Watershed Modeling with State and Local Partners in Illinois

The Illinois State Water Survey (ISWS) has been developing a Dynamic Watershed Simulation Model (DWSM) using physically based governing equations to simulate rainfall-runoff, soil and streambank erosion, and entrainment and transport of sediment and chemicals in agricultural and rural watersheds. The ISWS collected flow, sediment, nutrient, and pesticide/herbicide data during storm events from the upper Sangamon River basin in Illinois draining a 2,400-square-kilometer watershed into the Lake Decatur and used these data to test different components of the DWSM. In this study, the hydrologic component of the DWSM was applied to a 251-square-kilometer watershed of the Court Creek in Illinois. The Court Creek watershed is part of Illinois' multi-agency Pilot Watershed and Conservation Reserve Enhancement Programs. The Court Creek Watershed Planning Committee, a local citizen based group, is responsible for making the watershed restoration and management decisions and utilizing appropriated resources under the above government programs. The DWSM-hydrology was calibrated and verified using data monitored earlier. The model was then used to identify high, moderate, and low runoff potential areas of the watershed to guide the initial restoration programs. The model will be used to evaluate BMPs, such as wetlands, detention basins, and dry dams, in reducing downstream flooding, erosion, and sedimentation in sensitive areas. This study was conducted in partnerships with the ISWS, Illinois Department of Natural Resources, Court Creek Watershed Planning Committee, and the University of Illinois at Urbana-Champaign. The paper describes briefly the DWSM and results on its application to the Court Creek watershed.