Integrated Surface-Subsurface Modeling of Farmed Potholes

Wetlands in North America's Prairie Pothole Region (PPR) provide essential ecosystem services such as flood retention and wildlife habitat. Most of the wetlands in the portion of the State of Iowa within the PPR (known as the Des Moines Lobe) have been drained and are currently being farmed. We used integrated surface-subsurface modeling to study the hydrologic connectivity of three adjacent farmed wetlands in a 46-acre watershed in central Iowa. The model was calibrated against three years of monitored water table fluctuations. The calibrated model was used to run multi-year continuous simulations and study the surface and subsurface connectivity between the wetlands and ponding duration. Model results show that most of the ponding is driven by overland flow and subsurface tile drainage is the dominant hydrologic pathway. Furthermore, the maximum number of ponding days per year was approximately 100. In addition, we used the calibrated model to estimate the changes in potholes' water balance under projected climate changes. Our results can inform management decisions and profitability analysis for farmed potholes.