Coastal Resilience Benefits from Restoration and Protection of Mangroves and Tidal Marshes (Coastal Resilience Methodology)

Coastal ecosystems, especially mangroves and tidal marshes, provide communities with protection against the impacts of climate-related hazards and natural disasters by reducing erosion and flooding from storms and stabilizing and raising shorelines in the face of sea-level rise.

Restoring and protecting coastal ecosystems contributes to the United Nations’ Sustainable Development Goals 11 “Make cities and human settlements inclusive, safe, resilient, and sustainable,” and 13 “Take urgent action to combat climate change and its impacts,” concretely their Targets 11.5 “By 2030, significantly reduce the number of deaths and the number of people affected and substantially decrease the direct economic losses relative to global gross domestic product caused by disasters, including water-related disasters, with a focus on protecting the poor and people in vulnerable situations” and 13.1 “Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.”

This Coastal Resilience methodology estimates flooding for a range of storm probabilities (including a one-in-100-year event) to map where flooding would occur, how deep it would be, and the value of property expected to be damaged within the project impact area. This analysis is conducted for two scenarios: a baseline scenario (without the project) and a project scenario (with mangroves or tidal marshes restored or protected). The Coastal Resilience Asset is then calculated as the difference in expected annual damage (baseline minus project), and estimated based on the measured area of mangroves or tidal marshes actually restored or protected (i.e., the change in vegetated extent), yielding the net annual flood risk reduction benefit in monetary terms.

This methodology can be used to generate Coastal Resilience Assets and, optionally, claims of People Resilience Benefits.

• Coastal Resilience Assets represent the reduction in damage to property at risk of coastal flooding each year as a result of implementing a project that restores or protects coastal ecosystems, thereby reducing flood depth and extent. Coastal Resilience Assets cannot be used for offsetting purposes.
• Optional claims of People Resilience Benefits represent the annual reduction in the number of people at risk of coastal flooding.

This methodology applies to the restoration and protection of mangroves and tidal marshes.