Mangroves for Coastal Resilience in Bangladesh : Identification of Potential Locations, Assessment of Triple Dividends, and Cost Estimation

Bangladesh is highly vulnerable to extreme weather events due to its frequent exposure to floods and extensive low-lying areas. Coastal flood risks are expected to increase due climate change. Therefore, Bangladesh has been upgrading its coastal embankment system to enhance flood safety. This initiative includes not only hard flood defense infrastructure, but also nature-based solutions through planting mangroves on the seaside of embankments. Mangroves, serving as natural flood barriers, have been utilized in Bangladesh for coastal protection since the 1960s. However, their integration with embankment designs and their benefits in carbon sequestration remain underexplored. This paper consolidates current knowledge on the role of mangroves in coastal resilience in Bangladesh, incorporating recent studies and new analyses on their benefits on (i) flood risk reduction, (ii) livelihood enhancement, and (iii) carbon sequestration. The estimated benefits are mapped along the country's coastal system. The study identifies some of the most beneficial mangrove sites to be combined with embankment designs, such as a belt south of polder 45 (Amtali) with an average width of 1.77 kilometers, and a belt around the Kukri-Mukri polder with an average width of 1.82 kilometers. These mangrove forests can reduce the required thickness for slope protection by up to 80 percent, offer carbon service benefits of US$13,120 per hectare (over 2022–50, at a 6 percent discount rate), and provide livelihood benefits of more than US$22,000 per hectare. Other wide mangrove belts are found in Sandwip and Mirersarai. The findings aim to guide future investments in integrating mangroves into coastal protection systems, highlighting their triple dividends for building resilience.