A new method of estimating infiltration parameters for furrow irrigation

In this study, we present new two-point and one-point methods for estimating infiltration parameters in furrow irrigation. It is assumed that infiltration and waterfront advance along the furrow follow the Valiantzas two-parameter infiltration and power advance equations, respectively. The two parameters, the sorptivity (S) and the saturated hydraulic conductivity (K_s), are estimated by solving a quadratic equation. The presented solution of the infiltration-advance problem is one of the few that uses physically significant parameters (S, K_s), which can provide adequate infiltration and advance behaviour at all time scales. The prediction of infiltration from the proposed methods is compared with experimental data and with the two-point method of Ebrahimian et al. and the one-point method of Shepard et al. The values of S between the two-point methods are nearly identical in all cases, while the values of the A/K_s ratio range from 0.48 to 0.89 (parameter A is related to K_s). Regarding the one-point method, the two examined methods yield similar S values as their relationship is given by the equation S_Shepard = 1.043 S_new (coefficient of determination $R^2=0.999$), while the values of the parameters A and K_s are linked by the equation ${\rm A}=0.69K_s$.