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<br />SWfACl! WAtD 165 <br /> <br />TULE 5.7.1 <br />Approximate aver. velocities In ftIs 0I1'UlIOfr low for C8kub1tIaa <br />time 01 concentra.. <br /> <br />Do............ of ....... _ <br /> <br />t-J <br /> <br />Slope III ....- <br />4-7 1-11 <br /> <br />12- <br /> <br />: 5.6.4 <br />....... bydroppl 01 overlancl now. <br />,Iy flow q, is IIlIiDOd II lime of <br />.m ',. (Aller lzzInI, 1946.) <br /> <br />UIICOIICe\\IrIIed . <br /> <br />Woodland, <br /> <br />I'astuta <br /> <br />ClIItivaled <br /> <br />Pavements <br />Concentraaed.. <br /> <br />Outlet channel-detennine velocity by Maonina', l'Ilnnula <br /> <br />Naturo1 ch....1 001 <br />well defined 0-2 2-4 <br /> <br />0-1.5 <br />0-2.5 <br />0-3.0 <br />G-3.5 <br /> <br />1.5- 2.5 <br />2.5- B <br />3.0- 4.5 <br />1.5-13.5 <br /> <br />2.5- 3.;z, <br />3.5- 4.;z, <br />4.5- 5.5 <br />13.5-17 <br /> <br />3.25- <br />4.25- <br />5.5- <br />17- <br />(...:14lUlf..... <br />'(:!;I K'/.' I ~z <br />"J:. <br /> <br />v~~ K.Jt'5Y~ <br />~ <br /> <br />4-7 <br /> <br />7- <br /> <br />teady flow on the watershed. <br />;teady flow al equilibrium is <br />by Fig. S.6.4. Thus, the flow <br />.:d surface and in the stream <br /> <br />"This COlldition usually occurs in .... ...... ..- of a waImIIed prior to .... overland IIows _...... <br />ill I channel. <br />.~ values vary with the channel size and oda condiIioas. Wbere possible. more acaarMe ~ <br />should I>e made r.. ponicuw COlldi_ by .... -.. _I fmnula for velodly. <br />(500.." Dni.... Manual. laas Hipwoy ~. ~ VB. p. 0.28. 1970.) <br /> <br />.:d to another can be deduced <br />JI\ a stream are a distance L <br />n is v(/). where I is distance <br /> <br />Because of the travel time 10 the watershed outlet, only part of the watershed <br />may be contributing to swface waler flow at any time t after prec:ipitalion begins. <br />The growth of the contributing area may be visualized as in Fig. 5.7.1. IfraiilfaJl <br />of constant intensity begins and continues indefmitely. then the area bounded by <br />the dashed line labeled t I will contribute to streamflow at the watershed oudet <br />after time ,); likewise. the area bounded by the line labeled f2 will cootribute to <br /> <br />(S.7.1) <br /> <br /> <br />-........ <br />( .......... <br />\ ~---:: <br />/' <br /> <br />(5.7.2) <br /> <br />B <br /> <br />o increment of length Ai;. <br /> <br />(5.7.3) <br /> <br />tlGURE 5.7.1 <br />Isocbrones II I, Illd I, define .... .... COIIIt1'bu\ina ID now II !be outlet far niDfoll 01_ " <br />IJ1d I,. Time of conc:enll'llioa " is !be lime of ftow _ !be fatIbest poiDt in .... w-.bed (A) ID <br />!be outlet (8). <br /> <br />sing the methods described <br /> <br />