Comparison Of Infiltration Models: A Case Of Fentale Irrigation Scheme In Ethiopia

Abstract

Good understanding on the soil characteristics and site-specific steady infiltration rate could help to increase the irrigation water use efficiency in irrigated agriculture. The broad aim of this study was to evaluate performance of most commonly used infiltration models (Kostiakov, Modified Kostiakov, Philips, and Horton) in estimating steady infiltration characteristics and to find the best fit infiltration model for Fentale irrigation scheme in Ethiopia. Infiltration measurements were taken on irrigation command area of Fentale Irrigation Scheme using double ring infiltrometer at selected six points of the study area. Statistical model performance evaluation criteria namely coefficient of determination (R2), Root Mean Square Error (RMSE), Ei, GMER, and GSDER were used in addition to graphical observation technique to find the best fit infiltration model for the study area. Results revealed that Kostiakov infiltration model parameter such as the values of empirical constant and c were estimated in the range of 0.36-0.52 (in an average value of 0.42) and 5.84-28.01 in average 19.88 respectively. Modified Kostiakov parameters like values of empirical constants was estimated in the range of 0.27-0.52 (with an average value of 0.36). Philips infiltration models parameters like Sorptivity was found in the ranges of 6.68-69.77 mm/min0.5 (with an average value of 45.78 mm/min0.5) while Hortons models parameter such as constant was estimated in the range of 1.78-6.39 ( with an average value of 3.93). Results showed that Modified Kostiakovs model provided the lowest mean value for RMSE of 0.13, GSDER of 1.10, the lowest value for Ei of 23%, and the highest value for R2 of 0.99 as compared to Kostiakovs, Hortons, and Philips models. This indicated that infiltration can be well-described by the Modified Kostiakov model and gave a better fit to the measured cumulative infiltration depth and infiltration rate at the selected study area. Thus, the scheme administration is suggested to practice infiltration measurement