Field Evaluation and Analysis of Surface Irrigation System with WinSRFR (Case Study Furrow Irrigation)

The low irrigation application efficiency is the major problem of surface irrigation systems due to weak management and poor design. In this research، in order to analyze the performance of furrow irrigation system، a field experiment was conducted during maize growing season. Three furrow irrigation methods; conventional furrow irrigation، fixed alternate furrow irrigation and variable alternate furrow irrigation were considered to collect field data and، then، to evaluate the performance of WinSRFR (surface irrigation model). This model was calibrated and evaluated based on the experimental data with Zero-Inertia (ZI) and Kinematic Wave (KW) solutions. The sensitivity analysis of WinSRFR showed that the most sensitive parameters were inflow rate، cutoff time and parameters of the infiltration equation، respectively. There was a small difference between ZI and KW to estimate advance time، runoff and infiltration due to high field slope. The minimum absolute error for estimation of advance times was obtained about 1. 5% (0. 8 minute). The minimum absolute error in estimating runoff and infiltration were 5. 7 and 5. 0%، respectively. Using operations analysis of WinSRFR، the iso-performance contour plots of furrow irrigation system was obtained to optimize cutoff time and inflow rate under maximizing of application efficiency and distribution uniformity and minimizing of runoff and deep percolation. Application efficiency iso-performance contour plot of fixed alternate furrow irrigation، indicated by managing of cutoff time and inflow rate، application efficiency could be increasing from 54. 5% in current evaluation to 74%، provided water supply of Dreq. Also based on this contour plot، increasing of application efficiency more than 74% was impossible provided water supply of Dreq، under current furrow geometry parameters and it was possible with changing furrow geometry parameters.