Estimating Infiltration in Open‐ended Furrow Irrigation by Modifying Final Infiltration Rate

Abstract

AbstractThe Kostiakov–Lewis equation is one of the commonly used infiltration equations in furrow irrigation. Elliott and Walker developed a two‐point method to estimate coefficients of the Kostiakov–Lewis equation. The basic infiltration rate (fo) in the Kostiakov–Lewis equation is usually calculated by the inflow–outflow method to determine the other two Kostiakov–Lewis parameters. In that method the entire furrow is used as an infiltrometer, which can cause overestimation of fo. In this study, by considering a correction factor in the mathematical calculations where the newly calculated value of fo is represented as fo* and the values of the a and k parameters, as calculated during the advance phase, are represented as a* and k*. The amount of infiltration volume estimated by the proposed method was evaluated using 21 open‐ended furrow irrigation data sets by calculating the relative error (RE) index. The value of fo decreased and the values of a and k increased by using the proposed method as compared to the Elliott and Walker method. Therefore, the results showed that the proposed method estimated infiltration volume with greater accuracy (average absolute RE = 4.0%) as compared to the Elliott and Walker method (average absolute RE = 7.8%).