From Source to Sea: The Role of River Basins in Marine Pollution Under Development and Climate Change Variability in SADC

This article presents a systematic review of land-based marine pollution in the Southern African Development Community (SADC), focusing on the river–sea interface. Using the PRISMA protocol, 30 articles published between 2015 and 2025 were selected. Key pollutants identified include microplastics, nutrients, heavy metals, and urban effluents, which travel through river basins and impact coastal ecosystems and communities. The region faces serious challenges due to limited wastewater treatment coverage, with many urban areas lacking adequate infrastructure or using outdated technologies. This leads to widespread discharge of untreated effluents into rivers. Fragmented governance, weak institutional capacity, and insufficient implementation of regional treaties further hinder pollution control. Climate change exacerbates these pressures by increasing hydrological extremes and the vulnerability of sanitation systems. Despite existing legal instruments, cooperation on monitoring and wastewater management remains limited. The integration of basin and coastal planning, improved governance, and transboundary collaboration are essential to reduce pollution and promote ecological and social resilience in the region.