Simulation of Supplemental Irrigation from On‐Farm Ponds

Several researchers have shown that on‐farm runoff collection and supplemental irrigation systems can increase and stabilize crop production in many regions of the world. The objective of this study is to develop simulation capabilities to determine optimum pond size and irrigation strategies for supplemental irrigation systems. A comprehensive basin‐scale soil and water‐resource model is modified to simulate crop yield, supplemental irrigation, furrow diking, and economics. The simulation model is linked with a golden‐section search optimization scheme to optimize farm pond storage with respect to net profits from crop production under supplemental irrigation. The golden section is a direct search method and is applicable to optimization problems where an analytic expression for the objective function is unavailable. The model also produces monetary‐return frequency distributions for various pond sizes and is capable of determining the effects of various management strategies on crop production and water and sediment yields. The frequency distributions give decision makers a risk assessment tool for designing the pond. Simulated hydrologic components and crop yields are compared with measured values, showing the model performs well under various climate, soil, crop and management conditions. Finally, the model is applied to two basins in Texas, and results are analyzed.