Cost–benefit analysis of mangrove ecosystems in flood risk reduction: a case study of the Tana Delta, Kenya

Mangrove ecosystems are valuable and productive coastal ecosystems that provide several ecosystem services. Nevertheless, trivialization of the value of mangrove ecosystems has led to their decline at an annual global rate of 1–2%. Degradation undermines the resilience of these ecosystems and threatens the continuous supply of goods and services that they provide. Diverse mangroves that contribute to the well-being of coastal communities characterize Kenya’s coastal region. Despite their importance, 0.7% of the mangroves are destroyed annually. In this study, the value of mangroves with regard to coastal flood risk reduction was estimated via a case study of the Tana Delta, Kenya. The valuation was calculated using the total economic value framework where both direct and indirect use values that influence flood risk are calculated using flood-avoided damage approach and local market prices. For comparative purposes, all the estimates presented in this paper were standardized to the 2015 US$/ha equivalent value using the United States Consumer Price Index for all urban consumers. The net value of mangroves for flood reduction was estimated to be between US$238/ha/yr and US$311/ha/yr. The skewed distribution was largely attributed to a variation in flood frequency and mangrove forest density.