Hydrological impacts of land use and land cover change on the width of Bua River, Nkhotakota district, Malawi

Abstract

This study examined the impact of land use and land cover (LULC) changes on the width of the Bua River in Malawi, recognizing LULC change as a major environmental challenge with significant consequences for water and land resources. Deforestation, soil erosion, and agricultural expansion have contributed to land degradation, reducing both the quality and quantity of water. To monitor these dynamics, GIS and remote sensing techniques were employed, using Sentinel‑2 satellite imagery for 2016, 2020, and 2024. Classification and change detection analysis in ArcGIS 10.8 revealed that by 2024, the catchment experienced increases in built‑up areas and sparse vegetation, while water bodies, agricultural land, and forest cover declined. River width measurements, also derived from Sentinel‑2 data, showed a gradual increase in width over the study period, attributed to higher surface runoff, sedimentation, and discharge, alongside reduced infiltration and groundwater recharge. Given the decline in systematic river flow monitoring in Malawi since 2010, river width was used as a proxy for water volume. The study revealed that there is a positive relationship between LULC changes and river width variations. This suggests that human‑driven land use changes in the Bua catchment are closely associated with hydrological responses, particularly changes in river morphology. The findings align with broader regional studies that link forest loss and agricultural expansion to increased runoff and altered water availability. The study underscores the importance of integrating spatial technologies in environmental monitoring and highlights the urgent need for policymakers and stakeholders to implement effective land management policies. Ensuring sustainable land and water resource use requires active enforcement of legislation, promotion of afforestation, and regulation of settlement expansion. By addressing LULC challenges, Malawi can mitigate the negative impacts on river systems and safeguard water resources for future generations. This research demonstrates that combining GIS, remote sensing, and correlation analysis provides valuable insights into the interplay between land use dynamics and hydrological processes, offering a foundation for sustainable catchment management.