREl Would you feel confident to apply the mathe;;ati~al model to tne next down- stream power plant without doing a pnysical model also? Reply by R.Carson No.While l'\athl!l'litical mdel1ing of ice processes is stl:a::ily in,proving.1 do not believe it is qu1te as good as physical modellins.lotIicn,loti en properly constructed,operated and interpreted,can address tnree di~ension. al fi()1ol Cli~racteristics.The enonnous costs of constru~tion of the large cofferda~s and structures on the Nelson River gives ar.e:orllT1ic inc.entive to use all of the bes~techniques available. """""--_._~ .. - - - Abstract on the Lower and hanginf hEin~in~Ca'i.fOM:'iiE~~or. E"cp.:ir-:"er.t U:~~~J G~= 61 tht-lo:..r:'-shq'. develop:::-ent o!ice jams ane moni tor data,the- ci i scus£ion on lCl:'cover the-forn.at ion unci£T~ake~ discusses han~in~ice dams in the Manitoba Syster.and the col- data relevant to the anal)'sis oJ their resistance to river 5pf'Cifj~t.anFinr dar.,H the Ppper lielson RiVEr an::it!f'ffe::t or:the ~:v~~~vs:er.is oiscus~~:. The Manitoba Hydro system is primarily hydro-electric with its peak demand in the coldest part of the ,,·inter season.UnfortunBtel~..this time of the ~'ear is characterized b~'several hycJraulicall~'restrictive types of ice fo;rnation including stBtic ice.juxtaposition ice covers.ice jams.and ha~?ing dams. H.R.Hopper)and R.R.Raban2 HANGING DA.~S IN THE MANITOBA HYDRO SYSTEM ~:~-:::z.pc..Tnt'Ti1€tnC'c~:"~cht.c;Tli rtF ,,:-c;.,::,,'~encountered are Dres,€nL£oG for J,.1:-:rief description is presented I-e-:Eo 0:1 R i v e r wh i cr.iF at t a i ned by C2~f." This paper le:tion of ::10\0'. A~exa~r:E is presentee o!success!~J p~2sures taken tc virtually I:'~imin2te r;c.~?int ca.:-:-.fc,rm~:ior.0:-:c:sensitivE reach of thE E":Tr.~~·:o~~F.j\'~1?r nECi!'" :"":"I~.T>50~.,~:2nitobc:,,,:,en the pNenticJ staFinF could nN bt,tcleriltl"c. ..~. ,.,~.-........--_. ,.~!'Co •••-~s!"".:i[obc ___...._00""__-.. .".':-' Introduction with the hydr':}-E-lf!~tri( (Fi~uTe 1),~~hac ~n~~ proceed systems ------.----------- lrJ 196t "",her:tht-cecisior;~B~mad~to developnent of the Churchill ~elson river Manitoba E~'dro is monitoring and/or observing the process of freez.e-up and break-up over a large river system which could serve as a prototype for the study of the resistance of ice to river flow. The intent of this paper is to promote discussion on hanging ice dams and the collection of data which are relevant to the analysis of resistance to river flo1O'. We,at Manitoba Hydro,are not research scientists nor is the corporation structured for research.However,in our day-ta-day operation we encounter ice proble:s and the better our understandiOE!is,the more successful our operation becomes.Thus we invite sugp:estions on data collection and hs interprptation,and are prepared to freely share for llIutual benefit the results o~oar work. 'The collection of field data is expensive,so it is ·essential that we obtain and/or develop efficient ways of col1ectinE!relevant data for the analysis and understanding of the various phenomena of ice format ion ano break-up. ,... , " ·r~ -) f. ,iii .~-:-:-:-' ,~ .:..k ~~~~ of .c naTTO-"river ~hich expe.rienced ~3/s prior to diversion and 950 ~3/s that r.E:f;:ore diversion we !!air:somE w..ter,",ey sc,that adequate rciti~a:ion 1<ar-o eXO!Jlple on:leT of 20 -34 was imper ..t lve r..erlc\·i:lT of tnf: ,."L ;CJ ~-.;~~:..·",o:Ri ....·t-T \.o.·:nt~r :lo..·!t In tho:: appreciation of the potential problems that might result from ice formation and break-up but had not undertaken a comprehensive analysis of potential ice problems. The Lower Nelson river contains a 140km reach that is an example of a wide (l (l~O~)relatively shallow river where frazil ice is generated along its en:ir;,len~th (Fi!!ure 2>'tee cover is attained by the formation of ice .ia"'!~a"l:'han!!in~dams,their subsequent failure and reforming,with the ri"er .:-hannel eventuiolly becoming filled with ice accumulations 6m to 12m ti,irk.7n-:I""ar,;,four major power sites in this reach,tvo of which have bee"h~:It and the cofferdam constructed for the third.River handling lh:ri::~ronSlru;::ior:of the Kettle Generatin~Station is described in a p.ct'f!'~y ~la.donal:e1"::Hopper l .Ice processes at the limestone site are d~5:'!"'i~~?=in t:PE;.~J?:-'i..••Sim",~ser.anc Carsor.2 o to~er Selson River S:u·::~~~n~eTt..a~:er:by ~St'iitohe liydro an~consuJ:..snts];r icienti:~e~problem aT~'2;...·'~:~h an dN'um<!n:ec in unpublished reports.The most detailed study W4<the:c.crTiec out by Crippen Aeres Enginee~in~fOT ¥.anitoba Hydro and is ';"'~Ti:-..~i:l a pa,leT by HC'pper,Simonser.and Poulier3 • The concept of development visualized ten sites on the Nelson River and four sites along the Burntwood River plus the regulation of Lake Winnipeg and the diversion of a substantial flow from the Churchill River to the ~e:son via the Rat-Durntwood river system.This development complex in.luded many different ice regimes,each with unique problems. i).,~t":f :'~t·ar€'aS c·t concern \lWa~thE-l'~ac'h ,,1 thf rivf'!":l('l......inr past the c':y ,.:Tho"-;:-SOT.(Fi!'uTE:'3).It ..'as preOlCted that 2ll'icjOT hanging darr ......:;<':~'1"r.c causini=_river staji1ef thet "'eTe en:-in:.ly una.rceptable.The ."."-.21""<:aken tc forf'~c·tr.is p;::ten:i ..J can!?e:inducE:'the construction of ""p~~F!r~ct·;!,'t"C~C the ::t!"L:2~lc~ior:c!aT.ice boon'.2:'Manasan Fall~ ~::.~;,~tt 0:T~..~~r~o;~"Tht:£t.rUClUrE-c'ons:ist£of two roc~:an~ ·.c-:'.:.::.i:'l"(Jins.l~s tlLH'l>OH'is to in=rea~e the upHreall':water leveJ <:':;::~1"::y to pro~Ole :orma:io1"of a stable.ice cover behinc the upstrearr t ..~.~-a~e t;"u~e~ieinat:e ~hF jc~E=e:"~e1"a~in~reach cf opeL.tr.·.ater (Se~ .,·,!'to ....A Ge'=Tir.~io",of :;,~de!:?!"'anc construction of the concro: $:-r ::t".:.r~~!'-C',""H"I~iS~n@.C 1:"1 Go ;:.a?er ?T€?4Sred ~y Janzer:ane KulukL . end to nd he we he nd on i: el" ur t~ ,e .. t 1 I I :I! w i I £~ 1 C '"!:c.i c w w t:c & :~;·:.'.·~·~-~-C "a ..! ".' ~!~;~ t:~f . !~~~~Ud:; .:"~~ .~, !:•..,,.", ~. :. :~..:i ~i :.::::~: '-/1" I I-I I I ~i i,I I [ /j i I i, I/1 ! / -- '.i• ;t :~ '''''t>...... i ,_. .I ...: :-./""-' \.u -,)-r._-' ;_J{'- ...........-'" .. ~ "" l ~i:: "• j I I ! I I; ! -..~ "' 0' ... t, , ij~.-=-=--, ~-,.". -r l Il!!/!' - - - - :-," thE: The sub- ,2 3 KtLOM(T"'l$ seAL.!.. "/ .:c:":~co::?a.r~the resu'l:inr t.:.i5.ter sc.r-:acf'c!"\::ice profiles:for lS'~~'",inter seasor.to these pre-dietec,hac pre"entc.~ive measure~ lc."e~.The'resu]ts to cate have been total1:;suC'C'e~sful "o'ith T~:U'::-€:::by a!m:.Jc~;2~eight rn~t.re~fro~~hf'r·:;l~!:spvere :... !'t-r.~~,r-:~,~:..'~-:'""C c~cr.a~!f-:,i2f'O:by c Sf-':'"it='5 eo:""]d~e):r·c:r:.~fo~snc ..•.c·"-:·:...~,..-::~-:b:..-r,c!'r;·..~~r.,.·:nr rz;;:5s O~F~·:~!!~~·.<r;i ......ate! :~~-....;..":... ~ci-·~';...:::'7".:~€Z :-~!~:atic-:".p;r?j€~:pTOV)c:e~c Live StCT2~t:re-~crvcdT of .,Co r."::.~",:".".a p:-t,::".t:a:t o::~y,-~'of f"",r.Ftr':.a-c...•..elop-'ent.Re!'l:- a __.--i:.c::i:rH:':~:..C:cL.!'i.:rc,~~~TU{:UTt'Ci:...';'"~PF;Gr·?:"r.)·ir-:2t€'~:~'J2ClKr' ::·...·~.~:;~a---.c :".c~..;::"'c.~la¥~oo.::1~~~0rJtrv:a:~·a~Tcf.Li:!'Jcir:;. t~,e'::.~S r.-:::.€o?~ .\ ~-'--'-~'~-'-'-'-'-'-'-~-----.--'...--, ".'~'.~'-;,' ; ICE BOOM ICE BOOM -.t~~':'~--'.._._.- ~O'":1": ~~::·~s ... , '-. "-.:-::: .....,,s, ..OJ ... 1.::' I"I'!I i ~~~ :.;;~~~- i·".J;-, ~'~f ~~ ..:":.. aCTUAL ICE ,."OF'IL! " FLOW - ICE BODY P"EDICTEC aCE D&W 215 ~1951 0 190III c 185 r---e~_A 210·...I ui 205 ~ 200 220,-----------------------..., 220~-------------------------.! Fi.G1.'R!5 -IC!PRuFIl.E S50 r.3 i 5 MA!·;.;SAl;-TiiOMPSO~;REACii - ,,:~i.Uo. '':.:,."~~....f 2(; 1'::[e:OC'l'" 12 ,,,1f 1E· t.llC"'['lF<ES 10E16'""'0 215 210. iii 195 >,f==' c: o 190 ,.......r~A"\rt:=7/:..",Ii =;~<le~~!'\..'.'J -;,.- ~'-J\~,l i ~ISO .--{~ow - , ~i75',~--'~~~~.I ~170·::~~~~.~I !i~i'~i:! 165:i<=_c~--'~-i :":;."... iZ -..~.=--l :z~--:2-i!.--:2-=€-2.E.30 -' ui 205' :::E : 200 e;'~c::""-=~::' ~~!.:!-~:.i- £:.,.'_..'".. ir:i:e':'~5:ir.i or UrO:U5 ,:::.=:;.;,...;"'"--::-- s;-.~':.::=b-:cl?-:::r.:-::b:-~':,:r:."':::r ~:~~ ~i :..~...~I.L -:-:r ;c;;E ~"::0 J.;.]c boE J:::c::-:-~'r"~c .-:: ~,,~...!;.:i:!;:~i:i:"'t'f:'i:..::""it:;G ...A·..t=i.~-:~;=::'i; FIG~RI 7 -LAKE ~IN~IPEG OVTLEj LAKES The Or.:ina;:in bypass channel was cor-structed to supplement the capacity of the lie 1 so"Ri vel'throu~r,thE'Ki si pache~k.Metchanai s IiInc natura1 Otr.ina\o·in c~ann£-2:::::~"rE'~7 l>EL lts incorporation into the syste:::has rE'~t.:1tE'd iT'.;:s:g~~;ic.c.~:In:reaSE:in rJ(l"~sr.C SU~~E:C!uent hanfllnf can.forma-tic'!";in th~t:::'r'£-:"Co::i:u!\o"ir:ci;.c~nel.Fortunately th£-resultin~_los::in t:pper (~.iTia...·i;.c.ape;~i::)"i!=pa.:-tl:,~cot':?ensated by th~as.~.ocia:ed increase in flo ....... t~,T::l~~:.t":,..1'letchanai!'and Kisipach€\o~.lf·channels. ~:ard.t obc ~:-·dro h.a~.~m?1 en.enter::thf=fo1 j o..,.inr fie Ie pTog-rat:ior th£'P~!""POSE 0;d~::~in;~~,,~;n~cam~along thE Churchill River Diversion route: lce L:':"'7,,,t:o.,b to!Orr.ina-..ir.ri';;c:)-'ha!'bper:extr€T:I€ly va:--iable over the five year ?f:--iClC of l.ake \;innipe~rep.]s~lor..~.hiinginf carr.form::each :~t:ar;but it!=:locc:.io!"l cno size chan~e~P2cr,,.,·jnte:.;.~typicaJ exmple l €>:peri f'"a':G:;;rir,~the 1979/1980 \o-int er Sf,~on 1S sho"or:or,Fi gure 9.It 1:1;:'bE~:'1=-=e':;:G:r~t.sf€~'Ug to inco!"porate ic~co!"~:.rc,1 faci1 itie~or operating. :to:hr.l C;}~~t!"r€"du~!han;::i n~oar.,forma=iOI"'ir_tr.Ls reach. f '. .~ ,I ...,------------------------,...---------------------------------r--_______~~.........iIIiji:a;;;w;p ::;:;;;:;w .' r. I~L ;:~:'f --~~---,~--~~. Wt"'!f! ~.' .eI '---~_._---::------~---- I:I l C'I,'E.~'"t:.S ..-:- ~" Monitorin~Problems up to t ..·,:" i ~n:'"!r'':''€. la~-.·t-:r i~·~~iateJ\~uj't6~r ~h,C::}~S='::lG~E"C J;;:\>-e:-is i.'.~!l!...:!'e::h:p:-'Jilcir;;:h:-~:Jr~ ha~pC'in:~:end!",,-:ttl-'E l(1~~f :'C::':":.: J:i~difficult te,ic~r,ti::;th·::,:"...~.: i~Gl?fin~c a~t:~f'pc'.ir.:.c....,-·;-.~cr-_t~~-: Consolidated ice thickness, Heavy slush ice thickness, Light slush ice thickness, Snow cover thickness, Depth of water, Static water level and ice level, Water velocity profiles under the ice accumulation. S;u!=o}-"is pc~ncin~• :'-~liiyE:"f C: The measurements required at each test hole are: U:';iFh~ \.;i t r;oc:t FOT prac~ic..l naSC-::iS definitior;c'!1C,=censity has been divided intC'the fo 110..-i nI:thrf'~cat E:~O:-i e s_ Water surface profile$are required from a point upstream to a point do.~ stream of each apparent constri ct ion.Measurements should be spaced at 150m to sOOrn intervals.Elevations should be taken at each of the selected ice survey sections. Test sections shoujd be accurately referenced to existing cross sections and gau~es.Benchmarks should be established where profiles cannot be re- lated to known ~auges. \ole have not been able to obtain meaninf!ful measurements of slush ice den- sity anc porosity.~uccess is limited mainly because of the difficulty in obtainin~undisturbec sa~ples....·hen a salT'rle is extracted its properties chanre almost imm€':iiateiy in the characteristic sub-zero weather.'Irans- ferring tCl insu1ate:i containers further disturbs the samples and makes a H:a!istic:anaiysis difficull.Success iT.oblainin~ciensity and porosity measur·El:lenls is fUTther lin:iteci by tr.e fact that only the t0l'layer of the slush depClsit can be sa~pled. "~ea~y S1ust"if ~~~~11y f~une i~£ Fc:-f.ec€iCE".ThE':r.i::kne!::!-c!rhif it ..·itl"c sr~:ic;stee:probE::t:;c': E:t~~]ir:sid~fe:-in:pact (ri~\.:~E-lC). bo·ur.c a~:C"!tht.-h€c\"y S 1usn be::! "C~n"olidated Ice"h identified a~tht-!'olic !OUTface layer, trle:!"e~_:hicj.~J;t.;:-.:ich tr.:.:st bf.p'c-nctratec .....~itr,2!,;iC"~oiJt'er.Tr.r:<"'c wG!e~in thiE ley-er.rs:u211~·th:i~l,u,:"raCE:~i5yeT is rou~:~cnc ·\o-i:]-:silt-lik~impurities tha~tend t~dull aUEe:-b:ade~. .,4, ~.iirr~, I "'~-.":4:·}.1?,~"t '--~~:; 'i-"":,-~.,_..I :~.~~.:~~~".<...I ":::.'_,-:,,"~r~_. ~I.:.c;.~;;~.~~.~ .,....~.,.;-,.,'.~ ~:':/:-~:l .-.'"'1-::';.-~.; ~... -:&. ~ """, r -----,--~------------------- ....r - 3mm AIRCRAFT CABLE O. 10 mm NVLON ROPE Eta::,~a.a t er lE"'\'c-J an:icC:'1 eVE: ::~:a:!'~,.::E-P:',."':)£7.tr.€TE:i~b·~i It r.~!t·:..,-~.i or,e)::'!'ts,."i'10'0'C"\';:Ii lS \" E x 50cm 17 kg) FIPE FlGUF..I l(;-PROll:::'rOF.PEN::TR.~.Tlr-:G SLVSE ICE 'Tn€'!'"E i~oft e~~~rol,:e~ret ri p"'in!=the prob~throu!!!.tht:th i ckn deposi t 5 cf iCE-:l€CaUSfo it t€%"l'Of to freez~in.In man;'C25es thIE :;~aircraft cablE: UE-l:C tc suspend tilt:probe has fa:led ir.tenE-ior,curin.retrieval attempts. Sno~ccve'!'"thickne~E m~asurements arE strai~ht forwarc ~ith or.ly minor co~ plicaticnE introduced by driftin..and irrefularity of the ice surfacE. i.·a~er G-:;:.th~ar..o"t:~,,::ne::by 1 o;.'el'"i n.th..pre-bE to thE channel bot [o:n ani ~ound:~r ir::thE C'on\~en::i~na:manner.ijuic c!'ar i~fari!._clE'!'sE-ctionE:. ·\:d1~l@:'.:t.c puli th£w€iE:Ilt do·"",·;u=t::re2:t an~w.·iil s~'?tir.'l:e~re~iJlt in exag- ~@:;'"'a:f':C£t1tr,t!",Eas:;;:eme~:F.rsuc.~l:~thi$i!o c-w::ly c prl'""~:er.'"in narro",·deep f':E'~:jo~Y ....it1:1c!"f~ic~:if?C"!it:E J en::::ir~"·Fl"ritiesa 7he fr~f'water G':t:~l.:~~:f:I:"th€iet G€:FO!":'t i~S~le::=Jf-~difflcult [("I de:inf be-caUSE:the •!.u..-:-:-hr-·~n~C:T)·of th~lifht siusr:ci£?:,~it.i~not ('zs~1·~"~de!"lt i fi e-c.. r.:ea,f:.u~e~:en:~c'!t ~tTci~h:forward to U1=pTr!=!=i,;:"'t-un::e:;th~ice anci E.Ub 1 0"'- i!=tr,!7,c~~j::"'f!r.by fieic s!c=f tc,.thf: l~"Y~-=~..'~.i!s=--=,f-::~'::~f·r;~(.:"~r',:~r~i ;,,u:ie-:h~c·:""r-.s.::,,;i:5c~E-c i=~1zye!'"i!. .";:.-- 1r"'t ."c:'2:"'~~~'....:::.c.[ :-.~:f i:J,":,.~;'=':';7 ~~:~.::'oE :.~;- 44.,¢$ e!,,4;--:.:-:i.._:"'~O:~.~:~;c s~cn~c.r::j,,;'ir!~: a·~-:i:~:'~:'I:~~..;:-:-:1)"Tbt \o?~ir~:if