Spatial–temporal variability of the Bua River’s physicochemical water quality: a DPSIR-based analysis

Freshwater ecosystems are increasingly threatened by climate variability and catchment degradation, resulting in declining water quality and ecosystem resilience. We assessed spatial and seasonal variability in water quality along the Bua River, Malawi, and applied the Drivers–Pressures–State–Impact–Response (DPSIR) framework to identify degradation pathways and management responses. A stratified sampling design was used across upstream, midstream, and downstream sections during three distinct seasons. Downstream sections consistently exhibited poorer water quality, with turbidity reaching 17.17 ± 0.63 NTU, EC increasing to 183.00 ± 2.80 µS cm−1, ammonium concentrations reaching 120.14 ± 2.00 µg L−1, and chlorophyll-a increasing to 6.70 ± 0.70 µg L−1. Factorial ANOVA revealed significant seasonal effects (F₂,₅₂ = 21.84, p < 0.0001), site (F₂,₅₂ = 6.25, p = 0.0036), and water-quality parameters (F₁₃,₅₂ = 58.80, p < 0.0001). Elevated nutrient concentrations and sediment loads were associated with anthropogenic stressors. Our DPSIR linked these pressures to ecological degradation, declining fisheries productivity and increasing risks to water-dependent livelihoods. Our findings highlight the need for integrated catchment management, riparian restoration, climate-smart agriculture, and strengthened water-quality monitoring to support Malawi’s Nationally Determined Contributions (NDCs), and Sustainable Development Goals (SDGs).