Farm Pond Designs for Moderate to High Rainfall Zone of Marathwada Region based on Rainfall-Runoff Relationship

Abstract:Accurately designed farm ponds enhance water storage and agricultural resilience during Marathwada’s dry spells and variable monsoon patterns. In this study, runoff was estimated using the SCS Curve Number method, which considered various parameters such as soil type and vegetation. The rainfall-runoff relationship was analysed to facilitate the planning of small water harvesting structures, like farm ponds. The runoff potential was found to be 31.69% of the rainfall, indicating significant opportunities for rainwater harvesting and the construction of additional site-specific structures. The established rainfall-runoff relationship is represented by the equation Y = 0.608X – 209.2, with an R² value of 0.9575. This linear relationship will aid in predicting runoff for any rainfall event in the area, allowing for a more accurate determination of rainwater harvesting potential and its reuse for enhancing the productivity of various rainfed crops. Given the climatic variations in the last decade—particularly concerning rainfall intensity, duration, and frequency—there is a need to redesign farm pond sizes in Marathwada's rain-scarce zones for effective implementation of the farm pond program. The recommended farm pond sizes include storage capacities of 939 cum, 1,677 cum, and 2,811 cum for catchment areas of 1 ha, 2 ha, and 3 ha, respectively. Based on these storage capacities, square-shaped farm ponds with top dimensions of 22 x 22 m, 28 x 28 m, and 35 x 35 m, a depth of 3 m, and a trapezoidal side slope of 1.5:1 are proposed for the State Department of Agriculture's implementation.Key words: Curve number, farm pond, micro- catchment, rainfall, runoff.