Developing a Water Budget for a Constructed Stormwater Wetland

A thorough understanding of the hydrology of a constructed stormwater wetland (CSW) is essential to develop a water budget; that is a comprehensive view of all inputs and outputs in the system. Two of the principal functions of a CSW are to 1) reduce peak flows and 2) improve water quality. The latter is achieved through biological, chemical, and physical processes that are ultimately governed by the hydraulics and hydrology of the system. As these built systems populate the watershed management landscape, it is necessary to account for all flows that pass through the CSW to ensure that it is providing a benefit and does not have any deleterious effects on the watershed. One of the most significant and least understood aspects of a CSW is the groundwater-surface water exchange. This exchange is difficult to quantify, but is deserving of consideration because of the potential impact this exchange has on groundwater and surface water quantity and quality in a CSW system. Therefore, the goals of this study are to 1) use hydraulic and hydrologic computer models to create a water budget of the CSW, with a focus on quantifying groundwater-surface water fluxes, and 2) discuss the implications of how hydraulic and hydrologic processes affect the water quality within a CSW.