Evaluation of Potential Wetlands to Reduce Peak Flows in Future Climate Scenarios in the Eagle Creek Watershed, IN

Abstract:

Global climate change is expected to increase the severity of floods and droughts and the frequency of extreme streamflow events in the Midwestern United States. Managing these projected impacts poses a major challenge for water resources, conservation, and land use management. Wetlands have been considered as a conservation strategy and work to increase the capacity of watersheds by storing runoff upstream. The implementation of wetlands, especially in tile-drained agricultural watersheds, can reduce peak flows and help mitigate the anticipated impacts of climate change. The goal of this study was to evaluate the long-term performance of wetlands to reduce peak flows in future climate scenarios in the Eagle Creek Watershed in Indiana. A secondary goal of this research was to establish a methodology for incorporating climate change into hydrological models to conduct long-term land management studies and decisions. The Soil and Water Assessment Tool (SWAT) model was forced with an ensemble of bias corrected climate projections from the North American Regional Climate Change Assessment Program (NARCCAP) to evaluate the impacts of climate change on watershed hydrology and the ability of wetlands to reduce peak flows. Long-term monthly streamflow results predicted a slight increase in streamflow in the winter and a slight decrease in the summer from the past (1971-2000) to future (2041-2070) time periods. About half of the climate realizations produced an increase in the 5% exceedance flow and half a decrease, but all predictions agreed that high flow events will increase in frequency in the winter and decrease in the spring and summer. Results from the wetland analysis showed that if all potential wetlands identified in a previous study are installed in the watershed, maximum peak flow reductions of around 20-50 cubic meters per second for the past and future, as well as decreased frequency of extreme events, can be seen. Wetlands proved to be a robust solution for peak flow reduction, producing consistent reductions across all climate projections for both the past and future time periods.