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<br />Food S:ud~es
<br />u';its of measurement used and the factors fo:
<br />rnn~~rr>ic:: t~ cosmos u::i!s. Taese comer.
<br />Tien i:«,u:'s are Ficcn in appendix B. ]n the
<br />l'ni:~•ci ~.;:,:c•=. prccipi:a:;on is .r.casurcd rn
<br />inr!r.~ :,:..: ru:,,,,T i> mec~tn'c•d in cubic feet per
<br />.rco::d +.::-o rcf~rrrd to as sccond•tret or
<br />. ;; ). :1!-u, the cn~in~~er must be cod nip::n:
<br />....., :~ h; ,ire ern, !~ n.` Term runo`i ol~tained at
<br />,. ~L'~ra.'.::^^cr ~; ~ ,..;:oa represents a~,c o:
<br />... ..• (•~ :!:C i(~iin:•:IP,h I,.'prc o, runoT from the
<br />u~: t~ra!;cd: c!:r.^:~.~•!, surface, inter(lo:r, a^d
<br />ba<r :i~''• i:rie: de5ni;ions of these t_: pes arc:
<br />(-i,a r, r, r! rvn+~r: Cawed b;: rain falling on
<br />,i:c v:aicr ~m•face of the stream. ]t bc-
<br />~ir.; v.::h the eta;; o: precipitation and
<br />..~ .' t•e cisc~•rnible legs; a slight rise of
<br />;hc ;:~cirn_rnph ius: after rainfall begins,
<br />Uc; .i;i• r,;:n:rii!;: of channel runn^•,' is so
<br />n:ali t: is i;:nered in h::cro~raph analyses.
<br />~,~:~rc.. i:,,; o::~r Ucccrs o:;!_•: ~': iron the rain-
<br />.all Tate rca:cr l::^.::r. ;..^ re;cr,t~cn hiss
<br />n~t,•. T!.. ~:pc o` runoT: cansrs most
<br />;lnod., :::~,: :hc cor.:pu:z+Jor:al p roccdur~s
<br />tii~< text consid^:' this t}•pc o: runoff
<br />c{un:i::a:~t.
<br />!„~•~r:,,;r: Ucc•ars t+'hen rain; all in5!trat-
<br />. ,. ,..c soil surface encounters an under-
<br />,•ro:r.td tune of loucr pcrmcabilit~•, trac-
<br />.<,ho~e the tone to ;:^.c surface dottnhill,
<br />..::,! reappcar> to Leconte surface runoT.
<br />...,.:y r.r of rio~': n:ac a!so be c:a!ed sut>-
<br />.. f.,rc .".,,t•: or "yuic}: rc:urr. flout."
<br />i;•• ~r Nu,r: The fair;>~ ,tcady' fiotc of a
<br />,urar.+ ;-rnm r.:aura! >tora~e, as shot':r+ b}'
<br />h>•d,ro~ra,!ts during ncn-storm (or non-
<br />:,rucc _ no•.t me!;) penods.
<br />In tlnnd F.>'droh~: :; is customary to deal
<br />';,;,:;,;,;', ..•:i:h I,a,r fioa: and to combine aII
<br />"'`,. :}';,~: of Mott into dnec' Henn[' in un-
<br />1
<br />+~~~~':: prupcruun., ;u assumed in this text.
<br />1; is nece~.~ar: to 4:nov: thc• tca[ershed area
<br />,^n'^ib:rt i.^.~ the rt;no;C ..: a ; ccn cocas;rune
<br />1•'::::::n order to express :hc runoff col::mc in
<br />::~ hr • of dcpt!t o•: cr the at^rshcd for com-
<br />;..,+~.on i;h t,reci;,;:a'inn amount=. ~\-hen
<br />r:..~;.+n;r ,cch cami:a:'+vo:a. :hc :uncurtt of run-
<br />„il. c~;ns.-~,i :,; iuchr:, i< termed ra+nfall ex-
<br />" .unl rife d+ icrcncc L,clo:cc:+ the rainL,ll
<br />5.
<br />excess and the total precipitation is considerec
<br />retention toss.
<br />The d;scu=sign which follo~•:s dc~cribc= a
<br />mcthed o: making s rain`:li-runxT :utal},is.
<br />The obiccti~~es n` such ana'~:>ca art: (]) th,•
<br />drtcrn::nation of a retent+on r:rc•, :md (^_1 the
<br />dcicrnt~n::uo^ oC the duration ;ir.:c tntrrcal cf
<br />r.un`all excess. .\ come^sen o; rc:c::uo^
<br />rate: drricrd from =e•:crsl ana!•:sc< '.~::~.cs to
<br />adoptia, of a rate for design good comb:;:;,-
<br />tions. Tile de:err.:ina;ion of the durat:un of
<br />excess rainfall is necessar}' for t..e h>':'.rod:':::!t
<br />' cctcrmir,a-
<br />anal_:ses cnm;~uta:ions in•:o,:ir.°
<br />bons o' ut:i!~raph; and !ae ;irr_>.. t':hich arc•
<br />discos;ed in section; 53. ~~, ~;,, and ~~. In alI
<br />such anah'scs, the ntno`T toiume t':hich t< a~~r.:-
<br />Farcd «'i`n precipi:a:for.:.ntoun:~ i= th::: o:h:c•h
<br />re'.ate= ciure;l to tee ra:n`:.i: ,...::.•r s:c~'.;:.
<br />Titcrefoi'e.:hc bate "ott' of t`;e strc.'.:^i0~•• h;:-
<br />dre;:raph m::s: be subtracted out i,~forc• c"n;-
<br />paraen~ re made (>ec ~cc. 53) .
<br />(bl .-t r+t. (+/ctc rl Oi,>(rt r~! ;;^i,, i,: !1 !in h: -
<br />(1) 1fr.s^ rxr:rc ni rciu`r.ii.-`;... curcd<
<br />of cun:;a;ai•:c• rair.`all d,:rin;; ;::e r:~r.m l,rr:•,:i
<br />shotac! be piotud for all prcc:p:;at+o!: ;:a:inn-
<br />ir. and near :`te b::.=in, as sho~•:r. on 5gur• -
<br />2~(.y). To shout c'.earlr the reia:ion of rair-
<br />fa;l :o rung``, it a some:tmcs dcsirabic to ;,lot
<br />the mass r,+n'cs to the s.amc time sc:,le ^. .:-.c
<br />di<t!;arpe I:rc!ro;;rph o; storm rtino:T. \l'su-
<br />ai!;, hove'Ter, the cun•e~ should br ~iccn a
<br />more expanded time kale than tt is dc: iraJ!Ir to
<br />use for :he't;;dropraph ::naly<is. t','hen on!~'
<br />one recorc!:n; s:a;+on r, located ne::rC,}'. a^.! to
<br />the absence of l+ct;cr i..^.format:<~::. the n:::-s
<br />cun'e o` prccipi:anon ~, a nonmcordmt: ,:a-
<br />non is usually' co^sidcrcd to b^_ propor::or.ai in
<br />sh:cpc to that of the rcrnrd:nc station, c~S:•pt
<br />as o;hen'rise cicfin.ed by the ub~cner's rc:u!+^^s
<br />and notes (fib. =~(:1)). The speed :unl dinc-
<br />t:on of traecl of the rain's:rst ~houl,i I~„ taker.
<br />into account. Diant' rainia!1 ob:rrters enter
<br />the tirrca of Lc~inr.irr„ and cr,d:n;; on ;cr sate:
<br />line as the current da+lr reads:,. The r:o:cs
<br />may' thrrc.`cn refer ;o tl:c pr,^nrn+s d::}', c=pc-
<br />cialh' t•:!:cr. the y:::ce is rcpul::rly rcn! in the
<br />morn: n::.
<br />(°) Isuit!rrtc! n+r.p.•.-The u::al amount. of
<br />ran+fal! occurrin;: curing the portion oC the
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