The effect of surface/ground water interactions on wetland sites with different characteristics

Abstract

Wetlands have gained greater attention in the last two decades, since they have an important impact on water supply and water quality control. Treatment wetlands have recently been used as a best management practice to decrease the storm water runoff peaks and to improve storm water runoff water quality. Therefore, efforts have been made toward a better understanding of both wetland hydrology and wetland water quality. Wetlands are located between uplands and downstream flooded systems and surface/ground water interactions are usually observed in these critical transitional zones. Surface and ground water are mixed and the quality of both sources is affected by each other due to this interaction. Therefore, it is important to understand the role of surface/ground water interactions on wetland sites to develop accurate wetland models. In this study, the effect of surface/ground water interactions on wetland hydrology is investigated for different wetland conditions, such as vegetation, slope of the land site, and lateral and vertical hydraulic conductivities by using the wetland model WETland Solute TrANsport Dynamics (WETSAND). This wetland model has both surface flow and solute transport components, incorporates surface/ground water interactions and accounts for upstream contributions from urbanized areas. Simulations are conducted for the Duke University restored wetland site in the Sandy Creek watershed. It is observed that the effect of surface/ground water interaction on surface water depths becomes more dominant on wetland sites with high slopes and low vegetation.