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<br />MAR-28-2000 TUE 10:44 AM
<br />
<br />2b for tho storOl of April 1, 1970, wherc the rainfall
<br />that generated the runoff is reported too (~'ig\ll'o 2a),
<br />
<br />
<br /> O,e
<br /> os
<br /> ti
<br /> ~ 0,_
<br /> j:;
<br /> " 0.3
<br /> I!l
<br /> ~
<br /> ~ 02
<br /> ~
<br /> 0'
<br /> 0,0
<br /> 0
<br /> '00.
<br /> "'..00'
<br /> 200a
<br />'<;;'
<br />9. 'WQ
<br />~
<br />to;
<br /> 1CloO-
<br />
<br />':;(,~
<br />""i
<br />::l,~ r.
<br />~'a1Z.
<br />:~rr
<br />...i ~ .l .
<br />.'ll~\o !;~.~\
<br />~:'I:t ,,1.
<br />"/ rl~.",."
<br />.~) ''It'' II
<br />".r." fi.\:-
<br />",: : ~\~l
<br />':~~,-r~ l~\~-:::.
<br />
<br />'';'1,1-
<br />'~'1~r'
<br />~;,>. "
<br />.~!,!
<br />l.}~~' ,
<br />. ~l''\.
<br />,T';';
<br />~:"
<br />"y-t.'
<br />.
<br />
<br />1\,',
<br />
<br />["-:
<br />"
<br />'\"
<br />
<br />-',""
<br />
<br />. 7:~:
<br />':",
<br />", .
<br />
<br />$
<br />
<br />.
<br />
<br />, -
<br />2"'Cllolf 1'.811'1"11 P"IGClO
<br />
<br />
<br />-- Tol.., RUflOrl
<br />- - B:)seOow
<br />
<br />/--~
<br />,/ ~
<br />"../ ----,-
<br />-.J-
<br />o. . -"
<br />o
<br />
<br />SQo
<br />
<br />"'v H__r-'__'_'__"
<br />
<br />""
<br />
<br />2
<br />
<br />3 .
<br />Time (day)
<br />
<br />.
<br />
<br />.
<br />
<br />FIIfUI'C 2, St.rm or ^"rill, 1970, !AI Inm'mol1tol 1"'0-110\11'
<br />R:linCl\ll Pub.es; (n) UlU'lenoW St'lU\rntiol\.
<br />
<br />In principle, the recession (,Ollsh\nt is n ch:lrflcl:cris-
<br />tie oC tho watershed and is indeponuent of tho rainf"ll
<br />"vent. '1'" a rea.~onablo degree, this was observed for
<br />the I3rndford 511bbnsin, tUl evidenced by the COlllputed
<br />recession constnnts summarized in 'I'able 1, 'l'ho reces-
<br />si~n eonst,nnt varied from 24.5 days to 19,5 dnys with
<br />nn averago vnlue, kAva = 33,4 days, Figure 3 ,shows
<br />that recession constants were essentially independent
<br />of rninfnll depth and rainfall duration, which indi-
<br />cntes that the basonow separntioll procedlll'e WaR
<br />ullbiased,
<br />Tbo standard deviation of tho recession constant
<br />distribution is computed according to the eq\lation
<br />(Bard, 1971):
<br />
<br />( II 2)112
<br />Li_ I (I'i - k"v..)
<br />ak - ----.-...
<br />n-1
<br />
<br />JAWRA
<br />
<br />FAX NO.
<br />
<br />p, 04
<br />
<br />IIQurlldol
<br />
<br />wbere II i~ thl! total nlllllbor of observatilln:: 'Ii " 20\
<br />ami ki is tho rocession constallt obtained fl'''''' sl>'WI i.
<br />EqQation (3) gives a standard deviation of ". '"' 7.11
<br />days. The standard crrol' of knyo is cr.,,,., = "I: . 211!1l",
<br />= 1,GO days (IInyto1', l!l9Cl),
<br />
<br />lAI
<br />
<br />(S)
<br />
<br /> ..
<br /> >: so
<br /> '"
<br /> ~
<br /> ....,! .s 0
<br /> C
<br /> 1} '. 0 "
<br />7 {3
<br /> 3.
<br /> -~ . __...0--0---';
<br /> ~ 30 0
<br /> ~ 0
<br /> 0::. .. 0""
<br />
<br />o
<br />
<br />c
<br />
<br />y = O,p". .. ~1.~a
<br />r'" 0,02
<br />
<br />o
<br />
<br />o
<br />o
<br />
<br />___-..-...~.. 0
<br />o
<br />
<br />.
<br />
<br />20 .._".r-----'_r_____fir-_.___.."~_
<br />, :2 ~ "
<br />Rainfall Depth, (inch)
<br />
<br />.s
<br />
<br />..--...---.........
<br />
<br /> ~
<br /> '"
<br /> '"
<br /> ~
<br /> .>l
<br /> ;;:
<br />7 l1!
<br /> ~
<br /> 15
<br /> 'Iii
<br /> ..
<br /> ~
<br />
<br />'0
<br />
<br />y" -0 Of. . , 34.9
<br />? = o,ooa
<br />
<br />o
<br />
<br />..
<br />
<br />o
<br />
<br />'0
<br />
<br />c c 0 0
<br /> 0
<br /> __.0
<br /> VO----..-Cl___
<br /> 0
<br /> 0
<br /> e8 0 0
<br />
<br />35
<br />
<br />30
<br />
<br />00
<br />o
<br />
<br />" .
<br />
<br />20'-'''-T
<br />o '.
<br />
<br />,,-,"--
<br />
<br />20 30 0'\0
<br />Rainfall Duration, (hour)
<br />
<br />eo
<br />
<br />Fip.\lf<' 3. St.~ti!lLicnl <;on"f'lntic1l1 ('Irk wilh
<br />(A) 1b1..,l Runulri\no en) Slonn Dur.\LiOlt.
<br />
<br />(3)
<br />
<br />In the ubscnte of a pl'nbnbilily dil'lr'!>IIJi,,"
<br />~~sign to k, the Ghcbychcf inll<1\\alily ([!:I.I'tl
<br />199fJ:U7) can bc USl1U t,o pruvid(, a lowl>r 1,"':1,<1 un 1
<br />confidence in the Hlctln vnhl(~ knv\!' J [llWt'\'l'l', Jlll:
<br />information on the cOlllidOllt': in k.".c til" I." ohlil;n
<br />if k follows" probability dislribution, lI""wl,. till' n
<br />mal probability difJtrib\\tion, ^ I<olmug"')"-~;lI1irll
<br />(IIa.~tcr, 1!l!l6) tn~t ~I1JlPol'te,1 lhl! nl)l'1",oIil I' ..r k
<br />the 95 pen:""l confi<I,:'!1cc level. 'rhc Clllnlll,,1 il>.' r
<br />'1u"ncy distribution Wi!:""o 1) Rl,,>w~ ill"t I!l IIf t
<br />
<br />206
<br />
<br />JOURNAL o~ TilE AMI.;rtIC,"lN WArr.n rh.:~;t)IJI't"1 ,'. " ..,
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