21-1 Mitigating Flood Risk through Wetland (Re)Construction: a Proposal Evaluating the Economic and Environmental Impacts on Cape Cod

Session: Functions of River Corridors, Floodplains and Wetlands (Posters)

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Historically, Cape Cod, Massachusetts has been at higher risk of flooding than inland areas due to low elevation, significant precipitation events, and storm surges due to proximity to the ocean. However, a warming climate has greatly exacerbated these events, resulting in increased severity and frequency of flooding activity as well as rising flood insurance premiums. This project aims to understand to what extent placing constructed wetlands in coastal areas will a) mitigate flooding and b) decrease flood insurance rates. In order to accomplish this, viable sites were identified throughout Cape Cod which possessed some combination of characteristics necessary for a self-sustaining wetland: hydrology, hydrophytic vegetation, and hydric soil. These characteristics were assessed in situ at eight sites in Sandwich, Bourne, Barnstable, and Yarmouth, MA, and 19 soil samples were collected from representative soil horizons (O, A, B) and analyzed for pH, modified Morgan nutrients, exchangeable acidity, electrical conductivity, among other characteristics to confirm appropriateness for use in a constructed wetland. Then, flood modeling was carried out to evaluate runoff depth following precipitation events ranging from two to seven inches of rainfall based on current land cover type, as well as the extent of which following the conversion of current land cover to wetland within and outside of FEMA flood zones for Sandwich, MA. An analysis of historical trends of flood insurance rates in Sandwich correlatively to average precipitation events will be utilized to understand to what extent these rates will be mitigated based on the reduction of flooding itself. Overall, this project aims to explore the capabilities of green infrastructure and natural resources, whilst evaluating their effectiveness in alleviating intensifying weather events due to a changing climate.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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