|
FIDOJr SrVd~PS
<br />r~
<br />L J
<br />•
<br />•
<br />curse>: snch as sure 28(I3) are con-
<br />SL`JCtcd I)}' pi0:atlg lag times obtained
<br />from h}'ciro;;raph ana!cscs (fig. 2.)
<br />LL„
<br />~'c•rsus respcctnc -__ factors for
<br />\'J'
<br />basins of simi'.ar runo`T character-
<br />istics.)
<br />(e) c.Ic•~; .. di:r,_r.~ionless graph (ft,^^,.
<br />°3(C1)-u;u:!!.: t};c mean dimen-
<br />siri::r:ss graph of .. number of di-
<br />mc~:;ionirs praphs dcriced for the
<br />same stream or for s:ra.:ns of similar
<br />ci:aracten~;ics.
<br />(f) Select unit ra::fall d:: ration time-
<br />shcu~d be onc•-iourtl: or less of lag
<br />time icr basis:.
<br />(>;) Compute unitgraph (fit. 28(D) )
<br />t:s~n~
<br />(i) Easin area.
<br />(°) L: g time plus ona-haif unit rain-
<br />fall dura:ie:: time.
<br />(~) ;Jimer.sio:aess prza`t.
<br />(i;) Comt' ~ted uni:grap}: mar be used zs
<br />Sho•:..: on figure _^G(~).
<br />55. Tr;onGulcr Hydrogrcph Anclysis.-The pr3C-
<br />;:ca:•:i!.;?' o` repre,c.^.;;:gig a c>•dro.rapb as a
<br />...ar~ir and the re!atieahips that can be de-
<br />t.!~rn•~c' b~' s,,ch represzraation is presented on
<br />55. fsrimaring Tirnc of Con cenlrolion.-.i5
<br />>ho:~:r. on focre °_9, tea general equation for
<br />cor-.p:::!c~ the peak discharge resulti.^.g from
<br />. ~i•:c.^. antnur.: o: r;:no;T is r,;-"~T'~ in «~•r.ich
<br />r
<br />T.= ~ -O.ST.
<br />The term G.GT. is ar. c:npirica! relationship
<br />:rci~;r,cd by '^~ dro;o~is.s of the foil Cor.sen'a-
<br />.n: S~-:':icr..::: repn-'scn:atit•c of 1., lag uma.
<br />~~. bleb. is drimcd ns :he t:mc in hours from the
<br />^:u!;,oic: o` excess rai::fa!1, D. to the time of
<br />::~ di>ci:a:~c. The re:ariot:sit:r of L to other
<br />b,drr••'~pit factors is ='~nan or. ^gt:re'_`tO;).
<br />~•~:rput;::inn n: ::drr~rap}a inn ur.~nccd n'a-
<br />tcnhrd< b;: :.~,;tic:::icn c[ the egca::or.s gn'cn
<br />::' f:acre ~° is d^pcnden: c:: ar. es:~matc o: T„
<br />,.... o; car.,.,..._.~,-r;. o .... ,..,tens^~a. der'~ned
<br />,. -ce trace t.ma of v;a,er irom :he hcdrauli-
<br />~'~.'Ip r.,os: dis:a^: point ci t:~,e v:aurshed to the
<br />hc:nt o; tnteres:. Various methods of es:imao
<br />('
<br />ing T, ::rc giccn an fi~urc ~0. 'These data :ur
<br />admittcdl;: gcnrraltzcd br•c:wsc the roncon4'a-
<br />tion oC runuf` is aTce:cd by storm dititriLuunn
<br />o~'cr the •::atcr.,hed and storm intcr.s,t}', u~ t~cll
<br />as b}' the v:atershed's h~•drauhc sit:,ractc:'i,-
<br />tics. I: data me a~'ailabin, ma's titan w:u
<br />method of esuma;in;; time of concentratimr
<br />should Lc a:c~ to select :I reprr.cut:~:its c;r!uc
<br />for a p:u ticuLu' v.atcrshcd.
<br />Cuid~•~ to a_sa; in csrim:~;in~ T,rrn o:,ta.n-
<br />inp a umtpr:.pl, for contpu:ntion of ii~ oa i.,:'.r,:~:
<br />to a full rescr•:oir arc Ficc^ ir. ia.:rc ~1. F i~
<br />urc ~1 (A), (^n), ar.d (C) shnt~• three exa::;n~~•c
<br />of stream long;hs that control estim;ucs for a
<br />fu11 resen'oir. ~','hcccecr is is po=s~l,lc to ob-
<br />tain a T, ea!ue from strcamflo•.~ recr~rd: r,i t'nc
<br />strum o; ir.:crest or by dc;ailcd held i.ap,c-
<br />tion of stream channel and ~~:a:crshrd c::.`,r.:c-
<br />tcristics, t!:a: t•a!ue should be used. 1Chen i.
<br />is necessar>• to c tin:ate a T, t•aluc. inp• IGlIOIt'-
<br />ing equation, can be used
<br />T.= -li J
<br />In f.°urc 30. ..,, adjustment should be :n::a~~
<br />usit:g calucs from table ~ bclott'.
<br />TACLt: J-.a rlJus: n:[n.'s IUr T. Icr trc L'ry%I rtts ¢'('>:
<br />!l+5' mrn~hnu surf r,r..rnauiuo us r~urLrr-n~:~~ rrrf rra: r~.
<br />sh Pr.'s rest ar Jos' re rric ren. 1l of er pole tr r.,r :.:rn.
<br />~x r;: T',
<br />so i ..
<br />:o ~ ~
<br />co ~
<br />so - -
<br />\~'atcrshed rot•cr at:d surface riru,•i:::c<~
<br />cause a re:ardance o.r suriacr runoP.-. :', r. ~~<-
<br />timatc of tl:i; rc:ardance erect t...~ Lr•!r: incor-
<br />porated in t:ne rcno:T carte ::umt~ers CX ~~~ ;o
<br />C~ SO for .~I,.'C-II for t•:atcrshcr.= ~•:cst ni the
<br />105= meridian. This adjus::::r.:: i.:,:oa ^-; ~'
<br />al<o be used for ti.^.:bcrc,l «'atcrsi:;;.'s ir. °.oun-
<br />tainous rr~icns cast cf :he 10;, rxr~d.;:n, b.a is
<br />r.o: appiiceb!e to other ;y'pc rc~:a.< c.'st of the
<br />!OS' mcndi~n.
<br />57. Applicorion of Triangular Hy~~rographs.-
<br />~sampies of :he applicator. o' iLC t:tan.%u'.::r
<br />hydrograph concept are presented on r:gure ~^.
<br />
<br />
|