Mapping the potential loss and migration of mangroves in Northwest Madagascar due to sea level rise

Madagascar’s mangroves comprise 2% of the world’s total, but are at risk of loss due to increasing sea level rise (SLR). Vertical elevation gain (VEC) via sediment accumulation has historically allowed mangroves to adjust to SLR, but currently in many parts of the world, SLR is outpacing VEC. This study focuses on the Ambanja-Ambaro Bays (AAB) region in Northwestern Madagascar, with a 7km buffer inland to capture the terrestrial mangrove data and satellite altimeter data for sea level in the Indian Ocean from 2000 to 2016. Rates of change were determined for both SLR based on altimeter data from the Topex/Poseidon and Jason-1, 2, and 3 satellites and VEC data collected from 2016 to 2017 by the NGO Blue Ventures. DEM (from ASTER satellite tiles) and slope were combined with existing land cover classification data from Jones et al. (2016) to determine the potential of mangroves to migrate inland in response to SLR.