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0 0 0 <br />Runoff Coefficients for Undeveloped Areas <br />Watershed Types <br />' Extreme High Normal Low <br />Relief <br />Soil <br />Infiltration <br />Vegetal <br />Cover <br />Surface <br />Storage <br />Given: <br />.28-.35 <br />Steep, rugged terrain <br />with average slopes <br />above 30°% <br />.12-.16 <br />No effective soil <br />cover, either rock or <br />thin soil mantle of neg- <br />ligible infiltration <br />capacity <br />.12-.16 <br />No effective plant <br />cover, bare or very <br />sparse cover <br />.10-12 0,11 <br />Negligible surface <br />depression few and <br />shallow; <br />drainageways steep <br />and small, no marshes <br />.20-.28 <br />Hilly, with average <br />slopes of 10 to 30% <br />.08-.12 <br />Slow to take up water, <br />clay or shallow loam <br />soils of low infiltration <br />capacity, imperfectly or <br />poorly drained <br />.08-.12 "S' <br />Poor to fair; clean cul- <br />tivation crops, or poor <br />natural cover, less than <br />20°% of drainage area <br />over good cover <br />.08-.10 <br />Low; well defined sys- <br />tem of small <br />drainageways; no <br />ponds or marshes <br />.14-.20 U a 1 <br />Rolling, with average <br />slopes of 5 to 10% <br />.06-.08 ',�. 0 & <br />Normal; well drained <br />light or medium tex- <br />tured soils, sandy <br />loams, silt and silt <br />foams <br />.06-.08 O .O O <br />Fair to good: about <br />50% of area in good <br />grassland or wood- <br />land, not more than <br />50% of area in cul- <br />tivated crops <br />Normal; consider- <br />able surface depres- <br />sion storage; lakes <br />and pond marshes <br />An undeveloped watershed consisting of; 1) rolling terrain with average <br />slopes of 5%, 2) clay type soils, 3) good grassland area, and 4) normal <br />surface depressions. <br />The runoff coefficient, C, for the above watershed. <br />.08-.14 <br />Relatively flat land, with <br />average slopes of 0 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 />.04-.06 <br />Good to excellent; <br />about 90°% of drainage <br />area in good grassland, <br />woodland or equivalent <br />cover <br />.04-.06 <br />High; surface storage, <br />high; drainage system <br />not sharply defined; <br />large flood plain <br />storage or large num- <br />ber of ponds or marshes <br />YS <br />Solution: Relief 0.14 o,,ls- <br />Soil Infiltration 0.08 009 <br />Vegetal Cover 0.04 0,0 4o <br />Surface Storage 0.06 0„ I t <br />C = 0.32 <br />