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Table 9 <br />IA and RTIMP estimates for developed areas <br />(tu be used with the Green and Ampt infiltration equation for estimating rainfall losses) <br /> Surface Retention <br />LOSS (IA), inChes Effective Impervi~us Area <br />RTIMP, percemt <br />Land-use Mean Range Mean Range <br />(1) (2) (3) (4) (5) <br />Developed (Residential and Commercial) <br /> 1/4 acre 0.3 0.2-0.4 30 23-38 <br /> 1/3 acre 0.3 0.2-0.4 22 15-30 <br />Single Family <br />R~~sidential <br />1/2 acre <br />0.3 <br />0.2-0.4 <br />17 <br />9-25 <br /> 1 acre 0.3 0.2-0.4 14 8-20 <br /> 2 acres 0.3 0.2-0.4 12 7-20 <br />Multi-Family Residential 0.3 0.2-0.4 54 42-65 <br />Commercial 0.1 0.0-0.2 85 51-98 <br />Industrial 0.1 0.0-0.2 59 46-72 <br />Lawn and Turf 0.3 0.2-0.5 0 0 <br />Pavement and Roof Tops 0.1 0.0-0.2 95 95 <br />Agricultural <br />lilled fields irrigated pasture 0.5 0.1-1.0 0 0 <br />The i:hree infiltration parameters are functions of soil characteristics, ground surface <br />charzicteristics, and land management practices. The soil characteristics of interest are <br />partic:le size distribution (soil texture), organic matter, and bulk density. The primary soil <br />surface characteristics are vegetation canopy cover, ground cover, and soil crusting. <br />Value~s of Green and Ampt equation parameters as a function of soil characteristics alone <br />(bare; ground condition) have been obtained from published reports (Rawls and others, <br />1983; Rawls and Brakensiek, 1983), and average values of XKSAT and PSIF for each of the <br />soil t~~~ure classes are shown in columns (2) and (3) of Table 10. A best-fit plot of columns <br />(3), (4) and (5) in relation to XKSAT from column (1) is shown on Figure 4. Figure 4 should <br />be used for selection of values of PSIF and DTHETA based on bare ground XKSAT. The <br />19 March 2007 31 <br />