Protecting People and Property While Restoring Coastal Wetland Habitats

Flood mitigation and protection of coastal infrastructure are key elements of coastal management decisions. Similarly, regulating and provisioning roles of coastal habitats have increasingly prompted policy makers to consider the value of ecosystem goods and services in these same decisions, broadly defined as the benefits people obtain from ecosystems. We applied these principles to a study at three earthen levees used for flood protection. By restricting tidal flows, the levees degraded upstream wetlands, either by reducing salinity, creating standing water, and/or by supporting monocultures of invasive variety Phragmites australis. The wetlands, located at Greenwich, NJ, on Delaware Bay, were evaluated for restoration in this study. If unrestricted tidal flow were reestablished with mobile gates or similar devices, up to 226 ha of tidal salt marsh would be potentially restored to Spartina spp. dominance. Using existing literature and a value transfer approach, the estimated total economic value (TEV) of goods and services provided annually by these 226 ha of restored wetlands ranged from $2,058,182 to $2,390,854 y(-1). The associated annual engineering cost for including a mobile gate system to fully restore tidal flows to the upstream degraded wetlands was about $1,925,614 y(-1) resulting in a benefit-cost ratio range of 0.98-1.14 over 50 years (assuming no wetland benefits realized during the first 4 years). Thus, inclusion of a cost-effective mobile gate system in any engineering design to improve long-term flood resilience in the region would produce dual benefits of protecting people and property from major storms, while preserving and enhancing ecosystem values.

Automated summary

This study examines the cost-effectiveness of improving long-term flood resilience by restoring wetlands. By reestablishing tidal flows, a large area of tidal salt marsh could potentially be restored, providing ecosystem goods and services to people.