Water Balance Modeling of Temporary Ponding in a Drained Prairie Pothole Wetland

Farmed pothole depressions, common in the Prairie Pothole Region, frequently hold water during wet periods and play an important role in ecosystem dynamics such as flood retention and hosting migratory waterfowl. In this study, we developed a spreadsheet-based daily water budget model of a drained and farmed pothole in Hamilton County, Iowa, to evaluate how site-specific characteristics affect the frequency, depth, and duration of surface ponding. For a 3-year period characterized by a range of precipitation, the model predicted that on an annual basis ponded water would be present in the pothole approximately 14 to 47% of the time. Total ponding days ranged from 51 to 173 days year−1 and maximum ponding depth ranged from 112 to 334 mm. Infiltration rate, catchment-to-pothole ratio, and the presence of a surface intake had the largest impact on ponding depth and duration. Results of this study have implications for management of farmed and drained potholes and we can envision using the PPWB model to test potential strategies for pothole management from both agricultural profitability and ecological perspectives.