Sensitivity Analysis of Performance Indices of Surge-Flow Irrigation with System Variables Using the SIRMOD Model

Abstract

A current challenge of irrigationengineering is to modernize surface irrigation. For example, surge flow irrigation has the potential to increase the efficiency of applying irrigationwater. The objective of this study was to perform a sensitivity analysis using the performance indices: Application Efficiency (AE), Storage Efficiency (SE), Distribution Efficiency (DE), Deep Percolation (DP), and Runoff (RO), and to investigate their relationship with the main system variables: length (L), unit flow rate (Qo), surge cycles and surge time, using the SIRMOD model. The SIRMOD model simulates the hydraulics of surface irrigation at the field level. The model with the best fit of AE, DE, DP, and RO as a function of L, Qo, or surge cycles and surge time was a quadratic polynomial function with an R2 > 0.70. The model reflects the goodness of fit to the variable that is intended to be explained. The AE is an increasing function of L and a decreasing function of Qo, while DE and RO are decreasing functions of L and are increasing functions of Qo. The number of surges has an impact on the stream size of each surge and on the volume of water stored, but not on the performance indices. It was demonstrated that the SIRMOD model provided the ability to adjust the system parameters and design variables, giving answersto any surge flow configuration. The potential application efficiency (AEpot) (>80%) can be achieved by establishing, e.g., an optimal flow rate (Qopt), with a schedule for the cycle number and surge time, according to soil characteristics.