Evolution of Mangrove Landscapes in the Coubalan Municipality (Casamance, Senegal, West Africa): A Diachronic Analysis Using Remote Sensing

Abstract

The municipality of Coubalan has substantial socioeconomic potential because its mangrove forest supports local livelihoods. However, the forest is exposed to pressures that reduce its extent and species diversity. This study examines mangrove landscape dynamics in Coubalan. A diachronic analysis covering 1984–2024 used Landsat 5 TM, Landsat 7 ETM+, and Landsat 8 OLI-TIRS imagery processed in ENVI 5.3. Maximum likelihood supervised classification identified six land-use classes: mangroves; barren areas; water; mudflats; forests and savannas; and built-up areas, bare ground, fields, and fallow land. Water and mangroves were the most stable classes. During 1984–2003, mangroves and forests and savannas increased by 6.05% and 2.31%, respectively, while built-up areas, bare ground, fields, and fallow land and mudflats decreased by 2.86% and 7.56%. Mudflats converted to mangroves accounted for 5.90%. During 2003–2024, the trend reversed, with 7.84% of mangrove area converted into mudflats. Across the full period, mangroves and forests and savannas had average annual spatial expansion rates of −0.45% and −1.45%, while built-up areas, bare ground, fields, and fallow land and mudflats increased by 0.31% and 0.56%. Annual deforestation rates were 0.41% for mangroves and 1.10% for forests and savannas, and the 2024 anthropization index was 1.94. Mangrove cover declined from 19.93% in 1984 to 16.68% in 2024. The findings may support local mangrove management, while further research is needed to identify the principal drivers of degradation.