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parametric-regression method that can be used anywhere that certain soil, <br />• precipitation, and topographic factors are known (SCS, 1972). Runoff peaks <br />can be calculated for any recurrence interval for which precipitation values <br />are known. This method has the advantage of roughly accounting for land use <br />changes in the watershed. Thus, it is possible to compare pre-mining and <br />post-mining runoff values if the soil characteristics are significantly <br />altered. The fourth method is a regression based on the channel geometry <br />(U.S.G.S., unpublished Water-Supply Paper by Oster Kamp and Hedman). <br />Pryor Canyon does not have a measurable baseflow from snowmelt since <br />there is no cumulative snowpack in the basin. <br />3.1 Calculation of Peak Flow and Runoff Volume for Pryor Canyon entering <br />Permit Area. <br />Method 1 Arkansas River Basin Regression Analysis <br />The following relationship relates peak flow, 0 (cfs), to effective <br />drainage area, Ae(sq. mi.) <br />For 0.50 < Ae < 3.00 <br />010 = 500 Ae0.89 <br />025 840 Ae0.97 <br />0100 ° 1x550 Ae1.07 <br />The following relationship relates flood volume, V(ac-ft), to peak <br />discharge, Op (cfs) <br />V = 0.141 0 0.919 <br />F <br />For the Pryor Canyon drainage basin upstream of the point where the <br />drainage enters the permit area: <br />010 500 x (1.6 sq. mi),0.89 = 760 cfs <br />Q25 840 (1.6}'97 1325 cfs <br />0100 ° 1,550 (1.6 sq. mi.)1.07 = 2563 cfs <br />• <br />JFSA-36 <br />V= 63 ac, ft. <br />V= 104 ac. ft. <br />V= 191 ac. ft. <br />~~ 136 <br />1 E S112R 6 ASSQCIA7ES. tNC. <br />