BOARD OF NATURAL RESOURCES AND CONSERVATION

Abstract: An extensive literature review of existing hydrologic and hydraulic models has been conducted to select a mathematical model suitable for simulating the dynamic processes of wetlands and their impact on the hydrologic responses of the watershed containing the wetlands. Due to the lack of a single suitable model, a base model was developed by incorporating watershed and channel-routing components from two of the reviewed models. This physically based, distributed-parameter model has been tested and applied to one of the selected test watersheds in Illinois to evaluate the impact of wetlands on the watershed hydrology. The simulation results indicate that the peakflow reduction due to the presence of wetlands is significant for wetland areas of up to 60 percent of the watershed area. The reduction in peakflow was observed to diminish with distance downstream of the wetland outlet, indicating that the influence of the wetlands decreases as the distance from the wetland increases. The model results cannot be generalized for other watersheds until the model has been tested and verified for several watersheds i