Evaluation of the Impacts of Wetlands on Watershed Hydrologic Processes Based on a Wetland Network Concept and a Surface Delineation Algorithm

Wetlands play an important role in the hydrologic cycle; however, assessment of the impacts of individual wetlands at a watershed scale is limited. Particularly, it is a challenge to identify and quantify the dynamic interactions and impacts of individual wetlands using watershed-scale hydrologic models. To address the related issues, a concept of wetland networks is proposed in this study based on (1) wetland area, (2) wetland storage, and (3) contributing area. The goal of this study is to assess the impacts of wetland networks on watershed hydrologic processes. To achieve this goal, a surface delineation algorithm, Hydrologic Units Delineation with Depressions and Channels (HUD-DC), and the Soil and Water Assessment Tool (SWAT) were coupled to simulate hydrologic processes in a wetland-influenced watershed in North Dakota. The area, storage, and contributing area of each individual wetland were identified by HUD-DC. Based on the delineation results from HUD-DC, wetland networks were determined and parameterized for SWAT modeling. The performance of the SWAT model was evaluated by comparing the simulated and observed flow data. The validated SWAT model was further used to evaluate the changes in stream flow under various wetland network scenarios. The results demonstrated the applicability of the coupled HUD-DC and SWAT for assessment of the impacts of wetland networks on watershed hydrologic processes.