Spatio-Temporal Analysis of Urban Encroachment at the Sakumono Ramsar Site, Ghana (2005-2026)

Abstract Urban encroachment on protected wetlands poses one of the most critical land-use challenges in rapidly urbanising West African cities, of which Ghana is no exception. This study presents a Spatio-temporal analysis of land use and land cover (LULC) change at the Sakumono Ramsar Site in Ghana’s Greater Accra Region from 2005 to 2026, using multi-temporal Landsat satellite imagery, supervised Maximum Likelihood Classification (MLC), and post-classification change detection analysis. Four LULC classes were mapped: Open Water, Wetland Vegetation, Bare/Degraded Land, and Built-up/Urban. Results indicate that the built-up area expanded from 0.54 hectares (ha) (0.04% of the 1,362.42-hectare site) in 2005 to 675.99 ha (49.62%) by 2026. Encroachment accelerated markedly during 2015–2026, with the net built-up gain in that period approximately nine times larger than the preceding decade (2005–2015). Change detection matrix analysis identified Bare/Degraded Land as the dominant proximate source of urban expansion, with 547.11 ha converted directly to Built-up during the second epoch and a further 68.94 ha derived from Wetland Vegetation. Overall classification accuracy exceeded 80% for all three epochs, and Kappa coefficients ranged from 0.73 to 0.84, satisfying the minimum acceptance threshold of κ ≥ 0.70 applied in this study. The findings provide an updated baseline for wetland conservation planning and support targeted enforcement and restoration interventions within Ghana's Ramsar network.