When the big storm hits: The role of wetlands to limit urban and rural flood damage

This report assesses the potential for wetlands to affect the financial impacts associated with rural and urban flooding. Working with the Grand River Conservation Authority (Ontario), Credit Valley Conservation (Ontario) and Ducks Unlimited Canada, the Intact Centre on Climate Adaptation (Intact Centre) determined that wetlands, if maintained in their natural state, can substantially reduce flood damage costs to buildings (ranging from residential homes and apartment buildings, to industrial, commercial and institutional structures). This report demonstrates quantitatively that wetlands conservation is a cost-effective means to reduce flood risk in Canada.

These findings have national applicability, albeit the research focused on two Southern Ontario pilot sites, one rural and one urban. For both sites, computer models simulated a major Fall flood, to compare flood damages under conditions where wetlands were maintained in their natural state and where they were replaced with agricultural land use. The researchers found that flood damages were lower if wetlands were maintained in their natural state, with financial cost savings of 29 and 38 per cent in rural and urban areas, respectively.