Estimating Saturated Hydraulic Conductivity using Green-Ampt Equation

The potential of groundwater recharge and the transport of agricultural contaminants from recharge structures in Badakhera watershed were evaluated using the one-dimensional Green-Ampt infiltration equation and soil leachability model. The saturated hydraulic conductivity k s , a parameter of the Green-Ampt equation, is normally calculated using empirical equations. The in-situ measurement of k s for the recharge structures in the Badakhera watershed is lacking. For this purpose, a field experiment was conducted to evaluate the performance of an in-situ measurement of the k s from infiltration rate and three other k s estimation methods namely; soil texture (ST), percent clay content (PCC), and relative effective porosity (REP) based method. Most effective and the reliable k s estimation method was selected based upon four evaluation criteria, as; coefficient of determination (R 2 ), index of agreement (D), root mean square error (RMSE) and relative bias (RB). The optimised k s values from field-measured infiltration data using Marquardt algorithm were adjudged as the most promising method for simulating the infiltration rate from the recharge structures. The responses of the PCC and the ST based k s estimate methods were comparable to each other, while the response of the REP based method registered higher deviation. The optimised k s value from field infiltration data can successfully be used for estimating potential recharge and transport of agricultural contaminants from the recharge structures in the Badakhera watershed.