Cumulative Hydrologic Impact of Wetland Loss: Numerical Modeling Study of the Rideau River Watershed, Canada

This study was undertaken to discern and quantify the hydrologic functions of wetlands within the context of the Rideau River watershed. Using numerical modeling techniques (Mike11), the potential cumulative effect of the loss of wetlands on peak flood discharges and low flows at selected locations within the watershed were quantified. It was estimated that the combined effect of all wetlands (approximately 15% of the basin area) is a 10% reduction in flood peak. It was demonstrated that the flood risk would increase if wetlands were removed. The impact of wetland loss on flood risk diminishes downstream of long channels and lakes. The low flow will likely increase if wetlands are removed, although this impact diminishes rapidly downstream of long channels and lakes. This kind of site-specific technical analysis can be used for decision making and policy formulation regarding interference with and land development adjacent to wetlands.