Simulating the Flood Mitigation Role of Wetlands

A simulation methodology was developed for evaluating the flood mitigation potential of inland wetlands. The methodology accommodates widely used computer models with generally available input data. Being a watershed simulation approach, the methodology can assess the potential for downstream flooding resulting from a reduction in upstream wetland storage capacities. The wetland encroachment scheme resembles the well‐tested method of flood insurance studies and allows partial filling of a wetland. Simulations were performed for different antecedent moisture conditions, rainfall intensities and degrees of wetland encroachment. Results showed that encroachment on less than 25% of a wetland area would have only minimal impact on peak flows. In addition, results showed that downstream main‐stem wetlands are more effective in reducing downstream flooding than upstream wetlands.