Nature Meets Infrastructure
The Role of Mangroves in Strengthening Bangladesh’s Coastal Flood Defenses
Alejandra Gijón Mancheño (TU Delft - Hydraulic Structures and Flood Risk, World Bank)
Bramka Arga Jafino (World Bank)
Bas Hofland (TU Delft - Hydraulic Structures and Flood Risk)
Bregje Karien Van Wesenbeeck (Deltares, TU Delft - Coastal Engineering)
Swarna Kazi (World Bank)
I. Urrutia (World Bank)
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Abstract
Mangroves have been used for coastal protection in Bangladesh since the 1960s, but their integration with embankment designs has not been fully explored. This paper investigates the effect of existing mangroves on required embankment performance, with a focus on the wave-damping effect of mangroves. Existing mangroves reduce the required thickness of embankment revetment by up to 16–30% in the west, 47–82% in the central region, and 53–77% in the east. Notable mangrove sites include the belt south of polder 45 (Amtali), with an average width of 1.77 km, and the Kukri-Mukri polder, with an average width of 1.82 km. These mangroves reduce the need for thick slope protection, allowing the replacement of concrete revetments with softer materials, such as clay or grass, combined with mangrove foreshore. Additional large mangrove belts are found in Sandwip and Mirersarai. By replacing or reducing revetment requirements, mangrove forests can minimize carbon emissions from construction while providing carbon sequestration and other ecosystem services. This study can inform future sustainable investments in coastal protection systems by identifying areas where mangroves offer the greatest wave-damping benefits, which could be focus of follow-up feasibility studies.
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