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Relief <br />Soll <br />Infiltration <br />Vegetal <br />Cover <br />Surface <br />Storage <br />Given: <br />Find: <br />Runoff Coefficients for Undeveloped Areas <br />Watershed Types <br />Extreme High Normal <br />/ <br />0 ... 1~ .28-.35 .20-.28 .14-.20 <br />Steep, rugged terrain Hilly, with average Rolling, with average <br />with average slopes slopes of 10 to 30% slopes of 5 to 10% <br />above 30% <br />-· <br />~,o& .12-.16 .08-.12 .06-.08 <br />No effective soil Slow to take up water, Normal; well drained <br />cover, either rock or clay or shallow loam light or medium tex- <br />thin soil mantle of neg-soils of low infiltration tured soils, sandy <br />ligible Infiltration capacity, imperfectly or loams, silt and silt <br />capacity poorly drained loams <br />V <br />Low <br />.08-.14 <br />~ Relatlvely flat land, with <br />average slopes of O to <br />5% <br />.04-.06 <br />High; deep sand or <br />other soil that takes up <br />water readily, very light <br />well drained soils <br />.12-.16 .08-.12 0,0J ✓ .06-.08 o ,o.&> .04-.06 <br />No effective plant Poor to fair; clean cul-Fair to gocx:l: about Good to excellent; <br />cover, bare or very tivatlon crops, or poor 50% of area in gocx:l about 90% of drainage <br />sparse cover natural cover, less than grassland or wocx:l-area in good grassland, <br />20% of drainage area land, not more than wocx:lland or equivalent <br />over good cover 50% of area in cul-cover <br />tivated crops <br />.10-.12 -✓ u' I \ .08-.10 .06-.08 .04-.06 <br />Negligible surface Low; well defined sys-Normal; consider-High; surface storage, <br />depression few and tern of small able surface depres-high; drainage system <br />shallow; dralnageways; no sion storage; lakes not sharply defined; <br />dralnageways steep ponds or marshes and pond marshes large flocx:l plain <br />and small, no marshes storage or large num- <br />ber of ponds or marshes <br />!fSL <br />An undeveloped watershed consisting of; 1) rolling terrain with average Solution: Relief 0.14 o,,IS'" <br />slopes of 5%, 2) clay type solls, 3} gocx:l grassland area, and 4) normal Soil Infiltration 0.08 0),,(/)g <br />surface depressions. Vegetal Cover 0.04/!P-tJ{il) <br />Surface Storage 0.06 Cb" I I <br />The runoff coefficient, C, for the above watershed. C = 0.32 --···· '(Jl,4-<l <br />~ 00 <br />" <br />,-.,. <br />'< 0 <br />~ ' ...... <br />>--' °' (I'.) <br />00 <br />00 <br />::c ...... <br />0 ::c 0 ,, ~ -· ► )> OQ '"< <br />C: r <br />-i t::I <br />(\) t,,j -I <br />co UJ ::D ...... ..... 0 )> <br />lO z . z tv :::: l> ► en <br />z <br />c::: <br />► r