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HomeMy WebLinkAboutAPA2774SUSITNA HYDROELECTRIC PROJECT F EDER AL EN ERGY REGULA T ORY COMMIS SI ON PRO JE CT N o . 7 1 14 PREP A RED B Y ~ EWT&A R & M CONSULTANTS, INC. E. WOODY TRJHEY & ASSOCIATES UNDER CO N TRACT TO [}{]£(ru~£c~(ID£®©@ SUSJTNA JOINT VENTURE JIJL \6 - RESPONSE OF AQUATIC HABITAT SURFACE AREAS TO MAlNSTEM DISCHARGE IN THE YENTNA TO TALKEETNA REACH OF THE SUSITNA RIVER FINAL RE P ORT. JUNE 19 85 DOCU M ENT No. 2 774_ L..-...-------ALASKA POWER AUTHORITY ______ __. SUSITNA HYDROELECTRIC PROJECT RESPONSE OF AQUATIC HABITAT SURFACE AREAS TO MAINSTEM DISCHARGE IN THE YENTNA TO TALKEETNA REACH OF THE SUSITNA RIVER Prepar e d by R&M Cons ultants, Inc. William S . Ash t o n and E . Woody Trih ey and Associa t es S har o n A. Kling e r-K in gs l ey Unde r Co ntr 3ct To lfarza-Eb as c o Susit 11a Join t Ve n tu r e Prepare-d f o r Al~ska Po w ~r Allth or ity fi n al Re p o rt Jun o 1985 .. Do c,•m••1:t i\o . 27 74 5 u ..;i l ud F i l l! No . 4 .2 .2 .1 H13/l TABLE OF CONTENTS list o f Tables list of Figures Ackn owledgment 1.0 I NTRODUCTI ON 2 .0 SEGMEN T IDENTIFICATION AND \VETTED SURFACE A REA DETERMINATION 2 . 1 Lowe r River Segm ents 2 .2 C h annel an d I s lan d Cl assif i c ations 2 .3 Ph o tograph y 2 .4 Resu lts 2 . S Disc u ssio n 3 .0 HA B !TAT DE LI NEAT I ON AND SURFACE AREA MEASUREMENT S FOH SELECT ED STUDY AREAS 3 . 1 St u dy Sites 3 . 2 H abit at Type Design ation s 3 .3 Me thods 3.3.1 Fi,ld lvl \h od s 3.3.2 Office Proce du1·e 3 .4 Res ults 3.4.1 Genera l 3 .-1.2 Study Si t e 3 .~ Dis cussion ~.0 r,IORP HOL OG I C RESPONSE OF S IDE CH ,\N NE L CO I,IPL E.XES 4 . I G en~1·a l 4 . 2 Me th ods -1.3 Site Sp ec ific Desc ript io ns 4 .-1 Resul ts and Dis cuss i on Page ii iii i v 2 2 2 4 5 10 10 10 12 13 13 13 14 14 14 23 23 24 24 28 R23 /1 3 TABLE OF CONTENTS 5 .0 CO MBINED EVALUATION OF LO\\IER RIVER SIDE CHANNEL COM PLE X ES 5 .1 Gene ral 5.2 Channel Hyd ra ul ic Parameters 5 .3 Aerial Photography 5 . 4 Summa1·y 6 .0 REFERENCE S EX HIBIT A EX HIBIT B Aeria l Photog1·aphy Sh owing Mains t em and Side Channel Classifica ti o ns of th e Lower Susitna Ri er A e 1·ia l Photog1·ap h y for Se l ec t ed Rep ,·es ent- ative A1 ·cas Showin g Habitat Types at Se l ec t ed Ma instem Di sc h arges Page 36 36 36 37 38 38 R2 3/1 -1 LIST OF TABLES Table Number Description 2.1 Date a n d Discharge at Which Aerial Photography Was Obtai ned 2.2 3.1 3 .2 3 .3 Wetted Sur·face Ar ea at Selected Mainstem Discharges i n the Ye ntna to T a lkeetna Reach of the Susitr.a River Re pr·esentative Areas for the Lower Su s itn a River· Dates and Su si tna River Dis charges (as Measur·ed at Sunshine) a t Wh ich Aer·ia l Ph o t ogr·ap hy was Obtained a nd Helicopter Mapping Flights Were Flown . \Vetted S urface Ar·eas and Percent o f T ota l \Vetted Surface Ar·ea by Habita t Type a t F ive Ma inste m Discharges fo r Selected Repr·escntative Ar·eas . Page 4 7 10 13 16 ii LIST OF FIGURES Figure Number Description 2.1 2.2 2 .3 2 .4 3.1 3 .2 3 .3 Study Site Location M•p, Lower· Susitna Rive r . Surface Ar ·ea Responses t o Ma in stem Dischar·ge in the Lo wer Susitna Rive r: Mains tem and Segmen t I Side C h a nnel Co mpl exes. Su r·face Area Respon se s to Ma instem Di scharge in the Lower Su sitna River: Segment II Side Channel Comp lexes. Surface A r·ea Responses to Mainstem Dischar·ge in th e Lower· Susit n a River·: Segment Ill a nd IV Side Channel Comp lexes. Surface Ar·ea Responses t o Ma inste rn Di scharge in th e Lower Susitna Riv e r: SC IV -4 and Will o w Creek (SC 111-1). Sudace A r·ea Res ponses to i\'lainste m Discharge in th e Lo we r Susitn a River·: Caswe ll C r·cek and Sheep Cr·eek. Surface A r·ea Re sponses t o rv1ainst em Disch ,,r·ge in th e Lower Susi t na P.ive r·: Goos e C r ee k (SC 11-·1) and ~l on tan a C r·ee k (SC 11-1). Su r·face Area Responses t o Mains t ern Dis c har·ge in the Lower· Susitna River: Sunshine S lough (SC 1-5 ). Page 3 6 8 9 15 19 20 ~ 1 H1 l J I) LIST OF FIGURES Figure Number Description Page 4 .1 Compa r·ison of Vegetated River·banks and Islands 25 1951' 19 62 and 1983 : SC IV-4 . 4 .2 Compar·ison of Vegetated Riverbanks and Islands 26 1%1, 1962 and 19 83: Willow Cree k . 4.3 Compa r·ison of Vegetated River·b a nks and Islands 27 1951 , 19 62 a nd 19 83 : Sheep Cr·eek and Caswell C r·ee k. 4 .4 Compa r ison o f V ege tated Rive r·banks and Islands 29 19 5 1 , 1962 and 1983: Goose Cree k . 4 .5 Compari son o f Veget a ted Ri ver·banks and Islands 3 1 1%1 , 1962 a nd 1983: Monta n a Cr·e ek . 4.6 Cornpa r·ison o f Ve ge tated Rive rbanks and Is la nds 32 1951' 1962 and 1983: Sunshine Sl oug h . 4.7 Co mpa r·ison o f Vegetated Riv er b a nks and Is lands 34 195 1' 19 62 and 1983 : Birch Creek S loug h. iii R~3;1 ACKNOWLEDGMENTS This study was conducted under contract to Har·za-Ebasco Susitna Joint Ventur·e. Funding was pr-ovided by the Alaska Power Authority in conjunction with environmental impact assessment studies for the pr·oposed Susitna Hydr·oe lectric Project. The aer·ial photogr·aphs were taken by Air Photo Tech with photograph pr·inting and en largements by North Pacific Aer·ial Sur·veys . Dill Ashton, Sharo n Klinger -Kingsley and St eve Bre dthauer did the field checking of the habitat type designations. Jack Boik e, Rick Bennett and Len Stor·y digitized the wetted sur·face areas and Debbie S tephens assisted in data analysis . Steve Bredthauer , Woody Tr ·i hey and Cad Schoch pr·o vid ed many useful r·eview comments . Orl a ndo Paraoa n and Mar k Cor·dery dr·afted the figur e s and Ba r·b Estus ty ped the r epo r·t . iv H23 , 1 8 1.0 INTRODUCTION The pro posed Susitna Hydroe lectric Project will alter the natural streamflow regimes o f the Susitna River . In general, with -project flows will be lower than natural fl ow s during the summer and higher during the winter. These altered flows will a ffect the amount and seasonal availability of aquatic habitats present in the river . This report 'J)re~ents the results of three studies which examined the respo nse of wetted sudace ar ·eas to changes in mainstem discharge in the Yentna River Confluence to Talkeetna reach of the Susitna River (River Mile (RM) ~8 .5 to RM 98) (hereafter r·eferred to as the lower r·iver). The three s tu -:J ies were : 1) to define segments of sim ilar mor·phologi c char·acter·is tics and deter·mine the response of wetted sudace ar·ea o f the lowe r· river (RM 28.5 to RM 98) to cha n ges in ma inste m di schar·ge ; 2) id ~ntffication, mapping , and surface ar·ea determination o f aquatic h abita t ty pes in selec ted study areas in the low e r ri ver and eva luating the sudace ar·ea re·spon se to dischar·ge for these h ab itat types ; an d 3) an evaluation o f the mor ·phologic stability of islands and side cha nn els in the study areas using ae r·i al photogr·aphy taken dur·in g the per·iod 1951 to 1\.183 . Th e scope of th is s tudy is to pr·esent th e resul ts of th<! thr·ee subjects described above fo r· natu r·a l fl o w conditio ns. Al th oug h wetted surface ar·eas may be used a s an indicator o f habi t ,1t availabi lity , it does not r·epr·esen t habitat qua lit y. T hi s repo r·t does not conta in any sta t e ments co nce r·ni n g the su it abi lit y of the var·i o us habitat t ypes for· fish , n or does it addres s how the qua lit y o f th e ~e habitets may respond to changes in main s tem dischar·ge . Subsequent r epo r ts wi ll deta il th e effects of the with -pr-oject flo w regime on th ese three subj e cts. Pr·evio us work on the Susitna Riv e r· has used aeria l photog •·ap hy for aquatic habitat analysis . Klinger and Tr·ihey ( 1984 ) a nd Klin ge r·· Ki n gs ley ( 1985) rneasur·ed wetted surface a r·eas o f aquatic habitat t ypes in the -1· R2311 g Susitna River b etween Talkeetna and Devi l Canyon (RM 98 to RM 1·19 ) (referred to as the middl e river) a nd evaluated changes in wetted su r·f ace area as a response to rn ain stem discharg e. These studies provided background an d served as the basis fr·orn whi c h sections o f th is pa r ticular study wer·e developed. Both of th ese studies have shown that r·epeatable, visual ide ntification of the wetted sudace Heas associa t ed with di fferent aquatic habitat types can be made by various observer·s . Second ly, it was shown that accurate sudace area measur·e ments can be ob t ai ned by d igitizing the aerial photography. The abili ty t o ac hi eve both these g o a ls is essential fo r th e successful comp letion of a s tudy such as the present one. To adequately inter·pret the r·esu lt of sudace a r ea measurements, an evaluation must be made of the r·elat ivc stabi lity o f cha nn e ls and is la nds in the study a rea . For this r·eason, th e mo r·phol o gic c;ssessrne nt was per·for·med. This r·epo r·t cons is ts of five sec ti ons. Sec ti o n I p r·o vides backg r·ou nd o n th e scope o f this r·eport . Sec ti o n desc r ib es th e wett ed surface a r ea response to disc h arge fo r· the en tir·e lo we r ri ve r b e twee n Talkee tna and the Yen tn a Rive r· confluence . Sectio n 3 p r·esen t s r es ul ts o f de lineating a qua t ic habitat types and mea suring th e ir· sudace area r·e sponse t o disc h arge in s e lect ed rep r·es entat ive ar·e as . Sect ion -\ addr·esses the r e la tive s t ability of t h e channels and is lands in t h e s e le ct e d r ep r·cscr.t a li ve area~. The r·es u ll s of this e va lu atio n will provide s o rn e limit s w1t hin whi c h th e su d ace area r esponse data ca n be int e 1·p r·e t c d and wil l indicat e t o what extent ex trapo la ti o ns r.a n be mad e fro m th e m . discuss e s th e ir applicab ility t o the r e fer enced in th is r·epo r·t a r e b.1sed St'c ti o n ~ combi n e s th e r es ;,rlts a nd lo we 1· ri ve r . All tn ;"t inc: lcm fl ows o n th e U.S. Geo log ica l S urvey streamf lo w gage at S unshin e (N o. 1 529 ~780 ). 2 .0 SEGMENT IDENTIFICATION AND WETTED SURFACE AREA DETERMINATION 2.1 lower River Segments The water area of the lower Sus itna Riv e r was measured to provide an init ia l estimate of changes in wetted surface area in response to changes in mainstem di s charge . This estimate was then used to s elect r e presentative side channel complexes for detailed a nalysis (see Section 3). The lower river was divided into 5 segments based on r·iver mor·pho log y and hydr·o lo gy (Fi g ure 2 .1). The seg ments ar ·e descr·ibe d below and are del ina ted on ae r·ial photog r aphs in Exh ibit A . Segment I: RM 98 .5 to RM 78 This s egme nt extends fro m th e Chulitna River· confl ue n ce downstream to th e h ea d of th e s ide ch anne l complex just upstream o f Mon t a n a Cr·ee k . T he river is br·a ided, with th e main c h annel meandering thro ugh a wide gr·a vel flood pl ai n . La rge expa ns es o f gravel bar·s a r e exposed a t lo w fl ows . Th e c h a nnel is c o nstr·icted to a single c h an n e l a t the Par·ks Hi g hway Br·idge (RM 83 .8). Significa nt t ribut a r·ies in t his seg me nt in c lude Birch C r·eek, T r appe r C r·eek, S un shine Creek, and Rabideux C r·ce k . A t o tal of six side channel comp le xes were id e nti ~ied. Segment II: RM 78 to RM 5 ·1 This segrnent ex t ends fro m t h e side c h anne l above Mon tan a Cr·eek to th e h ea d o f Delt a Isl ands wh e re th e r·iver sp lit s in t o two main cha nn e ls. T he mo r·ph o l og y i n segme nt II is co mp l ex, with t o tal o f 9 side c h a nnel comp lexes a lo n g th e flood p l ain margi n , a nd two add itional side c h annP I comp lexes located within mid -channe l islands . S ig nificant tr·ibutar·i es i n this segment include fo ntana C r ee k, Goose C r ee k, S h eep Creek, Caswe ll Cr·cek a nd th e Kashwitna River·. -2- R2311 11 Segment Ill: RM Sl to RM 42 . S This segment encompasses the Delta Isl a nds r·each wher·e two mai n c h a nnels exist, o ne on the east and one on the west. A t o t al o f five side c h annel com p lex es exist in this segment , w ith a major complex between the two ma in channels. The segment ends whe r·e the t vo main channels r ejoi n . Significant tributaries in this s eg ment inc lu de little \villow Creek and 1\'i llow Cr·eek. Segment IV: RM 42 .5 to RM 28 .5 This segment ext e nds fr ·o m the l.>wer end of th e Delta Is lands to the conf lu ence wit h th e Ye ntn a RivH. Th e r·each is c h aracterized by br·aided pattem, with seven side c h an n e l comp lexes. The Deshka Rive r· enter·s th e upper end o f this r·each. Kro t o S lough br·anc h es o ff fro m th is segme nt, a nd ex t en ds t o the Yentna Riv e r. Segment V: RM 28>. 5 to RM 0 T hi s s e g men t ex t e n ds fro m the Yen t na R ive r , which co ntr·ibute s <rppr·oxima t e ly 40 per·c e nt o f the total fl o w o f the Susi t na Ri ve r. to Coo k I nlet. The segmen t is p rirnar·ily a sp l i l ·channc l configu r·ation down t o RM 19 , t he h ea d o f Al exande r S lo ugh. Th e S u si tna Riv e r has t wo c hann e ls fr·om RM 19 to Cook In let, wi th t he main cha nn e l on the e ast s ide. T h e wes t c h a nn e l is p r irnfi r·i ly an ov erfl o w c h ilnncl . It s up pe r sec ti on dewaters a t lo w flo w . whil e the lo we r s ec ti o n is fed by Alexa nder C r·ee k. Other tribut aries ente r·ing thi s segme nt rndu d c And e r so n C r ee k and Fis h C r·eek . 2. Channel and Island Classifications rwo mai n c,as s ifications w e r e id en tified wi t hin t h e segments, with subc l assi fi cai.ions recog n iz ed f o t· pu r pose o f fu tur disc us s io n bLJ t w c r·e n o t d rff e r erl tiated in th is ana lysis. SEGMENT NUMBER II Ill IV v I MONT ANA CREEK "'C' T.l ooo o ;•~ (\ GOOSE CREEK ) \\/ ..__ ··lr~:::iiiiiiiiii?.·o M u ~s n ~o 1 ~ o<if om ~l e t s 1\-----., SC IV-4 t - (.' ' " -~ -\ ~~) =~ EWT_&A 0 o o •0"0 o oM O o Ooo ''"''''' .,R E r>A RE D a ·,· I'I&M CONSULTANTS, INC. 0-~~=-~0 ~~CE ( --~ COOK INL ET STUDY SITE LOCATION MAP LOWER SUSITNA RIVER _,. ~· SLOUGH ------SHEEP CREEK CREEK FIGURE 2.1 PRfPA RE U F OR .lXJ&OO~& = ~®!£~'0©; SUS! TN ;, JOir-.. • •.1: ~ .;. R2 3/1 12 Mainstem Channel is that portion of the river floodplain between the v eg etated bound ar·ies, i ncluding the wide gravel fl oodplain and isolated v ege tated i•lands in mid-channel. Two subclassifications are : 1. Mainstem r·iver -the th a lweg channel and main subchannels . 2 . Al lu via l island complexes areas of b r·oad gr·avel islands with numerous subchannels which dewater as flow d ecreas es . Side Channel Comple xes c o nsist of one or· more channels fl owing amo ng a gr·oup of vegetated is lands . Th e se complexes are usually locate d along the edge of the mainste m riv e r but, in are as s uch as the De lta Is lands , may occur in the middle of the river . The side channel complexes were numbered in d owns tream o r·de r within eac h segment. Channels within the side c ha nnel c omplexes are classified within one o f three groups . These g r o u ps are diffe r·e nti a t ed by the pr·esence o r· absence of ove l'lopping fl ow in the p hotograp hy u sed in this analy s is (see Secti o n 2 .3). Once a subclassification is determined for a channel, th e channel will have that s u bc lassificatio n thro u g hout th e r ange of mains t ern flows . This subcla ssi fi cation is based sol e ly on overt oppi n g fl o ws and does no t cons ide r· pot e nti a l h ab ita t ch a r ac t e ri s ti cs of the channel. 1. 2 . Ma jo r side c h ann<>ls a r e over t o pped a t rnain s t e m fl ows o f 13,900 cfs and lowe r·. Th e y t e nd t o be, but are no t limited to , th e o ut side-mos t channel of a complex , c loses t to the edge o f the f loodp lain . These ch anne ls may co ll ec t g r o undwa t e r· seepage and t1 ·i bu t ary fl o w . I n t e nnedi a t e side c h an nels d ewa ter· a t th e i,. ups t1 ·earn be 1·m in th e ma in stem fl o w rang e of 13,900 cf s t o 59 ,100 cfs. After t hei r· u ps tr·ea rn benn dewa t c t·s , som e i nte l"rne d i ate ch anne l s ma i ntain turbid w a ter to a main s t e m fl ow o f 21,100 cf s or le ss, whil e o th ers contain cl ea rwater f1·om g r ou n dwa t e r and/o r· sur·f acc wat e r· inflow. O th er int ermed iate side chan n e ls dcwa ter the complet e le n g th o f th e c h ann e l be for e t h e -4- 1\:!3 /1 13 ma in stem flow d ecrease s to 21,100 cfs. lnter·med iate side cha nnels may be ex tens ions of trib utari es once th ei r· u pper· be r ms dewa t cr. 3 . Mino r· side c hanne ls dewater· at th e ir upstr·ea m berm at mainstem fl ows of 59, 100 cfs a nd higher . These c hann e ls tend to be dew atered the complete length of the c h a nn e l at mainstem fl ows of 36,600 cfs . 2 .3 Photography Black an d white aeria.l photog r·aphy a t a sca le o f 1" = 2 ,000 ' was obtained of the lower· S usitna River· at f ive mainst em disc h arges (Ta b le 2.1). Date 3-27-84 8-27 -33 9 -6 -83 9 -16-83 10 -2J -83 TABLE 2 .1. DATES AND DISCHARGE AT WHICH AERIAL PHOTOGRAPHY WAS O BTAINED Disc harge at S un s hine 75,200 cfs 59, 100 cfs 36,GOO cfs 2 1, 100 cfs 13,900 cfs Remarks Typical July -August natura l flow Typica l July -Augus t fl o w d ur ·ing p roject ope r·a ti o n . T r ansitiona l na t uJ·al fl o w a n d p r oj ec t o p e 1·a ti on fl ow during ivlay J nd Sept ember . ll ig h wint e r· fl ow du t·ing pro jec t ope t·a ti o n . Lo w win t e 1· fl o w du t·in g p 1·o j cc t ope r <t ti o n . Photo mosaics were pr·epar·ed from each set of photography for river Seg- ments 1 thr·ough 4. Segment 5 was not included due to inflow from the Yentna River and tidal inf :uences which were assumed to mask changes in habitat sudace areas due to project oper·ation. Boundar·ies of each mainstem or side channel compleK were defined. island and gr·avel bar was numbered and its boundary delineated. Each The total area of the segment was determined . Areas of islands and gr·avel bars wer·e subtracted from the total area to obtain wetted surface area (WSA) of the subsegment. Channels which extended thr·ough an island complex we;·e delineated. Backwater· areas were also included, but isolated pools were not digitized , as these ar·eas wer·e not consider·ed usable habitat. Sur·face ar ·ea dete:·minati o ns wer·e made using a HP-9845 computer· and ar·ea measur·ements wer·e calculated and displayed to an a ccuracy of 0 .0049 inches . This represents an accur·acy of 10 feel for· photogr·aphy at a scale of 1'"=2000". Individual rneasur·ements wer·e r·ep licated 2-4 times and the average value used. All meas ur·emenls were adjusted for a common scale due to minor scale differences between flights. The September· 16, 1983 set of photography was us ed as the base and all measurements adjusted to match that sca le. 2.4 Results Segment I The r·esponse o f th e we tt ed strr ·face ar·ea i n s ide channel compl e x (SC) 1-5 to rnainst e rn disc har·ge is ind ica tive o f a side channel complex with a mix of maj o r, inte rme diate, and min o r· s ide c hann e ls (Figure 2 .2, Table 2 .2 ~nd Exhibit A). SC 1-4 . a side c hannel complex with few inter·mediat<> and min or· side channels and n o maj o r side ch a nn e ls , has a slight change in we tted s ur·fa cc a rea with d cc r eJsi ng main s t e m di$c haf"ge (Figure 2.2). For· SC 1-1 a n d SC 1·2 the s light ri se in we tted surfac<> ar·ea at 13 ,900 cfs is -5- R~3/1 15 due to the problem of delinating the edge of water with the ice cover in the photogr·aphs . Segment II SC 11-6 is a large side channel compleK with many minor and inter·mediate channels (Figur·e 2.3). The sharp dr·op in wetted sud ace ar·ea at 21 ,100 cfs is due to dewatering of many intermediate channels. SC 11-1 shows the wetted surface area response of a side channel compleK with no major channels and a few inter·mediate channels. SC 11-9 consists of inter·mediate channels which rapidly dewater at main stem dischar·ges below 59,100 cfs (Figur·e 2 .3). At SC 11-8 the wette d sud a ce ar·ea at 75 ,200 cfs and 59,100 cfs ar ·e appr·oximately equal, but due to slight local scale changes in the air photos the wetted sudace area at 59,100 cfs digitized slighty larger . Segment Ill SC 111-2 has many minor· and interm edia te channels. The rate at wh ic h intermediate c hannels are dewatering increas es below 36 ,600 cfs, indicated by thP incr·eased slope of the wetted 5lrr·face ar-ea res ponse curve (Fi g ur ·e 2.4). In contr·ast. the r·ate at which intermediate c h a nnel s dewater· in S C 111 -5 is greater betwee n 59,100 cfs a nd 3G,GUU cfs th a n between 3G ,GOO cfs and 21.100 cfs (Fi gu r e 2 .4). Th is is p r·obably d ue t o the wide r· shallower· c ha nnels o f SC Ill -S. Segment IV SC IV -5 and S C IV-7 are sid e c hann e l cot up lc xes with on e intermedia t e sid e channel and no maj o r o r mino r· side c h , nn e ls (Figu re 2.·ll. SC IV -1 :.n d SC IV-2 il r e side c hannel complexes with 111t111 y mino r .1nd in t e rm ediil t t! sid e chann e ls a nd no major side chanr.~ls . The s lope o f th e we tt ed su rf.1cc ar·ca t·espo n se cur·ve is steepe r a t fl o ws t~b o ve 3G,GOO c f s beca u s e the channels in SC IV -1 a nd SC IV-2 a t·c gc n e t·a ll y wi de and s h a ll ow wh c t·cas th r chann e ls in SC IV -5 and SC IV -7 ar-c gc n e r·a lly deep a n d n a n·ow . II II • • II • • • • • I I I .;- 2 ,. N ,_ ... - < Ill a: < Ill (,) < ~ a: :::> .. 0 Ill ,_ ,_ Ill 3: 2 0 SEGMENT I SIDE CHANNEL COMPLEXES 1,000 MAINSTEM 10 ------s~cul~-2~----------------- "'-2 X ., ,_ ... < 100 Ill 1.0 a: < Ill (,) < ... a: :::> .. Q Ill sc 1-4 ----,_ ,_ Ill 3: 1 0 +--------.--------,---------,---·----,---------r-------~--------, 0.1 -1---------,--------,---· 10 lO so 40 00 •• 70 1 0 10 20 •• 40 •• 1 0 70 10 MAINSTEM DISCHARGE AT SUNSH I NE (ci s X 10 3 1 MAINSTEM DISCHARGE AT SUNSHINE (ci s X 10 3 1 PREPARED FO R ' PREPARED BY ' I SURFACE AREA RESPONSES TO MAINSTEM DISCHARGE ~EWT&A R &M CON SULTANTS, I NC. . ...... ···-.. .......... IN THE LOWER SUSITNA RIVER: ····-··· ..... ~... ............ ......... I MAINSTEM AND SEGMENT I SIDE CHANNEL COMPLEXES FIGURE 2 .2 ""-lt ·, .. \Jn l I t J\il 1fH 0 .. ( R22 /~-,a ' T A!3 LE 2 .2 . CHAN GE S IN WETTED SURFACE A REA AT SEL EC TED MAIN ST EM DISCHARGES IN THE Y ENTNA TO TALKEETNA REAC H OF THE SUS I TNA RIVER Date 8-27 -84 8 -27-83 9 -6 -83 9 -16 -83 10-25 -33 Disc harge(cfs ) 75,200 59 ,100 36 ,600 21,100 13 ,900 @ Sun sh i ne Percent of Pe r cen t of Pe rcent of Percent of Pe r·c e nt of WSA Subsegme n t WSA Subsegmen t WSA Sub segme nt WSA Subse g me nt WSA Su b se g me nt Subsegment ( 106 sq ft) Area 1 ( 106 sq ft) Area (106 sq ftl A rea ( 106 sq ft) A r ea ( 106 sq ft) A r ea Mains t em I 230 70.6 203 62 .8 156 48.2 123 38 .1 11 0 34 .1 sc 1-1 1 .10 23.6 0 .82 17 .3 0.67 14.1 0 .44 9 .3 0 .46 9 .8 sc 1-2 4.66 14.4 3 .83 11.8 3 .3 1 10.2 2 .47 7 .6 2.52 7 .8 sc .-3 2 .84 4 1.0 2 .76 40 .0 2.27 32 .9 1.63 23.6 1.14 16.6 sc 1-4 0 .5 1 36.8 0 .42 30.2 0 .40 28 .6 0 .41 29.9 0 .37 26.5 sc 1-5 15.6 29.7 14 26 .7 11.5 21.9 8.47 16 .2 6.84 13 .0 sc 1-6 2.06 25 .9 1.67 20 .9 1. 29 16 .2 1.14 14 .3 0. 55 6 .9 T o t al SC I 26 .8 26 .6 23 .5 22.2 19.4 18 .3 14 .6 13 .8 11 .9 11 .2 Mainstem II 339 63 .4 292 64.2 229 50 .3 199 43.8 160 35.2 sc 11 -1 1 ..1 1 13 .5 1.16 11 .2 1 .16 11.2 0 .58 5 .6 0 .25 2 .4 sc 11 -2 7.42 25.6 6.33 21 .8 4 .27 14.7 3.12 10.8 1.4 1 4.9 sc 11 -3 3 .90 27 .5 3.20 22.5 2.38 16 .8 2.39 16 .8 0. i9 5.5 sc 11-4 9 .95 17 .6 8 .34 15. ~) 4.97 8.5 3 .69 6.5 2.59 4 .6 sc 11 -5 6.24 31 .7 6 .22 39 .7 4. 77 28.0 4.20 24.6 2 .13 12 .5 sc 11-6 42.6 27.3 42 .8 27 .4 3 2 . I 20 .5 27.1 17 .3 11.9 7 .6 sc 11 -7 1.46 23 .6 1 .10 17.8 0.63 10 .2 0.5 1 8.2 0.36 5.8 sc 11-8 13 .1 2-1.1 13.5 24.9 lO .i 18 .7 9.15 17.0 5 .88 10 .8 sc 11 -9 0.76 11.5 0 .74 11.3 0.19 3.0 0.00 0.0 0.00 0.0 sc 11-10 1. 79 38.6 1. 50 32.5 1. 29 27.9 1. 25 27.0 0.59 12.8 sc 11 -11 39.5 18 .7 33.1 15.7 I S. 1 8.6 16 .8 7.9 6 .84 3.2 Tota l SC II 128 22 .5 118 21.7 SO.O 13 .9 GS.9 12 .2 32.7 5.8 Mai11stern I ll 103 79.3 9 1 .9 i O. 7 7-1. 7 57.5 6 1.9 47.7 52.4 40 .3 sc 111-1 (3) 11.8 29 .2 11.4 28 .1 10 .4 25.6 7.54 18.6 6 .23 15.5 sc 111 -2 IG.O 20.8 1-1.1 17.9 11.5 14.6 6.9 1 S.3 ·1.59 5.3 sc 111-3 '17.8 16 .5 46 .3 16 .0 38.2 13.2 27.6 9.5 2G.6 9.2 sc 111 -4 7. 18 3 1.6 7. 23 3 1.8 !:>.34 23.5 3.87 17.0 3.11 13.7 sc 111 -5 1. 7~> 21.2 1.34 16 .5 0 .57 6 .9 0 . •17 ~,.*I 0.33 ·1 .0 Tota l SC I l l 84 .!:> 19 .2 80.4 18 .6 66 .0 15.0 46.·1 10.5 -10.9 9.3 Mainstem IV 120 32 .0 103 69.3 87 .5 59.5 75.0 ~'I . 1 G6.3 4 S.2 sc IV-1 4.15 22.4 2.94 15 .8 1. 52 8.2 l. 05 5.6 0. G2 3.3 sc IV-2 2 .93 4 1.7 2 .32 32 .5 1.72 24 .1 1.31 18.3 0. ~·3 7. ·1 SC I V -3 12 .9 23 .2 12 .6 22 .6 10.!:> 18 .9 8. IG H .7 5.84 10 .5 SC I V -4 9 .25 29 .2 8.08 25 .5 6.64 20.9 4.7G 1:,.o 2 .80 8.3 sc IV-5 0 .86 28 .6 0.82 27.1 0 . 74 24.4 0.38 12.4 0 . 13 4.-1 sc IV-6 30 .4 3!:>.7 26.8 31.5 22 .0 2 ~>. 9 17.2 20 .2 12.2 14 .4 sc IV-7 0. 77 29 .2 0 . 77 29 .1 0.66 25.2 0.36 13.7 0. 14 !'>.4 T o t al SC IV 6 1.3 30 .2 54.3 26.7 43.8 2 1.5 33.2 16.3 22 .3 10.9 NOTES: -7- 1) (\Vetted surface area/side channel complex o r· mains t em a r·ea) X 100 •o 10 ~ 2 X N 1-... .. "' a: .. "' u .. ... a: :::> (II 0 "' 1- 1- "' ;l 1.0 o.z SEGMENT II SEGMENT II SIDE CHANNEL COMPLEXES s c SIDE CHANNEL COMPLEXES 10 I ~-/ '2 X N 1-... .. "' a: .. "' u .. ... a: :::> (II 0 sc 11-1 0 IU 1- 1- "' ;l 1.0 }IJ ,~ "'" o.z ·.--------,----------r-------~---------·r-------~70~------~oo 30 4 0 'o 3 eo DISCHARGE (cis X 10 ) 10 zo 4g1 SCHAR G E t ·.--;l_s_X--10_3 _) -;o----------,7,-0 --------,80 10 zo lO P.REPAREO FOR : PREPARED BY ' I I SURFACE AREA RESPONSES TO MAINSTEM DISCHARGE ~~------EWT&A IN THE LOWER SUSITNA RIVER : I'I&M CONSULT ANTS, I NC . . ....................... SEGMENT II SIDE CHANNEL COMPLEXES ..... , ....... ••D~O<to e r • .. ~D-OLOIIO e •• ........ •O•e F I GURE 2. 3 • .. • 111.. • \: : '.: i ~~ r "'-Q X ,, .... IL <t "' a: <t "' u <t IL a: ::> Vl 0 "' .... .... "' 3: 10 1.0 / 1 / 02 ~ SEGMENT Ill SIDE CHANNEL COMPLEXES __Jo ________ ~•o ________ •~o----~--·.~o ________ 7p DI SCHARG E ( c f o X 10 3 1 .$' <:? >( N .... IL .. "' a: .. "' u <t IL a: ::> Vl 0 "' .... .... "' 3: . ____ o,o 30 SEGMENT IV SIDE CHANNEL COMPLEXES 10 1.0 sc IV -7 0.1 20 30 •o 00 00 DISCHARGE (cfo X 10 3 ) PREPARED FOR ' PREPARED BY ' I EWT&A I SURFACE AREA RESPONSES TO MAINSTEM DISCHARGE :J3L~,.----------------FIGURE 2.4 70 00 R~3!l 16 2.5 Discussion The response of wetted surface area to Jischar·ge for side channel complexes is genera lly indicative of the mix o f major·, intermediate and minor side channels within a specific side channel complex and the cross-sectional shape of those side channels. For· examp le, when the mainste m discharge decr·eases from 75,200 cfs to 59 ,100 cfs side channel complexes with relatively few minor side channels and relative ly deep narr·o w inter·mediate side channels have little or no decrease in wetted surface area (see SC IV -5 and SC IV-7). As the ma ins tem discharge decrea ses fr"Om 59 ,1 00 cfs to 21,100 cfs the slope of the wetted surface area r·esponse cur·ve s in Figur·es 2 .2 thr·ough 2 .4, indicates the mix of inter mediate an d major side channels and their· cr·oss-sectional shape. For examp le , side channel complexes with wide shal low inter·rnediate side channels wrll ha ve a steeper· s lop ing line in Figur·es 2 .2 throu g h 2.4 than will a side channel complex with predominately nar-r·ow deep channels. As the rnainstern dischar·ge decreases to 13,900 cfs interme diate channels have dewater·ed completely or· have substa ntially smaller· wetted surface area than at 21 ,100 cfs. The we tt ed surface area at 13 ,900 cfs was difficu lt to digi t ize because the aeria l p hotog r·aphs were tak e n a fter ice had cover·ed low ve loc ity areas. Ther·efo re the wetted sut·fa ce a r ea fo r· the 13 ,900 cf s aer·ial photography is pr·o bably und e restimated fo r mos t side channels and over·estirna t c d for a few side cha11ncls. -10 - R13 /1 17 3.0 HABITAT DELINEATION AND SURFACE AREA MEASUREMENTS FOR SELECTED STUDY AREAS 3 .1 Study Sites The lower Susitna River· encompasses an extensive ar·ea of b :·a ide d c h annels and side channel complexes . Representative ar·eas we r·e chosen in the lower river for which ha bi tat types would be mapped and wetted surface areas measured (Figure 2 .1 ). Eight areas were selected as representative of the downstream variation in channel morphology present in the lower river (Tobie 3 . 1). SC IV ·•I TABLE 3 . 1 . REPRESENTATIVE AREAS FOR THE LOWER SUSITNA RIVER Area Name SC IV-4 1\!ill ow Cr·eek (SC 111 -1) Caswel l Creek Sheep C r·eek Goose C r·e ek ( SC 11 --1) Montana C r eek (SC 11 -1) Sunshine Slough (S C 1-5 ) Bir·c h Creek Slough Inclus ive River Miles 32 .5 36 .0 49 .0 52 .0 G-1.0 GG. 1 G3.5 1. 5 77 .ll ""Q l u. ll S-1 .0 8G.5 SS . 5 93.0 Side channel complex SC IV -4 is loc , ted be tw ee n ~~~~ 32 .5 an d RM 36 o n th e east bank of the Susitna River . This r·c j)r·esen t a ti ve tu·ea ha s tw o major· side channels that remain b r·e .1 c h ed a t 13 .900 cf~. One inte rmedia t e side channel becomes nonbr e ach cd be lw e n 21.100 a nd 13.900 cfs. R2311 18 Several smaller intermediate and minor· side channels exist . Most become dewatered as mainstem discharge dr·ops from 59,100 to 21,100 cfs. Willow Creek (SC 111-1) SC 111-1 extends from RM 49 to RM 52 . Willow Cr·eek enter·s the side channel complex at appr·o ximately RM 49, while Little Willow Creek ente r·s at RM 50 .5 . This representative area has one main major side chai>nel fl owing through the upper two-thirds of the complex with a maj o r· side channel branching off and continuing through the rest of the complex. There ar·e sever·al inter·mediate side channels . Little Willow Creek flows into an intermediate chann e l c : eating in clear-water ar·ea as main s tem s t ag e d ec reases and/or· tr·ibutar·y flow increases. Caswell Creek Ca swell Creek is a tr ·ibutary entering a side channel of the Susitna Riv e r at ap proximately RM 64. T he . upstream end of this si de channel is dewatered at 37 ,000 cfs . \\'h e n this occur·s the tributar·y mo uth e xtends app r ox imately 800 feet downstream. Sheep Creek Sheep Creek is a tri b ut a ry e nt er-ing a sid e r.hann e l o f th e Susitna Riv e r at RM GG . 1. Backwate r· effects d u e t o side channel s t age r·a nge from no effect at low mainstem d isch a rges (13 ,900 cfs). t o a b ack wate r zo ne o f app r o ximately ~>.000 fee t a t a mainstcm di sc h a r ge o f 52,000 cfs, with a g r ea ter· e xtent of back wa ter· at hi g h e r· fl ows . Goose Creek (SC 11-4) Goo se Cr·eek Side Channe l , loc ated be tw e en RM 68 .5 and RM 72.5 , is a la rge s id e chann e l comp lex. The comp le x h as o ne rna in intermediate side c h a nnel and nume r o u s smaller i nt e r-m ed ia t e a nd minor· side channels . Goose -11- R23 / 1 19 Cr·eek enter·s the main intermediate side channel of the side c hannel complex at appr·oximately RM 72-. Montana Creek ( SC 11-1) SC 11 -1 extends from RM 77 to RM 78 with Montana Cr·ee k enter·ing SC 11 -1 at its downstr·eam extent . SC 11-1 is a r·e latively small side channel complex with one main intermediate side channel and sever·al smaller intermediate and minor side channels . Montana Cr·eek h as relatively steep g r adient resulting in no backwate r· ar ·ea until mainstern flow inc r·ea se s to appr·oximately 38 ,000 cfs. Sunshine Slough (SC 1-5) Sunshine Side Channel complex is located b e tw ee n RM 8 4 and RM SG. 5 on the east bank of the Su si tna Riv e r . The side c h a nn e l comp lex consists of one maj or sid e channel , two main inte rmed ia t e side ch a nn e ls and severa l smaller inte rmediate and minor· side channels. Only th e maj o r· channel conveys water thr·ough o ut the fl ow ran ge inv es tig ated . T he othe r· channels become side sloughs, co ntain isol ated ponded wa t e t·, o r· d e wa t e r comp let e ly at 13 ,900 cfs. Sunsh i n e Ct·eek fl o ws into th e majo r s ide chann e l a t a p o in t app roximate ly 8,000 fee t u ps tr·eam from t h e con flu e n ce of th e side c hann e l with the mainstem Su si tn a . Birch Cr·eek Slough Bi r·ch Cr·eek Slough is a sing le ch an nel exte nd in g from 01pp r ox irn a t e ly RM 88.5 t o RM 93 on the cas t b a n k o f th e Susi tn a Ri ve t·. ll it ·cl> C r eek cn t e t·s th e sl o u g h at a point s li g htly les s th an a mil e ups trc om ft ·om it s co nf lu e nce with the Su s itna . Bit·ch Cr·ec k S lo u g h was chose n as a s tu dy si t e t o be r·ep r c se ntative of si ngle channel s ites in th e r iver. H13 /1 10 3 . 2 . Habitat Type Designations Aquatic habitats associated with the lower Susitna River wer·e classified into eight general categories: mainstem, primary side channel , secondary side channel , turbid backwater, clearwater, side slough, tributar·y mouth, and tributary . These categories represent physical char·acter·istics of the habitat type visually discernible from aerial r·econnaissance or examination of aerial photography . As such , these do not necessarily convey any specific bio logical significance nor do they indicate spe cific geographical locations . In some instances, tr·ansfor·mation of one habitat type into anoth e r may occur as river stage increases or decreases These habitat type designations differ fr ·om the channel classifications iro Sectio n 2 in that these are associated with aquatic habitat where as the ch a nnel cla ss ification s ar·e associa ted with channel geometry . Characteristics used to d e lineate the eight aquatic habit a t types ar·e de- scribed below. These descri p tio ns r ep r·es e nt physical att r ibut es of the habitat type during ice-fr·ee conditions. The se p hys ica l a ttrib u t es a r·e visually r·ecognizable du ri ng h e licopter r·ec on nais sa nce flights . Mainstem h ab itats r·ep r·esent the rnain s tem ri ver, cons istin g o f th e th a lw e g channel, maj or subchannels and a lluvial is la nd com ple xes. T h is h abita t type was, in most cases, outside the boundao·ie s of th e cont r·o l a o·eas used to define r·ep ,.e s en t et tiv e area s . Primary side channel habitats a r·e those c ha nne ls which nor·ma ll y c o nvey str·ea mflow thro ughout the enti r·e year-. Th e y ex hi b it c h arac t e ri s tics similar t o mi dd le Susitna Ri ve r· rnain stern h ab it a t types, a s described by Klinger· and Trihey ( 1984). Th e y a r·e char·ac t e r·izcd by tur·b id g lacia l water , h i gh velocit ies. and few mid -c h a nn e l g ,-ave l ba rs . Secondary side channel habita t s a lso h ave turbid water·. but ex hib it c h a r · ac t e r·istics o f th e midd le 1·iver s ide c han ne ls . For e)(a mple , t h e re a •·e -12 - H23 /l 1 1 mid-channel gr·avel bars and riffles or water· surface featur·es that indicate slower-moving , shallower water. Turbid backwater habitats are nonbrea ched channels containing tur·bid water. They have non-vegetated u ppe r thalwegs that are over·topped dur·ing periods of moder·ate to high mai nstem discharge . They rep r esent a tr·ansitional habitat type between br·eached secondar·y s ide channel habitats and nonbreached clear·water or side slough habitats . Clearwater habita ts a r·e nonbreached ch a nnels con t aining clear· water that d e water completely at a mainstem discharge o f 13 ,900 cfs or high e r . These c hannels have non -vegetated upper th a lw eg s that are overtopped dur·ing p er·iods ·of modera te to high mainstem disc h a r·ge . Gr·oundwater· a nd local surface r·unoff a p pea r t o s up ply wa t er· t o th ese a r ea s a t mainstem flows above 13 ,900 cf s . Side slough hab itats contain clear· wa t er·. Upwel li ng a nd loca l surface r·u noff a ppear· to supply sufficient cl ear· wate r· to th e se ·areas to maintain we tted ar·eas at a ma in stem disc h a rge o f 13 ,9 00 cfs . Side s loug hs also h ave non-vegetated upper· thalwegs that are ove rtopped at mode r a te to hi g h ma ins tern dischar·ges. Tributar·y mouth habitats a r·e c le a r water h abi t a t s th a t ex is t betwee n the dow n s tr ·cam ex t e nt of a clear-wa t e r· p lurn e a nd upstr·eam into th e tr ·i butary. t o th e uppe r extent of the b ac kwa t e r· influ e nce . The su d ace a r ea depend s on the di sc har·ge o f bo th th e tr ib utar·y and rnainstern . Tributary habi t at exis t s u ps tr ·earn o f th e tr ·ibutary mo uth h abita t. In this ana ly sis, tr·ibutar·y h a bita t was me asu r·ed o n ly t o th e bou nda r·y o f the dig it ized photo enlargemen t . T ri b utar·y habita t may inc r e ase d rama t ica lly wh e n th e tr·ib u t a ry fl ows into a no n b r eac hed side c h anne l and th e clear· tr·ibut a r·y flows thro u g h th e side chan n el t o joill th e Susi t na Hiv e r·. 1<2 3t I ~2 No n-we lted ar·eas were classi fied as gravel bars or· vegetated islands . We tted areas th a t wer-e not contiguous and connected to a s ide channel o r· mainstem were consider·ed ''ponded water" and their sur·face ar·ea was in c lude d in the measu r·emen t of gravel bars . Ar ·eas wh ic h were within the r·iver corridor but wer·e not r·e lev ant to the a nalysis wer-e cla ssified as ''backgr·ound''. 1.3 Methods 3 .3 .1 Field Me thods Black and white aer·ia l p ho t ography a t a sca le of 1 inch = 2 ,000 feet was o b t a ined o f the lowe r· Susit na River a t five mai n s t em discharges as mea sure d at the USGS Sun s hine gage . Helicop t e r· ma pping flights co nducted ove r the e ight r·c pre sc ntative areas at mainstcm discharg e s sim il a r to tho se at w hi c h th e a e r·ial ph o t og ra p h y was o btai n ed (Tab le 3 . ~). Dur·ing th e se fli ghts , a qua ti c h a bi t a t t ypes we r·e ide ntified and t hei r· loc a tions rn app ed o n b lu e -lin e p rints made from 1 inch = SOO f e e t e nl arg eme nt s o f th e study a r ea. G ravel ba r·s and d e wa t e r·e d strea mb a nk a re a s w e r·e ske t c h e d o n the b l u ~lin e s a lo n g with t h e bou nd a r ie s o f th e va riou s h a bit a t t ype s . TABLE 3.2 . DATES AND S USITNA RIVER DIS CHARGE (AS MEASURED AT SUNS HINE) AT WHICH AER IAL PHOTOGRAPHY WAS OBTA INED AN D HELICOPTER MAPPING FLIGHTS WERE FLOWN Ae ri a l Ph otography Mapping Flight 1 nstantaneou s Mea n Daily Da t e Discharge (cfs) Date Di sc har·ge (cfs) 03n 7/S4 75 ,200 03 /~7 /34 8 1 ,GUO osn7/S3 .;9 , 100 07 /~-1 /84 5 J.~00 o3nYs 'l 56 .300 09 /06/83 36 .600 08/31 /8 ,1 38.000 09/16 /83 ~I , 100 09/11 /84 23 , GUO 10/~5 /33 13 ,!l1JO 10/13/8 4 I ~. l Oll -13- / r IU.l I 23 3 .3 . ~ Office Procedure Habitat Type De l ineat ion s P hoto en largemen ts a t a scale of 1 inch -= 500 fee t we r·e pr ·epare d for eac h o f the eig ht repr·esentative a r eas a t each of the five discha r ges . Aquatic h abita t boundar·ies t lnat had b een mapped on the bl u eline p r·ints du r·ing the h e l ic.opter· r eco.,nais Eance flights we r·e tr·ansferred to acet a te overlays o n these ·enl a r·gernetHs . Extemal boundari e s of the r·epre!s e n t a t ive a r·e a (h erea fter· r·e fe rred to as co ntr·o l area s) t o be inclu ded in the s u rf ace a r·ea an a ly sis were d e fined o n ea c h e nlar·g e ment . Co nt r·ol ar-e a bound a ries we r e estab- li s h e d using fe a ture s id e nt if ia b le o n a ll fi v e sets o f p ho t :>g r ap h y. In som e c a se s , t1 g i v·e n e n lcw g cme n t \"i ·lS b r okC'n i n to mo r e th a n o ne co ntro l a r·ca to acco mmodat e th e siz e of th e d ig it ize r t abl e t used in th e ana ly si s. C o ntra \ a r e Js sr r v c d a s a n in d e x o f q u al i t y co n tr ·o l . Sur ·f ace area s of t he in d iv idua l elcne nt s wi thin eac h co ntro l a n:•a we r·e Sllnlnl ed a nd c om pared t o t h e to t a l ar ·ea o f the co ntr·o l a n~a . Thi s in s u r e d that n o h abita t e leme nt s we r e le f t un d ig iti z cd. Digitizing l3 o un d.1r ·ic s we r·e d r awn a r·o und eac h we tt C:d and no n we tt ed h ab it J t e lc111 cn t o n e tt c h c nl a r·gemc nt fo r· e ac h o f t he fr v c f low s . I nd rv idu J I a re a e leme nt s wc r·e ide nt i fi ed as to h abi t a t t yp e and assi ~n cd u nrq ue seq ue nti a l id e ntifi e r num b e r s. C h ~nn e l s wh ic h c n tai ned wa t e r· a t th e 7':>, 200 c f s fl o w we r·e a ss ig n ed un iq u e id e nti fi e r n umb r s t h t~t we r e u sed fo r th e S cllllC c h a n n e l a t lo w e r fl o ws. G r a v e l ba r s a nd eg et.1t ed i slan ds w e r e as si g ned uni q u e num be r·s fo r a g i v e n p ho to ('nl .l r getlli:n t. S ur ·fa ce a 1·ea d e t e rminat io n s wer ·e made u sin g a n H P-93 -1!> c 11 11 u t e r a n d ar ·c a mcaS llf'P nr e nt s we re ct"t lc u la t cd (1n d d i sp l.1y cd to tt n .l cct n·a cy o f 0 .00-19 in c h e s . fhis r cp r·ese nt s a n .1c c ur.:•CY o f 2 .:, f ee t fo r I cJ I :.!-1 3.4 photography at a scal e of 1" = !JOO'. The total sud ace ar·ea of a contr·ol a r·e a was digitized. Individual h ab itat ar·eas within that control a r ea were then digitized and their ar ·eas summed for comp<>r·ison t o th e control a r·ea. Rep lic ate measureme nts were made fo r· each area digitized to ensur·e repeatability within five percent . Compar·isons between summed individual areas and the total contr·ol a r·ea were considere d acceptable if the difference was less than five p e r·cent . Analysis Procedures Eac h indi v idua l surface ar·ea measu r e me nt e ntered into the d a ta base had a n identifie r· number· that allowed id e ntification by dischar·ge, r ep r esen t a tiv e a r·ea, h abi t at ty pe , a nd specific ar ·ea identification num be r . In t hi s way, da t a may be displ a yed by study area, by tr·acki n g a spec ific c han ne l, or using a var·iety o f other· fonna1:s. Du e t o wea th e r cond it ions during aer·ia l p hotog r·ap hy fli ghts, the differ·ent set s . o f p ho tographs we re o btained <tt slightly differ·ent scales. To make direc t compa r·isons between flight lin es, the Septembe r· I G, 1983, 21,100 cfs set o f phot ograp hy was c hosen as a base a nd correc tion fa c to r s \\c r·e determined to s t andardize measure- me nts to a colllmon se al e. Results 3 . ·1 . I Gene r al T h i! gene t·al r esponse for· to t a l w e tted s urface in a ll r·ep resentative ar·cas is a dec r·case with dec r eas in g ma instem dischar·ge (Figur·es 3.1 - 3 .4 ). The r·ep r·esentative a 1·eas are descr ibed b e low and the habita t ty pe designations are s hown o n ee r·ial photogr·aphs in Exhibit B. Mainstem, pr·imary and seco nda r·y side c hannel sudace area decreases with dec r·eas ing dischar·ge . The r·espo ns c o f we tted s urface area for -14- h2JI I 2:, 3.4 . tri buta ries va ri es depending o n the tr ibu t a r·ies confluence with the mainstem o r side channe l . The am oun t of cl e<>nvate r we tte d suda ce area increases with dec r·easing mainste m flow . As ma in s tem dischar·ge decreases many channels tr ·ansfor·m fr ·om side channels thr·oug h turb id backwaters and clearwater· areas to gr·avel bar·s. The di sc h arge at which the change occurs vari e s fo r each s ide c h an nel c omplex. Some channels tr·ansfor·m dir·ectly fr·om side channel to si de slouyh sk ipping tur·bid backwater· and main t ai n a base wint e r fl ow . Turbid backwater· wetted sudace a r·ea increases with decreasing dis c harge as the h eads of side channels dewater, th e n decreases as channels c h ange t o c leai·wat e r a r eas o r· dewate r· comp le t el y at lowe r· d isc h ar·ges. Study Sites SC IV-4 Seco ndary side c han ne l su d ace a rea dec re ases wi th decreas ing dischar·ge b e lo w J9, 100 c fs as scco ndat·y s id e ch a nne l s d ewater o r· become turbid back w at e r·s, c lear \Va t e r· a r e<t s , and sid e slo ughs ( l·igu t·e 3. I). The inct·ease in seco n da ry sid e c h a nn e l a t·ea from i"':J ,100 cfs to ~9. 100 c fs is due to th e tt·a n sfo nna ti o n o f a p rimary side c hannel to scco ndat·y side c h ~nnc l . Tu rbi d backwa te rs and clea n\'ale t· a r·eas fo nn as th e c!i sc har ·gc d £'c r case s f r·o m 7':>.100 c fs to :i9, 100 cfs. As th e discha•·gc c!e CI'cascs t o 3G ,GOO cfs tur·bid bl\c kwate r s t yp ica ll y tr·a n s itio n from tur bid wate r to cl ea r·wa te r· as i ntr·agrav e l fl O\\' f lu s h e s th e turbid w a t e r o ut thus fo r·min g c learwat e r areas . Cl ea n vat e r habita t disaj)pca r·s a t 1 1, lUO c fs b ecau se th e areas p r e se nt a t 3G.GOO c f s dry u p but no n ew o n e s are fonned by th e h eads of oth er side channe l s dewater·ing or turbid backwaters clec1ring u p . Be low 21,100 cfs the t urbid backwate r·s tra nsform to side s loug hs . .] i J J fl'l~I ,OOO J Nx J t: ~ ~ i "' u " u. a: ::> "' 0 ~ 100 I- "' 'it 10 10 -, 30 M AINSTEM SC IV-4 WETTED SURFACE AREA CLEARWATER <0 >O 60 eo DISCHARGE AT SUNSHINE (cfs X 103) WILLOW CREEK (SC 111-1) 20,000 AREA TOTAL WETTED 10,000 ... - ~ 1,000 X "' 1-u. " "' a: " "' u " u. a: I ::> "' CLEARWAT ER 0 IOO J "' 1-j <l' 1-"o 'it " -~1- 10 I - 10 20 30 40 >O 6 0 10 MAIN STEM DISCHARGE AT SUNS HI NE (c f !. X 103 ) PREPARED BY ~:~~S ULTAN T S INC ~I --~~!.~-~---1 ..... , ....... oo e rh n <>•••• u•o no~ou ••• .... ' .. ~•·o ••. SURFACE AREA RESPONSES TO MAINSTEM DISCHARGE IN THE LOWER SUSITNA RIVER: SC IV-4 AND WILLOW CREEK PREPAR E D FO R o FIGURE 3.1 [iL}~.:RIT /;:1-= :~g-:1.~:·"""(5) I 80 TAOLE 3 .3 WETTED SURFACE AREAS AND PERCENT OF TOTAL WETTED SURFACE AREA BY HABITAT TYPE AT FIVE MAINSTEM DISCHARGES FOR SELECTED REPRESENTATIVE AREAS Main stem Primary Side Channel Discharge at WSA Percent of WSA Percent of Sunshine (cfs) (ft' l( 10') Total WSA (ft' l( 10 3 ) Total WSA sc IV -4 75,200 7470 46.4 3510 21.8 59.100 6270 ~1.6 36, GOO 5880 47.6 21.100 5510 57 .3 13 ,900 5450 Gi . 1 WILLOW C:<EEK (SC 111 -1) 75,200 34 20 17.6 6870 35 .4 59,100 2990 16 .2 .. 36,600 2970 19 .3 21,100 227[) 17 .8 13 ,900 2030 20.2 CASWELL CREEK 75,200 143 23 .4 59,100 36,600 21 '100 13,900 SHEEP CREEK 75 .200 59,100 36 , GOO 2 1,100 13 ,900 GOOSE CREEK (SC 11-4) 75.200 8120 -18 .0 59 , 100 70 ,10 49.2 3 6 .60 0 3 590 37 .2 2 1' 100 943 13.9 13 ,900 MONTANA CREEK (SC 11 -1) 75.200 5000 63.9 59. 100 -1580 72 .1 36,600 3890 76 .7 2 1. 100 3320 8 1.6 13,900 1920 62.3 SUNSHINE CREEK (SC 1-5) 75 ,200 9520 37.8 !'>8 60 23 .3 !'>9, 100 38-10 36.2 5720 23 .4 36 ,600 7460 40 .0 21.100 6800 47 .9 13 ,900 5540 52.7 Secondary Side Channel Tur·bid Backwater Clearwater WSA Percent of WSA Percent of WSA Percent of ( ft' l( 10 3 ) Total WSA ( ft' l( 10 ·') Total WSA (ft' l( 10 3 ) Total WSA 5090 31 .6 7900 52 .4 491 3 .3 427 2 .3 5990 48 .5 79 .4 0.6 386 3 .1 4050 42 .1 55 .4 O.G 2580 31.8 7930 40 .9 14 5 0 . 7 31.7 0.2 13300 72.1 247 1.3 153 0 .8 101 00 65.7 320 2 .1 169 1.1 7700 60.3 249 1.9 178 1.4 5020 50.0 67 .9 0 .7 343 56 .2 402 77.3 259 66.'1 73.'1 35.0 ~3 . 7 31.6 319 25 .9 30 9 23.4 33 6 24 .5 153 1-1.9 11 6 11.6 78-10 -16.3 .fiG 2 .5 63 -10 -1-1.3 178 I . 2 62 .9 0.4 -12-10 .f3 .9 333 3.5 33 4 3 .5 -1650 68.6 35.7 0.5 1-17 2 2 2380 '18. 7 15.0 0 .3 17-10 24 .0 16.3 0 .2 112 0 17 .6 118 1.9 173 ~.7 590 11 . 6 273 5.4 425 10.4 8 59 27 .9 94 80 37.6 261 1.0 91 60 37.5 179 0 . 7 87.7 0.4 10300 SJ.3 4tl 8 2 .4 6330 tl4 .5 660 -1.6 8.9 0. 3350 31.9 95.8 0.9 -16 - WETTED SURFACE AREAS AND PERC ENT OF T OTA L M TAOLE 3 .3 (Continued) WETTED SURFACE AREA OY HAOITAT TYPE AT FIVE MAINSTEM DISCHARGES FOR SE LECTED REPRESENTATIVE AREAS Incremental Change Side Slough Tributary Mouth Tributary Gravel Bar Total Wetted Of Total WSA of WSA Percent of WSA Percent of WSA Pe r c ent cf Area Percent of Surface Area Given Discharge from Next Di schar·ge at ( ft' X 106 ) Sun shine (cfs) (ft' x 10') Total WSA (ft' X 10') Total WSA (ft2 X 10 ') Total WSA (ft' X 10 ') Total Area Lower Discharge (Pe rcent) sc IV -4 75,200 1750 3 .6 16.07 6 .5 59,100 3 140 6.5 15.09 22 .3 36 ,600 5700 11.7 12.34 28.3 21 ,100 8520 17 .5 9 .G2 18.5 13 ,900 85 .4 1 .0 12400 25.5 8 .12 WILLOW CREEK (SC 111 -1) 75,200 260 1 .3 73 2 3 .8 2030 2 .0 19 .39 5.1 59,100 784 4 .2 97 3 5 .2 2950 2 .9 18 .45 20 .0 3G , GOO 284 1.8 15tl 0 10 .0 5870 5 .7 15 .38 20 .5 21 ,100 558 4.3 1800 14.1 8G30 8 .5 12 .7G 27 .0 13,900 7G2 7 .G 13 1 1 .3 2040 20 .3 12GOO 12 .3 10 .05 CASWELL CREEK 75,200 7 1 .7 11.7 5 1.8 8.5 183 5.5 O.G1 17 .3 59,100 104 20 .0 1G.G 3 .2 247 7 .4 0.52 33.3 3G,GOO 25.3 G.5 10 1 25 .9 ·102 12. 1 0 .39 85.7 21 ,100 13 .1 G. 2 45 .3 2 1.5 7G.4 36.4 58 2 17.5 0.2 1 23 5 13,900 13.2 7 .8 10 2 60.0 Gil 18 .4 0.17 SHEEP CREEK 75,200 352 28 .G 53 1 45 .8 162 1.1 1 . 25 -5.7 59,100 649 49 .2 3G2 27 .4 2·19 1.6 1 .32 -3.G 3 6,60 11 349 25 .5 68 1 49 .7 213 1.4 1 .37 29 .2 2 1,100 19.8 1.9 883 83.3 508 3 .3 1.0G G.O 13 ,900 10.4 1 .0 875 87.5 57 3 3.8 1 .00 GOOSE CREEK (SC 11 -4 ) 7:,, 200 39.0 0 . 2 517 3 .1 5700 6 .2 1G .93 18 .3 59, 100 14 1 1 .0 55 3 3 .9 9570 10.4 14 .31 ·18 . 1 3G,GOO G5 1 G.7 G6. 1 0 . 7 445 4 .6 13500 14.8 9.66 42 .5 2 1, 100 471 G.9 30.4 0 .4 50 1 7 ~ 16000 17.5 G.78 14 .7 13 .900 75 1 12 .7 22 60 38.1 18 100 19 .7 5 .91 MONT A NA CREEK (SC 11-1) 75,200 132 1.8 372 5 .1 2no 10 .0 7 .2G 14 .3 59, 100 13 1 2 . I 226 3.G 2970 13 .7 G.3 5 25.3 36,600 10 .9 0 . 2 309 G. 1 4 1.1() 19 .0 5.07 24 .6 2 1,1110 41 .4 1.0 27 .0 0 . 7 260 6 .4 5370 24.7 4 .07 32 .1 13 ,900 29 .8 9 .7 7 .5 0 .2 168 5 .5 G.J3 0 29 .6 3 .08 SUNSHINE SLOUGH (SC 1-5 ) 75,100 57.9 0 .2 7.7 0.1 5920 5 .5 25.19 3 .2 ;,9 , 100 3 6 1 1 .5 76 .2 0.3 7580 7 . 1 2·1.42 3 1.0 36,600 3 35 1.8 37 .6 0 .2 6 1.2 0.3 12700 11.9 18 .64 3].2 2 1,1.00 338 2 .4 '(3. 5 0.5 16900 15 .8 14 .2 1 35.2 13 ,900 1390 13 .2 134 1 .3 22000 20 .G 10.51 -17 - RD/1 16 Willow Creek (SC 111-1) The ar·ea of s econ da ry side channel increases as rnainstem dischar·ge decreases from 75,200 cfs to 5!l , 100 cfs because the primary side channel transforms to a secondary side channel (Figur·e 3.1). Tr·ibutary surface ar-ea incr-ea s e s with decr·eas ing discharge because. the head of side channels dewater with decr·easing mainstem discharge and the tributary extends down the side channe ls . With decreasing rnainstern discharge trib u tary mouth surface ar·ea fluctuates depending on the tr ibu tary dischar·ge. Turbid backwater ar·ea incr·eases with decre asing dischar·ge as the heads of more side chann e ls become dewatered a t 3G, GOO cfs . Tur·bid backwa ters transfor·ms to side s lo ughs and gravel bars fr ·o m 21,100 cfs to 13 ,900 cfs. Caswell Creek Tribu t a ry and tl·ibutary_ mouth wetted surface a r·eas vary depe nding o n both rn a in s t e rn and tributar·y disc h a r ge ( F igu r·e 3 .1). Between 11,100 cfs and 13 ,900 cfs th e tl'ib u t a ry ar·ea incr·eases b ecause the head of th e side cha nn e l dcwa t ers and th e tr ·ibu tar·y extends down the side c h a nn e l. Shee p Creek Tributar·y rn o uth surface a r·ea dra matica lly dec r·eases with Jcc r·easi ng rnainstern disc h a rge b~cause o f th e flat g r·ad ien t of Sheep C r eek (Fi g ur·e 3 .2). As ma inst e rn disc h arge dcc r·eases, the side chan n e l into whi c h S hee p C r·ce k fl o ws h ~s le ss fl o w t·e sulting in less backwater· e ff e c t s. Tl"ibu l a t·y ar ·ca incr·cases as th e t l'ib~t ary mo uth area dec r e ases, h o weve r the t o t a l we tt ed sru·f ace area stays app t·oxi rn atcly the same . The s li ght ri se in we tted sur·face a r·ea with dec r easing flow is because of sl rgh t di ff c r·ences between th e 1983 a n d 1984 photogr·aphy. -18-· R13 /i 17 Goose Creek (SC 11-4) Tributary surface area increases at 13 ,900 cfs b eca us e the h ead of the side chan n el becomes dewater·ed and tlH. side channel into which the tr·ibutary flows b ecomes an extension o f the tr ·ibut ary (Figur·e 3 .3). Tributar·y mou th ar·ea is low at 75,100 cfs r ela ti ve to 59, IOU cfs due to the r-ainstorms prior to the 75,100 cfs aer·ial ·phot og r·aphy. The heavy rain resulted in high er tributary fl o w which the refore lessened the backwater effec t due to mainstem stage for th is stee p gradient tributar·y . Turbid backwater su d acc a rea increases between 59,100 an d 36 ,600 cfs as various channels become dewa t ered at th eir up pe r· berms and then decreases below 36, GOO cfs . C learwater a r·eas appear· a t 59 ,100 cfs , incr·easc in sudace ar-ea at 3G ,GOO cfs , and t h e n decr·ease at lowe r dischar·ges. Side s lo ughs appear at 36,600 cfs, decr·ease in surface a r ea s light ly at 21.100 c fs and th e n increilse ilt 13,900 cfs as turbid backwate r s tr·ansfor·rn to siJc s lo u g h s. Montana Creek ( SC 11-1) Mains t em s ur·face area decr·cas e s s l ig htly as mai n s t em di s c hJrge dec reases fr·orn 75,100 cf s t o ~l .llOO cfs IFi g rrr·e 3 .3 ). At 13 ,900 cfs, pa rt of the mainst e m a r·ca dewa t c r s c r·c..1 ting a sccon dar·y s:do c han nel. Seconda ry side c h a nnel s tran sfo rm to l u r·b uJ ba ck w a t c r·s .Jl 21,100 cfs. The tur·bid ba ck w a t e r· t ran sfo rm s t o s id e s lo u g h a t 13.900 c f s. Sunshine Slough (SC 1·5) F r·o m 2.1,100 cfs t o 13 .90fl fs s o 111c ma ms l e rn il r'CJ bee n1 es s?conda ry side c h a nn e l. Pr ·ima r·y side c h a nn e l s tays r·e la t ivc ly con s t.1n t fr ·o rn 7 ~•. :wn c fs t o ~,9, 100 c fs th e n trans fo r:ms t o seconda ry .;,ide c h a nn e l a t 3G,GOO c f s (Fig ur ·c 3 .·'1 . \\1i lh J ec r easi ng d isc har ge .s.eco nJdry side c hann els become tur b rd b ilc kw.)tcr·s. clea r·w a t e r c1 r cas. srJc s lo u g h s o r g r·avel bar·s. Tr·rbu tar y are,, dcc r·e a ses a t S9.1 00 cfs b ca use th e tr ibutar·y mou th habi t a t extend aci to th e cdoe of th e r:o ntro l t1rea: < w 0: < w (.) < ... 0: ::> U) c w .... 100 .... ~ ~ J CASWELL CREF.K MAINSTEM DISCHARGE AT SUNSHINE (et c X ~03 ) "' ~ 1,oooJ X .. .... ... <( w 0: < w (.) < ... 0: ::> ~ IJ .... ~ i J SHEEP CREEK ~----T!_!O.!_T~A!!_!L!,_.,!W!.,!E;.JTLJTL.!E~D!...,_.!;jS~Ul.flRlfF~Al£CL!E~~A,!!R~E,AA ___ _ ----- G RA V EL BAR 10 ,_--~----.--------y-------.------ 10 20 30 4 0 so 60 70 MAINSTEM DISCHARGE AT SUNSHINE (cfs X 103 ) PREPARED BY ' ~~------1 EWT&A I I=I&M CONSULTANTS, INC. · ...... '''"" • ........ . SURFACE AREA RESPONSES TO MAINSTEM DISCHARGE IN THE LOWER SUSITNA RIVER: CASWELL C~EEK AND SHEEP CREEK PREPARED F OR : FIGURE 3 . 2 1·.· ·.· ..... ,,...... ••o~aa•• y• .. ,. ... ,.,. 0 ,.,.... ....,., ., • •a•• 00 1,000 MONTANA CREEK (SC 11-1) GOOSE CREEK (SC 11-4) TOTA L WETTED SURFACE IO,OOC 1,000 SECONDARY TRIBUTAR y CLEARWATER ~ "'o 100 X 1,000 X "' "' ... ... ~ ~ T RIBU T ARY < ... x-< w o" w a: ..); a: < < w 'l-:>- w 0 s 0 < ... , <~>" " < ... ~ ... ... a: 'l-' a: •oo J ::> <. .,. ::> "' () "' 0 "' .... 0 w w ... 10 ... ... ... w w ;:: ;:: ~ ~"' ,.,..:;, IOJ I_O __ _l~---•• o---------,To---------.ro---------,,-o -------~~.~~o --------~7~0~--·~ MAIN S TEM D I SC H A RGE A T SUN SHI N E (e ll X 10 3 1 MAINST E M DISCH A RGE AT S UNSH I N E (c i s X 10 3 1 PREPA R E D B Y ' I I SURFACE AREA RESPONSES TO MAINSTEM DISCHARGE ~ ·--= EWT&A IN THE LOWER SUSI"rNA RIVER: R&M CONSULTANTS, INC .''''"""'"""'"'""' GOOSE CREEK AND MONTANA CREEK .NOI N···· ··O~O it o e ~• """"O~O<>••T e ......... •0 •• P REPARED F O R : F I G URE 3 .3 " .. --, 8 0 ·0,000.. ] ·~ i 1 ] i IIXJ 1 i ~ i i-l ~ i ~ooj < -w a: < w u < .. a: :::> "' 0 w .. .. w ::: 10 10 SUNSHINE SLOUGH (SC 1-5) WEllED sURf,t.CE ARE,t. TRIBUT A Ry 60 MAI NSTEM DI SCHA RG E AT SU NS HINE (X 10 3 ,c l s ) FIGURE 3 .4 I•R[I':,IIr;.O,ci::.;"-------~:~~L~:I~=--..,,..,=o,.- n&M C ON SULfANTS, INC. S URfACE Aflf.A ll t:SPOPlS[S TO t.'JoiiiST[M OISCil.\ACE ltl THE lOWER SUSIH14 AIV(A; SUNSHINE SLOUGH PU!.P:O I>(O rOA : G:J~.1n1~0. o @r;;J&®@@ -2 1- R ~3 /1 ~s Bi r c h C reek Sl ough Birc h Creek Slough is long, nan·ow , and meandering single , isolated channel , f ed by Bi r·c h C r·eek and gr·oundwater inf low. It f lows th r·ough a vegetated area for its ent i r·e length with vegetatio n exten ding d own to and over·hanging much o f the bank . The combination of the narrow channel, overhanging vegetation, and s h adows in t he pho t ograph y made detectio n o f wa t er's edge and th e edge of vegetation very difficu lt. For this r·easo n , de lineation and digitizing of habita t t ype su r·face areas was not done on Birch Creek S loug h . However·, a verba l desc r iption of the s lo u g h a n d its r·esponses to the mai nstem stage t hat were noted du r·i ng the h e licopte r· overflights ar·e discussed be low . Th e h ead o f Bir·ch Creek S loug h becomes dewa \e1·e d between mainstem dischar·g e s of 59,100 and 3G ,GOO cfs. A road crosses the s lo ugh appr·oxirnate ly 1 ,000 feet down s \re,1 m fr ·om th e head of the s loug h . Road construction in 19 34 appa r·e n\ly caused \he culvert t o be b locked, thus preven t in g over·topping ma inst e rn inf low. Th e upper po r·tion of th e s loug h co ntains nume r o us beave r· dams whi c h fo ,·m a ser ·ies of impo und ed poo l s. Th e se do no l appear· to have significant fl ow thro u g h th em as ev id e r•ced Gy s tagnan t -itppea ring wett e r·, a nd eJrly ice fo r·m a tion. During r eco nn aissa n ce su r·ve ys , no ev id ence of spawning was seen in th ese u ppe r J r cas in co ntra st to th e IO \\'l"l" r eac h es of th e sloug h wh e r·e sa lm o n spJ wning was obse r ved o n Aug u s t 31. 1984 an d ca r·c asses we r·c see n o n O c tobe r 10 , 198·1. The lo wer· r·cac h es of th e s lo ug h are c h aracleri7 c d by a p oo l -riffl e typ e of h abi tat which appca •·s to p 1·ovidc su1 t ab l e h abi l J t fo 1· spawn in g . The beave r dams appca t· to p r ov id e .1 barr·ie r to u ps tre am moveme nt o f sa lmon in th e s lo ugh a nd l im it fi sh ut i l ization to th e d ownstr·ea m a 1·e as . H~3 /1 29 3.5 Discussion Definitions for· aquatic habitat types used in this study repre.sent a set of visually recognizable, str·eamflow-dependent physical ·char·acter-istics that are not limited to fixed geographic locations. An example of the fl ow-dependent nature of these def ini tions are the for·mation of side slough, clear·water area , turbid backwater and side channel habitats . The ber·ms at the heads of side channels may become dewatered as the mainstem discharge decreases, forming tur·bid backwater habitat. As the discharge continues to decrease the tur·bid backwater may r·emain a turbid backwater or become a clearwater area or a side slough depending on the local influence of upwelling, channel length and channel slope. Clear·water areas form after the berm becomes dewatered. These areas clear· due to settling ou t of suspended par·ticles or· by displaceme nt of turbid water by flushing with clear·water· originating fr-om gr-c>undwater· sources. They eventually dewater· completely. Side sloughs ar·e clear· water habitats in which the flow is maintained by upwelling and sur-face water· runoff at 13,900 cfs or· lower·. \vhen mainstem dischar·ge incr-eases and r·iver stage r·ises , the berm at the head of the side channel is over ·~opped. Tur·bid mainst em water· flows into the over·flow channel and replaces the fo r·mer · clear·water-habita t with deeper, faster·-fl owi ng , tur·bid water. The aqua tic habitat type at this location then fits the definition of side channel h abi tat. The sur·face area r·esponse cur·ves for the repr·esentative ar·eas in the lower r·iver· appear· a t fir ·s t v e r·y complex without clear trends . This i• f unc ti on of the comp lexi ty of many of th ese representative ar·eas each containing nume r ous individual channels. \Vithin a side channe l complex, fo r· exam ple , var·ious channels or groups of channels have differ·ent breaching di sc harges . A typical sequence for· a channel is to transfo rm from a secondary side channel to a tur·bid backwater then b ecome a clear water· area and finally dewater. Another· sequence may show a secondar·y side c hannel b ecoming a side slough, or l'emaining a seco nd a r·y side ch a nn e l thr-oughout th e flow range . In combination, the lo ss of a given -22- R~3 ; I 30 habitat type in ne channel may be rep laced by the gain of that or another habitat type in another channel . The upstr·eam boundar·y of tributary mouth habitat is defined as the end of the backwater zone caused by mainstem flows. Field identification of the boundary was difficult for steeper gradient str·eams such as Willow, Montana and Goose Creeks and was mor ·e difficult and is subject to inter·pr·etation for flatter gr·adient str·ea ms such as Caswell, Sheep and Sunshine Creeks. Sur-face ar·ea responses are a function of str·eamflow and channel geometry. Pr ·evious work by Klinger and Trihey (1984) has shown the r·epeatability anc usefulness of wetted sudace ar·ea mapping on the Susitna River from RM 101 to RM 149, a single channel and split channel r·iver. Th e ability to r·e plicate sudace area measur·ern en ts for comparative purposes is dependent on stab le channel geometry, which is not the case fo r· br·aided r·ivers such as the ma in s tern . ConsequeDtly th is study limits its analysis to the side channel complexes . Th e ne x t sect ion a ddr·esses the stability of the side channe l complexes. Oiffer·e nces in cha nn e l morphology wer·e not ed between th e 19 83 aer·ial p ho t og r aphs and th e r·iver· in 1984 . This diffe rence was first observed during the h e licopter· overfli g ht on July 24, 1984 at a fl ow rate (55,200 cfs) less than th e fl ow r·ate of th e aerial rllotogr·aphy (59, 100 cfs). After fi e ld mappin g th e wetted surface a r ea for the 59, HIO cfs photogr·aphy, the delineations were field c h ecked on A u gust 22, 1984, at 5G,300 cfs. Betwee n th e da te s o f o ri g inal mapping and checking, a peak flow o f 82 ,000 cfs occu rT ed. By the time of the la t er fi e ld c h ecki n g, some o f the g ravel bars had in creased in size a n d c h anged loca tion. Even th o ugh channels within side chann e l com p le xes disp lay gr<1vc l bar· shifting on a r·e la ti ve ly s hort time sca le as ~1 r es ult of mod e r·ately high flow events, th e wetted sud,1ce a r·ea r·esponse to discharge 1s ge n e rally r·epea t ab le . This is because of the appa r e nt dynamic cquild.>r·ium o f the R23 /1 31 river as a whole. The net effort being that habitat lost (or gained) within a given reach is replaced (or lost) elsewher·e (Giova and Duncan, 1985). -23- R23 /1 32 4 .0 MORPHOLOGIC RESPONSE OF SIDE CHANNEL COMPLEXES 4 .1 General Braided rivers are dynamic systems whose channel shapes change significantly with only moderately high flow events. As the r·iver channel shifts acr·oss the floodplain, some gravel bars form, become vegetated and increase in size while other bar-s and/or islands er·ode . The purpose of this assessment is to quantify the natural change in vegetated island shapes in the r·epresentative area; studied in Section 3 .0. The rate of change or· shifts in tha·lweg position or in er ·osional changes is ver·y difficult to determine between successive sets of photogr·ap hy . Changes could occur at a constant, unifor·m rate or· they could be the r·esult of sudden , br·ief episodes occ ul"l"ing at a given time somewhere between the photo dates. Establishment and gr·owth of vegetation on gravel bar·s provides some indication of a period of r e lative s tability. However·, due to the time per·iod between p h oto dates, per·iods o f stability with vegetation growth may be interspe r·sed with p e riods of high erosio n . Ther·efo r·e, it is difficult to inter·pert c h anne l stabi lity from p hotos wh e n a n obv ious trend is not evident. In so me reach es o f th e r·i ver th e ma in low wate r· channels h ave been shifting from the wes t s ide o f th e fl oo dpla in lo th e eas t side; in o ther· r eac hes th e low wat e r c hann e l s a r c shift ing fr ·o rn ea st side to wes t s ide . In so rn e a r·eas, th e lo w w a t e r· chan11e l ha s bee n shiftin g fr ·o m a si ng le lo w w a ter· to a sp l it low water· c h an n e l . l\.s the c h a nn e l mea n de r· mov es down vall e y , areas whi c h hav e bee n s t a bl e fo r· a re lati ve ly lo n g tim e (is land s with t a ll co tto n woods) a r·e be ing eroded awily . Dur·ing th e pho to ana lysis it w a s no t ed th a t mos t o f th e c hil nnc l c hang e s occ urTcd outside o f th e study ar ·eas but th a t so me o f th e se c h a n ges R23 /1 33 affected the study areas . A significant change that occured in the sid~ channels was log jams. As relatively stable islands are eroded the trees fall into the river and are swept downstream . Jams may form at the heads of a side channel creating a low velocity area where sand and silts deposit. Over time these areas may aggrade thereby raising the elevation of the berm at the head of the side channel and increasing the discharge required to overtop it. 4 .2 Methods There are eleven complete sets of aerial photos of the lower river. For evaluating the mor·phologic change, four sets of photography spaning the years fr·om 1951 to 1983 were selected . Photography was obtained for the following dates: July 3, 1951, 1962, and 1963, August 24, 1980, August 27 and September 16 , 1983. The 1962 and 1963 photogr·aphy covered differ·ent portions of the l'iver, therefor·e only one date was used on any par·ticular portion of the ri ver . The photographs wer·e taken at differ·ent flows, ther·efor·e on ly r·elativ e ly lar·ge morphologic changes such as . lar·ge scal e d e position or er ·osion o f vege tated islands and the relative pos iti on o f major· c hann e ls we re compa r e d. De t ai led changes in cha nn e l cro ss~sec ti o nal s h ape, b r e aching dischar·ges or· debr·is jam pos ition cou ld n o t be d is ce r ned fr om th e p ho t og ra p hs . S ince th e photog r·ap hy wa s t ake n at d iffe r·e nt s ci\l ~s, chan g es we r e norma li zed b y sca li ng stable f ea tur·e s in th e p h v t og r a p h s. T h e le v e l o f p r ec isio n o f thi s me th o d was suffic ie n t fo r s t u r.:!y in !J ,-~!atlv e 111 o r p h o log i c cha n ge s . C h a n g e s th e Se p t e mb e r IG, 198 3 ph o t o g r iip h y. C .:-tsw c ll C r e e k .. 1nd S h eep C:r·cc k w e r e c!f-.lin ctt t ed o n the Aug u s t '!.7 , 1983 p h o t o s r ap h y b €'c<t u s o th e y \\o r·c no t c ov e r e d i n the S e p t e mber "16 th p ho t o g r·;tphy. T h e Augu s t ~4 , 1930 p h o t o g r·ap h y W(l s used t o e va lua t e tr ends and s h i ft s in tr ·ends but was not i n c l uc!cd i11 th e figur·c s -24 - R13/1 34 because of the slight differences from the September 16, 1983 photography. 4 .3 Site Specific Descriptions SC IV-4 Between 1964 and 1980, the west mainstem low water channel shifted towards the west bank . The east mainstem low water channel between 1980 and 1983 started eroding gravel bars on the west side of the side channel complex downstream of Hooligan Side Channel (Figure 4.1). The bar at the head of Hooligan Side Channel has gr·own since 1951 . Within the side channel complex itself, major changes are an increase in size and vegetation of small gravel bars . Since 1951 a small island downstream of the ADFLG Eagl e s Nest study site has ei'Oded away . Willow Creek (SC 111-1) The width of th e main chann e l thr·ou gh the study a r·ea ha s dec r eased fr·o m 195 1 to 1983 . Gr·ave l bars in th e c h a nn e l ar ·e increas in g in si ze a nd beco min g v egetated (I s la nd A, Fig ur·e ·1.2). The gr·ave l oa r s in th e n o r·thwe st corner o f th e s tu dy sit e a r·e becoming mo r·e s tabl e and vegetated. The c ntr·a n cc t o th e s ide c h a nn e l comp lex fro m th e eas t mai n s t em c hann e l incn:•as c J i n siz e fr·om 19 G2 t o 1930. T h e c h anne l a t th e mo uth o f \\1illow C r ee k h a s r emained re l a t ivc>l y s t ab le s i n c e 195 1. Ca s we ll Cr·ee k Cas w e ll C r ee k c h ann p l h as bee n r·:l a t i v 0 ly s t ab l e f ,·o m 19:>i . t o 1933 (F i g u r e LL 3). S in ce 19S I t h e s ide c h a n ne l a t th e II IVUlh o t C itswc ll C1·c e k has bee n sh t ft ing t o th e w es t tt w <ry fro 111 Cas w e ll C r f'c k . T h is h a s ca LJs e d (1 11 in c r ease in th e l e n Ci lh o f th e :o w w ~t c 1· c h .-:•n 11C I f 1·o m th e c r ee l-. mo uth t o th e s.1•!e t.:h a n n e l . ],_E G!'N!l_ 'lt::UET:,Ti::D liA NK S: DATE OF PHOTOGRAPHY: 9/1 6/83 r---~-pREPAREDf~----------------~============:-------------------------------------------------------------------------~G,~A~A:PI~II~C~S~C~A~t~-:E : ~~g··~--~~f• I PR EP AR ED BY ' -------' ' :-~~\J~J~-.:c_-.:==:"::-~=~: 1 EWT&A I coMPARisoN oF vEGETATED RIVERBANKs FIGURE4 .1 PREPARE D FOR R&M coNSULTJ>.NTS, INC._ .... ~,..:.,.,;., ......... _. AND ISLANDS 195 1, 196 2 and 1983: f?Q /i\ffi\2U;~c<~:~;;;·\i'S ~~Cl5) Ot.U1 ....... OO CLO<I•••• .. Y011l)L0f>"OI• ~U .. ¥0 YO .. O • . • . ~ , I ; .. , · t • • • ~1 YECET A TE D 8 ANK S : R&M CONSULTANTS, INC:. 195 1 1 911) ..... "T"-~"T"- DATE OF PHOTOGRAPHY : G/16/83 GRAPHIC SCALE: 0000 FT SlJS ll '\•\ Ulii\Jf : '\1 IIH CASWELL CREEK DATE OF PH O T O GRAPH Y: 8/27/8 3 R&M CONSULTANTS, INC. ··.:. )['.' 1.·". PREPAR ED B Y ' FIGURE 4.3 I I COMPARISON OF VEGETATED RIVERBANKS --~-~!.~.:':... AND ISLANDS 1951, 1962 and 1983: '----·-··_···_···_·_···_··_···_· ._ .• _ •• _.,._ ... _. _ .... _ ... _ .•. _. __ -_____ · ----~S~H.=E.=E~P CREEK AND CASWELL CREEK ~,.--------------- fl23t l 3~ Sheep Creek In 1951 the majority of the flow was on the east side of river flood- plain . From 1980 to 1983 the majority of flow shifted fr·om the .,ast side of the river' to the west side of the r-iver away fr·om the mouth of Sheep Creek. Sheep Cr·eek is now flowing into a side channel of the mainstem which may continue decr·easing in size under natural con- ditions (Figure 4 .3). Goose Creek (SC 11-4) The main mainstern channel has been shifting to the west sine~ 1951 . Erosion is limited, with the dominant process being deposition on and a.-ound gravel bars and islands, with vegetation covering these newly sta ble ar·eas. Island A (Figur·e 4 .4) was a slightly vegetated grave l bar· in 19!">1 with the exten t of vege tation incr·easing as the bar· b eca me mor·e stable . In 1951 the h ead of side channel B was a diverse set o f gravel bar·s (Figure 4.4 ). Sinc.e 19!">1 th e h ead of the side channel has beco me mor·e stable and decr·eased the amount of water· th a t could en ter· th is channel. Between 1963 and 1980 a debris jam fo rmed n ea 1· the mo uth o f Goose C1·eek dive rtin g a por ti o n of the cr ·ee k flow int o side channel C (Figure 4 .4). Montana Cr·eek ( SC II -I) The s ide chann e l co mpl e x h as a g graded s1n c e 1 9~ I . espe cia lly nc"r the c r·cc k mo uth (Fi9 lrr· -1 .~). Th e flh)uth o f ~l a ntana C r·eek shif t ed in th e u ps tr·eam dir·cc t io n b :->tw oC'n th r> 19:J 1 a n d \962 p h otog r ap h s, s hirt c d d o wn s tr·c arn be l\\cc n 19G2 t o 1930 1111 d upst n~a rn aga i n b e tw ;"\c n 1900 t o 19S3 (Fi g u r e -1.:1). Th i s land n e .1 r· th e u ps tr·(';t!TI e nd o f th e c.1':;t s id e c h .:tnn I h a s b ,conre mo r e vesc trtl ed s in ce 19:l l. Th e rn t e r io r· o f th e sid e c h a n ne l c rn p l e x i s r e lati\Ciy st ab l e with lumt c J a ;J g r ·;~dati o n .""!n d v cg e l .t tr o n g r·o \v th . -28 - R23 /J 313 -1.4 Sunshine Slough (SC 1-5) Sucker Side Channel has become narrower with vegetation encroaching on the channel (Figur·e 4.6). The islands near the ADF&G Sunrise and Sunset study sites have become more stable, transitioning fr·om gr·avel bars to vegetated islands from 19!">1 to 1984 (Figure 4,6). The head of Beaver Darn Slough has become more stable . The main channel has shifted slightly east so it impinges on the side channel complex and has caused relatively ra pid er-osion at point A (Figure 4.6). Debr·is jams within the side channel complex ar·e causing · ar·eas of aggradation, in creas ing the stability of the gr·avel bar·s. Birch Creek The up stream e nd of Birch Cree k S lo ugh is on the ou t s id e of a thalweg meander in a r e latively s t ab le area. The slough it se lf is stable, with littl e o r· no ch a nge s ince 1951. T h e d o wnstr·eern e nd o f the slough is on the insid e o f a t halweg me ande r·. Isl ands at t he sl oug h mouth hav e emd e d aw ay be tw e e n 195 1 a nd 1962 (Figur·e 4 . 7). Since 1 96 ~ the s lo ug h conflu e n ce with t h e 111ainstem h as been in t o a side c han n e l . Th e fre qu e ncy o f fl u s hi ng fl o ws thro u g h th e s loug h i s affected by a r o 21d ac.r·o ss th e s lo u g h t o acce ss <t tim b e r s.:,J e a r eil ( Figu r·e -1. i). Results and Discussion In d ivi d u a l bars rt nd isla n ds a lo ng th e pe rim0tc-r rn .1y bc C'r·od in g o r· ac~r ·a r!in9 ;,s the H hlin s ~C !Il c h "n e ls shif t \o f"=i tiv n . I IO\\•.:'\t,r·. th e c~.:nt r ·al p o r·tic•n of t hP s i 1 ~ c h n ne ! co:n;>l c \('S a r o std!,le. Dr·i1m Jtic c h <lll ~C s in c h i'nn I p o~i ti 0n ,,n•! k·n ll 1!1.1)' ,,cc.ur· wh C"rw vc r· th e l'iver r t'.-.'l ("h es b a nh.f ull s t a9 •. PREPARED BY · _;.cJ: ::i ,~ L. --- "'&M CON.SULTANTS, INC. COMPARISON OF VEGETATED RIVERBANKS AND ISLANDS 1951, 1962 and 1983 : GOOSE CREEK 1 of 2 DATE OF PHOTOGRAPHY : 9/15/133 FIGUR E 4 .4 LEGEND VECET AT E O Ot.tH<S : -r-r-r -r-r- P RE PAR E D BY · , .. ~~:.~.~ ... 1 COMPARISON OF VEGETATED RIVERBANKS AND ISLANDS 1951, 1962 and 1983: GOOSE CREEt~ 2 of 2 DATE OF PHOTOGRAPHY : 9/19/83 """ "" 0 GRAPHIC SCALE : _0 __ -- 0000 22JFT FIGURE4.4 PRE PARED F O R ' V E GET A T E D 0 .\U KS : .,1 95: PREPARED BY ' _g~'l R SM C'!OO:N:""'::'S~U=:L.:":::T=A=N==T=S=,=,=N-C~· .~ COMPARISON OF VEGETATED RIVERBANKS AND ISLANDS 1951, 1962 and 1983: MONT ANA CREEK DATE OF PHOTOGRAPHY : 9/1 6/83 FIGURE 4 .5 L EGE1!Q. VE GETA T ED [J,\r~KS ; 1962 -r-r -r,--:--r PRE PAR ED BY · ='S~i.::'!10f-_--=:_-_____ _ R&M CONSULTANTS, INC. COMPARISON OF VEGETATED RIVERBANKS AND ISLANDS 1951, 1962 and 1983: SUNSHINE SLOUGH 1 of 2 FIGURE 4.6 _LEGEND V EGETATI:U OAtfK S ; __; :!·;,~!ff¥1------ R&M CONSULTANTS, INC. COMPARISON OF VEGETATED RIVERBANKS AND ISLANDS 1951, 1962 and 1983: SUNSHINE SLOUGH 2 of 2 FIGURE 4.6 PREPARED FOR ' "' ., ., ; ;.: l: .. " a: " 0 >- 0 l: .. ... 0 "' >- " 0 >-s ... I 0 f .. ... " u ., !::! l: .. " a: " LEG J;.!i.Q. YE CE TA TEO UA NK S ; I'J !o1 ··---- 1'J G2 -r ,.,...,.,_, R&M coNsULTANTs, IN-c:- COMPARISON OF VEGETATED RIVERBANKS AND ISLANDS 1951, 1962 and 1983: BIRCH CREEK SLOUGH 1 of 2 FIGURE 4. 7 DATE OF PHOTOGRA PHY : 8 /27/83 ___ !2JfT , 'If '.:. 1'-.' \; . , i 'i· ll~_llil- VEGETATED DANKS : 19SI ----- t9 61 -r -.-,,,.,... PREPARED BV ' ~~r.~-N-S_U_L:_:T_A_N_T_S_, I -NC.-.u-1 .• ~ .. ~!.~-~ ... , ..... ,.,.•••• ••o ~o••••• oo•u •o ~o10•• •• ,. ..... ,.. wo •• · . COMPARISON OF VEGETATED RIVERBANKS AND ISLANDS 1951, 1962 and 1983: BIRCH CREEK SLOUGH 2 of 2 DATE OF PHOTOGRAPHY ' 8/27/83 >00 GRAPHIC SCALE' -- FIGURE 4 .7 PREPARED FOR ' IXI&lm~&"' ~®&®©@ 0000 FT H2Jt l :!i fl oodplain s cour·s a nd fills as bed mater·ial is moved down valley . The main channel may change its location dramatically, intercepting other channels at differ·ent locati o ns causing them to readjust. In general, the channel geome try of the main channel remains uniform as it changes location within the floodplain . Minor chan~els respond to processes such as main channel and major side channel changes of location, debris jam formation and local . sediment movement. Debr·is jams influence the meandering patter·n of major subchannels , while they may control the ov •,rtopping discharge of side channels . Debris jams form, increase and decrease in size during floods approaching bankfull sta ge . When the debr·is jams increase in size they can increase the o ver·t o pping dischar·ge for · a s ide channel. -36 - R~:J / I 33 5.0 COMBINED EVALUATION OF LOWER RIVER SIDE CHANNEL COMPLEXES 5 .1 General The r·esponse of wetted surfa ce ar ·ea s are affected by factors other· than dischar·ge, including : chann e l cro s s-se c tion a l s ha pe , channel gradient, stability of the channel bed , and whether the wetted surface area was delin e ated o n the r·ising or f a lling limb o f th e hydr·og r·a ph . The r·esponse of ind iv idu a l c h an n e ls within a si d e c hannel comp lex is si milar for b oth the middle r·ive r a nd lowe r river. Howeve r , the r es p o nse of a n e ntire s ide chann e l c ompl ex in th e lowe r· r·ive r· wi ll be di ffe r·e nt th a n fo r a given s e c ti o n of the mi dd le riv e r·. T h P. di ff e r e n ce is d u e t o the combin a ti o n of majo r , int ermed i a t e an d min o r· chann e ls p r·ovid in g s u rfac e a r·eas as t h e ma inst e m d i sc h a r·g e d ec l"e a ses. o f th e s e f ac t o r s is de t ai led be low . 5 . Channel Hydra •rlic Parame ter·s re p la ceme nt wetted T h e inf l u e nce of e a ch T h e rn o r·pho lc.gy o f c h M1n els wit hi n side c h a n n e l comp le x e s (e .g. the c r o ss -sec t io na l sh ape , g r ·adi~n t o f th e c h a nn e l a nd bed ma t e r ia l) co nt r·o ls th e ma nn e r· in w hi c h t h e c h a n n e l s n~spv n d to c h ange s i n d isc h a r·ge . Fo r· ex amp le. th e r a te o f c h a n g e o f w e lt d s ur-f ace a r·ea f o r d ec r eas ing d i sc h a r g e wi ll b e g r·c(1t e r· fo r· a wi de s h a ll ow c h a nn e l t ha n fo r· a n ar r o w deep c h a n n e l. I n a p lo t o f d isch a r g e v s . we tt ed surfac e a r·ea. a st eep line wi ll ge n e r·a ll y indica t e a si d e c h a n nel comp lc :o-. w i th mo r e nlllne rous ~u ·avel ba r·s a nd f ewe r nar r o w dC'ep c h an n els t h a n d oe s a l i n e w it h a fl a tte r s lope. A n e xc ept io n oc cu rs w h e n th e rn eil n s t r·ca mb cd e-leva t io n o f t h e c h a nn e ls o f a pa r t ic u la r s id e c h a n ne l comp lex a r·c hi g h r·c la t iv e to o t h e r side c h a nn e l comp le xe s . T h e se comp le xe s dew a t c r ~t a h ig h e r d i scha r·g e , su c h as a t SC 11 ·9 (Fig ur ·e 2 .3 ). Goo se C r·c c k S 1de C h a nn e l Comp le x (:)C 11 -!j ) co n ta in s p r e d omin a t e ly w ide s h al lo w mi no r c h a nn e l s, so me o f w h ic h dcwa t er a t 59 , 100 c fs . T h e R13 /1 39 inter·mediate side ch a nn e ls transfor·m to turbid backwate r·s and side sloughs at 36,600 cfs and dry up at 21,100 cfs . In contrast, SC IV -4 is an example of side ch a nnel complex with ma ny relatively nan·ow deep channels which predominately start dewater·ing b e low 36 ,600 cfs . These two side channel complexes have approximately the same total wetted surface ar·ea at 75,200 cfs 16 .07 million squ a re feet for· SC IV -4 as compared to 16 .93 million squar·e feet for Goose Creek (Table 3.3). However, at 36 ,600 cfs the total wetted sudace ar·ea for· Goose Cr·eek is 9.66 mill ion squar·e feet, wher·eas SC IV-4 has 12 .34 million squar·e feet. Side channel gr·adient control s th e rate at · which a channel may make the tran s formati o n from a turbid bac kwate r· to a cl e ar water· ar·ea. Given the same upstr·eam berm elevation, channe l le ngth and relative positi o n in a side channel complex, a channel with a s t eepe r gr·a dient may h ave mo r·e wate r· in the lower por·tions of channel than would a flatter· gr·adient channel . This is due to th e b ackwate r e ffect o f the ma inste m on the downstr·ea m e nd of the channel. 5.3 Aerial Photography Air· pho t o interpretation is highly d e p ende n\ on th e quality o f the photography. Althoug h each set o f p ho togr·aphs used in this s tu dy we r·e generally of hi g h r·esolution, th e lim e o f day. da t e, a nd p r·evai ling we ather co nditions nt t he ti •·1e the il e rial p ho tog r·(lphic mi ssio ns we r e fl own affec t ed the extent to which detailed r·iv e rin e fe atures w e re visib le. T h e 13.900 cfs photographs, o btai ned o n October 15, 1983, were taken afte r ice had b eg un to for ·m a long the r·iver· and ligh t s now f a ll had c ovc r·e d the gr·ound. This made de t e nn ind ti on o f th e water·'s edge more difficult. The r·ernainder o f th e photography was ob tain ed in late August through mid -Sep t e mber. At this time o f the year comb in a t ion o f ;un a ngle a nd well-developed deciduous fo li a t ion r es ult ed in ex t ensive s hadow s a long the south shor ·e l ines. T h ese shadows some t imes ob scur·ed the wa ter 's edge and -37- R2 3/1 ·10 made sudace area de lineations difficult. This was the r ea son Birch C r ee k Slough was dr·opped from our· analysis . The shado ws made it imposs ible to accurately delineate the change in we tted sudace area with d isch a rge. There wer·e problems different years and in tr·uthing obtained in encountered using aerial p hotography from two delinea ting the 1983 photography using ground 1984 . Mos t of the pr ·o blerns dealt with 1984 observations of gravel bars of larger sizes ·a nd in differ·ent loc at io ns than in the 1933 photog r·aphy. Whether the photogr·a phs were tak en on a rising, f a ll ing, or steady stage influences the habitat type , specifically w h ethe r a c h annel is dassif ied a clearwater~ area or turbid backwater·. On a r·i si ng st age an inte rm ed iate side channel could be a clearwa t er a r ea o r· side s lo ugh if t h e re h as been sufficient time between periods of over·toppi n g fl ow fo r th e c h a nn el wa t e r· to clear up . On a falling limb , a n inte r·rn e diate side c hannel co uld be a r urb id backwater if the ae r·ia l photogr·aphy we r e t a ke n imm ed iate ly af t er the b e nn dewater·ed. If th e chan ne l was influen ced by upwe ll ing then as the dischar·ge continued to d r op, th e turbi d backw,t l'r' wo uld tran sfo rm to a side s lo ugh . If upwe lling was no t p r ese nt, the c h t n n e l wo u ld r·emai n a tuo ·bid backwater· until the wate r· c lea red by s e ttling o f th e sed im e n t . T hi s was noticed at SC IV -~ b e twee n th e 3G,GOO c h a nd 21, WO cfs p hot og r·aphs. The folio\ ·i ng is desc r·iption of th e fl o w r·cgi me s wh e n the aeria l phot og r·aphs we r e take n . Date 08/27 /84 08/27/83 09 /()6 /83 09/16/83 llli25/83 Discharge (ds ) at Sun s hine 75 ,200 59,100 3G,GOO 21 ' 100 13,900 .I l Flow Regir·o e a n~pid l y ftllling stage at 0 1· near a peak sta ~1f' a slow ly fa llin g s t age a sl owly falling st t1ge n e ar· base fl ow a sl owly fall i ng st ag e ne .1r base fl ow , some loc al ice effec t s H~J /1 ·II 5.4 Summary In general, the habitat sudace area response curves for the lower r·iver study areas appear different than those for the middle river (as presented in Klinger and Tr·ihey, 1984 and Klinger-Kingsley, 1985). Differences and cer·tain similarities exist between the lower river and the middle river which help explarn the surface ar·ea responses . The middle river is a single or split channel r·iver whereas the lower river is a braided channel with many mo r e channels p!·esent in a gi v en length of the river· than for the same length in the middle river . This results in a greater buffer·ing or dampening effect o n the habitat type surface area response for the lower· r·iver than for the middle river. The net loss or gain of a given habitat type within the lower river viewed as a whole may be minor·. In contr·a st, with fewer channels in a given le ngth of the middle river·, this buffHing e ff e ct is le ss pr·onouced, and the sudace ar·ea response cur·ves are more dir·ectly link ed to changes in dischar·ge. Looki ng at iso lated channels within lower r·ive r side channel c omplexes reveals s imilar pr·o cesses occurring as in m idd le river· channels . Th e concept of br·a ided r·iver·s provid i ng a r e lativ e ly stable amou nt o f low ve locity wetted surf ace area for · a range of d isc har·ges is suppo r·ted by de tailed studies of Ne w Zea land br·aided r·iv e rs (Mos ley, 198 2 . Glov a and Duncan, 1985). Mosley (1 982) found for · br·a ided r·iv ers in New Zeala nd th a t the suda ce a r ea associated with s hall ow , s low water· r e mai ned r·e la tively c ons tant over· a wide r·ange of flows . ev en though t h e phy s ical location changed . This is because braided rivers a r·e composed of nwnerous channels with a r·a ngc in si z es a nd ove rtoppi ng discha r·ges , thus pr·oviding rn o r·e s t ab le wetted surface area re spon s e to changes in di schar·ge than a singl e-threa d chann e l. -38- R~3 t 1 ·I~ REFERENCES Glova , G .J . and M.J . Duncan . 1985 . Pot e ntial Effec ts of Re duce d Flows on Fish Habitats in a Large Br ·aided Ri v er , Ne w Zealand . Tr·ansact io ns of the American Fisher·ies Society . Vol. 1 14 . Pa ges 165 -181 . Klinger-Kingsley, S .A . 1985. Re spons e of Aquatic Hab itat S ur·f ace Ar·eas to Mainstem Dischar·ge in the Talk eetna -to -Devi l Canyon Re ach of the Susitna River·, Alaska . E . Wood y Trihey and As s ociates . Draft Repor·t for · Alaska Powe r Authority , Susitna Hy dr·oelec t r·i c Project, Anch o rage, Alaska . Klin ger·, S . and E .W. Trihey. 1984 . Res ponse of Aquat ic Habi t a t Surface Ar·eas t o Mainstem Dischar·ge in th e T a lk ee tna t o Devi l Canyon Reach o f the Su s itna River·, Alaska . E . Woody Trih e y a nd Associa t es. Re port for · Alaska Pow e r Author·ity, S u s itn a Hydroe lec tric Project , Anchor·a ge , Alaska. Do cume nt No. 1693 . 1 Vo lume. Mo sl ey. M.P. 1982. A nal ysis o f th e Effec t of Changi ng Discharge o n Channel Mo rph o log y and ln st r·earn Uses in a Braided Ri ve r·, Ohau River·, New Zea land. \Vater· R esources Resea r·c h . Vol . 18 , No. 4 Pages 800-8 12 . R23 /1 -13 EXHIBIT A Aerial Photography Sho wing Mainstem and Side Channel Classifications of the Lower Susitna River. zooo 1000 zooo 4 000 LOWER SUSITNA RIVER DATE OF PHOT OGRAPHY : SEPTEMBER 16, 1883 DISCHARGE AT SUNSHINE : 21 ,100 cfo SCALE IN FEET PREPARED BY ' FIGURE A -1 P REPARED FOR : _g~~~L liiAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULTANTS, INC. IIIVEA MILE 8 4 TO 9 0 2000 1000 zooc· 4000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 18, 11183 DISCHARGE AT SUNSHINE : 21,100 cfo SCALE IN FEET PREPARED BY ' FIGURE A-2 PREPARED FOR : ~~~------------MAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULTANTS, INC::. RIVER MILE Q 0 TO Q 5 ;u:-ill ~"~:. 11 w . 1 \': · 2000 1000 2000 4000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER HI, 1883 DISCHARGE AT SUNSHINE: 21,100 cto SCALE IN FEET PREPARED BY ' ~~EwT&AI -R&M CONSULTANTS, INC . . .,.,, .. """' .. _,,.,: .... , .. •••• ••cno•••t e "'"o•o LOGo••• ..... ,.. ,..,. •• FIGURE A-3 P REPARED F OR : IIAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION IIIYER MILE 8 4 TO 8 II <.:;tJ~II•'J,\ HH~!I Vt i\i t.Hi 2000 1000 2000 4000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 18, 1883 DISCHARGE AT SUNSHINE : 21,100 cia SCA L E IN FEET PREPARED BY : FIGURE A-4 P REPA ~E D FOR : ~~-----------IUINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION [):(]£00~& 0 ~®&®©@ R&M CONSULTANTS, INC. RIVER MILE a 0 TO a 5 DATE OF PHOTOGRAPHY : SEPTEMBER 18, 11183 PREPARED BY : ~~--------------- R&M CONSULTANTS, INC. LOWER SUSITNA RIVER DISCHARGE AT SUNSHINE: 21,100 cia MA1NSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION RIVER MILE 7 5 TO 8 0 2000 1000 2000 4 000 SCALE IN FEET FIGURE A -5 P REPARE D F OR : '•IJ',J ',, Jl)f '.l V: '.It •H LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 16, 1983 DISCHARGE AT SUNSHINE: 21 ,100 ch PREPARED ev : FIGURE A-6 ~~--------------MAINSTBI AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULTANTS, INC. RIVER MILE 7 1 TO 7 ~ 2000 1000 .. ,.·. ~""~,'~ /-- /' 2000 SCALE IN FEET PR EPARED FOR : / 4000 2000 1000 2000 4 000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 18, 1883 DISCHARGE AT SUNSHINE : 21,100 cte SCALE IN FE E T PREPARED BY ' FIGURE A -7 P REPAR E D F OR : ~ IIAINSTEII AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULTANTS, INC . AlYEA IIILE 8 7 TO 7 2 SUS! I PJ.\ J()t I Vr N l u rn 2000 1000 2000 4 000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 16, 1963 DISCHARGE AT SUNSHINE : 21,100 ch S CA L E IN FEET PREPARED BY ' FIGURE A-6 P REPARE D F OR : r-----------------~ IIAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULTANTS, INC. RIVER MILE 6 3 TO 6 8 DATE OF PHOTOGRAPHY : SEPTEMBER 16, 1883 PREPARED BY ' ~~---------------- R&M CONSULTANTS, INC. KASHWITNA R IVER LOWER SUSITNA RIVER DISCHARGE AT SUNSHINE: 21,100 eta IIAINSTEII AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION RIVER MILE 58 TO 8 5 2000 1000 2000 •ooo SCALE IN FEET FIGURE A-9 PREPARED FOR : .., 'lfl \,:, , ... 1 V: ·. ,r. zooo 0000 zooo •ooo LOWER SUSITNA RIVER DAlE OF PHOTOGRAPHY: SEPTEMBER 16 , 1983 DISCHARGE AT SUNSHINE : 21 ,100 cts SC ALE IN FEET PR E PA RED 9 Y · FIGURE A-10 P REP A R E D F OR : MAIHSTEM AND SIDE CHANNEl MORPHOLOGIC ClASSIFICATION fXJ&OOzUi.\"' !1;®£i:\C· c'@ RIVER MILE 58 TO 511 2000 1000 2000 4 000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 16 , 1963 DISCHARGE AT SUNSHINE : 21,100 cia SCALE IN FEET PREPARE D BY ' ~-------- R&M CONSULTANTS, INC. I EWT&A I o '""'~" ,., .. ., 0 nw• Ouo • FIGURE A-11 PREPARED FO R: IUVEA MILE 54 TO 57 MAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION 2000 1000 20<)0 4 000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPH Y: SEPTEMBER 18, 1Q83 DISCHARGE AT SUNSHINE : 21,100 c h SCALE IN FEET P REPARED BY ' FIGURE A-12 PREPARED FO R : ~r.~------------------IIAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULT ANTS, INC. RIVER MILE 51 TO 53 2000 1000 2 000 •ooo LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 16 , 1983 DISCHARGE AT SUNSHINE : 21 ,100 eta SC ALE IN FEET PREPARED BY · FIGURE A-13 P REPARED FO R ' ~J].:;-~~i l = ------~ ~ MAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULTANTS, INC . RIVER MILE 4 8 TO 50 ,. . '.1 ' 2000 1000 2000 4 000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY: SEPTEMBER 16, 1983 DISCHARGE AT SUNSHINE : 21,100 cia SCALE IN FEET PREPARED BY ' FIGURE A-14 PREPARED FOR : C> ~c;----------~-MAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULTANTS, INC . RIVER MILE 4 5 TO 4 7 2 000 1000 2000 4 000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 18, 1883 DISCHARGE AT SUNSHINE : 21 ,100 ch SCALE I N FEET RIVER MILE 4 3 TO 4 4 ·.;~ ,., I •• :. l•li 'J I V· ··:l ,•: PREPARED BY ' ~ONSULTANTS, INC:. I· -~~!.~-~ ... 1 FIGURE A -1& PREPARED FOR : MAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION .Nit-···· ••o~O•••'• "'YD .. O~OO •• •• ....... " O•e 2000 1000 2000 •ooo LOWER SUSITNA RIVER DATE Of PHOTOGRAPHY : SEPTEMBER 18 , 10 83 DISCHARGE AT SUNSHINE : 21,100 c1o SCALE IN fEET P REPARED BY ' fiGURE A-16 P RE P ARE D FOR : ·-----~ IUINSTEM ANO SIDE CHA.,NEL MORPHOLOGIC CLASSifiCATION R&M CONSULTANTS, INC . RIVER MILE 3 9 TO 4 4 ' , i I '! I \ · .. i 2000 1000 2000 4 ()()(\ LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 18, 1883 DISCHARGE AT SUNSHINE : 21,100 cto SCAlE IN FEET PR EPARED BY ' ----~~::::::::::::~----------------------------------------------------------------------~F~t;G~U~R;;E~A~-~1 ~7 ------~P~R~EEP~AARREEOD~FOORR~:-------------------j ~.r.~----~-~-u-.. -~?'-.~-.-~-.~-~-.. -.. -•. ~-.':-.--. 1 .. ~~!~-~ ... ~ RIVER MILE 3 8 TO 41 IIIAIIISTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION 2000 1000 2000 4000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY : SEPTEMBER 18, 1883 DISCHARGE AT SUNSHINE : 21,100 cto SCALE IN FEET PREFAREO BY ' FIGURE A-18 PRE P ARED F OR : ~~----------------MAINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULTANTS, INC. RIVER MILE 3 4 TO 3 7 : r1 ' •. \ J(,lt\ll Vt \,1 d · 2000 1000 2000 4000 LOWER SUSITNA RIVER DATE OF PHOTOGRAPHY: SEPTEMBER 18, 18113 DISCHARGE AT SUNSHINE : 21,100 cto SCALE IN FEET PREPARED BY ' FIGURE A-19 PREPARED FOR : ~ IUINSTEM AND SIDE CHANNEL MORPHOLOGIC CLASSIFICATION R&M CONSULTANTS, INC. RIVER MILE 2 II TO 3 5 EXHIBIT B Aerial Photography for Select e d Rep resent a tive Areas Showing Habitat Types at Selected Mains tern Disc harg es. ,SC 'AIMAA'I' 5101 CHANNIL CW C L [A RWATER AR E A SS S lOE SLOUGH fAIIUTAAl' .. OIHH SSC SECONDA,_Y SIDE CHANN£L T TRIBUTARY Tl TUAIID BACKWATIIl AIYUt MILl PREPARED BY ' ~,.---------- R&M CONSULTANTS, INC. DATE OF PHOTOGRAPHY : 8/27/84 GRAPHIC SCALE: SC IV-4 FIGURE B-1 PREPARED FOR ' DISCHARGE AT SUNSHINE : 75,200 ell '-~' r~J · ' .. \ I• 111>! Vz ':!' .:. ~ c;w CLf:AAWATEA AAEA Ill MAUU T IIII PSG II'RIIIIAitY SlOE CHANNEL SS SIDI SLOUGH Till TltiBUTAitY MOUTH DATE OF PHOTOGRAPHY: 8/27/83 SIC SICONOAit'f SIDE CHANMU, T TIUaUTAit\' TB TU .. 81D 8ACIItWATUt lltiiVEit MILl SC IV-4 FIGURE 8-2 PREPARE D FOR : PREPARED BY : ~---------------- R&M CONSULTANTS, INC. DISCHARGE AT SUNSHINE ' Se, 100 ch ' ', ,", I '!'": J \ : '. • ·~; PSC I'IIIIMARY SIDE CHANNEL CW CLEARWATER AR E A SS $10( SLOUGH TR18UTUU MOUT)f SSC SfCONO.UU SIOf CHANNEL T Tlti8UfAIII'f IIIV[IIt MILE PREPARED BY ' ~--------------- R&M CONSULTANTS, INC. DATE OF PHOTOGRAPHY : 9/6/83 GRAPHIC SCALE: ~. ~~~--~~~~~~ FT SC IV-4 FIGURE B-3 PREPARED FOR : DISCHARGE AT SUNSHINE : 38,800 clo C LEARWAT ER AR EA MS MAINSTEM $S SIDI SlOUOH TM T"IIUTAilllf MOUTN DATE OF PHOTOGRAPHY: 9/16 /83 l'S C '"u•a•u SIOf CHANNIL SSC Sf:COMDA"'f SIDE C~A IIffii(L T T"IIIIIUTA"'f Tl T UIIIII ID IACKWATftlll "lVII' MILt GRAPHIC PREP ARED BY ' ]::2~:1~ -----SC IV-4 FI GU RE B-· -R&M CONSULTANTS, INC. DISCHARGE AT SUNSHINE : 21,100 cis cw Ctr AHwArtlt .ut L.r. SlOE SlOUC " ~SC P"IWAAT ~HOE C HAHH(l TRIBUTARY YOUTH SSC SECONOAAf SIDf C HAHH(L f Tflt i "UTA RY TURSI O 8ACKWATI!I' PREPARED BY _; .-:· .: .. i: ~ RIV ER M IL [ R&M CONSULTANTS, INC. SC IV-4 DISCHARGE AT SUNSHINE : 13 ,900 ch z-···· - DA TE OF P HOT O GRAPtiY : 10/25/83 GRAPHIC SCALE: ,,~,::.,;~_,.. ______ F T FIGURE B-5 P REP ARED FOR ' I'G/~[.~~~.0:. '-' ;~-~·,j.V)\t(Q) :_ ~~---~:}~~ ~ -=-------:- R&M CONSULTANTS, INC . P SC i'I'IM.\I!Y 5 10[ CH.UINE L SSC SE CO NO.Iolt"f S ID[ CH ANNEL ra l"U111810 9.1oCICWA TUt S IO f S lOUGH TRIOUTUIY "'OUTH AlYE A )olll[ DATE OF PHOTOGRAPHY : 8/27/84 ~ ·.oo ., GRAPHIC SCALE ' ~----------FT ..• PSC PI:U\1.\i'l'r Sl Ot C !o<.H IN EL S l Ot SLOU~" ,... r;uaur:.R'r "0 U fH DATE OF PHOTOGRAPHY : 8/27/83 SSC '>tC O •l:)Jo;tv 5 10£ C H4 1'1N EL T T8 TURaJO !I.&CKW A fE I'I R I VER MIL( GRAPHIC SCALE: • '00 • --_______ FT .?-;:.·--:;r; __:~ -=:""=":=:c==="-:":~~ R&M CONSULTANTS, INC . DA TE OF PHOTOGRAPHY : GRAPHIC SCALE: ii::...'-'-;;('"':;;;-.;;. ................ '! FT ~:;=~,;;-----__ , EWT&A I R~IVi coNsuLTANTs, INc :-· ..................... . ..... , ... ••• ••o~ao•• • • .. •a•o~o o••• • """"' • • a•• " PSC ;>Ai•U IU 'H OE CtUNNE ~ SSC SF.CONOioAY S lOE CtuNN[l T ;u i'!IID !UC•w •T ER S I D[ SL OUC'ol"l TAI!\Uf.U:I Y \I OUl>t T"I"UT.lAY AIV £A • ._E DA TE OF PHO T OGRAPH Y' 9 /1 6/83 GRAPHIC SCA LE: . ...,., _FT •I '. I \'• . .. PS G P"I .. AA 1' :>:OE CHANNfL f t,~ TqiDUf,liU I,IQU TH DATE OF PHOTOGRAPHY : 10/25/83 R&M CONSULTANTS, INC. SSC SECONOAA' Sl OE CHANNEL T TAIIIUf ,UU AIV[illl MIL[ GRAPHIC SCALE: Tl TUJtii O BACICW ATflt WETTED SlJRFACE AR-EA FOR 59,100 cfs ClEA~WAT£A ARE A MAIN STEM SS S IDE SlOUGH Tit TltleUTAIIY MOUTH WETTED SURFACE AREA FOR 75,200 cfs DATE OF PHOTOGRAPHY : 8/27/83 PSC PfiiMAAY SID£ CHANNEL SSC S£CONOAAY SIDf CH ANNEL T re TufleiO e.t.CICWATEfl IIIYEfl MILE DATE OF PHOTOGRAPHY: 8/2 7/8 4 GR,\PHIC SCALE : PREPARED ev : ~c,;---------_ CASWELL CREEK FIGURE 8-11 PREPARED F O R : R&M CONSULTANTS, INC . 1•. i \ t .,' WETTED SURFACE AREA FOR 21, 10U LEGEND CW CL E A AWA T(A AA£A MA INSTEM 55 SIDE SLOUGH II'SC PRIMARY S lOE CHANNEL TM TJ118UTAAY .. OUTH SSC SE CO NOA 'H SlOE CHANNEL T Tl TUI'II ID 8ACIII.W A TEI'I I'IIVf.l'l MILE PREPARED ev : ~~,.------------ -R&M CONSULTANTS, INC. \ .. :~:.~-~---1 WETTED SURFACE AREA FOR 13,900 DATE OF PHOTOGRAPHY : 8/27183 GRAPHIC SCALE : L--- CASWELL CREEK FIGURE B-12 P REPARED F OR : l:!l "•.:. ...r ,~·,:1 I'' @ <>00 FT C W C l EAAW A fER A A[ A S S SID£ SlOU GH "5C PRUURY 5 10[ CHAP..H[l Till TRIIUTAA Y .WOUTH DATE OF PHOTOGRAPHY : 8/27/84 SSC SECONDARY SI DE CHANNEl T T"IBUTAAY >oo ___ , Tl TUR .. ID BACitW.t.T:;R RIVER llllll( GRAPHIC SCALE : L.-FT SHEEP CREEK FIGURE B-13 PREPARE D F OR o INC. DISCHARGE AT SUNSHINE : 75,200 ch LEGEND cw CLfAAWATEA o\AEA IllS IIIAINSTtM IS SID£ SLOU ,SC ,f'IMAII't SIDlE CHANNIL SSC lfCONDAIII'f SlOt CMANNll T TRIIUTAIItY T. TUfll810 .ACICWATIIIl al'lflt IIIIL( GRAPHIC SCALE : SHEEP CREEK FIGURE B-14 PREPARED FOR ' PREPARED BY ' ~ R&M CONSULTANTS, INC. lrol $ M A I HS T £M PSC P RIM A RY 51 0[ CHA N NEL SECONDARY Sl O E CtiAN N EL T T III IIU T A MY TUR BID 8ACitW A T EA A IY[A M IL[ PR E PARED BY ' ~~,.---------------- R&M CONSU,LTANTS, INC. SHEEP CREEK FIGURE B-15 DISCHARGE AT SUNSHINE : ~9,100 ch GRAPHIC SCAL E: PR E PAR E D FO R : ·l~lli\:.\ 1!N I V· ·.j + !Co~() FT . . . ~ • 0 • 2 • u . ~ . "0 • . " . ~ ~ ~ u •• PREPARED BY · -------~~.~~Lb=-================ R&M CONSULTANTS, INC. GOOSE CREEK 1 of 2 FIGURE B-16 DISCHARGE AT SUNSHINE : 75,200 ch • % . ~ • 0 • % • ~ g ~ • 0 • • J • 1:[ 41'1 ~ • w • ~ e K u •• ~:: ~ .. 0 '""' GRAPHIC SCALE : ______ FT DISCHARGE AT SUNSHINE : 75,200 elo ·.1 \ ·. FIGURE B-16 P REPAR~O FOR : 1. -~.~~~~.~ ... I GOOSE CREEK 2 of 2 % . , 0 c: :z; ~ • 0 " , > • 0 • . " . c: ~ ~ •• 0 z ~ ~ PREPARED BY · ~~~----·--_------- R&M CONSULTANTS, INC. .... •-••• ••o~co••• •• .... o•o~o••• •• • .,.,.. ... .,... GRAPHIC SC ALE : FIGURE D-17 P REP A RED F O R ' GOOSE CREEK 1 of 2 DISCHARGE AT SUNSHINE ' St,100 clo ... '1!',:, 1'.' ,, ~~~· ~·000~ GRAPHIC SCALE~ ----FT ~----FP~R~E~P~AUR~EEDD~B~Y~'------------~::::::::::::~--------------------------~-------------~F~I;,G~U~R~E~B~-~~~7----FP~RUEPARED FOR o ~N·-.. -;:-~-.a.;-~~--~-.-~-.~-s-."-•• !.~~· 1. -~·~!.~-~ .. -~ o~~~A~~A~:~s~:E : se~1:: c~a GRAPHIC SC ALE : ____ FT PREPAR E D BY · P REPAR E D F OR ' I ~ -~-:~:.~.:<\ .. 1 FIGURE 8-18 GOOSE CREEK 1 of 2 _ __;:.-=;~·._5.2..· ~ R & M co=C'N:=:':S':"':"U:":L.:"::T::'A::"':N":':TC::S~,~INC . DISCHARGE AT SUNSHINE, 31,800 ell GOOSE CREEK 2 of 2 FIGURE B-18 R&M CONSULTANTS, INC. DISCHARGE AT SUNSHINE o 31 ,100 clo GRAPHIC SCALE o PREPARED F O R o ';, ':' 1 • ' • .', I ' • ~ \ • 0000 _Fl ~ 0 . . a w g . w ~ . ~ ; . i . . w ~ . ~ Q ~ . u ; ;; PREPARED B Y ' ------------------~ R&M CONSULTANTS, INC. ... .,,.•••• ••o .. o••••• .. ,o•c ... a .. •••• ..... ,. ...... FIGURE 8-19 GOOSE CREEK 1 of 2 DISCHARGE AT SUNSHINE : 21,100 clo DATE OF PHOTOGRAPHY : 9/16/83 GRAPHIC SCAlE : PREPARED FOR : . .,.,. -----FT . -. u-...... P REPARED BV ' ~:~~~r.l_~----------- R&iVI CONSULTANTS, INC. GRAPHIC SCALE: GOOSE CREEK 2 of 2 FIGURE B-1 9 DISCHARGE AT SUNSHINE: 21,100 ell ,,,., ...• ··.1 . ~ w . 0 . . 0 • ~ ~ . ~ . ~ . ~ w ~ . 0 ~ u ;; • . ~ u . ~ PREPAREO BY ' ~~--.---------GOOSE CREEK 1 of 2 R&M CONSULTANTS, INC. OISCHARGE AT SUNSHINE : 13,.00 eft FIGURE B-20 ""' GRAPHIC SCALE : --- PREPAREO FOR : o1 i -.... ·. Jill !!l \; ·. i H · 0000 FT ~~~.cl ~~[vaJ 8 ~ 2 Ul c !:i ~ 2 -t _Ul 2 n • II 01 -< 00 ~ >-! ~ > " iii C) n 0 % .. 0 "' C> C/) m m .. .... 0 .. c: ::a z m .. % m z ;:II; m N LEGEND CW CLEARWATER AREA .. , IIIAINSTEM SS SID( SLOUGH ,SC ,IJIIMAAT SIDE CHANNtL TM TIUIUTAAY MOUTH SSC II:COHOARY SIDE CHANNEL T TIIIIIUT.UIY RIVER MILE Tl TUAIIO IACKWATE .. .. 0 I llrlllll$ ._.!; .~1111_, _,.,.t.~WIJ. .. 0 0 " . .... N .., i5 c "' "' CD I "' 0 C> "' ,. .. ::t ;; 25 ., .. "I~ "' ... " m .. {, ~ -~ ~ ~6 "' "' 0 0 ., l d •a UUil @ ~ (}!ji) © @ l.§ ~ ;:_ ~· .~ c4 ~ ..... I ,;,.,CJ , a q :"J , "''·"'<'· .. ··-\ MONT C R CLEARW AT t.R AH [A MS MA I NSTEM SS SlOt SLOUCH PSC PRIMARY $1 0[ CHANNEL TAIIUTAAY M OUTH SSC SECON DARY S I DE CHANNEL T TUA810 8A CKW AT[lft .UVUI WILE R&M CONSULTANTS, INC. 1-. ~~:.~.~---1 PREPARED BY ' ~~ r--------------------- _ _r-.. MONTANA CREEK FIGUREB-21 DI SCHAR GE AT SUNSHINE : 75,200 cts DATE OF PHOTOGRAPHY : 9/27/84 GRAPHIC SCALE: PR EPARED F OR : •;i •,J ' :. !'ll r .· '.·'.i """' FT C l EiiRWAifll AO[A PSC PRIMARY SIDE CHANNEl TM T R IBUTARY M0UT~ MS MAIHSTEM S ID£ SLOU CH DATE OF PHOTOGFi APHY : B/27/83 SSC SECONDAnY SIDE: CHANNEl T T8 TUA810 BACKWATER GRAPHIC SCALE: ~ FT PREPARED BY : ~~~----- R&M CONSULTANTS, INC . 1 .. ~.~.:.~.~ ... I MONTANA CREEK FIGURE B-2~ PREPARE D FOR : DISCHARGE AT SUNSHINE: 59 ,100 cis '•: I • I I ' , 1 '. • ' 1 ~ • M S hUIN STE M PS C PA IIoiARY $10 £ CHANNEL MONT CR CLEARWATER AR(A SS SID£ SLOUGH TAI P'UTA R Y MOUTH S IE CO NOAA Y SlOE CN ANNII!L T T UA810 B A CJtW AT EA AlYEA MILE PREPARED BY · ~------_;·z~~~~~~==~~~~==~~ R&M CONSULTANTS, INC. DATE OF PH OT OGRAPHY : 9/6/83 GRAPHIC SCA LE : FT MONTANA CREEK FIGURE B-23 PREPARED F OR ' DISCHARGE AT SUNSHINE: 38 ,600 cfs C L(AI'IWA T[A AA[,t, MS '-lA I NSTE W SS SID( S LOUCH P SC PRIMARY SlOE CM ANN (I. TY TAIIIUTAIU MO UTH DATE OF PHOTOGRAPHY : 9 /1 6/63 SSC S ECON DAR Y SI D l CHANNEL T T. TURIIID BA CKWA T[III IIIIV[III Ml l.l GRAPHIC ______ FT PREPAREO g y : ~~ FIGURE B-24 MONTANA CREEK -R -&M CONSULTANTS, INC. DISCHARGE AT SUNSHINE : 21,100 cfs .,..,,,.•••• ••o ~oo 1 e y e ,. ~ o •o~ou•e • • •u •v • • o •• loU IHSTC:M PSC Plt iM A Al' 510[ CHANNEL MONT A CRE C W Cl [UfWo\T [n AR[A SS SI DE SLOUGH TAIIUTAAt "'OUTH ,SC S(C OHOARl' SID£ CH ANNEl T TURBID 84CitWAT[R AIV [It M IL[ PREPARED BY ' TI{§:~ 1----------- R"&"M CONSULTANTS, INC. DATE OF PHOTOGRAPHY : 10/25/83 GRAPHIC SCALE: FT MONTANA CREEK FIGUREB -25 EW.T~A.I . ............... ~-·· .. DISCHARGE AT SUNSHINE: 13,900 cts . % . ~ 0 % . g . . ~ ; . ~ 0 ~ u • ~ ~ u . .. "' 01 ;:: N ;;; ~· z z z . % . z u . ,. r 0. <( % . a: u 0 . • " w 0 0 u ~ . . w . 0 0 z 01 ~ ! 0 ~ z :;; u w. : " u u w • . ~ ...J • 1--' 0 <( :r u 0. "' "-~ 0 :r w 0. 1-<( <( a: 0 " PREPARED BY ' -J3.\ 2J~x--------SUNSHINE SLOUGH 1 of 2 FIGURE B-26 -R&M CONSULTANTS, INC-DISCHARGE AT SUPtSHINE : 75,200 cfs % , 0 . P REPARED BY , ~ ~~,lL~ ~ -~ R&M CONSULTANTS, INC . DATE OF PHOTOGilA PtH : 8 /27/8 .1 SUNSHINE SLOUGH 2 of 2 FIGURE 8-26 DIS CHARGE AT SUNSHINE : 75 .200 cts • ~ > u "' ..... PREPA RE D BY · n:. !. __ v---. --~~ -== R&M CONSULTANTS, INC . P RE ~AR E O F O R : ){]&,[~~, FIGURE B-27 SUNSHINE SLOUGH 1 of 2 DIS CHARGE AT S UNSHIN E : 59 , tOO cts ;.. § ... -I I C') 0 "' I ... "' "' ;; ::t .. "' <: " 0 w 1--' 0 "' :z: u .. "' ... ':! 0 l: w .. .... "' "' "' 0 " < ~ 0 ; g : • 0 • . " . It ..... ; • w • ~; ~ . . . u . P REPARED B Y : =S\!1~] -. SUNSHINE SLOUGH 2 of 2 ~&M CONSULTANTS, INC. I .. ~.~~:.~.:\ ·I . . DISCHARGE AT SUNSHINE : 59 ,100 cfs L_~···=··"·~····=··· .. ~···=·····=·· .... ~ ... ·=--···~·~==~----~ FIGURE B-2 7 ... ~ ... .., "' 01 ... N ~ 1 > l: Q. < a: " '" 0 ... _, 0 < l: u .. "' ... ~ 0 l: w .. ... "' "' a: 0 " . . , 0 E g : • 0 • ! ;: ; ; ~ ~ v ~ " P REPARED BY ' ~~---------------- R&M CONSULTANTS, INC. FIGURE B-28 SUNSHINE SLOUGH 1 of 2 DISCHAR GE AT SUNSHINE : li ,SOO cfs . .. (') c ., ;; I ~ ~I ,.. :r .. .. a: " 0 w .... -' 0 .. :r u .. VI ... u 0 ;:: w .. .... .. .. a: 0 " . . c ~ • 0 • % • ~ g I» • 0 c 3: ;: ! . , c"' a ~; ! PREPARED gy . ~· ~:JR,J . ::-- R&M CONSULTANTS, INC. ... G• .. ••oo• ••o~ou •••• ... ., ... .,o,.•••• •••••• •O•• 9/ /83 G RAPHI C SCALE : ~~.-----· FT SUNSHINE SLOUGH 2 of 2 FIGURE B-2 8 PREPAR E D FO R ' DISCHARGE AT SUNSHINE : 38,600 r:h • . ' V 1 '~ l • M 2 0 ~ PREPARED BY ::-:!:s2i"t:. ------ I=I &M CONSULTANTS, INC . SUNSHINE SLOUGH 1 of 2 FIGURE B - 2 9 PREP ARE D FO R · u·b 00 DISCHARGE AT SU ~SHINE : 21,100 cia ,. "' Q. .. c: " 0 ... 0 .. ... 0 w ... .. " w ... .. u "' ~ :r .. .. c: " .. ' tJ ~· ;. .. PR EP A R ED ...r3~{:~J01 ----~~-SUNSHINE SLOUGH 2 of 2 R &M CON S U L TAN T S , IN C . DI SCHARGE AT SUNS H I NE : 2 1 ,100 cts .,. .. ,,. •• ,.. ••o o.<>u•••• -• .,,.., .. ., .. ,. •• ........ •o ... "' " "' ;;; ,.. :r .. " a: 0 0 .. 0 :r .. ... 0 w ... " 0 .. g "-• cl ' w _, " u ., u i: .. .. a: 0 M .. "' " 0 > , 0. « a: 0 0 w .... -' 0 " ;;: u "' u. u 0 ;: w 0. ... " " a: 0 " P REPARED BY · -~:S~v~~-~ ----SUNSHINE SLOUGH 1 of 2 FIGURE B-30 ~&M CONSULTANTS, INC. D ISCHARGE AT SUNSHINE : 13 ,900 cts PREPARED BY ' ~---------------~ R & M CObN=:S:CU=:':"LT:::":A":N=:T;:S:",=I;-::N=:C:=.= DISCHARGE AT SUNSHINE : 13,100 ell SUNSHINE SLOUGH 2 of 2 FIGURE B-30