Spatiotemporal Dynamics of Wetland Ecosystems in The Gambia (1985–2022)
Genesis Tambang Yengoh *
National Environment Agency, The Gambia Environment House, Jimpex Road, Kanifing, The Gambia.
*Author to whom correspondence should be addressed.
Abstract
Wetlands in The Gambia support biodiversity and livelihoods, yet long-term, country-scale evidence of change remains limited. Using the 30 m Global Land Cover with Fine Classification System (GLC_FCS30D) product, this study mapped national wetland extent and classes from 1985 to 2022 and summarised patterns across administrative regions. Total wetland area increased from 1,136.2 km² in 1985 to 1,252.9 km² in 2022 (net +116.7 km²; +10.3%). Floodplain wetlands remained the dominant class, while the largest proportional gains occurred in marsh and tidal-flat units. Trend analysis using ordinary least squares regression indicated a significant positive national trajectory, and Pettitt’s test detected a change point in 2011. K-Means clustering revealed three distinct regional typologies: Cluster 0 (North Bank, Lower River) showed conversion of flooded flats to marsh and mangrove; Cluster 1 (Kanifing, Upper River, West Coast) exhibited mixed trends; Cluster 2 (Central River) displayed mangrove loss (−8.50 km²) alongside major marsh expansion (+51.03 km²). Regionally, wetland expansion was greatest in the West Coast and Lower River regions and was spatially concentrated along the Gambia River corridor and coastal wetland complexes. The resulting time series and spatial products provide a baseline for monitoring, prioritising wetland management, and assessing the sensitivity of Gambian wetlands to climate variability and land-use change.
Keywords: Wetland dynamics, land cover change, remote sensing, The Gambia, ecosystem services, K-means clustering