Three Decades of Land Use and Land Cover Changes in Mjini Magharibi, Zanzibar, Tanzania: Implications on the Coastal Mangrove Forest Ecosystems and Urban Development

Abstract

Mangroves are vital coastal ecosystems that serve as natural barriers against erosion, support diverse marine life, and play a crucial role in mitigating climate change through carbon sequestration. This study uses remote sensing techniques to examine land use and land cover (LULC) changes in Mjini Magharibi, Zanzibar, from 1994 to 2024. The classification of LULC changes using Landsat images achieved high accuracy in thematic mapping, with overall accuracy and kappa coefficients ranging from 79.7% to 92.5%. The results revealed significant landscape transformations with environmental sustainability and coastal management implications. Furthermore, the results depicted a consistent increase in areas covered with water bodies, from 20,736.27 ha in 1994 to 22,422.51 ha in 2024, suggesting potential sea level rise and coastal land erosion. Concurrently, bare soil and built-up areas expanded from 1,981.44 ha to 3,406.14 ha, indicating rapid urbanization. The study highlights a substantial decrease in mangrove and dense forest cover, with a loss of approximately 35.5% over 30 years, posing significant ecological and socioeconomic challenges. Sparse vegetation and farmland areas also decreased, while mixed land uses increased, reflecting the diversification of land use patterns. These changes underscore the adverse pressure of urban expansion on natural resources, including pristine beaches, mangrove areas, and marine ecosystems. The findings emphasise the urgent need for sustainable management practices and conservation initiatives to protect the remaining mangrove forests, mitigate land use change impacts, and ensure the long-term ecological balance of Mjini Magharibi's mangrove ecosystems.