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<br />is integrated to obtain the post-ponding infiltration function which is expressed <br />mathematically as follows: <br /> <br />where, <br /> <br />(FISt) - In(l+(F/St)) = (K/Sf).(t+te+lp) <br />te = (Sf/K)"(FplSf)-ln(l+Fp/Sf))) <br /> <br />(16) <br />(17) <br /> <br />Sf = Product of wetting front suction and soil moisture <br />deficit at the beginning of storm ( wf . (p-wc) ) <br />t = time in hours <br />lp = ponding time in hours <br /> <br />Parameters of the Green-Ampt equation can be estimated either by calibration or <br />from information available from soil survey data, Methods have been developed by to <br />detennine parameters from laboratory measurments of water content, soil porosity, residual <br />saturation, bubbling pressure, and pore size. In lieu of detailed measurments, the following <br />parameter estimates can be used based on soil texture classes: <br /> <br /> GREEN-AMPT PARAMETERS <br /> TOTAL WETTED FRONT HYDRAULIC <br />SOIL TYPE POROSITY SUCTION CONDUCTIVITY <br /> wf(In) k (In/hr) <br /> p <br />Sand 0.437 1.95 4.135 <br />Loamy Sand 0.437 2.41 1.205 <br />Sandy Loam 0.453 4.33 0.510 <br />Loam 0.463 3.50 0.260 <br />Silt Loam 0.501 6.57 0.135 <br />Sandy Loam Clay 0.398 8.60 0.085 <br />Clay Loam 0.464 8.22 0,046 <br />Silty Clay Loam 0.471 10.75 0.033 <br />Sandy Clay 0,430 9,41 0.025 <br />Silty Clay 0.479 11.50 0.018 <br />Clay 0.475 12.45 0.012 <br /> <br />Colorado Flood <br />Hydrology Manual <br /> <br />DRAFI <br /> <br />7.19 <br />