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HomeMy WebLinkAboutDAUPHINAIS MOSELEY FILING 1 DRAINAGE STUDYo hlnter-Mountain At-gineerinqLrd. DRAINAGE STUDY FOR LION'S RIDGE SUBDIVIS]ON FILING NO. 5 TOWN OF VAIL EAGLE COIJNTY, COLORADO PREPAREII FOR: DAUPHlNAI S-},IOSELEY CONSTRUCTI ON FROJECT NUMBER V-8312E APRIL 1990 Box No. 978 . Avon, Colorado81620' 94*5072Denver893-1531 1420 Vance Street . Lakewood, Colorado 80215' Phone: 232-0158 I I I I I I I T I t I I I I I t t I NTRODTJ(.]TION This report addresses the storm flows and drainage crear,ed by the Lion's Ridge No- 5 Subdivision, which is .l-ocabed in the 'fown ot' Vail. Uolorarlo - The site is bordered by Li:on s Rrdge Loop Roarl to the nr:rth. by Interstate Highway 'l;) Lo the south, Solar t-irest r-londr:miniums to the east. and Br:ffer {-reek Strodivisi-on to the west,- it also addresses the e:{isting and ,leweloped sborm flows ancl drainage patterne for the eniire orainage basin which is borciered by Buffer Creek Road to the rvest, Interstate'/o tcr the south, and Lion-s Ridge to the north and east, to the drainage I j-ne which extends north from the Solar Cregt Condominiums to the top ot Lions Ridse from Intergtate Highway 70 - ( See Figure l. ) EXISTING AND DEVELOPED CONDITTONS The existing Bite is undevelopeci. The native vegetation consists of oah brush, a6pen, mountaj.n brush and grasses igee Figure ? and Tables l and 2), and drai-ns to the $te6t into the Buffer Creei< Subdivision, then aeross Interstate '70 to Gore Creek. The proposed development consists of a new roadetay and 19 single-family lots. Several feet of fill will be placed on the eite with construction of the new road. Development of the site wlll increase the storm runoff from the slte and follow the r I e-.<ist j-ng clrainage F,artern to rjore 'Jreer. I rjf tsi-te I The otfsi:t:e area consists ct a portion Dt the Buffer [-lreei< I Subciivi-si-on ancl portione ,rt t"he Lion.s Ridge No. 2 and :J tillngs. I The nati','e vegetat j-r:n ot the unde'"reloped areas cnnsisb ot oak I brush. aepen, mountain bruoh and grasses. The de,zeloped areae I conelst ot ree itienttal Lot,s wi+.-h a minimum of ltJ.t)t)t") sqs3pe feet. I I I L]RI'IERIA I The following reterence.s were used in the preparation of ! this report: 1 . PIat f or Lion I s Ridee flo - 5 Subclivision., 'll ovrn ot VaiI, t Eagle County, Colorado. I 2. TopograFhical map for Lion's Ri-dge No- 5 St-tbdivision. I prepared by Inter-Mountain Engineering, Ltd- I 3- Gore Creel< Flood Plain. Current t-londitiona. a component I of the Compreheneive Plan, Town of Vail. Eagle Count:r', Colorado, I prepared by Briscoe. Maphis, flurray. Lamont. Inc-. Management I Consultants, in 1977. I 4. Urban Hydrology for Small i^latersheds. IR 55' USDA Soil I Coneervation Service. June 1986- I 5. Handbooh of Hydraulics, Fifth Edition, King and Brater, t McGraw-Hill Publiohing Co. The storm flows generated by a 1o-year, Z4-hour and 1OO- I year, Z4-hour frequency storn rdere analyzed. Flowe were computed I t I I I I t I I t I I I I t I I I I I I t I uEing the methods outli-ned in SCS Tet-hnrcal Release No. 55' ,June !966 Edibion- SUBBASINS (-lnqi fa F',tr the purF,ose Lrt ca Lcttlating r.he siorm t lcl'rtE on and acrosg the prcposed srte two sei,arate eubbasin 'tere detined- Subbasj,n I Iies adjacent to the North Frontage Road ot Interst.ate Highway 7t.t and inci-udeg lots 9. lii, 1l anct 12 oi the Bufter Ureek Subdi.,rision. Flows sheet flow from the north to the F'rontage Road ditch then to the e:<isting drainage Btructure across Interstate Highway 70 to Gore Creek. Subbasin II includes most of the proposed subdivision and an area north of Lion's Ridge Loop to the top of the ridge- The subbasi:n j.s bisected by Lion's Ridee loop which has a small roadside ditch on the north side of the pavement. For the purpose of this design, hte assumed that during the rnajor atorm event this ditch would flow fulI and not i.ntereept any storm drainage. The f lor,ss sheet f low acrose the road into the proposed subdivision and concentrate in a natural drainage which exits on Meadow Drive in the Buffer Creek Subdivision- It then flows through an existing culvert along Meadow Drive or sheet flows on Meadow dri.ve to an inlet which diverte the flow acrosa Interstate Highway 7O to Gore Creek. Offsite For the purpose of this study" offeite drainage was considered to determine if the exieting drainage Btructurea were I tl I I I I I I I I I I I I I I I I T I I I Iarge enough to rrarry the Ceve icFect t. iord lrom the enc rre ,Jrainage basrn to the cen+r,rar coliectl.cn lnirets on Meaciow L'rive. then acrose Interstate Hiehwav 7(-) to Gore r,lreek. For the offei-te drainage area, f ive separate subbasins were rleiined. Subbasin III includes an area norlh ot Lion.s Ri.,lge Loop to the ridge. then eouth rrt Lion-s Ridge Loop, and a portion ot Lot 21 ot the Brrtf en rlreei< Subcliwi:-:i'rn. F.garn, tcr rhe purpose .Jt ilhis strrcii.r we ae€llmed the small ditch norlt.h 'rt rhe pavement on Lion-s Ridge Loop will not intercept the f lows ancl ',viLl sheet tlow across the road anci concentrate in an existing drainage cn the south side ot the road- It then flowe to Rictge Road in the Euft'er Creek Subdivision and onto Meadow Drive to the existing central colLection inlets- Subbasin IV li-ee to the west and adjacent to Subbasin III, west to Buffer tlreek Road anci includes a portion ot Lots 18 and 21. and Lots 19 and 2O of the Bufier Creek Subdivision- During the major 6torm event, the area north of Lion s Ridge Loop sheet flows to the road an,l foilow the north side r:f the road to an inlet wi.th a Z4-inch Cl4P across Lion's Ridge Loop at the intersect ion of Buffer r-lreeh Rc-aci - It then follows Buffer Creek Road to Meadow drive and into the central collection. The remaining gubbasin area also flowg to Buffer Creek Road and to l,leadow Drive. By vislral inepecti-on it appears that during the major storms. flows frorn this basin will sheet flow across Buffer Creek Road and directly into Buffer Creek- Subbasin V includes the developed Lota 13, 15 and a portion of Lot 2L of the Buffer Creek Subdivieion. Subbasin VI i.ncludes the developed Lote 15, 16, 17, and a portion of Lots 18 and 21 of the I I I I I I I I I I I I I I I I I I I I I t Buffer {lreek Subdi-visi.on. 'l'hese bas:ns sheet tlow ontrf Plea,lc.rw Drive then into the central colleetion ini"et- Subbas Ln VII congists ot Lots '7 and I of the Bufter t,lreeit Subtli-vi-sron and sheet tlows to the di.tch on the north side or Ehe Front,-ege Road then to the exi-stinEi drainagie structure across interstate Highway 70. (See Figure 5 for subbasin bounciaries- t FLOWS tr'lows for the exrsting and cieveloped couclrtions were eomputed using the methods outl j.ned in SCS 'Iechnieal Release No- 55, June 1986 edition- The ot'fici.al zoning map for the Town of Vail was utilised to determine the proiected densities ot the undeveloped areas in this etudy. A conservative runoff curve number (CN) of 87 was ueed for fLow calculations in the existing and proposed developed areas with a B,zC hydrologic soil group- This corresponds to the eugge.rted coefficient defined by the {JSDA for flows calculated by the SCS method for resi-dential- distriets with lot sizes of l,r8 acre or less. (See Tables 3 & 4. t AII flows ."r ".]"rrlated fc,r the lu{j-year, Z4-hour storm event. A summary of these flows is detailed below in the followi"ng table: t I I T I I I I I t I I T I I I I I I I I 56 65 5S 87 87 67 oi 1u. t 1il- 1 13. 9 ?3,I 14-3 14-3 6.4 6.4 0-9 o-9 1-5 1-5 1-3 t_3 Subbasin UN gl_lt-rt-t -rrr, 24-[a t- . r;5 r..14 li. L1 E. ti3 0. 4,! :J. IJE rJ . i3(j 2-L7 o. B4 o.84 o. 38 0.38 2.46 I (P) (D) II (P) 6? o.L Pr3 (D) IlI (P) (t') IV (P) V (P I (D) VI (P) (D) inr ?? VII (P) 87 (Dl 87 (P = present conditions; D = developed eonditi-ons ) FiEure No. 5 depicts the eeparate drainage subbasins with subbasin flows and accumul,ated subbasin tlows. The accumulated present condition flow from the seven subbaeine tota] 7.32 ct-s which diecharges through a Z4-inch CMP across Interstate Highway 7O and into Gore Creek. I l I I T I I I I I I I I I t I I t T t I I T|RAINAGE F.ACTLITIES E:<ist i ng Figure 6 depicts the existing anct propose,l rjrarn;ege f aci-Iities and Table 5 tabul-ateo the p j.pe data anci maxrmum n,=nnni iw rr.t'nl nt' rrer"h ninc The tnial e.<i nt.in.o tLow f rr:m the?qtr',f.rrvJ }/!F.e. seven subbasins of '7 - 6? cf s is discharge in tiore (lreeh by a 24- inch tlMP acrDBS Interstate i{ignway '70. Prcposed Figure 6 deFrct,s the p'roposed rirainage tacilitres to c'-r.rr'y the 100-year, Z4-hrrup st')rm event. A drai.nage dicch musr be constructed aLong the east sj.de ot Buffer Creek Road .Lo a proposed 18-inch CMP (Pipe No- 10) near the southwest corner of Subbasin IV which will discharge direct.Ly into Butfer Creeh- The drainage ditches between existin€i pipes 1-Z and 2-3 mugb be enlarged enoug:h to carry the flows from the proposed Lion-s Ridge No. 5 subdivisi-on (subbasin I1) and subbasin III. The existing l5-inch CMP (pipe no. l) will be replaced by an 18-inch CMP to carry the flows for the developed conditions of subbasin I1- All other drainage facilities are large enough to carry the lU0-year, 24-hour storm event for al-i developed conditions. The existing Z4-inch CMPg (pipe nos - 6, 7 and 8 ) across Interetate Highway 7Ct will camy a Qnax of 33. 25 and 36 cfs reepectiely. By di.verting subbasin IV to Buffer Creel< the Qma:< for cleveloped conditions of the entire basin wiII be 15.75 cfs. The onsite runoff will flow to the drainage ditch afong the propoaed Lion's Ridge Lane within the eubdivision- It will flow to the west and concentrate at the existing natural draj.nage on I I t I I I I I I I I I I I I t I t I ,T T I the weet end of the proieet. A l5-inch CMP wil-l be installerl across the driveways ot the proposed lrrts. CC)NCLUSIONS The improvement:5 for the proposeci subdivision will t:aLrse an inere.ese in runoff within subbasin II. 'Ihe proposed Lot ,lesisn wiII not alter the rlralnage basin botrndartes- AII the e:<isting and i-ncreased runotf wilI be oiverted to the existing naturai- drainage and the existing ,lrainage facilities wi:thin the Butfer tlreek Subdivision- Hi-storieally, the runoff from eubbasin IV drained into Buffer Creek. By instaLLing an l8-inch CMP (PiPe no- 10) at the low point of the subbasi-n the runoff will be diverted to its natural origin - With the exception of the existing 15-inch CMP (pipe no. 1) which will be replaced by a lS-inch CMP, and by improving the roadslde ditches on the north side of Meadow Drive, the exi.stlng drainage facilities are adequate to earry the developed condition runoff for the entire basin. I I I I I I I I I I I I t I I t I I I I I I lu, tG ffi.ffirrrEr Attf' vlfi;;'ff;l*"**- ffiInter-Mountain ::-:t l--::-iiia= A=-sineerincrLrd- SUITE 'O!t,t20 VANCE STREET LAt(Erooo, coLo. 80215 (303) 232-0!58 Lo*' l-19 ['o-s R,;:rz i-r.r.:5 l-e-p, "1a i..\:4 ei ??.*jZZMMNN4"Z *-'Dne:st A,crg BA>rr'r5 "xY,ir/, -- :Ni\\-,wffi,$)r:li-E N?il N7*dr.ild Gore Creek F Arrqrt Goldins Acw 3c.. ate " l"' voo'Tan CtH | - t/rc',vtrY IVIAP I t I I I t I I I I I I I I I t I I I I I I I I I I I I I I I t I I t I I I I I P.o.qu cr8 oero ltoTTIlFHAra AV6[ Cq-O.8r82o ($31 9,10-5072 !t rlE tot t4e0 vAtlcE gTEEr LAKEltoo. clLo.80215 (30:1, ?3F0158Engineeringr.ta. Inter-MountainROAt) For.ct Lo. t/ 83 /78 o.t. / By: Strlat No. /oTS ',') trt': e 't ci ru.zryc 6 €DITE T C(I-ORADO BIAT€ SOIL L-,.VEY AAP€N-CYPgttl sFlcE oit JAttuaRY 4, 1909 AREA. PARTS OE EAEUE, OARFI€LO 66 F7 5A ?j9 6r, 6l 63 64 ---l I--1 I - -.1 I : l j-t I__l I---1 I -_l I I"-t I--1 i -I--l -.tIJ I TASLE AI,...ACR€AG€ANO PNOPORT IO',IATE lJodaio loai, I to l2 parc!nt rloparlhi lSor. .r lt lot.---------iKobr. tr lty cl.y 1o.., t to 6 p.rc.nt tlop.t----------ixobrr .a lty clry lot., 6 to l2 p.r<.nt .lop.r---------fKoDr. ri lty cl.y lor., LZ lo 25 p.rc.nt rtop.r--------:Kobar tllty clry loa,., <t..y, 3 to 26 g.rcant alopar----lL..vittvi I la lora, a to 25 D.rc.nl .1o9..------------- llla I l.rlak. lot., !5 to 30 p.rc.ot tlo9.a--------------lftio. forr, lZ to 4t p.rc.ot rlopra--llli.|a lorn, 23 to 6t' grrc.ot rtog.i--llllircl. loar, 3 lo 30 parcant rtop.r----------llioan rtony loaa, I to 6 prrcant atopat----------------fioan rtony loar, 6 to L? p.ra.nl, alopar---------------!Io.n rtcny loa.r 12 to 23 p.r<.nt ttop.r--------------!ion.<f alna trndy 1o.., l? ro 23 p.r..ni rtop.r--------lilooad lih. arody 1o.., 2t to 50 p.ra.ot atop.r--------lliorval lol|rr t to 6 p.rcant itogar----------liorv.l lorr, 6 to 26 p.rc.nt slop.r----------illvrv.l lorr.r ZO to aO p.rcrnt tlop.r--lilorvrl-Trldal I cortrlar, !2 to 50 p.r<.nt rlopr.-------lltoyarrDn-Rock outrrop cor.t,lax, !6 to 60 parcahi aloptr!iuatal l"aa, I tc 6 prrcant rlopra----------ill$tr.l 1o.., 5 to la p.rc.nt rlot.r----------iEust.l lr.i, l? to Zg p.rc.nt iloprr--iRadrob lo.r, I to o p.rcrnt !lop.r----------iR..g.rt vir'y rtor,y rrn.ty to.i, 25 to 65 p.rcrnt ilop.tilihoy.ltcr-irrrv.l cont,l.x, 5 to l5 p.rc.ot rlogcr------lSt,.ie.ltrr'.ltorv.l cniFlex, l5 to :.5 ocrc.nl slopor-----!!n.rtl'.(. 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I z.l o..a o.z _i-T' t.2' o.3 ;-TT.f-mT'TI-l I 1 -rrrT-l-T l !i li fr atc, / I t I I I I I I I I I I I I I I I I t I I ";;;'Srfi3r"**^" ffiInter-MountainTI:ii-:::?iia: A"..gineerintrr.rd. !t lrE 101 r4eo v^l{cE STEET LAKErmo. c0L0.80a15 (3031 23a-0150 /o7- -') ,-,,'.t//-' ("',.';€ FtL.,,,,tC {D ?,2 .t'/ i€ , arlra!.r o!.otaoo tt^rt rrtct o J^rJxr.r trat"- --. atll. aatat rti*trn'ir alr, t-lt d. ar.a, al'rala, a- a]trta ot-rlat, ae'trD trla x.---tl x{a |ttr tlrtrE--c{rr.r.. r ,.tri r..r r||r. | &..(r i t rtaa a, a-;-r- - l--- r-- -, rr-.r I t.tr. t ar.G.dy I Lrt.i tt ar. I t|.ria t at.a tt.rt. rO.rtr[i.a- r r...t [r.{r.a tC*..a..r.-l Il',r ao' al. aa'___l| -i5'-'----; " i"-------i tltrl--i tt ad.a.--- att-----tt-.Irl --- lr.a...t.---laat----- --.rtl--- ri.......---rxrt-----rr-. --r tr.a...a.---$l|i----ttd. lra.r-a.t I l.O-3.o1 ttt*..t I J.n-D.. 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Itl ttl ti...--------t ---tl1i...-------.t --- Titete Z I T I I I t I I I t I I I I t I I T I I I I P.o.aox 070 0st0 torrtl€t^la AV6L CC-o.61820(s3l 9a$-5072 noro Inter-Mountain sulrE 101 14EO VANCE STFEET LAKEIo@. CoLO.8o2i5 1303123:l-0r58Engineeringrta. Pr"otact No.Y t'gtz Q O.t. / ',ll Shsat No. Lor=I Lro*'r *l '=j.1tDz14 -S Pua)*A4€. .*t- -+I I ---.i- I -----1. I_T I I 3. a3,; 'lO q,lro--rl< *,1cE tio-tiJ-1.ct'cJ 'itl,I , 5t & ilgl .aE l3 iEtrr .----r--- -1 I ) I .l-'1 --T- I I __r, I I I( I I t'; I F_-- I I t-\ I I I l--- I "@l let l,...._ {fEL'- J V; r ri , i ri Frauee 3 I I I I I I I I I I I I I I t t I I I I I P.0.B0x e7a 09to I0TT IN6|tAra ROAD AVS|, CO-O.81E20 (:n3l s.F507e surrE !01 taao v^fcE STEET LAKEi000. co-o . ao2!5 (303, a32-0154 *i)'F,tae tt!t. / 8y: Shlrt tlo. | | tar ] + .--L4t | - tY L rc>r.rc i<.:rqe_ -S DreA,*n,qc- fioupa- + IIII t :.I IIIIIITITIIIIIII I I 4t I Tablc 2-2a--&rnofr curvc numbcrr for urtu enast I t Caver descriotion Curre numberr for hydrulogic soil gtoup- Cover tlae end hydrologic condition AYerzg€ percent lmperbu rreet DA I I I I li :l. t I FUIIV da,el@ ulen otzos (oqqtztion cstablishtd) Open spce (lrwru, parks, golf counes, cenet€riec, .t4)t Poc codition (grass cover < 5{l%) .............. Frb condition Qrzss cover 5096 to ?5%).......,.,. Crood ondition Grzss cover > 75%, . . . . . . . . . . . . . . Iqervious rrers: Paved parking lots, mofs. drive*ays, etr, (erduding rightof-ray). Streets end roads: Peved; curts and stornr sewers (exeluding riShtof-say). . . . Ftved; open ditches (including right{f.way) ...,.,. Cravel (induding right.of-$ey) Dbt 0nduding rightof-way) W€lErrr desert urban rreas: Nabral dese!'t landscaping (penrious ararr onlyF... Artificid desert hndrcaping 0mpen'ious weed bqrier, deren shnb with l. to 2'inch slrld or gevel Euldr and brcin borden). Urtan district!: Comcrcial Ntd businels.. . . Industrid....... R€3idertid districts by average lot size: .tn ecre or tess tto*.rt housed- -. .. -. -. -........... I U4 arre : lB ecle 1ii2eclr.....,.. 1ecre.......... 2 arrel ......... -Dclrl@&tg ttttrln aw Norty greded rnas (pewioru uees only, rb veget tion)t . , ldla latd! (CN's a€ determined using cover t1ryer d'nil-r to tbore in teble 2-&), 68 49 39 98 98 83 ?6 72 63 96 89 8r n 6ttl 6{ 5t t6 85 72 66 38 30 %n t:2 ?9 1669 7961 74 89 E4 80 9E 98g] 9l E9 88 96 95 93 92 c7 86 854 .&, 9898 98 9889 9285 89c2 gl n85 96 94 '91 r-1B;n9o -89 EIg) ?9 a, 92 88 85 ao 7','2 m 6E 65 E6n I I I l. i 9{9l rAvq?8! rrnotr condition, rnd l. - 0-i6.tltc rrra*c pcrent ir:npcwinri rne shosr rrs urcd to dcvclop thr conpodte Clfr Oth:r rremptilu rn rr loltonr: Inrpcn*)ur rrcurt dirtctlt cmncct+{ lo thc drdnr|8? lyst m. irnpcrviol rnrr hrr.o r CN of $. nd pcrviur rr.a rf. srri.lerd Gquirrhnt to oDan !q!! in Sood hydmlogic coditlorr. CN'r for othcr conbinrtiru of condtion! ntry b. comput d ndnt ftun 23 or Z.l.rCN! shorn_erc cquivrlent to dr6. of Futun. Conrporitc CN'r rnry bc conpurrd tor otLr coo&irutioil ol opcn rprcc corcr typo, 'Conpoitc.CN'r lor nrtunl dcrcn bndreping $out'd b. courpur.d idrf, tlgirn 2{ o" 24 b{.d 06 rh impJriod rrrl p.rsriri4r tCX -.-9t) rnd th9- pnbur errr CN. The pcn'iour rnr CN'r lr ilumd rquiv-dont !o d.r.n rfrnb h poor hydrologic condiiion.rCoqqiu CNt to usa for thc &dgrr- of trrqonry rrrrunr durin6 jniffu nnd corrrtrucbn rhouli lc cinpua using tlprrr !3 or 2.{.br.d oo Uc dr&rc of dcvclopnont (imprniour rnr pcnrat4r, end ttn CNI for tb ne*ly 3rrded pcniour rrrlaP t €IOVI-TR-55, Second Ed", Jurc 1986) fnac€ s 2.6 I t I t_Trblc Z-2d.-Runo(f currc numbcrr for arid rnd !.mhrid En3?l.ndrr Covcr dcscriptbn Cunc numben for hydnlogic roil 3tup- Oover t12e Hydmloglc conditiodr ar I t t I I 75 E658 7841 6t 6rm51 8335n n8572 8r68n 68 55 49 hor Fdr Good t I Herbeccour-mixnrc of gnr* wecd* end low-growiry brus\ eitb bruh th. ntinor element. Ork-erpen-mount in bnrlh mixtrrc of or& bnuh, aspen, rnountein mehogenn bitter bnrsb maplc, rnd other bnrh. Phyott junipcr-pinf'on, juniper, or both; gnss undentory. h6 Frir Cood hor Frir C'ood hor F.b Cood Poor Frir Good fl)aTL Ei6e 71 I Sagebruh with 8!rs! undentory, Derert rhrub-major phDts indude srltbush, grearewood, cr,ecotebudr, bhakbnrh, bunrge, pslo verde, mesquite, ard crctu!" s" 80- 85 ?9 63 48 89 s, ?r E5 70 oo 88 E684i 1 66 r-r 7lsl54 sgt- tl I I I rAgent! ruroe conditioal sd L - o.lCS. For rrrg: in hunid r!Sbtq u!. t$t g.zc- rlbor <-fllil _3nund cove (fttcr. grzrr. sd btrrtt onntorylfoir iill ro ?Iltt Srlrrr|d covlr. Guxl: >1UI jrund covcr, rCun'e nunrbcnr for gmup A lirve bccn drvetop.d only for deaet shnrb. t I I I 1,.efCVl-TR-s5, Second Ed., June lS) /aace 4 t I I T I t I I I I t I I I I t I T I t TABLE 5 Plpe No. .L I (P) 2 ? 4 5 6 I 9 10 (P) P = Proposed Length (ft) 59 59 r65 49 48.5 r31 7L 83 4t .5 30 65 Dlaneter (1n) l5 18 l8 l8 18 18 24 24 24 24 18 Head (ft) 2.25 2.25 L7 .79 3.93 3.7 4 8.59 4. r8 2.65 3.70 2.4r 3.5 Q-.*(cfs) 7.5 9.0 11 .0 1l .0 L2.O 13.0 33.0 25.O 36 30 t2 Type CMP cuP CMP CMP CMP cuP cuP CMP CMP CMP cuP T I TABLE 5 PIPE DATA I I I I I t I I I I I APPENDTX I t I I I t I t I I L. Saa+lczuF I T t I I I I I t I I I I I I I I I I I Wor&rhcct 2: Brurotleurvr numbcr end nrnofi lroJrer Ltoru's Rtoe e !S-)g Dru? rcrclon lr/rar, c- C O ct*r. o-r@ D.e.log.d ,l 'l I t. I ..t t. lunof( cunrr ruobr r (Ct) ttoll oer end hydrolojlc group (egpcadtr A) Cotr s d.rcsl,pttoo (corri !ypr, cf.rt!.ac, :ad bydrologlc condlElor: Frc.a! tlp.retour; uraom.c!.d/co[o.c!.d l,lprnr!,out erer reclo) Prodct ot Cl r erre ,e,;1{! )-";- 'oorn: { g 7a Oah -r\iD2^ , .+- tr.1 ra .\ itr: -t - -nr'- .-ond,/roS <-t I ciert ! lq '/> or-. 3,'l.I (z/. Gr (rrrghrrd) - t::*p:"*e -t#. b/,( | ure clf r V/n 2. Runot! lnqurncy Setrtrlt, lllolt, Q(Ure ? oa .qr. ..aaaaaaaa.aa P (20tqrr) ........o.......r. |!d-Q{ rtBh rebk 2-lr ll3. 2-1,2-t rnd 2-{.) tr tr lc Stotr ll SBor! ,2 Ston 13 /oo ?.,4 o, t7 glSVt.TB.tq S.cood Ed- &ru. Uff) RUNOFF FOR INCHES OF RAINFALL I I I I I t T I I I I I I I I I I I I I I I 1{0TE: Runotf value determined by eguation q = (P-0'Z S)2 P+ 0.8 S REFEREI{CE: ilational Engineering Handbook, Section l, HYOROLOGY N 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 I 0.00 0.c0 0.01 0.02 0.03 c.04 0 .06 2 0.07 c. c9 0.L2 c. l4 0.1?c.20 o.2t 0.26 0.29 0. 33 3 0.37 0. 40 o.44 0.49 0.53 o.57 0.6 2 0.67 0. 71 0. 76 4 0. 8l c. 86 0.92 0.9?I.C2 i. 08 r.14 l. 19 I.25 1.3I 5 1.37 I .43 1.49 1.55 L.62 l. 68 L .14 l.8l I.87 1.94 6 2 .01 2 .07 2.l4 2.2L 2.28 2.35 2.42 2.49 2.56 2.63 7 2.70 2.78 2.85 2.92 3.0 0 3. 07 3.14 3.22 3.29 3. 3? 8 3.45 1.52 3.60 3.68 3.15 3. 83 3.91 3. 99 4.07 4.15 9 4.21 4.31 4.38 4.47 4.55 4.63 4.?l 4.79 4.87 4.95 10 5.03 5. L2 5.20 5.28 5.76 5.45 5.53 5.61 5.70 5.78 11 5.87 5.95 6.04 6.12 6.20 6.29 6.38 6.46 6.55 6.63 L2 6.72 6. 80 6.89 6.98 7.06 ?. 15 1 .24 7.12 ?.41 7. 5C 13 7.59 7.61 7.76 ?.89 7 .94 8. 03 8.11 8.20 8.29 8.38 l4 8 .47 8. 56 8.65 8. ?4 8.82 8.91 9.00 9.09 9 .18 9.27 15 9. 36 9.4 5 9. 14 9.63 9.t 2 9. 8l 9.90 9.99 lo.0€10.t8 16 LO.27 10.36 10.45 10.54 lo.6 3 10. ?2 10.81 10.90 11.00 I 1.09 t7 ll.l8 11.27 11. 36 I t.45 11.55 11.64 I I.73 I1.82 I 1.91 12.01 18 12.10 12. I9 12.28 12.38 L2.47 I 56 L2.65 T2.T5 L2.84 12.9t l9 13.03 13.12 I3.2t 13. 30 13.{0 13.49 13.58 13.68 13.77 13.86 20 I3. 96 14.05 14.15 14.24 14.33 I4.43 L4.52 14.61 14.71 14. 8C 4l tvfu!o I I I l' I I I I I I I I I I -@o.oo7 (nL)o'Ee' 'r - -116ffi'I-?2r Shrttos conccatreted flor -@10. Arenjc reloel.ry. 9 (t!,Srrc 3-l) ........... Cclt IU. lB .5EAT CorPutr 1. ...... nt I t, It( I I C6puc. v ....... Cclt ll' rtd 19)....... Sue-aA$t N t Worksheet 3: Time of concentration CIs) or b6vel time Cl1) IroJ.cr /rur't 2,o& a' 5-:\,,r%e ChecLrd Gtrch oar: Ptar.nt Dav.loPcd Glrch or: tc ta tbrouSh rsb.to ft!S: Sp.c. lor o leay r. ttto ..gmotr prr tlo ltpa crl bc urod tor och uortrhcrg. taclodr r rPr achGlaclc, or darcrigtloo o! flou reglcntr ' -@!$, (Appllcrble to t ooJ,y)Se3*at lD l. Sqrlecr dctcrtpBloo (.teblc 3-t) 2. Irul,q'r roughacr cocff., o (!.b1. 3-t) .. 3. Ifor bn3Gh' L (cotel L < 300 ft) ft f . lrlort? 2{-|rr rrlahll, P2 .. . ..... . t'! 5. Ltrd.lop.' | .. ttlia Coopqt. l! ...... br Segcnt ID 7. Sortecc d.rcrlpBlo! (Dtvrd or rnprved ) ..... 6. Elov l.otrh, L . lt 9. tlrtrtconrrc dope , I o r o o o r r e r r r . . . . . . . . . . . . frllt Ch.nn 1 flod S.gr.nt ID 12. Cron .cstlon l flotrt tsc.' I oooorrooroooore Cc2 13. U.t!.d p.rlr!.r. p, . .. .. .. . . . . !t tl. lydnullc rrdlu. t t'.i CotPut. ! ....o.. tGir 15. cb.!!.l rloge, r ............. ftlfc 16. . llrndaj'r rou3haer eocft., ! o oo oo r.. r o o r r r r?. y - t.tg r13 rtl2 l!. tlor Ls8th, L . tt Ilt. lr.ffiT Colput. tr ...... hr 20. llrtrrrhed ot rrb.s.r tc or tG (rdd ta ln rtrpr 6, el$VI-TR-sS, Sccond Ed, Jutt U[6) 'a D8 +l oCIo 6 o6L:toa, oIPa- .10 - .06 - .04 - | | | | | | | tt24610 Average veloclty, ftlsec FlOrt &1.-Avcnfc rclociticr for crtimrtin3 brval aitn! for rhdlor conc.trttrt d llo?. $2 (2fGVI.TR-55, Second Ed", June 1986) I I t I I I I I I I I I I I I I I I I I I /\ ?roJecr ( ro u's ?,t c-e- d{ /-Iaercton Vatc, CO ct rc lr oo. {-fcr e]]DDrvc lop rd l. Drcr: Dsrtnag. ar.. .......i.. \. Rumtl curvr nruber .... CX - Ttr of colcaolraBt oo .. ta . lelntall dktrtburlotr ttg. . Poad and sraop ar:ar rprted Ehroughout urccrrhad ....rr t Fraquency Bellfall, P (2i-hour) Intctal ebo!,racgl,oo, Ir .......... (Ucc ql tdEh r.b1e 4-l;) CoEFrr. Ia/p ........ 5qg^Wrlr tr Checkrd Drtr Drco d2 (rcrcr/640) (Pro norkghccc 2) hr (Froc sorkshccc 3) (I, tA, II, TIt) p.!c!o! of rn (- acr.! or ol2 covcred) SBoE! rl scoro 9z Scor f3 /0 0 2,4 !a yr tn l,zt t 1 .<? , t7 | 4- a-a I I I , i II 2. 3. 5. 8. 9. 6. 0otc pcrk dtrchargc, q,' ..........e..... . cu/to' (Urc Tc aad lalp ntBh &trf,Utc t-21 3 lol 7. Ruaof!, a ..,........ (Fror rorkshccc 2). Pood aod rre4 adJwtoclE lactor, F- ....(Urc pcrccne pond and Jr.op arre . P rtBh trb1. 4-2. Facgor k 1.0 tor zaro. pcrcanB pond and t-renp erca.) Plek dtscherg.r qp . . . . . . . . . . . . . . . . . . . . . . .clr (tlhcr q, - quArq?p) PrGvf.TR.C5, S€cond Ed., Juac ts6) /,0 Workshcct 4: Graphical Pesk DischarSc method ryD"b 'oL -rE- , zc4 ---lv l, -l I. i I Chapter 4: Graphical Peak Discharge method this chapter preserts the Graphical Peak Discharge met}od for computing pedr discharge from rural and urten areas. The Graphical method was developed fton hydrograph analyses using TR.@ "Computer Pmgram for hoject Forzlrlation -HydrologT" (SCS 1988). tte perk discharge equation used is Qp = guAmQFp tEq. a'11 - Freak discharge (cfs); - unit peak discharg€ (csm/in); - drainsge area (mi4; = runoff (in); and =.pond and swamp adjustment factor. The input requir€ments for the Graphical method are . gs follows: (1) Tc 6r), (2) drainage area (mi4, 6) sppropdate rainfall distribution (I, lA, II, or III), (4) 2,|-hour rainfall 0n), and (5) CN. If pond and swamp :reas ane sprad tluoughout the watershed and are not considered in the T" computation, an adjustment for pond and swamp areas is also needed. Peak dischargp computation Fore seleeted rainfall frequency, the 24hour rainfdl (P) is obtained &om appendix B or more detailed local precipitation maps. CN and total runoff (Q) for tlle watenhed are computed according to the metlods outlined in chapter 2. The CN is used to determine the initial abstraction 0J &om t:ble 4.1. I.lP is then computed. il the computed IrlP ratio is outside the nnge showrr h exhibit 4 (eI,4tA, &II, and 4-IID for rhe rainfdl distribution of inter"est, t}en the limiting value sborild be used. If the ratio falls between the limiting values, use linear intcrpolation. Figure 4l illustrates tlte sensitivity of IrlP to CN and P. Peek discharge per rquere mile per inch of nrnofi (qJ is obained from exhibit &I, t-IA, &II, or &IIl by using Tc (chapter 3), rainfall distribution tlpe, and I./P ntio. Ttre pond and swamp adjustment factor is obtained from table 4.2 (rounded to the nearest tabte vdue). Use worksheet 4 in eppendix D to aid in computing the peak discharge using the Gnphicd Dethod T I I I T I I I I I I where Cp 9u Ar! e Fp rttrtutt ll.t ll (tt. t..Lr Flfurc &1.-Varirtion of I.1P for P ond C'!{. Ir 0n) Ir 0n) Cunre number I I I I I I i I 40 4la 43 tt4 45 46 47 4E 49 50 5t 52 53 54 55 66 57 58 59 60 6l 68 63 6{ L' 66tl 6E @ (2ICVI-TR-55, Second Ed., Jurc 1986) 3.000 2Ar8 L7@ 2.651 25{5z& 2.W 2255 Lr61 LW 2.000 1gD t.846Lnl I.?TN 1.636 15?r 1509 1.4rl8 1390 L:rts r.gEt% t.r?t r.1!5 Ltn t.0g) 0.985 0.9{l 0499 0.857 0.E17 0.n8 0.7{0 0.?08 0.66',t 0.dp 0.597 0.564 0.582 0.500 0.{69 0.4it9 0.{10 038r 0.353 0346 0299 0n3 0247 0.92 0.198 0.1?4 0.151 0.128 0.105 0,083 0.062 0.oil 70 ?l 72 78 74 76 76 at 78 79 80 8l & E3 84 85 E6 87 88 89 90 9l 92 $t 94 95 96n 98 Tablc &1.-I. valucs for nrnoff curve numbcrs +l It I I I' t .,1.*-.,,_. -..,..: €86I aunf "Pg Puoc€ 's9'uI-lA-0Iz) Unit peak discharge (Qg), csm/in coctooooootJ'r olo<) I I (-, 5 (tl orE - 9 P3CQ-r" x 5 (D &o rt oa .D Frla ca E(' r.l t9 a D E O :l I c 5 Oi @ =(D 0 {l 'oo =oo =.' .e'r} oJ o st81\o-: aDurl I T I I I, I T I I I I I I P I -- or- 0g- E- Lrory'S ?>Oa oS rl ,i I I I : I T I I I I t I I I t I t ;t t I I T I t I Fo*rhcct e nurroll currG nrmrbcr rnd nuroll Sap^$Asta{ / o.c. {- ?-?o D.g. ,,DAEoJ.cc Loc.lton Clrch oar: Ptrrcs l. lsnot? €urnr lllLr (ctr) liotl aec rod $rologie tlouP (egpcndtr A) Cor.s d.rcstpctoa (corrr B7pr, !ru!lrl!, tad Itdrolo8lc cotdirlo!; FAc.ot tlp.avtour; rconaccrd./ cooctcBrd lry.tv1orr!erq reclo) Producg ot Cl r rme 3u, tJ'^'7 s I tL) 6oct Lt' : , r, I l/1s-s- {cL = r L-A J.'^r : th,tla Lq < 6O1, - /*5 PQn - ttouhfa )" t -l t Ilo rus l, - Co,- <c"J,,1.'i^ 'fu,,, o"-. s, /e: ( -,1 /r/ Urc orly or C! ronrcr p.r lt!..tocelr r t..:2 V G! (rrr8hrrd) . ffi$ .@3-. 6?.1 _ or d[ .lr.. /0 /@ 2. Runo!! 6CVl-:t8.54 Sccond Ed-.fur. lS) Ston ll Scotl 12 Scon ft /o 0 2, cl d.z I :.:T I I I I t I I I t I I I I I I I t t I I I CURVE 63 RUNOFF FOR INCHES OF RAINFALL ll0TE: Runotl nlue determined by equation q = (P-0'2 S)2 P+ 0.8 S REFERETICE: l{atimal.Engineering Handbook, Sectim f, HYDROL0GY N 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 1 0.00 0.00 0.01 0.02 0.0 3 0.04 c.0 6 0.08 2 0.10 0. l3 0.15 o. r8a 0.2 r 0,24 o.2e 0.3 I 0.3 5 0. 39 3 0 .43 0.48 0.52 0.57 0.cl 0. 66 0 .71 0.76 0.8 I 0. 86 4 0.92 0.9?1.03 l. c9 1.I4 l. 20 L.26 L.32 1.38 I .45 5 I .51 L.57 1.64 l. 70 1.77 i. 84 1.90 1.97 2.04 2.ll 6 2.18 2.25 2.32 z. )9 2.C 6 2.53 2.6L 2.68 2.7 5 2.82 7 2. e0 2.98 3. o5 3.l3 3.20 3.28 3 .36 3.44 3.51 3.59 8 3.67 3.r5 3.83 3. 9l 3.99 4.O1 4.L5 4.23 4.31 4. 39 9 4.47 4.55 4.64 4.72 4.8 0 ll.88 4.91 5.0 5 5.I3 ,.22 t0 5.30 5. 38 5.47 5.55 5.C4 5.72 5.81 5.89 5.98 6.07 11 6.15 6.24 6.32 6.41 6.5 0 6. 58 6.67 6.7 6 6.84 6.93 L2 1.O2 7.lt 7 .20 7 .28 7 .37 7 .46 7 .55 7.64 7.7t 7.81 l3 7.90 7.9 9 8.08 8.17 8.26 8. 35 8.44 8.53 e.6 2 8.71 T4 I .80 8. 89 8.98 9.07 9. l6 9.25 9 .34 9.43 9.52 9.61 15 9.71 9. 80 89 9.98 lc.c7 10. 15 10.25 10.35 10.44 10.53 16 10.62 10.71 10.80 10.99 Ll.08 ll.l7 r 1.2?11.36 1r.45 t7 11.54 I 1.64 11. 73 11. 82 11.92 12.01 12.10 12. l9 L2.29 12. 38 18 L2.47 L2.57 12.66 L2.75 12.85 12.94 13.04 13.13 L?.22 Lt.32 19 13.41 13. 50 l.3. 60 I 2 69 13.79 I3. 88 13.97 14.0?14.16 14. 26 20 t4.35 14.45 L4.14 14.63 14.77 L4.62 14.92 15.0I l5.lt 15.20 43 S"e - B,rs tp Z Worksheet 3: Time of concentration CI") or travel time (T1) J-_ !ro5.c! Lr c zv s /<1 o G ei .--S I It, I I t I I I t li I I I I I t, I l( I t |+ Iu' r. '53ftn Ghrnncl flos Capu!. f....... U S.tnnr ID Caput_. v ....... Cclt ,O&D.t. Drt. y'-?-qa t-t c.rloa l /et <^ C O drrckrd Gtrclr oor: ?rcrrat Clrek or: lc ?a throu8h rab.nr FttiS: Sprcr lor rr !.!t ar Rlo aaSnntr 9ar lloe ttP. ctd be urad for uch rcrkrharg. taeludr r up, tebrorclcr c daactlptloo ol flor raglcncr. Shrct !1ou (Appllcrblr to T. ooly)Sr3rcac ID l. Surtrcr dcrcrlptton (rrbla 3,.l) 2. tirnnlag'r roughacsr corft., a (erbtr 3-l) .. !. llos l.ngth, L (rotrl LSX0 ft) .......... ft a. nro-tr 2A-hr nhfell, 12......... t! 5. Lnd rlop., r .. Itltz6't,'tr#Coc?ut. tt ...... bt Shrlloc conceatretcd floo Scgccnt ID 7. Surtrcc d.!cs1pB1oo (prvrd or roprrrd) ..... 8. filor lea8th, L ............ !r 9. llrlcc,ogrrc lLoge, a ........................ ttlll t0. lvetrgc r.loclty. Y (!lnm 3-t) ........... tc-lt 12. Grou arctlonal flor rnr, l ....i.......... fe2 l!. tfetred p.rh.!rr, pj .......r... !r lf. EydreuLic rrdtur, s'--! Ccputr a oo..... la lt. cbrml rlopc, r .....1:.................... ftlfc t6. - ltraolaj'r torghnerr corlf., o l?. y - l.'9 r2lt rll2 ! -@ .@ al!. llos hajrh. L . lt tlt. lG - 56frT cquc. lG ...... hr 2O. Irtrrrbed or rrbetc tc o! 13 (rdd ta ll .3.p. 6' ll' od 19) ....... tr 0lloVI-TR{6, S.cotd Ed.' JUP r$5)D8 {J +, o CLo 6 ot!Ltor,go.P.!- I I I t l, t I I I I I ,l .10 : .06 - .04 - .02 -t I I I t I I t I I | | | | | | | | tlt?4610 Average veloclty, ftlsec Flturr &'1.-.{vcnf vclociucr fo? ..tintrtin3 lnvcl tirnc for rhrllor concqtttibd nor. €fOVI-TR-55, Second Ed.. June 1986) I | | | tl Workshcct 4: Graphicat Pesk Dbchars€ rnethod ,l!!o1.c! Lro a/ S l(r u G e- A S 1c- Co Frequancy l:tof:lI, P (2{-hour) Iltclrl ebrcracBtor, It ................. (Urq Gt rrth hbl. 4-t:) Corpucc l./p ........ vWe Chrckrd 5ue'gAs/rv T I i tt t! ,/7t! 2. 3. 6. 5. 7. t. \ D{ I I I I t I I I I I I I I I I I I I I I I 6. golr pcek dlschergr (rhr r" aad r./p ,"htjiiii';8j"" '.".dla t. D.B.: Dntnrgr .r.l ....... jo. { . , OZ d2 (rcro/640) loaof! curvr orrlbc .... d - 63 (trl trortrhoc 2) ttrr of concrcGrtcloo .. ta . , Z 7 hr (lrot rrortrhtr r 3) klatell dtrrrlbuElor Eyp. - -f- (I, tA, II, lll) Pood asd sneop araer rnrudrhroughout rnlrrrhrd .:.... . € p.!c.o! of \ (- rcr.! or nl2 covcrcd) PcaL dtrchergar {O . . . . . . . . . . . . . . . . . . . . .. .clr (t|hrrr q, - qrAnQFr) Scor-d ,l Scon f2 StoEE 13 /ou 2.4 o.+7 szol ^l,zl t,3( Burof!, q.......... (9roo mrkshrcr 2). Pood eod reog edJuruclB feetor, p_ . . ..(Orc pcrcrar pord .nd *-p .r""- .P rtch tebla 4-2. F.cEo! ir 1.0 for aaro. parcrnt poad aod rnup trca.) e[OVl.tRJq Srcod Ed.,Jq r$O Chapter 4: Graphical Peak Discharge method this chapter pes€nts the Graphical Peak Discharg€ mthod for computing peak discharge from nral and urbsn ereas. lhe Gnphicai method was developed from hydrograph anelyses using TR.20, ',Computer Progran for hoject Formulatior-Ilydrology" (SCS l!Hl). lbe peak discharge equation used is q, - q{nQFp lgq' ell - peak discharge (ds); - unit peak discharge (csrn/in); = drainage area (miz); - nlroff (in); and = pond and swamp adustment faclor. lbe hput requirements for the Graphical met}od are . er follows: (1) Tc Gr), (2) drainage area (mi4, €) epropriete rainfall distribution (I, lA, II, or lll), (,1) %-to,rr rahfdl 0n), and (5) CN. U pond and swamp aelul ane spread throughout the watershed and are aot coruidered in the Tc computation, an adustmant6r pond and swamp areas is dso needed. Peah discharge computation For e selected ninfdl frequency, the 2rt-hour rainfall(l) is obtained iom appendix B or more detailed bcel precipitation megs. CN and total nnrofi (Q) fon tie rpetershed are aomputed according to the netlods outlined in cbapter 2. The CN is used to &terraine &e initial abstnction 0J from table &1.IjP is t}en computed" if the computed l"tr ratio is outside tlle range showr h exhibit 4 ({.I, +IA, &II, and 4-III) for the rainfell dirtribution of interest, then tlre limiting value lhordd be used. If the ratio fdts between the linitirg velueq use linear interpolation. Figure 41 illustrat€g tle sensitivity of I./P to CN and p. Pertc dischzrge per squere mile per inch of nlrotr (qd ir obtained ftom exhibit 4.I, &IA, 4lI, or &lll lf_uOtE T. (chapter 3), rainfall disrribution type, rnd l./P ntio. The pond and sramp adjustment f".to. i. obtained from table 4.2 (rcunded to the nearest table vduel Us€ worksheet 4 in appendix D to aid in cotputing the pedr dilch$ge using the Grephiol aethod l, I t I I I I It. t. I I I rbere qp Qu AE Q Fp I. 0D) Cune number I. 0n) I I I I lttrtuD Lt.t ll (t l. l.Or.a FlFr. 4.1.-Vrrirtton of I.1P for P and €T{. I I ii I I 40 41 42 43# 15 46 lil {8 ,19 50 5l *, 59 64 oo 66 TI 58 50 60 6l 62 GS 64 66 66 at 68 @ @IOVI-TR-SS, Second E&, June 1986) &000 28'8, L7e e65r ?-845 2.44 L 22-55 L16l L@, e0(x) t.szz I.8{5 \n4 1.704 LA6 1.5?l t.500 1.148 l.&n l.&ts tztg t,26 l.l?5 1.125\gn 1.080 0.985 0.9{l 0399 0a57 0au 0.7?8 0.7{0 o.?tB 0.6dt 0.632 0.59t 0.564 05@ 0500 0.{@ 0.4tl9 0.410 038r 035it 0326 0290 0g13 02A7 0.u, 0.1$ 0.1?{ 0.tst 0.128 0.105 0.083 0.0@ 0.0il 70 7tn 73 ?4 75 76n 78 ?9 80 8l u, 83 8l 85 86 s7 88 89 90 9l 92 s! 9{ 95 96n 98 Tablc {-1.-I. valucr for runofr cun'e numbcrr &l I I I t l' I T t I I l, I t I I T I t I P I (tr otoo (986I eunf '?g Puor€'t9-uJ,'lA{Ia Unit peak discharge (9u), csm/in E H 3', e gg 9? @oooc)o trtx 5 E ('D ?h(t Fl Gl(D €c eia a 5 {tr = E. o{ c 3o o '..loto .D5 a+.' -c, 0: o rt\o: rltt r Gh- oo- b- a Worlshcct 2: Runofr curvc numbcr and runofr ?roJrct /ta+s Q'cor *3 Jt_-rre Locetton l1z'r, C O Chrckcd D.t. /=----Ctrcl. on : E!!SS-' Drvrlopod t. Runolt curvr rlrbc ( Clf) 4.e at>F Soll lrr rod hydrologlc trollP (epprodtr A) Cov.! d.rctlpctor (covrt Bypt, Erctclra!, ud hydrologlc condlrlon;p.rc.ol loprtvtour; unconnrccrd/cooo.clrd tcpcrvlous.r.r rrtlo) Product ol Clf r erre -n't2t,-n '; Y-tc <- 1.., -r._ -1= ?.C-.\i9eF- 2J. t),.. - t t- ).J,'rL" -"c .: ', /F ' (r la Qo'c - ,\3 pP^ ^ 4a:) /4 -) '^ [:rt-''. -- !^o:. c4rct,/ro'^ Urc only oac G{ rourct pcr ll,ac.Tocals . I T T I T I I I I I I I I I I I I t I I I cr (r.rshr.d) .Irorg:I# .'!r7=, 2. Runotf Frrqurncy 8e1n!:11, P (26-hour) &rnotf, a ...........(Ur P ead CU rl, rh ceblr 2-lr !tg. 2-1,or .qt. 2-3 rud 2-4.) 62.) t U& Clf - tr h ta -tzl Scom 11 Scom 12 Stoo 13 /d, /. /-1 'r 1 .'l ,''4 e D2 €fGVt-TR65, Second Ed., Juno 1986) rJ 'J t I I I I I I I I I t I I t I I I RUNOFF FOR INCHES OF RAINFALL _ ( P-0.2 S)2 P+ 0.8 S Section {, HYDR0L0GY L- I _ll0TE: Runoff value deternined by equation Q lrrr*rnar, larimat Engineering Handbok, T I i J-tr J qr r'r d,tr ) Tr r; I N 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 I 0. 00 c.0t \0,.02 l: o.o:0.0 5 0.07 2 0.09 0.ll 0. l3 0. l6 1 0.le ', 0.22 0.25 0.2e o.12 0. 36 3 0.40 0.44 0.48 52 0.57 c.62 0.66 0. 7l 0.76 0.8t 4 0.86 0.92 0.97 l. 03 l.c8 i. t4 !.(U L.26 L.12 1.38 5 L.44 1.50 l. 56 1.63 1.69 l. 76 1..82 l.8e l.e5 2.,.)2 6 2 .09 2.l6 2.21 2.30 2. )7 2.44 2.rL 2.58 2.65 2-71 7 2"80 2.8-l 2.95 3. 02 3.tc 3.l?3.2t 3.33 3 .40 3. 48 8 3.56 3.63 3.7L 3.79 3.8 7 3. 95 4.0 3 4.lt 4.19 4.27 9 4.15 4.47 4. 5l 4.59 4 .67 4.75 4.8 3 4.92 5.00 5.08l05.17 5.25 5.11 5.42 5.50 5. 58 ,.67 5.7 5 5.84 5 -92 11 6.01 6.09 6.18 6.26 6 .35 6.43 6.52 6.61 6.69 6. 78 L2 6.87 6.95 7. 04 7.l3 t.22 7.30 7 .39 7.48 1.57 ?.65t37.74 7.83 7.92 8.01 8.IO 8.19 8.27 8.36 8.45 8 - 54l4E.63 8.72 8.8t 8.90 8.99 9.08 9. 1?9.26 9.35 9.44 15 9.5 3 9. 62 9.7l 9. 80 9.89 9. 99 10.08 10.17 10.26 10.35 16 10.44 10.53 1,0.62 10. 72 10.81 10.90 10.99 11.08 ll.t8 r1.27 T7 11 .36 I1.45 11. 54 I1.64 11.73 11.82 lt.9l 12.0 r 12. 10 12.19 18 t9 L2.28 12. 38 L2.47 12. 56 12.66 L2.75 L2.84 L2.94 13.03 l3.li? L3.22 13.31 13.40 13. 50 13.59 13.68 13.78 13.87 13.97 14.06 20 14.15 L4.25 L4.14 t4.43 I4.53 14.62 14.t 2 14.81 l4.el 15. o0 42 ll I I I t I I I I .-r':.,!'.j'rir,.:.+i. -tt - ; ,Worbhcct 3: Timc of conccntratlon Oc) or b?vel ttme Og) tro3.sr L-'t.:'): . a:t:'L-j ,r>"ILr. 2 '1'? ) LcrG!,oo '/^'- ''\Cb.cl.d DrB. Ctrclr oar: .!:::!t Drrrlosed Qltclr or: ta ta chrouSh ruber.| Fl!S: Spcr tor u rray .r GJo a.trctr 9er llor ctp. crl bt utrd tor reeh sor'Lb..t. lacludr . [p, acb.o.rlc, or {..crltclot of llou ..t!.tlta. Sbert llan (AplUcrblr co t oaly) l. Surfrcr d.rcrlptlo! (grbtr 3-t) 2. llraolcj'r rou3hlcrt coc!f., ! (!.b1. 3-l) .. 3. nog brgrh, L (86!.t L < 300 tE) .......... a. $ro-t! 24-trr rrl.afrll, P2 ......... ls 5. trsd dopc, r .. CtlCc Scarot tD fB t I I I t I ,li- ti I I I :l . .r - o.oo7 (nL)o'E'B--irEt- '2' thrtloe cotcestrrt.d flo? -@ t0. Arrrr3c rcloc1ct, V (fl3ure 3-l) ..........r ltlt tll. r. .55ftn c{Frr. Ir, ...... * C.cpnt lt ...... bt Setrlt lD ?. Sudrcl dorcriptloo (prvrd or rnprvrd) .. ... t. Etdr LqtEh, L . tt 9. lhtrrcoonr llopc, I oo o r r o o r r o e o. .. . .. .. .. . ttltt €hranrl flan Scjrnt lD 12. Grorr a.ctlou:, flo etrr, I orrrrorrrororoo lc2 ll. Irted p.rlr!.a, pa ..1........ l! lf. Eydrrultc redtur, 3'.! Ciprr. !....... !t fl l!. tulnrl .lop., . ............. ltllt 16. .ltroaia3'r rou3hoor cort!., o tr. y - l.a9 t2lt .llz ! It. nor hrttb, L . lt lt. ts.# 20. Irtrrrhed or lubrr.. lG oE lG (.ad tB ta .t.p. 6, -@ i I I,t I Cflput. I ....... Cclt Caps3. 13 ...... ht il f€o .t4 b,D ,o4 l" elGVl.ll{5. S.cod Ed.'&n tg8d) .E Dt l'F- ' .10 - .06 - .04 - (u CLo ,n o6g:o(,t-at.t, a!- I t I I l' I I I I I I 'l ,l I I I I I I I I | | | | | tl24510 Average veloclty, ftlsec Fl1ur: $I.-.lvrrar v.bcitl.. lor crtlmrtlnj tnvcl tirnr for rhdlor concrntntcd llor. (21CVI-TR-i5, Second Eil, June 1986) IatBlal abats.cBlor, Ir ,,.......(Urc Gt ntBh cabl. 6-l;) Corpurc Ialp ........ 6. Untc Acak dkcherge, q,. . . . . . . . . . . . . . , . . . . ctq/ir(Urc t aad I./p ntBh :xhlblB LL 3).21 ? 2. 3. 0. I I I I I t I I I I T I I I PrlJ.cG Ltoars Qtoae 4? r"7- Iacrlton l/f "- C O /--._---.--Clrclr oart E:!:ac__Drvclopcd l. Drta: Dnlnegc arre ....... i.. \ &roolf curvr nrlbe r . . .. Cl flr o! co0c.olr.Eloo .. t blnlall dl.trtbosloo Irp. tood aad stnop errer rgrred Ehroughout rnCcrrhrd ...... --3.i a c. , o3a d2 (rcrrc/640) 62 (?ro gorkrhrct 2) ta a ra ra - Praqucncy Retnfall, trL'bor'n I-7Tl.-l : Workslrcct 4: Graphical Pcsk lXlclrar3c mcthod Chrckrd Drc. D.Ga 2-6^? br (Pror rorkrhrcc (1, ra, lr, ur) parc.oc of A. (_ ectcr or d2 covcrcd) 7. Ruoo!!, a ..........(froc rorkshccc 2). E. Pood aod sweop edJurtlcot facGor, l_ ....(Urc pcrcaor goud aad llrnrp ar.a . P vlch cablc 4-2. p.ccor tr 1.0 lor rcto. parccot good and rranp arca. ) 9. Pcek, dbcharg.r qD . . . . . . . . . . . . . . . . . . . . . . (I{hcrc {, - SotQPp) P (2i-hour) Stotr ll slotu tZ Sco6 ,3 /0 /c, /,6 Z, tt t! tr 1[ /. zz;1 J 2>6 ltt t- o. 50 o o | ?oo' O,oZlO.t1 o.zz - ll' cfr I I t I I I I i : 'l BIGVI.TB-56, Second Ed., Jur lS6)D' Chapter 4: Graphical Peak Discharge method This drapter prcsents the Gnphical Peak Discharge method for computing pe* discharge from nual and urben erees, lhe Grzphical nretiod uras developed &om hydrogrzph andyses using TR.20, ,,Computer Program for hoject Fomurlation-Ilydrologr" (SCS f98). Ite peak dbdnrge equation used is qe - qnA6QFp 6gq. a-U where gp = pealc disclurge (ds} 9u = uit peak dgcharge (csnr/in); An - drainage area (m!z; Q - rurof (in) andF, = pond urd swarnp eqiustment factor, The bput requirunents for tlre Graphical metlrod ar= as followr: (l) T. (hrL (2) dni!8ge aree (Dd4, 6) epprcpriate rainhll distribution ([, IA, II, or JII), (4) Z*horrr rainfall 0n), end (5) CN. If pond and swamp eners are spread tluoughout t}e watershed and are not considered in the T" computation, an adustment for pond and suranrp areas is also needed. Peah discharge computation For e selected ninfall frequency, the 26hour rainfall (P) is obtained 6om appendix B or morc detailed local precipitation nr+s. CN urd toal runotr (Q) for the rraterched are computed according to the metlo& outlined in chepter 2 Ttre CN is used to detcmine the initial abstnction (IJ ftorn table 4-1. I.lP is then comput€d. if the computed Ir/P ratio is ouGide tlre range shown in exhibit 4 (&I, 4LA,,4II, rnd &III) for tlre ninfdl distribution of intercst" th€n ttre lirniting value should be us€d. tf tlle rztio falls between the limiting vdues, use line;r interpolation. Figur€ 4l illustra,t€s the sensitivity of IrlP ro CN end p. Ped< discherg€ per squane mile per inch of runofr(qj ir obtained from exhibit {-1, 4-lA, &II, or {.III -bV *ing Tc (chepter 3), rrinfrll distribution t1ae, end I"/P ntio. Ilre pond end swemp rCj$tm€nt fector is obteined from table 4-2 (rotrnded to the neerest ttble vdue). Uc€ rorltshe€t 4 h appendix D to eid in computing the peak diEcharge using the Graphicd method rtttu Ll.t ll (tl. lr|.t Flruc &1.-Verirtion of I./P for P end C!l. Cunre number Trblc &1.-1. valucr for runofi cuve numben Ir 6n) &000 2Ar8 t0 |l & t3u a5 {6 z7@ z65l 2.WLU 23,,81? 2.%548 Ll6l,19 LWt0 e00o5l tgn 70 ?l 72 78 7r ,o 76n ?8 ?9 60 8t &2 83 8{ 8rt 86 87 8{3 89 90 9t v2 gil 9{ 95 96 97 98 Ltn l.(tso 0385 094r 0J99 65 66tI 68 60 I I I I I I I 52 1.8{6 .5il Ln16{ r.?(x55 r.61656 t.trtr57 1.50958 l.{4850 139060 r3fr|6l tg's .Jc.i*FLdfl'!Fl63 t.t756{ LYJ5 l'(2!OVI-TR-55, Second Ed., June 1986) Ir 0n) 0.E5? 0-8t? 0.7t8 0.?{t 0.?ts 0.667 0.63e 0.597 056{ 0.532 05m 0.{@ 0.439 0.{10 0381 035i1 0346 0290 0n3 02a70w 0.t98 0.t?{ 0.151 0.t2E 0.r05 0.o83 0.0@ 0.(Xr It€86I aunf r?g Puores'91'uJ,'l^{tz) Unit peak discharge (Qu), csm/in I I I I Ii I I I I I I I I I ,'l I I I @ooooot\)oo arS('tchI I8tlJr otoo Ex 5I tt(D a &(t !!-l GI(! 4tB F :l cnou .D -l 19 =F g a 0 5 oo- lrl r 3o o 'ooto,|D t.'.t ot o 96\t\o..|.| 5- c- 0o- E. tr tn t! I I t I I I I I I I I I i I I I I I I t I ' Workrhcct 2: Runof curtc numhr snd runoff ?ro3.cB /"lor^ts ?rOe * a3 ,r%. r.c.rlon 14rC Co Ctrclr oar: Prrseac .-*@\__ t. &Uott cuwr ruobrr (dl) Sao-bosin V (Pev) D.t. I I I ..i I cil (rntghcrd) .4-Foducg -/1oi - 1/,4 ug clf -BoE.l .r.. Z.j , ? -t w 2. Runof! Fs.qu.ocy Retnlall, Runott, Q(Urr P or aqr. P (2{-trqrr) .rd C{ etBh c:llo 2-1, !18. 2-1,2-! erd 2-1.) 3o11 nec aad hydrolo3lc 8tou9 (eppcnd!,r A) Covrr drrcrlgtloa ( covrr typr, craacsaaE, a[d hydrologlc condtrloo; t).tc.n! tap.retour; rroconarcced/connrcard bprrvtouserlr reclo) cn -ll A!aa E acErrtrulor Ptoduct oCGlrtne(l I a IeF IF. c b I a\a d b Te rton-A ot^'S (2)r".o"'.: (oL/c i'utc. t'i^ Do. i- - l: c?- - .2l46ya!'a'a.a a.,...': 1 - ..-r'/' a C'-..t 1'e/-b 5. 1 €t! J er.-t ;/n' li.; 'i<e./tcz.: f q7, ; 0.t''o--t.',, ,t a- : - 2 6.t 4+ Ll tlr1i4'/'?:E(B) Ve'?') L) ' z4qar tt (+)( (3/8e) 132i)b"-\ ,4.1 ; t-,. : ZBr4 qB /,4 /37 ftu';1 Te,ra <e s '7 tr'ti; : /8 c o 11 Y 37J.=4239 78 /o oPe4 sqa ce | 6 ,- r'--r;':T,.': lf.l /-ov.t n5, p":it:. {i- 5,'- <:-?.-'j^:))') J! Urc only 6. c[ rourc. p.r lha.totalt -z3.q t ?0'7 Scoro ll Scotl f2 Scon 13 /a /Do /,6 z,/ o, t3 D. 44 8rCVI-TR{A S.cond 84, Junc 1986) I I I I T I I I I I I I I I I I I I I Itl I t: I I I I t, I CURVE 71 I I RUNOFF FOR INCHES OF RAINFALL 1{0TE: Runofl value determined by equation q = ( i-O'z S)2 0 P+ 0.8 S REFERET{CE: llational Engineering Handbook, Section l, HYDROLOGY N 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 0.00 I 0.01 c.02 c. 03 05 0.0?o.l0 \0.13 o.l6 0.19 o.23 2 o.27 c.3t 35 0.40 rJ.44 ) o.+s 0.54 0 ;60 0.65 0.7c 3 0.76 c.82 0.88 0.94 I .00 1.07 1.ll t. I9 1.26 't 2? 4 I .40 1.46 I <2 I. 60 i AQ l. 75 1.82 1.89 1.97 2.04 5 2.12 2. t9 2. 27 2.35 2.43 2.50 ?.52 2.66 2.7 4 2.82 6 2 .90 2. 98 3. 06 3.14 3.21 l.3t 3.1?) .47 3.56 3.64 7 ).71 3.8t 3. 89 3.98 4. 06 4. L5 4.24 4.12 4.41 4.50 8 4.58 4 .67 4.76 4.84 4.93 5. 02 5.I I 5.20 5.28 ,.37 9 5.46 55 5. 64 5.7 ?,.82 5.91 6 .00 6;09 6. l8 6.27 10 6.36 6.45 6.54 6.6 ]6.7 2 6. 8t 6.90 7.00 ?.0 9 7.18 11 7 .27 7 .76 7 .45 7.55 't .64 'l 73 7 .e2 7.92 I .01 8. l0 I2 8.I9 8.29 8.38 8.4?8.5 7 8. 66 8.75 8.85 8.94 9. 0, 13 9. l3 t. tt 9.50 9. 60 9.69 9.79 9 .88 9.97 14 10.07 10. l6 LLI r ZO 1C.35 10.4 5 LC.54 IO.64 10.73 10.83 10. 92 15 1I.02 ll.ll ll 2L 11. 30 II 4\)i.:..49 ll.5e 11.6e lt.?8 11. 87 16 11.97 I2.06 12.I6 t2.25 12.3)12.45 L2.54 L2.64 t2.71 t2. 8t t7 L2.93 13.02 I3. l.2 13.21 lt.3l t 3.41 13 5C I 3.6C I 3.69 13.79 18 13.89 13. 98 14. 08 14.18 14 .27 i rt. 3?L4.41 14.56 I4.66 14. 76 19 I4 I5 I4. 95 15. O5 15. t4 L5 .24 1r.34 15.q3 I R E2 15.63 15.7? 20 15082 15.92 I6.01 l6.ll I6.2I 16. 30 1.6.4{J 16.50 16.60 16.69 L- 5t ll I I I I I I I t0. Ante3e ecloclct, Y (flfirc 3-l) ........... ttlt Itl. r. .53ftn c{put. I. ...... b I T I I I I I I l- I I S.lrat ID l. Surlrcr d!.cslptloa ('rrblc !-l) 2. llrnnla3'r roughlcr cocff., I (ttbk 3-f) .. t. Ilo l,cr€th, L (r6hl LS300 ft) .......... t3 a. lrc-tt 24{rr rrlalrtl, P2 ......... h t. r'.d .top., r .. l.al tr Cdput. lg ...... hs Shrllor coaccntrrtcd floe Secsc ID ?. Surfrcc dcrcrtpcloo (prvad or uoprvrd ) ..... E. Elor l.otBhr L ............ lt 9. lletrrcourra .Iop., r ....................... t!/lt Chrnncl flog S:3rnt lD 12. G:orr rcctt,onrl flor rnr, I o.rreeoroorro.r Cc2 t3. t S!.d gcrtrrrr, p, ........... tt tl. lydrrult c ndlur, ;'.! Ccprtr r o...... ttr! 15. Ghron:l .lop., r ............. ttlft 15. .liraola3'r sou8h.... eoeff., o roroooorrrrorr rr. r. l.$ tzli .ll2 ! tt. tlor Lrtth, I . tt 6. r..tr#F lt.:8.# -ta t ts^c r^l\ u d t€O goo d.0s-0,t0 s,b s,z .o tl+1 ,o4 -l .;l Co.pu3. V ....... CalJ Caguc. ?t...... hr T I I 20. Irtereh.d ot rubrnr tc or tr (rdd la lD .t.p. 6' ll, ..d lr) ....... tr PIGVI-!B{5, S.cond E.t, Jun 1985) '-l}.,€qb^ao:/4 T (?ta; Worksheet 3: Time of concentration (Tc) or travel time O1) lsoj.ct .t -t G-Ltont;1tOGF'3 Drcr z- c'-? d Chcct rd DrSa Glrck oar: Prt..nG Clrclr or: lc Ta chrouth rnbrrlr ItrlzS 3 Sprcr tor .r rrot ra lco a.tmatr prr f1o BtP. cr! le urcd f or och rorhrh.ag. tacludr r ap, lcbrortlc, or d.rcrlplloa of flor rrtanB.. Sheet llos (Appltcrblr co T. ooly)+-B !:.. t at) /,).2 L/ 3 00 niQ ,2.51+ -H Dt I $ !,CIo t o6L5o Eo+,s ',1,l I Average veloclty, ftlsec Flnrrr &l'-'{vcrat. vclocltlcr for 6timrtln3 tnv.l t'nc for rhrltor conertnt d ltor. 45 g2 (2IOVI-TR"tO, Second Ed., June l9g{l) I I I I I I I I I I I I I T I I I I t I I t crtton (o r a Co ctrclr onc: prcsrnr @D Dnlnagc rrlt .......... \ ., 0 3 7 d,2 (rcrcr/640) Ruaolf curvr m.robrr.... Cf,. Itll of cocceolrelloo .. t . Ratnfall dtttrlburlon ryp. - -)!l- Poqd ead sraop arear rprrad lhrouShouc gecarshcd ...... . 0 p.rclag oe \ L:Zecrcs or nl2 covcred) - \'E (Qc-u): ProJ.cr Wo*sheet {: Graphical Lront's Q,,>c-€ *3 Pca& Discharye mcthod ,aL^L'in ry?glc s1s2 2-Q- /o Orcckcd Drcc l. lbce: Frcquency 8:tnfall, P (2i-hour) Scor[ tl Scoru 12 Storo 13 1o ,/o o /,b ') // O,r/) | o. fr7 0.3/ 3o 0l S:a o,t4 10.q a/ ,30 (Ero norkthrcc 2) hr (Prol rukshact 3) (r, IA, rr, ttl) l ' cfr t,4tt I g,ez Tn.rurt d,s'.lno-7* Z'/l c{s fns,,,oru b. S> cfs 'f F ttr z. 3. 6. 5. 6. 7. l Intclal abetraccloo, I. .......... tn(Osc ef t tch bbl. 4-l;) Coopucc lalp ........ Untt pcak dkchargc, 1. ......... (Ure T. and I./P rdEh ;xhtbl,B 4- 2) Ruooff, q.......... (froo norkshcec 2). Pond aod rraop adJuGaaBB !:ctor, F- ....(Usc pcrccot pond and !n rp s,E.e . v slch cablc 4-2. Facror tr 1.0 tor zaro. p€tccnB pood aod sraog erca.) PaaL dkcharg., qp . . . . . . . . . . . . . . . . . . . r . . (l{hcrc A, . qu[QPp) csdla Itr I I It i 9. €IOVI-TB€6, S€eond Ed, Junc 19B6) D{ iJr' I I, I I I I I I I I I I I I I I I I I I (986I aunf "pg Puoras ,gts.UJ-I,1{13; Unit peak discharge (qu), csm/in 9t (tl OrOo 3E g g grg gs s c.' Ll trtx 5 o iF &(l !9 od(D &c F ll u2 (4t IJ |D t D- 0a F J5 =l.D o ',., 6 o5o 56'.' oJ c| i N-oto? t -----...........I fi- ll I I I IIJI I I Chapter 4: Graphical Peak Discharge method This dupter presents the Graphical Peak Discharye metlod for computing peak discharge from nual and ultan ar\eas. The Graphical metiod was developed fron hydrcgraph analyses luing TR.2O ,.Coraputer Program for hoject Formulatio*-llydrology" (SCS l9&l). lte peak discharge equation used is qp = quAnQFp Pq. eU wbere Qp - peak discharge (ds) 9u = unit peak discharge (c$n/in) An = drainage a,rea (mi4 Q = runotr (in); andFn = pond and swamp adustnnent factor. The input reguirements for the Graphical metlpd are as follows: (f) T. 164, €) drainage area (mi4, €) sppropriate rainfall distribution 0, tA, II, or III), (4) 24hour rainfall (in), and (5) CN. If pond and swamp arreas are spread throughout the watershed and are not cnnsidered in the T" cornputation, an adjustment for pond and swamp areas is also needed. - Peah discharge computation For a select€d rainfdl frequency, the 24hour rainfdl (P) is obtained fmm appendix B or more detailed local precipitation maps. CN and total rwrofr (Q) for the watershed are computed ar.,cording to the methods outlined in dlapter 2. The CN is used to determine tlre initial abstr"ction (IJ hom ta,ble lt.I. I./P is then computed. if the computed Ir/P retio is outside the nnge shown in exhibit 4 (4-I, 4.IA,4II, and 4-IID for rhe rainfdl distn'bution of interest, then the limiting vdue Ebordd be used. lf tl|e ratio falls between the limiting values, use linear interpolation. Figure 4-l illusttates tlre sercitivity of l.tr to CN and p. Peek discharge per squ.ne mile per inch of runof (qd is obtained fuom €xhibit 4.I, 4-IA, 4-II, or 4.III bV using T" (chapter 3), reinfatl distribution t1rye, end Ir/P ntio. Ttre pond urd swernp adjustment fector is obt ined from table {.2 (rounded to the nearcst table vdue). Use worksheet 4 in appendix D to dd in computing the peak discharye using tlre Gnphicd method. Curre number {0fla 43 tU ,t5 ,t6 17 .18 {9 50 5l 52 53 6{ 55 66 67 58 59 60 6l 62 63 6{ 65 66 6? 68 69 t t t t t rt DLlit ll (rt, l.cr.t Fljurc &1.-Vrrirtion of l./P for P end cl{. 0.85? 0-817 0.7t8 0.70 0.?ql 0.66? 0.dp 0597 0J64 05@ o.s{n 0.{69 0.,#B 0.{t0 0.381 0.35it 0Je6 029!) 0-??3 0247 0.8 0.198 0.t?a 0.t5r 0.r28 0.1(5 0.0&t 0.063 0.04r Table {.1.-1. vducr for runoE cuwe numberr Ir 0n) Curve nunber Ir 6n) &000 e8?8 L7@ 2.65rzffiLU 2.W 22ti5 Lt67 LW 2000 r9?2, t3t6 \n4 r.?0{ LA6 t57r lJ09 l.{48 l39o l.*ts tztgt% l.l?5 Lr25 r.o7l l.m0 0.985 0.9{l 0t99 70 ?ln 73 74 ID ?6 ta ?8 ?9 8{) EI 82 83u 85 86n 88 89 90 9l g2 9:l 9{ 95 96 97 98 €IGVI-TR€S, Second Ed-, June 1986)rl-l Scze-8As.rd I4 ' F tI r! I I I tr t I I I I I I t ,l I I t I I I lle t Fortdrcet 2: Rrmofi curre number and nurofi FroJ.cB honC ,Qrreg*/ w Dle t crBtor y'ar e Drra Ctrclr onr: €AAtr.1 Drvrlopcd:_=/ l. Runof! c|tEll. rrobr r (CI) 2. Runof! !icqurncy Eelnfell, P (2{-hour) &r9o^ll, _Q(Ut. P .nd Gl t'tth c.bl. 2-1, ttg. 2-1,or .qr. 2-t end 2-{.) G[ (rnl8hcd) . .!gq.r eroducE .ffi - 5i,6 , urc of . ,t a I @ Sotl oer :td hydrologie tEouP (eppcndlr A) Ccrr dercrtpclol (covrr typr, Brarloaag, .nd hydrologtc condllLor; Frc.nc tap.rvtour; unconoaccrd/connec Brd loptrvtour erce reclo) ProducB of Cn r erre {)qt- ,.+S .D2 r. - r2 ,Lt-.- t ' ,. .Br,,t ) - C, '- z->n t -' o'n ei'&.-''t'iy o '-' =,1". i.e./. U'. only onr Cn losrcr pcr llne.tocalt. Storl fl Scorl 12 Scon f3 1c, o 2V Ae, 8IGVI.TR.55, Socond Ed., Junr 1986) I I I t t I t I I I I I I t I I I I I t _t CURVE 56 I E It'4 r r'L,. RUNOFF FOR INCHES OF RAINFALL _ (P-0.2 S)2 P+ 0.8 S REFERETICE: tlationat Engineedng Handhok, Sectim {, HYDROLOGY llOTE: Runoff rnlue deterrnined by equation Q N 0.0 0.1 0.2 0.3 0.4 0.5 0.5 0.7 0.8 0.9 0 I 0 .00 0.00 0.01 0.0 t 2 o.o2 c.o3 0.05 0. c6 0.08 ,' o.lo 0.t2 0.l4 0. l7 0.l9 3 o.22 o .25 z-6 0. 31 0.34 0. 38 Q.42 o.45 o.49 0. 53 4 o.57 t/. OZ 0. 66 c. 70 0.?5 0. 79 0.8 9 0.9 4 0.99 5 l.04 1.09 I. l5 1.20 L.25 1.31 I .36 L.42 1.48 l. 54 6 I .60 I .66 L.72 l. 78 1. e4 l. 90 I .96 2.02 2.09 2.L5 7 2.22 2.28 2.t5 4I 2.48 z. ))2.62 2.68 2.75 2.82 8 2.89 2.96 3.03 3. 10 3. 1?3.25 7.32 3. 39 3.46 3.54 9 3.6t 3.68 3.76 3. 83 3. 9l l. 98 4.06 4. L3 4.2L 4.28 10 4.36 q.44 4. 51 4.59 +.67 4 .75 4.8 3 4.90 4. 98 5. 06 11 5.14 5.22 5. 30 5. 38 5.46 ,.54 5.6?5.70 5.78 5, 86 L2 5 .95 6.03 6. 1l 6.19 6.2'l 6.36 6.44 6.52 6 .60 6.69 13 6.77 6.85 6.94 7 .02 7.1I t.l9 7 .2?7.36 7.44 7.53 14 7.6I 7. 70 7.78 7.87 7.95 8.04 8.13 8.21 8.30 8.38 15 8.47 8. 56 8. 64 8.71 8.82 8. 90 8.99 9.08 9.16 e.25 16 9.34 9.41 9.52 9.60 9.69 9.78 9.8 7 9.96 l0 .04 10.13 L7 LO.22 tn 31 10. 40 10. {9 10.5I t0.67 10.?5 10.84 10. e3 t 1.02 18 tI.ll 1i .20 I I.29 11.38 t1.47 I1.56 11.65 I l.?4 11.8 3 It.e2 l9 12.01 12. t0 12. t9 12.28 t2 .17 12.46 t2 .55 L2.65 L2.7 4 12.83 20 L2.92 13.01 13.10 13. t9 13.28 Ll. ?7 L3.41 13. 56 13.6 5 13.?4 36 Sa9'Rtst'L' ll/' Worksheet 3: Time of concentration (Is) or travel time (t1) !t Duie D.B. {' 4'? o Lc.cton /o' '- C 6 I' I I l' I' I I I I I I I I I I I I T I I t Chcckcd ctrch orr: @ Dcvclogcd Cltcl. da: tc tt thtouSh rubrrrr lults ! 3grcr tor .r rr[y rr tF ..$!cnt. P.r flon ttP. c8a bc urcd for rrch . rorlrhrct. toctld. r orp, rchcoellc ' or daacslPtlon of flou 'c8!'nlr' Slrcct tlor (Appllcrblc co 1" oaly)SGtlGnr ID l. Surfrcr dercalptlo! (.trble 3-l) 2. [rnulsS'r tou3hocsa cocff., o (!tbl. 3-l) .. 3. !1or l'.ngrh, L (rdtr1 L < 300 ts) l. tr.o* 24+rs arlnfrll, P2 ......... 5. Irnd rlopc, r ft 1a cUfr hr Ill. 1..56ffi Chrnncl flog -@Coaputr l! ...... Shallos conccrtrrtcd flos Scgucnt II) 7. Surfrcc datcslptloa (pevcd ot troPrvcd ) ..... E. tlog l.atth' L ............ lt 9. tlrtrrcourrr rlopr, | ....rrrrroo............. f!/tt 10. Avragc wloclty, V (flgurc 3-l) ........... ttls -@ 12. Crolr rocttonll flor rrle, I rrorrrrreorrrrr ft2 13. tfctt.d g.al,!.t.r, pr......r.... fl ll. Eydrrutlc rrdiur, r'.! corput. r ....... tl PU ll. Chrmct .lop., . ............. ftlft 15. .l|l.n{nt'r roughnerr coeff.r n r..r.oor...... r?. v - t.s t2l3 ,tlz Cocput. Ia ...... * Scgrcnt ID Coaput. v ....... Ctlt l!. l1or l.!tth, L . ft re. 13 -#ColFrt. lt ...... ha 20. Lrt.r.h.d oa .ut s.. Tc or 1B (edd ta tn.t.P.6' llr rad 19) ....... hr elOVl-TR-65, S€cotd Ed, Jttnc 156) u'i?7 sf,o loo ,28 , /0 e.{-'t L''t '0Ll+l ,ol a DA .10 - .05 - .04 - +, oCIo 6 o6g tou o {Ja!- t I I I I I I I t I t I I t I I I I I I I I | | t I t,^t t,-t t2 4 !- ...tO Average velocity, ftlsec Fltr|r! &I.-lvctqr vclocitlcr for crtinrtlnf ttrvcl timc lor rh.tlor concfltrrt d flor. (21GVI-TR-55, Second Ed.. June 1986) 2. 3. 4. 7. D{ I I I I I I tr t I I I I I t I I I I t I I I 6. 0nic pcak dtrchtrgr, qo .........x cto/la(Urc t aad I./p ,acn &trtrr 4_b Ruooft, a...........(9rot roorlshcec 2). Pond and reeq adJuacoccc lecEor, F_ ....(Urc pcrccoc pood end t !r.ap araa . P rlch gablc 4-2. Faccor i,t 1.0 lorzero pGrcen! pond eod suanp araa.) 9. Peak dl!ch.!g., {p ....... .cfc (lJhrrr qn . qu\QFp) €fOVI.TR{5, S€coDd Ed.' Jrnc fS6) Pro1.cr (. ro ,r', P (2t-hour) Sua ^ats '+-',/r\l t I t pcac.nc of { (- acr.! or ol2 covcrcd) Storn Sl S co r-o 02 Storu il3 /c/ o z,Lf tq yr tn ,s7 | r L?J oo ,48 It. Drrlnegc 8r!E .......... \ - , OZ d2 (ecrcr/640) Rnooll cnrrc nrobrr .... q - f L (Fro rorkrhcer 2) Ttr o! coocraGrectoo .. t" . ,2 t hr (lrol norkshcct 3) Ralafall dkrrlburlon Eyp. - aT (t, IA, Il, tII) Pond aod lrrop arcar rprtad Ehroughout retershcd .:.... - Ercquency R:tnfall, InlCtal aboBracc,loo, I. ..........(Urc 6l rdBh rable 4-l:) 5. Cocprte lalp ...... , Worksheet 4: Graphical Pca& Discharge method Q,>zt !*b t%:ol.ct y'-4'?o Chrckcd Drcc ------\,Ctrcle onr: ,@pt Dcvclopcd l. D.ca: A I I T- I Ir 0n) Curre number Ir 0n) I I T I I I I I T I T I I I wtere 9p 'peak dischare€ (ds} 9u = unit peak discharge (csrn/in);An = drainage area (mB; Q = runoff (in); andFo =.pond and swarnp adustment factor, Tbe hput rcquirements for the Graphical method are as follows: O) T. 1p1, (2) dninage ar€a (miq, (g) sppropriate rainfall distribution (I, IA, II, or III), (4) 24hour minfall (in), and (5) CN. If pond and swamp areatt are spread throughout t}e watershed and are not considered in tbe Tc computation, an adjustment for pond and swamp areas is-also needed. - Peak discharge computation For s selected rainfall frequency, the 24hotr rainfall (P) is obtained from appendix B or more detailed local precipitation maps. CN and total r.unoff (Q) for the wstershed a^re computed according to t}e rnetiods outlined in drapter 2. The CN b used to determine the initial abstraction (lJ from table 41. I./P is then computed. if tlre computed l.tr ratio is outside the rznge shown in exhibit 4 (eI, 4lA,4II, and 4III) for thoninfall digFibution of interes! then the limiting value sbould b€ used" If tle ratio filts between the limiting vdues, use linear interpolation Figure &l illustrateJ tlre sensitivity of lrt? to CN and p. Peek discharge per square mile per inch of nrnofr (qJ ir obtained hom e.rhibit +I, 4.IA, 4.II, or 4.III lV_usinS T" (chapter 3), rainfall distribution t1Ae, and I.P retio. The pond and snnmp aqiustnent iactor is obtained hom table &2 (rounded to tjre nearest table vdue), Us€ worksheet 4 in appendix D to Nid in com-puting the pedr dbch:rgE using the Gnphicd method 3.0(n 2AI€, L7@, e65l L 2-& 2.W 2253 Lt61 LW e000 t92, 1846 Ln1 L?04 LA6l5a L50g 1.4{8 t39o l.gB r.gtgt% l.l?5 1.125\tn t.ut0 0.985 0.94r 0899 70 7l 72 fil 74 JD ?6n 78 ?9 80 8t &, 83u 85 86 g7 88 89 90 9l 92 9:' 9{ 95 96 9? 98 I Chapter 4: Graphical Peak Discharge method This chapter pr€s€nts the Graphical Peak Discharge netlod for computing peak discharge ftom rr:ral and r5bu areas. lhe Graphical method was developed fron hydrograph ar:alyses using TR-20, ,,Crcmputer &ograrr for hojec Forrulrtion{lydroloeiy" (SCS l9B3I the peak dfudarge equation used is g = q'drnQF tEq. 4-U Curve number 40.lla 4il tU 45 {6 47 48 49 50 5l 52 53 5,1 oo 66 67 58 59 60 6l 62 63 6{ 65 66 67 68 69 (21GVI-TR65, Second Ed., June 1986) tttrtlltt Ltit ll (t l. txr.a Fljun {-1.-Vrrbtion of l.1P for P rnd Cl|. 085? 0-El7 0.Tt8 0.7{) 0.703 0.6dt 0.692 0.59? 0-564 0.5@ 0.500 0.469 0.439 0.410 oitSl 0.31t3 03al 0*299 0.2?:t 0.247 0.u, 0.198 0.1?,t 0.151 0.r28 0.r0i0.8 0.062 0.(xl Table &1.-I. values for runofr cunc numbers &1 9tt I I I I t I oo €86I aunf l'pg Puor€ 'gg'uJ'I^{ra Un'it peak discharge (9r), csm/inE H g a ge trlx 5 (! ao 0a(D €c o- u at -E(! rt =D' o.t tc ca =.D o C'r'oo =cl.$o '+a.ou o3 .| $truqir\.,\o.; || t. I I I t T I I I I t I ? T I t t I I I I I I I I I I I I I T I I t I -sz16^8/lnSza-n E lroJ.ct Worblrcct 2: Bunoficurrc number and runoi srDlU- Chrchrd l*- q,DrBl DrB. Ctrclr oar: Prrra! .Etryg_)\= l. Runolf currrr ruqbrr (el) €roc-c-+5- Sol! oen :nd hydrolo3lc tlouP (eppcndk A) €orr drrcrtpetot (cota! !tpa, craelrat, eld h'drologlc condt clor; 9.tc.oB tlp.rvtoq;.r'coalrccrd/connrcBrd tlpalrlourtro recto) Producf oldrene &a iPd c.t{ .?1 . m,,rc, '2:,t- -/. OAE - As pe, t\ - ,r7oa., .r.ai .'\ $-.rs I - Co). 4.orq, t ist,\ e.\ I &a i,4 ,1 Ls oe-a- s,f<i' .!/ - U". only oe Clf rourcc pcr llac. G! (rcl8hcrd) ffirylF -?-3{{1r('a /4'7 2. Runof! Prrqurncy .................. F Relntell, P (Z4{rour) t! Ruaotlr_Q ta(ur P end Gt rteh cebl 2-lr ai;:-i:i. -or .qr. 2-l end 2-{.) b{, Ll u.. 6r -lz51 Scon ll,Scon 12 Scon lt /ao z, r/ E. LL efOVI.TR.tq S.otrd Ea, Jrurr 1986) I I t I I I I I I I I t I T I t I I I I I RUNOFF FOR INCHES OF RATNFALL N0TE: Runolf valuedetennined byequation q = (P-0.2S)2 p+ 0.8 S REFEREIICE: t{ational Engineering Handbook, Section l, HYDR0LOGY N 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 1 0.00 0. 00 0.01 u.trt 0.03 0.05 0.06 c.09 o-ll z 0.t4 l6 0.19 0.211 0.2 6 0.30 0.34 0.3e 4.42 0.46 2 0.51 o.55 0. 60 0.65 0.70 0. 75 0.8t 0. 86 0.9 ?0.97 4 I . UJ t. c9 l. l5 I.2t | .27 l. 33 1.39 1.46 1.52 l. 5e 5 1.65 1.72 1.79 l. 86 1.93 z. 00 2.07 2. Ltl 2.21 2 -2e 6 2 .35 2.4)2.50 2. 57 2.65 2.7 2 2.80 2.87 2.95 3.03 7 3.10 3. l8 3.26 3.34 3.42 3. 50 3.58 3.56 3.7 4 1- 82 8 3 .90.3.98 4.06 4. L4 4.22 4.30 4.39 4.47 4.55 +.64 9 4.72 4. 80 4.89 4.91 5.C6 5. t4 5.23 5. 3l 5.qo 5-48l05.57 5.65 5.74 5.83 5.91 6. 00 6.0e 6.1?c.26 6- 351l6.44 6.52 6I 6. ?0 6.7 9 6. 88 6 .96 7.0 5 7.14 7 -27t27 .32 7.4L 7.50 7.59 7.6I 7 .7f 7.86 7.95 8.04 8- 13l38.22 8.31 8. 40 8.49 8.58 e.67 8.76 8.85 e.94 9-O?l4 e.13 9.22 3l 9.40 9.4 9 58 9.68 9.77 9.86 9.95 15 10.04 r0.14 1O.23 10.32 10.41 r0.51 10.60 10.69 10.78 0.88 16 10.97 I 1.06 ll. t6 r1.25 1I.34 1I.44 11.53 11.62 11..?2 11.81 L7 11 .90 12.00 12. 09 12. t8 L2.2e 12.37 L2.41 12.56 12.65 l2 -75 18 L2.84 12.94 13.03 13.I2 L3.22 I3. 3l I3.41 13. 50 13.60 13.69l913.79 13. 88 13. 98 14. 0?14. l7 14.26 I4.35 L+.45 L4.54 14.64 20 L4.73 14.83 14.93 15.02 I5. l2 15.2t 15.31 15.4C 15.50 15. 59 45 I I a I I I' I I t l'. 1.. t I I I t li I I t t I l, Il( I I fr. Colput. It ...... fc 1a ct|tc hr -@ -@ Workshect 3: Time of concentration (ts) or travel time (T1) troJ.ct C/ONJ ZtgcF {S ryElb- , / ..- /-\trcrclon ,/A,( L u chccked Clscla oaa: tc ta chrou8h rubrrar FflS s Sgrcr lor .t !.!t r. !r.o ..gEca!r P.r f 1ou ttPc era bc urcd for uch roslthcag. Iacludr r t Pr acbclatlc ' ot darellPlloo ol flou rcg;ocncr. Sihcct llos (Appllcrblc to t" ool!)Scglcnt ID l. Surfrcr dascrt ptloo (.trblc 3-l) 2. tlrnnlng'e roughacra eocff., s (trbl. 3-l) .. t. llw lcngrh, L (BdBrl LS 300 fs) .......... t[. l\ro-yt 24-hr reLafall, PZ ......... 5. Lnd .lopc, I Ctteh oor: Prc3ca! ,@ffi=-\ 6. rG.t#.# Shatlos coaccnlretad flor Scgaent ID ?. Sorfrcc dllcslpt1oo (prved or unPrvcd ) ..... t. lla lcatth, L ............ tt 9. Trtrrcourra rlopc, 3 ro.oo.orrr............. ft/tt 10. lvrregc v.loclty, v (!t8urc 3-l) ........... tt'[s u. r. - 36fun Cooput! l. .. . ... hr Chrnncl flos Srgrcnc ID 11. Grorr acctton l flor rrcr, r o..roor.ooororr Ct2 t3. l|cttcd parlnlcr, Er ....................... fL ll. Eyrtrrullc rrdlur, t'.-1 Colputr r ....... fc tI t5. Cterncl rlopc, r ............. fclfs 16. .lbnotng'r roughnrtr cocff., o rrrrrroorrorro rr. v - r.es '1l3 .l/2 le. tr.#Corprra TG ...... ha 20. tlrrrrrhcd or rubrro ?c or ts (.dd tt ln rtrpr 5, Corpute v ....... ftlr, SIGVI-TR.I5, Second Ed., Jum l$5) D.ta lrrla F 7 :s ",,4" o ,28 t0 /o,1 /. J ,oll+l ,ot .m[f D8 I I I I I I I I I I I I I t I I I I I I I I oclo 6 o UIL:toa,Lc,{J,t- .10 - .06 - .04 - | | | | | t,t I t tr II 2 4 5' 10. 20 Average ve1ocl ty, ftlsec Flgrr & 1.-Avcra;c vclociticr for clrtflrtint tEvGl tirnc for shr||or concmtrrtcd nor, (21OVI-TR-55, Second Ed", June 1986) I I I t I I I I I I I I I I I I I I I Drelnage sre. .......i.. \. ,O -L o(2 (rer$/640) Rnnof! curvr nuober .... q - 6 { (Fro gorkrhccc 2) tloa of concsols.tloo .. T. . , ? 7 hr (lrol erorkrhr.E R:l,afall dlrtrlbucloa rypo - fu (I, t/|, II; III) Po[d and suaap ar:as lgrrad trhroughoqt rncershtd .:. ... - 3) pcrcaoB of L ( .crr!os slz covcred) 2. 3. 8rcquency...... Ralnfall, P (2t-hour) SEoEr! ,t Scoro tZ StorE t3 /d cl 2,4 l,[ ,t t! /,oYl '4f q0 06. 7. 8. 6. lntBlal abscraclion, Ia .......... (Use et FfEh Eable 4-l:) 5. Coopucc talp ........ Untc peak dlschergc, qu ..........(Uae T" eod I./p r.fch :rhlbft 4-_) Runof!, a ........... (Froo norkshecr 2). Pood aud sralp edJurto:B! fectoa, p_ ....(Urc pcrcent pond and $raop erle . P rtch c.blc 4-2. !.cBor tr 1.0 forrero pcrcenB pond and rralp erca.) 9. Prak dttchargcr rl, ...... .c!r (tfhcrc qO . quAsQFp) cru/1n 1o o ,zL z'oa l* I PIOVI.TR{S, S€cond Ed, Jum f9$) Sc/8'8rr /,- fu Iforkshcct 4: Graphical Peak Ilischarye method /'ProJGct Lr"^LE'(,Oa€{{ tt Dth"o.c, {^d- z o locrcton U+t t Lct Checkcd Drcc Clrclc ooc: Prcrcn! t. Drc.: I I T I l, l. t. I T I I wb€re Qp Qu An a Ir tu) Ir 0n) I I li I I t The input requiremenrs for the Graphical method are ss follows: (l) Tc ftr), (2) drainage area (mi4, G) appropriate rainfall distribution (I, [A, II, or III), (4) .24hour Binfdt (in), and (5) CN. If pond and swa,mp anea,s arc spread throughout the watershed and are uot consjdered in the T. computation, en adiustrnent for pond aad $rEnp areas is-also needed. Peah discharge computation For a selected rainfdl frequency, lhe Z4hour rainfall (P) is obtained from appendix B or more detailed local precipitation maps. CN and total nrnoff (Q) for tle wetenhed are computed according to t$e methods outlined h chapter 2, The CN is used to deternine the initial abstrzction (IJ fum table 41. I./P is then computed" if tlte computed I./P ratio is outside tl|e range shownh exhibir 4 (+I, sIA, sII, and 4-IID for rhtrainfall distribution of intercst, tllen tlre limiting velue cbould b€ rxed. If the ratio falls between the liniting vdues, use linear interpolation. Figure 41 illustratei tlrc sensitivity of I"lP to CN and p. Peek discharge p€r square mile per inch of runoE (qd ir obained from erhibir +I, 4-IA 4.II, or 4-IlI !y_*ing Tc (chepter 3), rainfatl distribution tlpe, urd I1P retio. The pond end swemp adjustment iector is obtained Aom uble 1.2 (rormded to tlre neerest Eblevducl Use norksheet 4 in eppendix D to .id in coutpulinS thc pedr rxing the Grrphicat acthod- 40 ,u 4tlI 44 45 46 17 IE t9 50 5l 5:t 8t 54 55 56 TI 58 59o 6l 6ea 0l 66 68 CT 6Ec 3.000 LS.IS L?@, a65r Lffi 2.44 L3,d,8 2255 LI6I LW 2.0(n ts2, r.846 Ln4 l.?:04 l.616 l.57l 1.509 l.{48 t.gx] t.cBtzn tl26 l.r?5 l.ti5\tn 1.080 oss ogal 0t99 70 .L 72 73 74 ?5 ?6 tan ?9 80 8t & 83 EI 85 86tl 88 89 90 9ln 93 9{ 95 96n 96 I li t T ]T Ed., Junc tg86) Chapter 4: Graphical Peak Discharge method This clrapter prcsents tle Graphical Peak Discharge metlpd for compuring pealr discharge &om nual and urtan areas. Ttre Graphical method was deveioped ftom hydrograph anaiyses using TR-20, ,,Computer hogran for hoject Formulation-llydrology,'- (SCS 198i1). Tbe peak discharge equarion used is qp = qoA'QFp 6Eq. a.U - peak discharge (ds); - tmit pedr discharge (csr:/in); = drainage area (mi4; = runotr (h); and = pond and srramp adjustment factor. ttlrtlllt Llrt ll (tlt t..rr, Fljurc &1.-Varirtion of l./! for P rnd C]{. Cune number 0.857 0al? o7t8 o74{t 0.?(ts 0.66'/ 0.68 0.597 0.56{ 0"5@ 0.5(n 0.4a 0.4:p 0.410 OJEI 03sl o.&tr 0:9!t 0213 02470E 0.r98 0.t?{ 0.15r 0.t8 0.1(F Q.083 0.0e10r|l Tablc &1.-1. valucr for runof currc numbers €rGVI-TR.SS, Sccond +l It(986I aunr "pg Puot€ '9S'UI'I.\{tz) Uni t peak d ischarge (Qu ) , csm/i n E E H e:gg l.,' T I I t. I oooo Gi '. 5 a 6(t GI(t Ec i u) a2 -tt |D l| E 0 rl o3 3o o 'c|o5oot.' .!| o5 o +tqi5st\o,^|D t I I I I I I t I I I t I J I t on- . Og- E- 1DCE I t-J r.loP.d ,I i I I : I I II I I I t I I I I I I t t t I I I I I I t Sua^B15z,t-, -;T Wcfohcct 2: Runotl cuwc numbcr and runofi koJrct l. Luao! f curvr nnber (Cil) 2. Runof! ''.-\ . ./ ,'n -W2o2. D... 4/<//O ChrcLed Dtsr Qf (rnrghccd) . .:::l t:::i. .8 . 54, ,/ uro clf .st' 6,./ -; f?1 lrequcncy .. ...... ..... ,s 8elnfell, P (20-hogr) t! Ruaolt, q ........... lo(Ur P ead Ctr stch crbt 2-lr !ii:-i:i. -- or .qt. 2-3 rad 2-t. ) t9o{L aer end hydrologtc tao|lP (eppcadlr A) Co,vtr dr:crtgcloa (covrr typr, !!ar!E nt, ead hydrologlc condlElo!; p.tcaaE tap.rvtoot; uncomgclrd/coanreBrd l,!pa!l'tou!.r.t rrB10) Producr oldrene Ur. onlt olr CU rourcc Acr ltnc.localr. Scoru lt Scon 12 Sto 13 /d o 2.4 ,t3 8[GVI-TR.54 Sccond Ed, Juno l$ID I I I I I I I I t t T I I I I I I t t t I 1{0TE: Runoff value detemined by equatim Q RUNOFF FOR INCHES OF RAINFALL _ (P-0.2 S)2 P+ 0.8 S ll I ii I tl rl.l |l REFEREilCE: ilational Engineaing Handhok, Sction 1, HYDR0LOGY CURVE 59 N 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 1 0.00 0. 00 0.0 r 0.0 t 0.02 0. 2 0.05 0.0?0. 08 0. l1 0. l3 0.l5 0.13 0.21 0.24 0.27 3 0.30 0. 34 0.3?0.41 0.45 0.49 o.5 3 0.58 0.62 0. 67 4 0.71 0.76 0.81 0.86 0. 91 0. 96 l.0I 1.0?t.l2 1.18 5 1.23 L.29 t. 35 t.4l L.47 1.53 I.59 1.6 5 l.7l l. 77 6 I .84 1.90 1.97 2.03 2. l0 2. Lf 2.21 2.30 2.3r 2. 44 7 2.5L 1e 58 2.65 2.72 2.79 2.86 2.93 3.00 3.08 3.15 8 4.22 3.30 3.31 ?.45 t.52 3.60 t.67 3.75 3.82 3.90 9 3. 98 4.05 4.l3 4.21 4.29 4.31 4.45 4.53 4.60 4. 6e r0 4.76 4.84 4.92 5.01 5.C9 5.l7 5.25 5.t3 5.4t 5.49 l1 5 .58 5.66 5.74 5. AZ 5 .91 5.99 6.07 6.l6 6.24 6.t3 t2 6.41 6. 50 6.58 6.66 6.7 5 6.83 6.92 ?.01 ? .0e 7. 18 13 7 .26 7.t5 7.4t 7.52 7.61 7.69 7.78 7.87 7.95 I 14 8.13 8.22 8. 30 8. 39 8.4 8 8.57 8.66 8.7 4 8.8 3 8. 92 15 9.01 9. t0 9. t9 9.28 9.36 9.45 9.54 9.63 9.72 9. 81 16 9 .90 9.99 10.08 10.17 10.26 10.35 10.44 10.53 10.62 10. ?l l7 10 .80 r0.89 10.98 11.07 1!.l6 11.25 11.35 I 1.44 11.53 I 1.62 18 ll.7l 11.80 11. 89 t1.98 12.C8 I2.17 L2.26 L2.t5 12.44 L2.53 19 L2.6!t2.72 12.81 12. 90 13.C0 t3.09 t3.18 Lt.21 13.36 13.46 20 13.55 13.64 t3.74 13.83 13.92 14.01 t4.ll 14.20 L4.29 14. 39 39 I I I l' l Saa -,9 ls,','l r+r- Worksheet 3: Time of concentration Ctg) or travel time (Ti) I,oni" Q,o ce fg ,,LL ^r, y'-4 -7 olsoJ.cr Lcatloo Fllli: Specr for rt lray.a tro r.SEGott P.r flou !t9. cra br ulcd for och rorbhcat. toctudr r np, rchclrltct ot &acrlPBtoo of llou n3lcn!r' Sihrct tlor (Appllcrble co t. ooly)Segrcnt ID t. Surfrcr d.tcalpttoo (.trbk 3-l) 2. lt nnl,!8'. routh!.!. cocft., o ( erbt'c a-f) .. 3. Ilor bn8th, L (86..1 LS 3O0 ft) .......... l! a. ti o-tr 20-hr rrlofrll, P2 ......... 1o 5. Lnd .lopc, r .. trl la Ch.cl.d - llrl. I t t t I t I I I I I I 6't.-t# l?. e . t.rg {/t .trz -w Strllos coaccatrrtcd floe Scgreat lD 7. Sqrftcc dclcslpcloo (prvrd or unPeved) ..... t. Eld l.otth, L ............ ft 9. ltrrtrrcoutr rlope, | . r . r r r o o o o r . . . . . . . . . ... . lBllt 10. Ayrtega roloclty, V (figurc 3-l) ........... Cclt Irt. l. .55ft1 Ghrnncl tlor 12. Ctorr rcctlonrl flou rro, I oorooooooorrooo k2 13. L!t.d p.sl-c.r, p,........... ft ll. Ey&rullc rrdts., r'-i C6prt. r....... fB 15. Ghraoot .lop., | .....]:.................... f!/fB 15. .llraalnj'r rorghaer corff., a rrooorrorr...r Co6pu3. tt ...... hr Cooputa Tt ... ... Scgrrnc ID Cooputr v ....... tclt -@ Il( I I It. Ilor l.nlth, L . lt ?19. lr .IffiT Cmputr tG ...... hr 20. lt !.t.h.d ot .ub.r.r tc or lG (rdd ta ln .3.P. 6, tl, md 19) ..".... hr @IOVI.TB{6, Sccoad Ed"' Jtlrrc lS) l/n,. ac uP UP 300 4oa ,/O '32 5 )l , oLl+l ,o I g Ild o CLo ai oa^L =o(,Lru+ra- l, I I I l, I I I I t I I .to : .06 - .04 - .02 -I 'l t I I I t I I t | | I | | | | | | | r/L 2 4:6 10 Average velocl ty, ft,/sec F[un l.l.-.{vcn3: vclocitlcr for Grtimiainf tt|vcl tinc for rhdlor com.ntnt d llor. efOVl-TR-s5, Secoad Ed., June l98ti) I I I I I t I t I I I I I I I I I I I I I Worksheet 4: Graphical Pea& Discharge mcthod BtDe4e D.!. r/u/?orr-_ Chcckcd D.E. l. D.ca: Drelnege .,r.r .......... \ - ,O I d.2 (rcrar/640) Rrnolf curve mrb.r .... q - 59 (lra rrorkrhmr, 2) tLlr o! coocaorreEloa .. t . ,5 I hr (!rot norkshecc 3) -narufaii <itrcrrbqcron Eyp.- . 7 (r, tA, rr, rrt) Potd eod straop arrar rprced Ehroughout secarrhrd ...... - 2. 3. Frequency Ralntall,P (2i-hour) Storq fl Stom 12 5l0r! ,3 /o0 311 ,56 230|' , t3 l' yl to la6. 5. 6. 7. 8. Inlrl,al ebrBracElot, Ir .......... (Usc Gl rrtEh rable 4-t:) Coopuc! Ia/p .................. Ucl,r pcak dkchargc, qo .........y(Usc t aad I./p rdBh ;xhtbtB t--lt I Runoff, a...........(Froo rorkshcec 2). Poad aod rr:op adJurtocat facGor, ?- ....(Usc pcrccor poad aod ssirEp arla . P rtBh r.bl. 4-2. gecBor k 1.0 lorlero p€rcant gond and sranp erca.) PeaL, dl,rchargG, ep ...... (tfhcrr qO . qo{QPp) cro/1o to ' cfr ,3 O,. €IGVI.TB€6, Sccond Ed., Jum l9&DD{ I, I T, wbetrg qp Qu AtD e FP t l. I I I I I I I Ir 6n) Currre number Ir Cn) 3.000 agrS z7@ a65tzffiL& 214828 Lra LW 2.000 1qD r.8{6 Ln4 LTIN l.636 t5?r 1.50!t 1.448 r.390 t.3!ts l2?9 t.26 l.t?ti t.xls Lgn 1.Gil' 0.985 0.9{r 08srt 70 7l 72 ?3 74 75 76n ftl ?9 80 8l e, &lu E5 E6 c7 8{1 89 90 9l 92 93 94 95 96 9? 98 40 4l 4t2 4846 16 47 48 49 60 5l 52 5it 5{ 55 66 67 58 59 60 6l 6A 63 6{ 65 66 TI 68 69 I I I I I I i I I I Chapter 4: Graphical Peak Discharge method This cbapter presents the Graphicd Peak Discharge method for computing pesk discharye from rural and urtan areas. The Graphical method was developed qun hydroqph analyses using TR-20, ,.Computer Progran for hojec Forzrulation-Ilydrologyd (SCS 1S). lte peat Os*arge equation r:sed is Qp - guArnQFp tEq. 4-U - fpak discharge (cfs); = rurit peak discharg€ (csn/in} = draina8e area (mi4; = runotr (in); and - pond and svamp adustment factor. lte input r€quirements for the Graphical method are es follows: (l) Tc ftr), (2) drainage area (mi4, €) rppropri.te rainfall distribution (I, IA, II, or III), (4) 2&bou ninfdl (in), and (5) CN. If pond and swamp rrautarc spread t}roughout the watershed and arre not considered in the T. computation, an adjustment for pond and swamp areas is also needed. Peak discharge computation For e selected ninfall frequency, the 2Ahour rainfall (P) is obtained from appendix B or more detailed hcal precipitation maps. CN and totd nurotr (e) for ttre watcnhed are computed according to the metbods outlined in chapter 2. The CN is used to deternrlne the initial abstraction 0J from uble 4.1. I./P is then computed" if the computed I.1P ratio is outside the range shown h exhibit 4 (&I,4IA,4II, and 4.IID for thtrahfall dismution of interest" then tlle limiting value lhould be used. If tbe ratio falls between the limiting vdue3, use linear interpolation, Figure 4l i ustrateJ tJte sensitivity of I"/P to CN and p. Pesk discharge p€r square rnile per inch of nurof (grJ is obteined from e.rhibit .|.I, 4.IA, 4-II, oll-III -bl_*tng Tc (chapter 3), rainfall distribution t1pe, and I./P ntio lte pond and swamp adjustment iactor is obteined from table 4-2 (rounded to the nesr€t t3ble vduel Ure worksheet 4 in rppendix D to eid in com-puting the peak disch$ge using the Graphicd method (2fOVI-TR-55, S€cond Ed., &nc 1986) lttrt!ttt Ltit ll (tt. !.cla Flturr {.1.-Yrriatlon of I.{P for P end CN. 0.857 081? 0.n8 0.7& 0.?Gt 0.66.t 0.6n 0.597 0.56{ 0.5@ 0.500 0.469 0.€9 0.{10 o38r 0.353 03!6 02sg 0.273 0247 0.u, 0.198 0.17{ 0.151 0.ua 0.105 0.0&t 0.062 0.ur Teblc &1.-I. ralues for runofi cure numben +t 9? I: T or C'roo I I (986I aunf "Pg Puoras '9g'uI-IA{IZ) Unit peak discharge (Qu), csm/in @ooo (.)S('lqls = 3 8t coooooo t' t I I I I r,x 5I a ID!t =g o(t rt GI(D = aia u !t.! {E =tr ELo ig c =o o 'oo:'oot a+.' .4, ot o \* \o.i rrltt I I I I I I t T P a: E- I I" 3uB-$4st,u EI I I I l I I I t I I t Fortsh:ct 2: Brurof? ctuyG nutnhr and nuroll EL-"e,r'<e- Chrcltcd an l'J'?Q D.ra l. lunof I curvt ruohr (Ct) rl I ! /t'Ctrck onr: Pr.a.ac /Drvdoprd Soll nar ead hydrologlc tloup (eppendlr A) Covtr docrtptlon ( covrr !ypr, !raaEaa!!, .!d bydrolog!,c condlrloo; p.tcanc tlprrvtour; unconaccctd/connrc Brd tlpan lou!.r.. serlo) Paoduc! ol Cl : erle ?ai< -,4.: 5 Q z' . .1" J'r." ?.' -' b/-..': - - ^r', <')/^1'-'52. | '=n-2.^ ' 2a /o' ): '''- --'-le-, Utc only onr Gf gonrcc pcr ltna.locals . T ,l t I I t I I t ,l.t>rl Gr (rnlshred) . g!!,!_t@! .?;- 73,L z urc Gr -w 2. Runof! !icqucncy Retntall, ? (l0-hoqr) ..":""""""' &rao-tf , _Q(Ur P ead ef etrh ceblr 2-1, iii:-i:i,o! .qt. 2-t rrd 2-a.) tr tl lo Ston ll Slon ,2 Scon 13 //o 2,1 a,s I elGVI.TB"t6, Sccod Ed., Jnnc 1986) I' I T I I t t t I I I I t III I ;tI I I ;t RUNOFF FOR INCHES OF RAINFALL I{OTE: Runoff value determined by equation q = ( P- 0'2 S ) 2 p+ 0.8 S REFERET{CE: tlational Engineering fiandbook, Sectim {, HYDROLOGY CURVE 73 N 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 0.00 0.01 I 0.02 c. 03 05 c. 07 0.lc 0. l3 0. l6 0.20 0.24 0.28 2 0.32 0.37 0. 4l 0. 46 (;.;0.57 0.62 0.6 8 0.74 0. 8c 3 0.86 0. 92 u. v6 1.05 1.ll i.l8 L.Z)I.32 1.39 1.46 4 I.53 I.60 1.67 I.75 l. e2 i. 90 I.97 2.05 2. L2 2.24 5 2 .2a 2.36 2.44 2.5?2 .6C 2.68 2.f 6 2.84 2.92 3.01 6 3 .09 3. 1?3.25 1.34 1.4 2 3. 5l 3.59 3.68 ?.7 6 3.85 7 3..93 4.02 4. tl 4. l9 4.2e 4.31 4.46 4.54 c.63 4.72 8 4. 8l 4 .90 4.99 q no 5.17 ).1)5.34 5.41 5.52 5.61 9 5.70 5.80 5.89 5.98 6.c7 6. 16 6.21 6. ?4 e.qt 6.52 10 o.6?6. 7l 6.80 6. 89 6.9I 7.08 7 .11 7.26 7 .35 7.45 t1 7 .54 7.6J .,73 7 .82 ,.tl e.0r 8.10 8.19 e.29 8.38 L2 8.48 8.57 8. 66 8. ?6 8.€5 8.95 9.0 4 9.13 9.21 9.32 13 9.42 9. 5l 9.61 9. 70 9.8C 9. 89 10.08 t0.18 t0.27 14 10.37 I0.46 1c. 56 1c.65 i0.?5 \c. 84 I0.94 11.04 ll 13 f 1.2:2 15 11 .32 I 1.42 lt.5I lt 6l 1t.71 1i. 80 11 .90 I1 .9e 12.09 12.19 16 12.28 t2.38 L2.41 L2 .51 12.C7 12.76 12.86 12.96 l2 nF 13.15 T7 r3.25 13.34 13.44 13.54 I3.63 l2 ?1 13.83 L}.92 14.02 14. l2 18 t4.21 14.31 I4. 4l 14. 50 14.6C i4.70 14.?9 14.89 I.r.99 15.0e 19 I5.18 15.28 15.38 L5.47 15.57 15.67 L5.77 15.86 l5 .96 16.06 20 16.16 16.25 I6.35 16.45 16.55 Ir,.64 l6 . ?rr 1,6. 8 4 16.94 17.03 5J I I t l' I t I I I I I I I I I I I I I I I ,rfu" Chrckrd Clrclr orr: ,t.r.{@ Cltelr onr: tc lc ghrouSh .ub.rQ' fiytls: Sprcr for r. lrot rr tuo a.tmotr prr tlor ltF cra bc urcd lor "chEtk h.at. tncludr a !aP' lchaElBtcr or daacrlPtloo of flor reglcnrr' Slrcct floo (Appl,lcablc to t" ooly)S.8!cnt ID l. Ssrfece dcrcrlpiloo (crblc 3-l) 2. llrnnttS'r roughncla cocft., o (trbl. 3-t) .. 3. llou lcn8rh, L (rdlrl L < 300 l!) 4. tno-t! 24-trr rrl,ofel.l, P2 ......... 5. Ilnd llopc, t Cooputr TB ...... Scgocnt ID ?. Surfecc drlcrlpBloo (Pevcd or uapeved ) ..... E. Elon lcnt3h, L .........;.... . ft 9. tlrtorcourc llope, r ........................ !r/ft 10. Averegc wloclty, V (flgurc 3-l) ........... lclt Ill. ?. .53ftn cooPut. It ...... ha Chrnncl tloc Scgrcnt ID t2. Ctou rcctloo.l flor trer, I reer;ooorrrrorr Cc2 13. l|c!!.d p.rlc!.r, p, . .... .... .. f t ll. Eydrrullc trdlua, a . j corPu!. I .o..... fipr 15. Graacl .lop., . ............. ltltB 16. . lleuoLn3'r roughoer coaff .t o .. o oo o... r..rr 17. v - t.lg r1l3 .r/z It. llou lca3th, L ............ tt I19. t3 .5ffiT Colpuc. tG ...... hr 20. lt t.rrh.d or rubrro tc os tr (rdd ta 18 .c.P. 6' ll' .!d t9) ..r.... elGVl-TR65, Second Ed., June 1986) fr 1! Ctl tt h!-@n! 0.007 (nL)-'-c' 't - -I]E5.'..TFE2 t Shrllos conccacretcd flos -@ Coputt Y ....... C.clt SuB^8*stJ T IVorksheet 3: Time of concenhation Ct6) or tnvel time Crl) /,,,^,.. 1,;,^^'3{Psolact \ ,'r '/ \) "\ " i' € !- \)D.t. Ibt. utr uP 2 ?c ,J, 'J ) ll , oL l+l .ol E D8 |uao 6 o UIg =o(, 3.{,{Ja!- I I I I I I I I I t I I I I I I I I I I I ,l .10 - .06 - .04 - t24610 Average veloclty, ftlsec Fltun 3.1.-.&cnC vclociticc for cttimstint tnvd tim. for rhdlor concc|rtrrt d flor. (2lOVl-TR-i5, Second Ed., June 1986) ttl I I I I I I I I I I I I I t I I I I I t I Wor{sheet 4: Graphical Peak Dlschargl method 'i--t, 'l to Clrrckrd S.r9^$d5,rry @ b.. q-J'?0 Drca plrcrnB of L ( acrar or ct2 eovcred) SEorr ,l ScorE rz Slot-o f3 /o6 2U yr tn 11q .5,/l a,t/ efGvI.TR{q Second Ed., Jrrae l$6) 4. 5. IotCtal abe!rac!,1on, I. (Use Gl Elch bblc 4-t:) Coopuce lelp ........ 6. Untc peak dlrchergr, q.. . . . . . . . . . . r. . . . . . . cct/l,o(Uec t aad I./p t tth ;xhlbrt a-Ll Ctrclc ocr: P!.r.nc Drvcloocd I. Drca! Dr:lnagc .rar .......... Rsnoff curvc mnbcr .... Frcquency Ratnfall,P (2i-hour) 7. Runoff, q .......... (8roo rorkshecg 2). 8. Pond aad sraop adJurrenE facBor, F- ....(Urc perceor pond ead $raap rrra . P vtBh cable 4-2. Factor ls 1.0 tor zaro. perccnt pond aod rratp :rca.) 9. Pca&, dkchargr. .lp ...... (utrcrc qO - 9'r\QFp) ntt' 'J' cl' (ecrcs/640) --2- 2 (Ero norkehacs 2) Itna of cooc.rlt.ltoc .. Tc - ,{J hr (Froc rorkrhcac 3) Relnfall dltBrltuBtoo typ. - 1> (t, IA, Il, II!) Poad and sraop ereer rgrted(hroughouc saE:rrhad \ cil 2. 3. ' efr D{ I I l, I I I T I I I I Ir 0n) Ir (in) I I I I I I I ii I T I wteFe Qp - peak discharge (ds); Qu = unit pealt disciurge (csm/rn); Am = drainage area (miz); Q = nrnoff (in); andFo = pond and swamp adustment factor. The input requir€ments for the Graphical method are . es follows: O) T. (hr), (2) drainage area (mi4, €) rpprcpriate rainfall distribution (I, IA, II, or III), ({) 24hour mhfall (in), snd (5) CN. If pond and swamp {rcas:rre spread throughout the watershed and are Dot considered in the T. computation, an adjustment for pond and swamp areas is also needed. - Peak discharge computation For a s€lected ninfall ftequency, the 24-hour rainfall (P) is obtained frorn appendix B or more detailed local pr€cipitation maps. CN and total nrnoff (Q) for tlp watershed are computed according to the netltods outlined in drapter 2. the CN is used to detetmine the initial ebstraction (IJ from table 4-1. I"t? is then computed" if the computed lntr ratio is outside. tlre range shown h €xhibit 4 (+I, &lA,4II, and 4-III) for tlre rainfall distribution of interest, then the limiting vdue .hould be used. If tbe ratio falls between the limiting values, use linear intcrpolation. Figrre 4.1 illustrates the sensitivity of I"r? to CN end p. Peelc discharge p€r square mile per inch of nrnoE (qJ i,s obkined from exhibit +I, 4tA, {.II, or 4.III by trsing Tc (chapter 3), rainfdl distribution t1pe, and IJ? ratio. The pond and sramp adjustment factor is obtained hom table {.2 (rounded to tlre nearest table vdue). Use worlsheet { h rppendix D to aid in computing the peak dbctnrge using the Graphicd nethod 3.000 2A|.8 L7d2 e65r 2545 2.U 2.48 22fi LI6I eo82 2000 t.c2, la46 Lfu 1.flX 1.636 t.571 r.tql 1.448 1.390 l.&t3 tn9 t.26 Lr?5 t.lzti Ltn t.(tso 0.985 0.94r 0"699 ?0 7l 72 ?3 74 75 76n 7E ?9 80 6la 83 84 85 86 c7 88s 90 9l 92 git 94 95 96n 96 Chapter 4: Graphical Peak Discharge method Tbis drapter pr€sents the Graphical Peak Discharge metlod for computing pe:k discharge ftom nrral and urtan areas. fire Graphical method was developed ftom hydrograph analyses rrsing TR-20, "Computer Prograrn for hoject Forurulation-llydmlogy" (SCS l9B3). Tbe peak discherg'e equation used is qp = quAnQFp teq.a-u ,|{) ,tI 42 .a tA 45 46 47 ,a 49 50 5r 62 53 5{ oo 56 57 58 59 60 6le 63 64 65 66 el €8I (2lCVl-TR-55, Second Ed., June 1986) t t t l t lt D tt.t ll (t t. l.<r.a Flnrc &1.-Vrriatton of I./P for P rnd C'I{, Currye nulber 0a57 08r7 0.7t8 o.7& 0.7G 0.66't 0.dp 0.597 0.564 0.582 0.500 0.4dt 0.4:F 0.{10 0.381 0.3|3 0346 0290 0zt3 02t7 0.u, 0.198 0.1?{ 0.151 0.r28 0.105 0.083 0.064 0.ul Tablc {.1.-1. valuct for runofr currc numbers +l It(986I aunf "pg puoJas '-o9'uI'IA{IZ) Unit peak discharge (Qu), csm/in I I T l. I T I I I .l @ooooor\! ul 5 (t orI I 3 88 t5, 5 o r? rl GIo e Fta a2 x l| !9)F !! r.t =03 3o o '.tIo.$o' .. .q, l-- ot o *fru.3S\oraT I T T T I I I II I 53 , tr ta h I I I I T t I t I I I I t I Ij I t I T t ,/ /'1Pro1.ct CidrlS Z,DGE* -S t/Lc.clon y'a r:- t-" l. Runolf cunre ruubar (C!t) Wor&rhcct 2: Rrurofi currc numhr and nurof? E -J,-/AQ Ghrckrd I ,I I I i : I G[ (rntShrrd) . tour eroduct. JSZ - <t,O 2. turnof! Ur Clf -t-s3t Sqg-D+:rtrt F-l r,.c.y''l'?e *a.'- Ctrctr onr: ''- Prrrcac @pcloged ttotl ner :od hydrologtc t!oqP (:ppcadlr A) Conr dccrtgctoa (corrr typr, cr!.c!.uc, .!d hydrologle condlrlon; D.lcaoB ttp.rylout; unconnccBad/connrclcd tlp.frt oq!errr racto) (..r.t trux Product of CI r erre OFa,- : .a '. .<- /ij cea .'.>-- t.J- - , - Ar/3'1 --2 - a2,'1,'')^ Urc onty oar Gl rorcc por ltcr.toc.lr - 3tom lt Ston 12 Ston f3 /tc) z. q ,0{ 8ICVI.TR-54 Sccond Ed, Junr l!f,6) I t lr l. t t I I t t I taxhre b grven in appendix A for determining the lliQ r'l'qeifcation for disturbed soils. CorE ttTe Trbl€ 2-2 address€s most cover t1pes, srch as vegdation, bare soil, afrd imperviorx surfaces. Th€re rre e nunrber'of methods for determining cover tJry€. the mct common are field reconnaissance, aerial gbotographs, and land use map8. a. Tnatncnt Mnnl is a cover type modifier (used only in t ble 2-2b) to describe tlle management of cultivated {ri,ntltural lands. It includes mechanical ptzctices, och as contouring and terracing, and management Fecdcq such as crop totstions and reduced or no flrya Ilydrologic condition Huil.mloob conditimt indicates t}e efrects of mver trttre and treatment on infiltntion and runofr and is le'nerallv estimated ftom density of plant and residue 6ue" on sample areas' 6ood hydrologic condition indicates that the soil rxually has a low nrnofr Dotential for that specific hydrologic soil group' cover iile. and treatrnertt. Some factors to consider in ,iii-ating the efrect of cover on infillration and nrnofi are (a) canopy or density of lawrs' ctlps' or other vegetative areas; (b) amount of year'rcund cover; (cI amount of grass or closeseeded legumes in tltstions; (d) pereent of residue cover; and (e) degree of surface roughness. Tablc 2-I.-Runofi &pth for sclcctcd CNr and rainfall amountsr Rrmotr depth for curve number of- lLhf.ll {} 15 50 53 55 98959065 t I I I I itnhts I t.0 0.00 0.00 0.00 0.mt2 .00 .m .00 .(}Lt .00 .m .m .c)1.6 .m .00 .00 .mll .00 .(n .00 .002A, J .6 .m .00 .^<.vz25- ' .00 .m .(2 '"-.$ . ' &0 .00 .@, .09 .19 35 .@, .08 .6 35{0 .06 .18 33 53- 15 .r4 J9 50 ,74att 2A .a .69 S 60 5() "S l.l4 lJc?.0 a4 121 1.68 LUZ&0 125 r.74 225 Ln9.0 l.?t 2E e88 3.4910.0 2.a e80 &56 18It.o z.?a 3.5i! 4fi 5.00t2.0 8.s 1.19 5.00 5.?9l3r) ro {.89 6.76 6.61tro 4.65 6.62 455 7.u. tfo 531 6.36 7.C6 Ae) 0.00 0.00' 0.00 0.03 0.08 0.r7 0J2 0.56 0.79 .$ .(n .(B -91 .15 g .46 .74 39 .00 .v2 .06 .13 2A 39 .61 .92 r.l8 .01 .(E .ll 20 g 52 .76 l.tl lsE .G .G) .l? a .u .65 98 129 158 .06 .14 21 38 56 .80 1.00 1.48 Ln .t? 30 .46 .65 39 1.18 r53 l'96 2n 33 5r .?l .96 t25 1.59 1.98 L45 Ln -sil .75 t.ol 130 1.64 2.t2 L45 2.94 3n .?6 r.0:l lJ3 l.6r LU 2.46 Lgz 3'41 3'n r3o 1.65 a(x z{5 2.89 &87 &E8 4.4i1 {.?6 13:t ut' ?sl 828 &78 Un 4t5 5.rl t?6 160 &10 &68 {.15 1.69 5% 582 6.41 6.?6 xct 3J9 {.46 6.fi 5.63 621 6.8r ?.{0 ?.76 \ dlo 1.72 53it t.96 6.5? 7.18 7.79 8.40 8.76 {.90 i56 612, 648 7.52 E.16 8.78 9.{0 9.?6 nT2 6{3 ?.r3 731 8.48 9.13 9.n 1039 10.?6 6.56 7.n &05 8.?6 9.45 10.11 10.?6 u39 11.76 7.4i2 82! 85 9.?l 10.42 ll.l0 lt.?6 ut39 ra?6 E3o 9.U 9.9r 10.6"t lt.ttg rz08 l2?5 13.39 t&?6 9.19 ro.fi l0a5 ll.61 1237 l&fi l&?{ l1J9 l{-76 I t lit I ,l rtrroohtr rho nl[a dlovn to obtrh nurf &lrhr for CN'r or ninfrlt urur mt rlloun' (2IGVI-TB-55, Second Ed., Jrure 1985)24 )\/I I I l' l. I I t I I I I I I I I I I I t I S,€^gA:t,v .A Iforlshect 3: Time of concentration (Is) or travel time (T1) I /^ JJ_ _ t!oj.c! Lr,'azJ '{.rDG€ -S t.o.rrton ;/o' '- '- I Ch.ckcd llrt. [OT!S ! 3prcr lor .r trty aa 3to ..gs!!a P.s tlor tyPG cra bc urcd fot ereh . rcrlrhc.t. Iocludr . !.Pr 3chcE tle. or dercrlgtloo of flor rcglcntr' Sihrct llou (ApPllcrblc co T. oaly)Scgocot ID l. Surfrcr dGtctipclo! (trblc 3-l) 2. u.nntq'. tougloco cocff., o (ttblc 3-l) .. 3. lloo l-n8th, L (totel L ( 300 ft) i[. tgo-yr 2{-hr rrtafell, P2 ......... 5. lrnd llopc, r fr 1o trl ft b36. 1,.?#$# l?. v - l.{e r:/3 .t/2 Cosput. tr .......G{1 Sh.lloe cooccotntcd flor Scgncnt ID ?. Surtrca dclcrlpBloa (prvrd or unptvrd ) ..... 6. Fla l.oath, L . fc 9. grtcscou:rc rlope, 3 rrrorrorrorr........... tlllt 10. Avrregc rclocltt, v (fl$rc 3-t) ........... ttl. Irl. t. .36ftn co8put. Ie ...... tr Chenncl tlor Scgncnt ID 12. Ctor rccBlonrl f!,or rne, I rrrrrrroooorooe Crz 13. g.t!.d g.sl-!.a, p, ........... ft l{. Bydrrullc ndtrr, t'-i c6ps3. ! ....... fB ?Y 15. Cbraml .log., . ............. ftlft 16. .llraala3'r rou3hn.r. cocft.r o rrorooorrr.... .[,;! tt. llor La3rh, L . ft tr. rr -# 20. ta.t.r.h.d or lubrr.. tc or lt (rdd ta h 3c.Pt 6' Corputr Y ....... Ctl. CocFrS. lG ...... hr ef0Vl-fR-s1 Second Ed"' June 1986) H a D€ I I I I I I I I I I I I I t I I I I I I I ,l: .10 - .06 - .04 - +,rb oILo cl oU'Ltoi,Lo.a,a- | | -ta | | | | | | t It2-46lo20 Average veloclty, ftlsec Flpn &l.-.{vcnfe vclociticr for crtimrtin3 tnvcl tirne for shrltor co||ccntrtt d fl,or. (2IOVI-TR.55, Second Ed-, June 1986) 5. 6. 7. E. 9. I I I I I I I I I I I I I I I I I I I I I Workshect 4: Graphical Peah Discharge mcthod Pro1.cr L,un,s Q:a,€ *{rvu* t !/,/^-\LcrBlon :/ .L'(- - J Clrrckcd ---f--Ctrclr oot: Prc!.nB Dcvrloocd l. Drce: Dretnegc arla ...... .. .. \. Ruaoft curvc nrobcr . ... Cf,. ttr of cooc.olrait oo .. tc . Ratlfall, dtrcrlboclon tygc - Pood .nd lraop arcar rgreadghroqghout rraccrshed Frcqucncy Ratafall, .ed q d2 (rcrcr/640) '== r (Pro tlort,thrcg 2) , Z"? hr (?rol sorkshacc 3)T J.t/- (I, lA, lI, III) 2. 3.P (Zt-hour) p.rccn! of A" (- acrcs or c12 covcrcd) SEor[ el Slom tZ Scon 03 /o o z-. + tn yr tn 'ttJ IotBlal abalracBtou, I. .......... (Usc C$ irlth hble 4,-l:) CoEpuBc lalp ........ Untt pcdc dkchargc, q. . . . . . . . . . . ,,r. . . . .(Uac T. aod I./P rdth ;rhtbtt 4-L) Ruoolf, q ........... (8roo workshccc 2). Pond aud rveap adJurtocuG f.cEor, F- ....(0rc perceor pond and !*ratrp aree . Y utBh rabla tb-2. Factor ls 1.0 lor z€ro pctccnt pond .nd sraap erca.) Pcak dlscharg., qp ...... (Thcrc q, . quAJFp) 32d ,05-l' ' ct.,OG cro/la to : 'l BIGVI.TR"66, Second Ed., Junc 19g6) Sqa'Bksttr Gn o.c, y'-'! -7't DrE. D{ I I l, l. t I I Ir 0!r) Ir 0n) I I I I t I I I I I T li I I I rhelr g - peak aischarg€ (ds}qr - urdt peak discharge (csrn/in}Aa - dretnage area (mi4; Q - nurofr (in)r and Fp - pond and swamp adjustment factor. Tbq gp"t requirements for t}e Graphical method are rs follorru: O) T. 161, (2) drainage aiea (nrfl), (g) lpfoedate rainfall distnlbution (I, IA, tI, c lltl, tO2l.furr rsinfall (in), and (5) CN. If pond and o*,.rp' argalr arte spread thmughout the watershed and ari not corcjdered in the Tc computation, an adjtrstment tor poad and ssamp areas is also needed" Peah discharge computation For r celect€d rainfall frequency, t}e 24-hour rainfall (P) is obtained from appendix Ii or morc detailed local precipitation rmps. CN and total nrnofi (Q) for the vatershed ar.e computed according to the T€thds outlined in drapter 2. The CN is used to detxririne the initid abstnction (I.) from bble 41.I/P is then computed. pt\ -clmputed Ir/P ratio is outside tlre rznge shownb e*ibit 4 (4-1, +llt" 4II, and &lII) for the-rainfail distribution of intercsl t}en tlre limiting value sbrdd be used. lf tbe ratio falls between the limiting vdues, use linear interpolation Figure 4l iltustrates- tne sensitivity of I"r? to CN and p. Peak dischrrge per squane mile per inch of nrnof(qd ia obuined from exhibit +I, 4-IA, 4.lI, or {.Ilt .by-*q Tc (chapter 3), tzinfall disei[ution type, anaItf? ntio. Tbe pond and swamp a4iustment iector is obteined lrom table {.2 (rounded to tlre neerest tablevduel Use wor.lsheet 4 in :ppendix D to rid in conpulins the peek discharge using the Gnphical Dethod &000 2.918 z?@ z65l LW 2.4A4 2348 2255 z161 z0lJz 4000 r.9?9, r.846 I.TIl 1.704 1.636 t.5?l 1.500 t.{48 1.390 r.cB t.ztg t.26 1.175 Llzi\tn 1.080 0.985 0.941 0499 70 7t 72 7B 74 75 76n ?8 ?9 80 8l &, t3 8r 85 &t cl EE 89 90 9l c2 98 9{ 95 96n 98 Chapter 4: Graphical Peak Discharge method 1$is drapter prcsents the Graphical peak Discharce uethod for computing peak discharge ftom nrrat ird tlrbrn ereas. the Graphical method was develooed fron hydrogrzph aralyses using TR.20, ,.Complter ryFlg for hoject Forzurlation-Ilydrology; (SCSlS). 1le pesk discharg,e equation rised is-- Qp 'QriAa1QFp tEq.4-U @IGVI-TR.55, Second Ed, June 1986) IIt,tult t trt n (D, ti.,|.r Fllurr &1.-Yrrlrtion of l./p for p lrd CN. Curre number 40 4l 42 ,a & ,15 {6 47 {8 49 60 5l 62 68 5{ 55 56 57 58 59 6{' 6l 68 63u 65 66 el 6E @ 0.E57 0tl7 0.?78 0.70 (l.7IB 0.6frt 0.$a 0597 0564 0.532 0.5q) 0.{69 0.439 0.{t0 038r 035!t 0Jat 0299 0.ct! 0247 0.u2 0.t98 0.t?{ 0.151 0.128 ot05 0.088 0.0G2 0.oil Tablc ,t-I.-I. valucr for nrnofi curve numbcrs +l T I I l' I I T I I It(986I aunf "pg Puor€ 'gg-UI'l/\{Ia Unit peak discharge (9r), csm/inl, oooor\r (, 5 !4 Or = I t 8t , 5 Er! a GI |D €B F Ia u) !t |D -lE, D' cL t :l 0 -{s I(D o C'r'c)ota.5@ -l-n, u o = fl $fr.r YOst\o,: .i Gfi - I I I I t I I t P I Oo- 5- ,,1 .,- - = S r,r8-BlJ ru { Lt O /\t J lforlshcct 2: Runofi curvc numbcr and nurof? Drc orr.4-r'^ ?p DrC. Clrelr onr: l. Eunof? cunrr nnbrr (6f) 't :rl t !. I 'i ISotl nar ead hydrologle trouP (epgcndlr A) Covrr dercrlpct on (covcr Bypr, !r!ag!art!, aod bydrologlc condl r.1oo: p.rcanc ttp.rtout; uncourccrd/cocn.clad tapcrvtoureru racto) Ptoducg ot Gl : eru Q- <" u- - , Urc only one C[ rourcc A.r ttn..locals. cr (rnrshrrd) ffiff 1'h3 . 32 _ usr ct -r.. o,q -; @ 2. Runolf Fiequcncy rr Selnttll, P (2i-hour) tr &rnofl,_Q .!............ 10(Ur ? ead ef rtBh rebrr 2-1, iii:-i:i. -oa .q.. 2-! ud 2-t.) Storo ll Scon 12 Scoo f3 /o o 2, I €IGVI.TB-$6, Sccond Ed., Junc 1986) l I I I I II I I I I I II IIi :1 ,l ,l t RUNOFF FOR INCHES OF RAINFALL NOTE: Runoff value determined by equation q = (P-0'2 S)2 p+ 0.8 S REFEREIICE: flationat Engineering Handbook, Section 4, HyDROLOGY N 0.0 0.1 o.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 00 0.cl v.uz 0.05 0.0 9 c. l3 l? I 0.22 0.2a 0.34 c.40 0.4 7 c.54 0.6 !0.6I 0.?5 0.83 2 0.el 0.99 t. o7 t. l5 \r.23-l.3t I .40 1.48 1.5 7 1.65 3 i .74 I.83 l. e2 2.0l ?.10 2. 19 2.22 2 .37 2.46 2.55 4 2.64 2.7 3 2.82 2.92 t at l. 10 3.20 3.2e 3.38 3.48 5 3.57 -2.66 3. 76 3.85 J.9)4. 04 4.14 4.23 4.33 4.41 6 4.52 4.62 4.7L 4. 8l 4.9C 5.10 5.19 5.29 5.39 7 5.48 5.58 5.68 5.77 |. q7 5. 97 6.06 6. t6 6 .26 6. 36 g 9 6.45 6.55 6.65 6.75 6.84 6. 94 7 .0q 7.t4 7.2t f.33 7 .43 7.53 1.63 7.12 7 .82 7.e2 8.02 8.L2 8 .21 8. 3l 10 8.41 8. 51 8.6l 8.71 d.tsu 8.90 9.00 9.lc 9.20 9.3C 11 9.39 9.49 9.59 Y. OY 9.7 9 9.89 9.99 10.o8 lc. t8 t0.2e t2 10.38 10.4e 10.5e 1C.68 10.78 I c.87 10.97 11.07 lr.t7 r 1.2? l3 1I .37 II.47 11. 57 I l. 67 1l 7o 11.86 11.96 LIoUE 12.16 12 .26 14 I2.36 12.46 lz. f o 12. 56 t2.75 12.85 12.95 13.05 13.15 13. ?5 15 1r.35 13.4 5 13.55 13.65 t1 75 I 84 i.3 .94 14.04 14.14 L4.?4 16 1i.34 Lq.44 L4.54 I {. 64 L4 .1tl L4.84 L4.94 15.0 4 15. l4 t5.21 L7 15.33 I5.43 15.53 15.63 15,73 I5.83 I5.91 16.03 l6 t3 L6.23 l8 16.33 t6.43 16.53 16.63 I6.7 3 16. 82 I6.92 t7 .o2 t?.12 L7.22 19 L7 .t2 Ll .42 L7 .52 L7 .62 17.72 17.82 L1 .92 18.02 l8 L2 t8 .22 20 I e.32 18.42 t8.52 I8. 62 18.?l Ir.8l I8.91 19.01 t9.tl 19.21 67 t I I t' l. I I I I t I I I I I I I I I I I Worksheet 3: Time of concentration (1") or havel time (I1) S,e -}astN q D.c. ,/- /-?o Drt. Ltc,.,,s /2,,> le<,,> .J?A-<rt--'-'u:ePlojact i-'t'u '\t a /<\;-' 't '- - Dt-: t/,,, r:\OreekcdLcftlon t/ u _ \_ iJLC|tloo Glrclr oor : -tr!tj'b{G;D Ctrclr oc: tc tt throuSh rubrru mts: Sprcr lor .a r.oy .r tro a.tmolr prr flor ttP' cro bc urrd lor och . rorlrharc. tacludr I up, rcbrorllcr ot d.acrlPlioo oa flou rrglrntl' -@.,1!$, (Appllcrblc co 1" only)S.tacnB lD l. Surfrcc d..crlpilon (.trblc 3-l) 2. thnnlng'r toughacr eorft., a (trble 3-l) .. 3. llog 1.n8th, L (rot.l L < 300 tt) .......... l. flro-7r 2{-hr rrlofell, ?2 ......... 5. Lnd.lopcr t 1o C.lf,r hr6.r,."#+# te. tr.# -m Slrrlloc coocaorr.tcd floe Sctlcng ID 1. $rrfrcc d.!c!1P31oo (prvrd or uoprvcd ) ..... Coaput. tt ...... E. FIor lca3th' L ............ 9. lbcrrcoutrr rlopr, | .ooroooorerr 10. Avrrrgc vrloclty, V (!18urc 3-l) ........... u. rr -#Cooput. It ...... Ghenncl tlos Scglcnc ID fc C.lCc Cclt ha '7/o'i1 12. Croaa .cctlona! flot tro, I roe.roo..rrrr.r tr2 13. tfGtlcd p.rtct.a, p" ........... ft ta. E drrullc ndtur, t'-J CotPut. r .......ru lt. Cbraa:l .lop.. . ............. fcllB 16. . llennlnj'r rou3hnrrr cocl!., n .. o r r.. o r o o. oo lr. v - t.lr t3l3 .tlz cooputr y ....... It. Flou hn3ch, L ............ Corput. tt ...... fB Cc-l t fr h! 20. gr3.s.h.d or .ut r.r tc or tB (.dd tB ln 33.P. 6' ll' rnd 19) ....... hr elGVI.'lB-54 Second Ed.' June 1986) a DA I I I I I I I I I t I T T I I I I I I I I I a,I .P c,Cl'o ta orat- =o(,go .aJ a!- .10 - .06 - .04 - .02 - .005 I | | | | | | | tt124610 Average veloclty, ftlsec Flpn 3,'1.-.{vcrq: vclocilicr for Grtirnrtint tnvcl lime for rhrllor comcntnLd llor, I | | | ttt (21&VI.TR-55, Second Ed., June 1986) \ ne ^8AS t rv p,I I I I I I I t I I I I I t t I T I I T T Worksheet 4: Graphical Pcsk Discharsc mcthod //1pro1ecr Lrct^lS 2',DCe *S- ry Dql-n t ll ' . ," .rlocrcton i/+l l , i- u Chcckrd D.ta DrB. l. Drca: Dr.llt|g. tr.r .....,.d.. \. Rsaotf curvr nnbrr . . .. Cll . tl!! of coac.ota.lLo[ .. tc . Ralafell dktrlbutlon Eyp. - Poad aod sreop trcar rprud Bhroughouc raccrshcd ...... . ' oo / d2 (rcro/640) E i (trq rorlrhrcq 2) V hr (?ror rcrkgh.r 3) - 2. 3. Ercqucncy R:lnfall, P (2i-hour) latelal abrlracEloo, Ir .......... (Urc Gl sfth B.blc 4,-l:) Coupucc Ia/P........ .......... Poad and ts.!p .djulrq.tc fteGor, l_ ....(Urc pcrccot pood end $ralp araa . P rlch 8.b1. tl-2. FacBor lt 1.0 lor zero pcaccnt pond and srrop erca.) Pealc dtgcherg.! qp ...... .c!r (Thcrr {, - q,r[QFp) p.rcloB of A, (-.cr.! or nt2 covcrcd) Scon ,[SBorl! rZ storl! ,3 /o) .') 'J t! rE ta ,?aa ,13 80 l.zz I t. '8. 9.,8a elOlrI.TR.56, Second Ed., Junc lgBB) -,/-l o Clrclc om: /prrsrrr. F;;; 6. 0ctc pcat dttchergr, q. ..........r....... crdta(Urc T" ead I"/p r'lBh &htbt B 4-h D. t l, I I t' I I t I t t T t I I whet€ 9p 9u An a FP Chapter 4: Graphical Peak Discharge method This chapter presents the Graphical Peak Discharge metJrod for computing peak disctrarge from nrral elrd urtan areas. ltre Gnphical method was developed fron hydrogrzph analyses using TR.Z0, ,.Computer Proqry for hoject Formularion-llydrology,'' (SCS l9B3I Tbe pe* aisctsrge eqr:ation us€d is Tb9 input requirements for the Graphical method ar€rs follows: (f) Tc ftr), (? drainage area (mr?, (B) lpptDpriate rainfall distntution 0, IA, II, or III), (4) 24-bour rainfalt (in} end (S) CN. If pond and ,*"rrrp treas aFe spred tluoughout the uatenhed and are not considered in the T. computation, an adjustment ror pond atd suramp areas is dso needed. Peah discharge computation For a seleced rainfall ftequency, tlre 24-hour rainfall . (P) is obtained from appendix B or morc detailed local precipitation maps. CN and total runof (Q) for tlre watersh€d are comput€d according to the methods outlined in chapter Z. The CN is used to deterrnrine the initial abstraction (lJ from tabte 41.IjP is ttren mmputed. if t}e computed I"/P ratio is outside tlre range shown in exhibit 4 (eI, eIA,4II, and &IID for ttrininfan distribution of interest, t}en the lirniting value chould be used. lf the ratio falls betwe€n the limiting vdues, use linear interpolation Figure +l illustratBi' &e sensitivity of Ir/P to CN and p. Peek disch:rge per squrre mile per inch of nrnotr(qrt i! obtaitled from exhibit +I, {-IA" 4II, or &IIt lf_uSnq Tc (chapter 3), rainfall distriburion t1rye, and Irt? ntio. The pond and slpamp eqiustment iactor is obEined bom table +2 (rounded to the neerest tablevduel Us€ uorksheet 4 in appendix D to 8id in conpuling tbe peak dirhargi'rrsing t}e Graphicat l!€thod 9p - Qu&nQFp tEq. a.U - lreak discharge (ds); - unit peak discharg€ (csn/in); = dminage area (mi4; = runoff (in) and = pond and swamp adustment factor, ltrrtlllt br.t n (t). t|.t a Flpr: &1.-Vrriation of L/P for P and C?{. Curye number Ir 0n) L tu) Ed., June 1986) I I i t t T 40{l 42 43 tt4 45 46 47 4E 49 60 5l 62 63 51 56 56 TI 5E 59 6{' 6l 62 63 6{ et 66 6' 6E 69 ma 7i2 ?:t 74 75 76n 78 ?!) 80 8l & 83 84 85 86 a7 88 89 90 9r c2 git 9{ 95 96n 98 &0(n z.EE z7e, aetr 2.W 2-1/A 2.W 22fi LITIzw 2.000 t.w2, 1.846 \n1 l.7It4 1.636 L5n 1.509 t.t4E LSn laB t-??t t.% Lr?5 t.r4i LUNl.m 0.985 0.9{r 0f99 0.657 0817 0.n8 0.7{0 0.flB 0.6{it 0.frE 0.597 0.564 0.5:P 0.500 0.{69 0.4i8 0.410 0381 0.353 0326 0299 0.n3 0247 0.n, 0.r98 0.1?,r 0.r51 0.r2E 0.105 0.083 0.06c 0.0{l Table ,l-1.-1. valuer for nrnoff cunc numbcn €IOVI-TR-SS, Second +l 9?(986I aunf "pg puor€'9S-uI'IA{IZ) Unit peak d ischarge (9u), cstn/in H HE I t I T- t I t I I t I I I t I I. 5- Or- @- I gg E E3B B 8 * 5 E(! a(: GI(D :r a ta (D :l D F @{(tI t :l - CN clt l\) ao o 'oo5oot.' .ll o5 o +f Y'Dqt\o--6t/|l I I I P I Wclrshcct 2: Rrurof? curvc numbcr and runof? ,-l^!roj.c! -'J" I <': 'i'i : S rgf-iJ tocecton \/z '- ( ) crr.t. o*@{ l. l,unof! curvr urobcr (Ctrf) :, I I. I I D.ta Drcr Soll aec eod hydrologlc troqP (eppcndlr A) CoY.a dalcstpctoa (corc cypc, Brarcaa!!, atd bydrol,oglc condlBlo!; Frcanc t oprrvtour;,.nconcoc!ad/coanac!.d Lopcnrlour:rca ragl,o) EJ actatElrz Produc! ot6 r rrce Qe:,.2- -' i 1 ,1.- -z I .{ - U* only oar Gl coqrcr pcr ltnc.lotak . 9@t O a tr ta lo I I t I I I t I I I I I I I I I I I I I I cr (nc!8hcrd) . ffis$ss' -'r'! - /,i 2. Runot! lraqucncy btnlell, P (24-hour) Runotf, q........... (Ur. P .nd cil ntrh teble 2-1, fig. i-i.or .qr. 2-t end 2-0.) Urc Gf -GT Scon fl Sconr 12 Stotl 13 /o o Z4 ,37 enVIjtR.56, Sccond Ed., Jnnc 1986) I I I I I I I I CU RVE 67 tb It ': i ,II I RUNOFF FOR INCHES OF RAINFALL I t I I II :I t I I I I I tloTE: Runoff value determined bv eouation g = (P-0'2 S)2' P+0.8S REFERENCE: National Engineering Handbook, Section {, HYDROLOGY N 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 1 0 .00 0.00 0l 0.02 0.c3 0.05 0.07 0.0 9 0.12 0.l( 2 0.l7 c.2l o.24 0.z8 a .32 0. 36 0.40 o.44 0 .49 0. 54 3 0.59 0.64 0.69 o,7 4 n in 0.85 0.9?1.03 1.09 4 t.l5 l.2t 1.27 l. 34 1.40 i. 4?1.53 1.60 1.67 1.74 5 1.80 1.8?1. 95 2.02 2.Ce Z. 16 2.23 2.31 2.38 2 .46, 5 2.53 2 .61 2.o6 2.7 6 2.84 2.92 2.99 3.07 3. 15 3.23 7 3.31 3.39 3.47 3.55 3.6 3 l.7t 3. ?9 3.88 3.96 4.04 I 4.L2 4.2L 4.29 4 .37 4.46 4.54 4.63 4. 7l 4.80 4.88 9 4.97 5.05 5. l4 5.2?5. 31 5.40 5.4 8 5.51 5.66 5.75 l0 5.83 5.92 6.0l 6.lo 6.18 6.27 6.36 6.45 6.54 6.62 11 6.12 6. 8l 6. 90 6.98 7.C7 7.16 7.2t 7.34 7 .4)7.52 T2 ? .61 ?.71 t.80 7.89 ?.9 E 8. 07 8.16 a.25 e.34 8. 43 13 8.53 8. 62 8.71 8. 80 8.89 e. 98 9.0I 9.1?9.26 9.J5 L4 9.45 9.54 9.63 9.12 e.e2 9. 9l t0.c0 10.09 10.t9 10.2e 15 10.3?1C.47 1c. 56 10.65 I0.?5 I 0.84 l0 .94 ll.0?11.t2 Lt.22 16 I I.31 I 1.40 1I. 50 11.59 11.69 11.78 t1.87 1I.97 12.06 12. t6 t7 L2.25 12.35 12.44 t2.54 12.63 12.7 7 L2 82 l2 .91 t3.01 13.10 18 13.20 13.29 13. 39 13.48 13.58 13.6?L3.77 t3.8?13.96 14.06 19 I4.15 14.25 L4.34 L4.44 L4.53 1q.63 L4.7 2 14.82 14.92 15.01 20 l5.lt 15.20 15.30 15.39 L5 .49 15.59 15.68 15.78 15.8 7 15.97 47 Iij_ I I I l' I' I I I I I I I I I I I I I I I I mlts ! Sgrcr lor rt lray la tuo ..t!Gotl prr tlor BtP. c'o bc urcd fot elch rcrkahact. tacludr r orp, rcheortlcr os drrcltptlon of flou 3'8ECn!r ' -@!$, (Appl!.crblc co l. only) Scgocnt ID l. Sur-frcc dcscrlptloo (i.bl. 3.l) 2. ltrnnJ'ag'e roughnc$ coc!t., o (t.bl. 3-l) .. 3. Flos length, L (lotrl LS 300 tl) .......... fr {. trroTr 24-hr rdafell, P2......... 10 5. lrad .lopr' t .. trllt Ctrclc our: tt.::DGD Ct rclc onc: T]- Tr lhrou8h rubrnr 6.?r-w lt. e - t.tg ,]/3 .l/2 .ECorput. lt ...... br Shrllog conccntratcd flor Sagp.nc ID 7. Ssrfrce dclcrlPBloa (prvtd or uaprvcd ) ..... 8. Etor lcotth' L ............ lt 9. uetcrcourrc rlopc, I or.roor..rro........... !t/fl 10. Avctrge vcloclGy, Y (fl8ure 3-l) ........... tclc tll. t. -33ftn colPura I. ...... * Chenncl florr SG8!Gn! tD t2. Ctolr rccttonel flou rru, l rorroreroorrrrr ttl t3. gcrlcd p.rlo.tar, p. ........... f! la. Btdrrullc rrdtur, r'.-! CoEPut. t ......r fttv 15. Chrancl .lope' . ............. ftlfc 16. . ltenntng'r roughncrr cocff., a .rorrr.rrrr.ro -t4 re. tr -51fu c put. Y ....... Cclt Cooput. tG ...... hr 20. grrrtrhcd or rubrrrl Tc or tG (rdd ta 1n 3c.P. 6. ll' rnd t9) ....... hr efGVI-Tn-5S, Sccond Ed.' Junc 1986) 1 L e ^9 Lstr"t E Worksheet 3: Tirne of concentration CIs) or haYel time CI1) ' ''.- *"+Pso1.ct Ltotr 3' ltDC€ .:*Du'!e ArrM,' t./Lcrcton '/^' ,_ '.- ') Cheekrd - Drl. E D8 I T I I I I I I I I T I I I I I I I t I I I oCIo ai o6L =o(, Lc, o- .10 - .06 - .04 - .005 | | | t | | t)t I t1246'10 Average veloclty, ftlsec Fltun 3-I.-.{vcng: velocitics for rrtimrtinf tnvcl timc for shellow concmtntcd tlor. ttl (ZI0-VI.TR-55. Second Ed.. June 1986) 2. 3. 4. 7. 8. 9. \ I I I I I t I T I T I I I I I I T I t I T ' Sae-84J "'tT " Workshcet 4: Graphical Peak Discharye method ProJGcr Lro ni': 2t C Z+- I -9 rttZU Gtrrcked rg D*o t<'' j' 2 ) DrE. l. Deca: Dralnegr .r€. .......... \ . Ruaoft curvr nnbrr .... Cn. lln of coEcaolaaclol .. Ta - Ratnfall dlttrlbuElon rtp. ,. Pood aad sreop ercar rgrtedghroughouC rnccrshcd ....r. I ,OO Z-a.2 (rcrcr/640) 67, (?ro sorkrhcct, 2) ' 'o hr (Prol rorkrhrcc 3).-- (r, Il, tr, trr) ceo/1o ltr pclccoB of A, (_ acrar or u12 covcred) Frcquency lalnfall, P (2{-hour) Scora Sl s to ro lrz Stor[ ,3 /a o -) /; 1o yr 1tr ,qgslIntclal abclracBlon, Ia ....... (Usc 6l ertBh reble Gl:) Coopucc la,/p ........ 6. Oolc pcak dl.schergc, q.. ..... ......l-....(Use T. ead I./p dBh ;xhtblt q-21 Ruoof!, a...........(froo rorlrshccc 2). Pond and svalp adJurtoc[! facBor, F_ ....(Usc pcrccnt pood and $raap arca . P ulch cabl,c 4-2. Faccor k 1.0 lor zero. p€rccot poad aad sraop area.) Peak dtscherg.r qp ...... (tJtrcrc qO - e,rA.QFn) ,4/ 6oo ,3zl ' cfa ,38 @IGVI.TR.56, Second Ed.' Juao l$6)DI I t Chapter 4: Graphical Peak Discharge method This chaptcr pr€sents the Graphical Peak Discharge method for omputing pe8k discharge from rural and urtan areas. lte Graphiel method wes devetoped from bydrograph analyses ruing TR.20, "Computer Prcgram for hoject Formulation-Ilydrology" (SCS 1983). lte peak discharge equation used is qp 'quAEQFp [Eq.4-l] where gp - peak disclurge (ds); qu - unit peak dirchargp (csrdin) Arn - dreinagB area (mi4; Q = nrnofr Cur); and Fp = pond and sramp adustment factor. The input reguiremgnts for the Graphical met}od are . es follows: (f) Tc ftr), (2) drainage area (miz), (8) appopriate rainfall distribution (I, IA, II, or III), (4) 24hour rainfdl 0n), and (5) CN. If pond and swamp arean ane spread thmughout the watershed and ar.e oot considered in the T" computation, an adjustment for pond and swamp areas is dso needed. Peak discharge computation For a relected rainfall frequency, the Z-hour rainfall (P) is obtained from appendix B ormore detailed local precipitation maps. CN and total nrnofi (Q) for t}re watershed are computed according to the methods outlined in chapter 2. The CN is used to determine the initial abstraction (IJ from t3,ble 4.1. I/P is then compute4 if the computed I./P ratio is outside the rznge shown in erhibit 4 (+I, ,LlA, +lI, and 4-lll) for the rainfdl distribution of ints€st tllen the limiting vdue should be used. If the ratio falls between the limiting values, use linear interpolation. Figure 4.1 illustrates the sensitivity of Ir/P to CN end P. Peak discharge per squane mile per inch of rrurofr (qd is obtained from exhibit 4.I, 4-IA, 4II, or 4-III by uing T" (chapter 3), rainfall distribution tlpe, and l./P ntio. The pond and swamp adjustment factor is obteined Fom table 4-2 (rounded to tlre nearest table vdue). Use worksheet { in appendix D to aid in computing the peak using the Graphical met}od I It' i I I I I I I lr 0n) Cunre Lnurnber Cn) I T I t I Ii ttrrtlllt Ll.t ll (tl. lraa Fldre l-1,-Vrrirfmn of l./P for P ud Cll. Cune number I I I I I & {t 1t2{la 45 46 17 48 49 50 5l 52 59 5{ 55 66 5? 58 59 60 6l 6A 63 6{ 65 66 6? 68 60 &000 ?AE zTd\ 2651 23tS L14,' z.ga 2.8 LI6I 2.o&, Lmotg, It46 Ln4 L?IX L536 r5n L509 1.4r8 1J90 13:B tgtr t92tt l.l?5 t.125 Ltn l.tBo 0.s5 0.9{l 0-E99 0.857 0817 0.7?8 0.7{0 0.7(E 0.66'/ 0.6u 0.597 0.56{ 0.532 0500 0.,163 0.{i}9 0.4r0 0381 035:l 0346 0299 0nB 0247 0.w 0.r98 0.1?4 0.r51 0.128 0.!05 0.083 0.0@ 0.041 70 7l 72 73 74 ?5 76n ?8 ?9 g) 8r & 83 8r 85 E6 cl 88 89 90 9rn 93 9{ 95 96 9? 98 t Tablc &1.-1. nlucc for runofi cuuc numbcrs (2IGVI-TR-55, Second Ed-, June 1986)+t I t I I l. I t I I t l, I I I I t t II. ) J €85I aunf "Pg Puotas 'gg'uJ'Lt{Ia Unit peak discharge (9u), csm/inH se 9? (t or =x I (tr coo 5 gl qt l\t 3o o 'oo5.lo =C}.' .!, o:l o ,\: :PYOs,\o.^ rDvlt trJI 5 (D !9 a(t rl GI .D B o-t u) CA E(! rltr =g, a a i F = Ol- O0- E- I. I I I I I I I I I I I I ; I I I T I I I I lo*rhcct 2: Rnnotlcur'! numhr and nurofi SuB -g+s/N V7'- lc.cton tJ+r .- f- C) ryD.la Qrrckrd Drcr ',' ' n- I I 0.r. '/.-'--><'--\C,ltch oar: r?rurag-litlvrlopcd j l. luaolf cunrt rubrr (6|) ,t i :. I Sotl orn .!d bydrolo3te Sroup (:pprtrdlr A) €a .r d.rcEtpclo8 (corrr Eypr, Braalo [:, rod Lydrolog!.c condt!,loa; t rca6t tlp.rtour; |[conn cf.d/coacrcBcd tsp.!?lou!.r.. F rlo) ProducE ot6l r enr ".<q: --)r '' ) t.:/fl l: r.z a'j e -- = -V - Ur. ottlt on C[ ronrcr grt llnr. cr (crrShrd) .ffis -/'r'.=l .rBra /,3 2. &rnof! toEelr . A'-O / Urc Cf, -,GV, lrrgurncy . . . . . . . ,, . . . . . . . . F lelntell, P (26tour) tl lumft, _Q tD(ur. p .rd cr vtr,h cebtr 2-t, iii:-i:i. -- or .qr. 2-t ead 2-{. ) AbVI.TR.56 thcond E4 Junr llllD Ston ll Scotl f2 Scoa 13 /ad Z-,-f /.zc RUNOFF FOR INCHES OF RAINFALL (P-0.2S)2 P+ 0.8 S REFEREI{CE: l{ational Engineering Handbook, Section {, HYDR0LOGY I I I I T I I I I t I ! I II I I ] ll0TE: Runotf value determined by equation Q = CURVE 87 N 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 c.00 0.cl L.02 0.05 0.0 9 c.l3 0.t? 1 0.22 0.28 0. 34 c. q0 0.47 c. 54 0.61 0.68 c.75 0.83 2 0,91 0.99 l.I5 'r ,1 l. 3I 1.40 1.48 1.5?1.65 3 i .74 1.83 Lo-rZ 2.01 2.10 2. Le 2.22 2.37 2.46 2.55 4 2.64 2.7t 2.82 2.92 3.CI i. l0 3.20 3.29 3.38 3.48 5 3.57 ).7 6 3. S5 3.95 4.04 4.14 4.23 4.31 4 .4? 6 4.52 4.62 4.71 4. 8l 4.9C 5.10 5. le ,.29 5.)9 7 5 .48 5.58 5.68 5.17 r 07 5. 9?6.06 6.l6 6.26 6. 36 8 6.45 6.55 6. 65 6.75 6. e4 6. 94 7.0.+7.14 7.23 7.33 9 7 .43 7.53 7. 63 't.72 7.e2 7.92 8.02 8.T2 I .21 8. 3l 10 8.41 o <t 8.6I 8.71 8.80 e.90 9.0f.r 9.lc 9 .20 9. 3C 11 9.39 9 .49 9.59 9. 69 9.?9 9.89 9.99 10. o8 lc.I8 10.2e L2 10.38 10.4e 10.58 1C.68 I0.?3 I 'J. 87 10.97 I1.0?I I.I7 I I.27 l3 1r .37 11.47 1t. 57 I t. 6?II.?O 11.86 r1.96 12.06 12.16 12 .26 14 12.36 12.46 L2.56 12. 66 12.?5 r2.85 12.9'13.0 5 t3.r5 Lt.25 15 13.35 I3.4 5 L3. r,I3. 65 I3.?5 r 3.84 13.94 14.04 l(I4 14.?tl 16 I {.34 I (.44 I4. 54 l(.64 t4.?4 I4. 84 14.94 15.04 15.14 t5.2? L7 15.33 15. 43 15.53 I5.63 15.?3 I5. 83 15.9 3 16.0 3 l6 L3 L6.23 18 33I6 16.43 16.53 16.61 16.71 I6.82 t6.92 l?.02 l?.12 L7.22 19 I7.32 L7 .42 l?.52 17.62 17.72 17. 82 l?.92 18.02 I8 L2 L8.22 20 18.32 18.42 18.52 18.62 18.?l I b. 8t 1.8 .9 1 19.01 19.11 19.21 67 -t.l .,i J z.r.| t I I I' I I I I I I t I T l I I I. T I I tr lroJ.c! Lc.31on !uo--a,{!,r4 fr Worksheet 3: Time of concentration Cts) or travel time Cl1) tr l 'tko Drt. Chrckrd - Drt. ,t t>-4 Ctrch oorf Prrlrne-' DrvrloPcd crr.r. *.i-:] t.-trroultr ruberrr 2 a - O'007 (nL)0'6s. .r - -ll-dl5--6-FE2 | Strrllog concrltrrtcd flos m.t!:l: Specr lot r. !.ot rr tso r.t!Gq!t P.r lloe ttD' crq br ured for .|cb . srlrb..t. tacludr a crPt acb.tatte, or derctl'ptton ol llor rclpcntl' Sbcct llos (Appllcrblc to t- oaly)Segrac ID l. 3grfrec dclcr1pc1on (trblr 3-l) 2. tlrmlog'r roughlase coc!f., I (srblr 3.l).. !. !1or, lcngth, L (!ot.l tS 3OO ll) .......... ft l. lrro-yr 2{-hr rrlsfell,, 12 ......... 1a 5. lrnd rlopc, r .. tr.ltl- Coqut. 1g...... br Scgcnt ID 7. Surlecr &rcrlptloo (prvrd or uaPrvrd ) ..... 8. Eloo 1ea3th, L ............ 9. Hrtorcorrrr rlope, a ............ 10. lvrrrgc vrlocitt, f (ftjurr 3.l) ........... Iu. r. '53ft1 6emc1 f 1or 12. ftor .GcBloorl flor erre, I ooo.rroo.rr-ro Cx2 1,3. lhttrd pcrlr!.s, pr........... !3 ll. lydrultc rrdlur, r-- f Cqst. r ....... ttPI l!. Cbeonel .lop., . ............. ftltB t6. . lhanlaj'r !os8ho.r corft., !.rrrrrorer.... l?. r-t.qg'lj.rl2 l!. llor lmjth, L ............ lc ttt. lB . ffi6T Caprlc. tt ...... hr 20. tLt.r.h.d ot erbrro tc or t! (.dd tG b rcrpl 6' efSVI-lB{6, Sccod Ed' &m 1I5) Crput. It ...... -E -tI -fl I,eol Ir trltr ttlt br Scpcnr lD Capo3. V ....... Cll'' ll, ead 19) ....... br D8 I T I I I I I t I I I I I I T t I I l* T I SyS -8,,n-s, u liL D.Ea Drr. ., 1, O-Q ,t t[ 1! z. 3. {. 5. tr AGVI.TR{6, Srcod Ed., Jun rS6) Worksltcct 4: Graphical Pcsk Dfuchar3l mcthod lFoj.cr ( tons Qt DG €- ,---S:ll-Dz/k .f - -)Lc.rton |/ttc-. t-'J Cbrckrd Ctrclr oor : {_Pr"""!rr_rylgrd/ l. Drcs: \ Dot-g. .rcr .......... \ . ,'JC L- d2 (rcro/640) tnoo!! curn nllber .... q - O a .(lrl rorbhecc 2) tt'r o! coic.qrr.Bror .. t . =T hr (tra norkrh.c 3) iatllaii dtrErrbuclor Byg.= . =r' (t, IA, tI, tll) Posd atd :saqp arcar lprrad rhroughout mtarrhrd ....-- ' , p.rc.aB ol rn (- .cr.! or ct2 covered) Frcqucncy 8:tolall, P (Zitour) Ittctal ebrcraccloc, Ir .......... (Urc Gl rrlth c.bl. 4,-l;) colpuca la/p . . . . . . . . . . . . . . . . . | . . . . . . . . .. 7. Rurott, a ........... :......(9roc rlorkrhaec 2). 6. Pood end rrnlp edJurcnrc! fecEor, F- ....(0tc prrecot goad ead tr:ap .raa . Y rtch ctbh 4-2. Frccor tr l.O lora.ro pa-rclnr, poad end sreag erre.) 9' ?cel' dtrchergQr {p . . . . . . . . . . . . . . . ,. . . . . . . (lllnrr q, . e.,flafr) 'ct. SEoE! ,1,Scora tz SBor! ,3 /c c/ ,zq 7l , /Z ,Jd c /,23 | ?,q6 6. Untc Acak d&chergr, q.' . . . . . . . . . . , . . . . . . . cro./t q (Urc t rod I./p ntBh &drrbtc L-h Chapter 4: Graphical Peak Discharge method Ilis chapter presents the Graphical Peak Discharge method for eomputing pesk discharg€ from ntal and utaa areas. Tbe Graphical method was developed lon hydrogaph uralyses using TR.20, ,.ftmputer lryryn for hoject Formulation-tlydmloeiy,'- (SCS 1983). lte peak discharg€ equation used is qp = quAnQFp [Eq. 4-r] where qp - peak discharge (cfs); 9u - unit peak dischargt (csnr/in); Attr = drainage area (miz); Q = nrnoff (in); and Fo = pond and sramp adjustment factor. Tbe input requirements for the Graphical method are . rs follows: (1) Tc Or), (0 drainage area (mi4, (g) lppropriate rainfail distn"bution (I, lA, II, or III), (4) 24boru rainfdl (in), and (S) CN. If pond and srramp arss aFe spread thrcughout the watershed and are not considered in the T" computation, an adjustment for pond and swamp areas is also needed. Peah discharge computation Fora seleCed rainfdl frequency, the 2rthour rainfall (P) is obtained from appendix B or morc detailed local preeipitation maps. CN and total nmotr (Q) for tle watcrshed are computed according to the methods outlined in chapter 2. fire CN is used to deterzrine the initial abstrzction 0J fum table &1.IjP is tien computed" if the computed I./P ratio is outside the range shownh exhibit 4 (+I, &IA,4II, and 4-III) for thtrainfall distribution of interes! tien t}re limiting value lhdrld b€ used. If ttre ratio falls between t}e limiting vdues, use linear interpolation. Figure 4l illustrateJ tlle sensitivity of I"t? to CN and F. Perk dischrrge p€r square mile per inch of nrnoff (qd is obtained from exhibit 4I, 4.IA, 4.II, or 4-III _bf_usinS Tc (chapter 3), rainfall distribution t1rye, andI.P:atio. The pond and sramp a4iustment i""tor is obteined bom table 4.2 (rounded to the nearest table velue). Us€ nor&sheet 4 in appendix D to 8id in cotrputing the pedr dbcharye rrsing the Graphical netbod I l. t, I t. I I T I I I T I I tttrrlltt . Ll.t ll (r). i.cr.t Fl3n 1.1.-Varirtion of l./P for P and Cl{. Cune number Ir 0n) Ir 0n) I. I T i i!I' 40 ,tla 43u {5 ,16 47 {8 {9 50 5t 6i2 5g 54 oo 66 67 58 59 60 6t 62 63 64 65 56 61 68 69 70 tt 72 ?3 74 IJ ?6 al ?8 ?9 80 8lp, 83 84 as) 86n 88 89 90 9l 92 93 94 95 96 97 98 &000 aaTtl z7@ z65t 2At5LU 2.W 2255 Lr61 e0{P 4000 t.E2 l846 Ln4 l.?04 L686 1.571 1.509 1.44E 1390 t.&t3 tzt9 tc26 l.r?5 l.lzi \gn l.0g) o96tt o94t 0899 0.85? 0.8r7 0.n8 0.740 O.?IB 0.667 0.en 0.597 0.564 0.582 0.500 0.{@ 0.{39 0.410 0381 0.353 0.326 0299 o.gig 0247 0.@, 0.198 0.t?4 0.151 or28 ot(E 0.083 0.@ 0.fir 1986) T €lOn-TR-ss, Second Ed., June I Tablc {.1.-I. valucs for runoff cutre numbcn ,l'l I ,- I I I l. l' I I T I I I I I l. . , J (986I eunr'?g puoJas 'gg-uJ,'lA{Ia Unit peak discharge (Qr), csm/in It r\l (, 5 (Jt Ol = I t -t @ o(rr oroo I -1 I t I l: 5 Or co 3 |D o 'floao |De '+.' .D 0: {o st8S\orat x 5 o .Do GIo a o- a rt -r9o E i!t E' a a i(t = Or- @- 5- I I