A model to estimate hydrological processes and water budget in an irrigation farm pond
With increased interest to conserve groundwater resources without reducing crop yield potential, more on-farm water storage ponds have been constructed in recent years in USA and around the world. However, the hydrological processes, water budget, and environmental benefits and consequences of these ponds have not yet been fully quantified. This study developed a computer model to estimate farm pond hydrological processes and water budgets using the STELLA (Structural Thinking and Experiential Learning Laboratory with Animation) software. The model was applied, as demonstrations, to estimate the diurnal and seasonal pond hydrological processes and water budget at Metcalf Farm (33o 39 48 N, 90o 39 12W) in Porter Bayou Watershed located in Mississippi Delta, USA. Two simulation scenarios were chosen in this study, one without and the other with pumping pond water for soybeans irrigation. Simulations showed that the evaporative loss of water from the pond was minimal, while the runoff water from rainfall was a major source of water entering into the pond. Therefore, factors that would affect surface water runoff should be considered in locating and sizing a farm pond in Mississippi. The seasonal rainwater and runoff water collected by the pond was: winter > spring > summer > fall, which corresponded well to the seasonal rainfall events; whereas seasonal order of pond evaporation was: summer > spring > fall > winter, which corresponded well to the seasonal solar radiation and air temperature. The STELLA model developed proved to be a useful tool for estimating pond water budget and consequently irrigation practices for crops.