Multivariate analysis of land use/land cover (LULC) effects on water quality in the Lower Mara River catchment

ABSTRACT The Lower Mara River catchment is increasingly subjected to anthropogenic pressure due to land-use/land-cover (LULC) changes, which significantly influence river water quality. This study assessed the effects of LULC on water quality in the Lower Mara River catchment. Water samples were collected from 12 sampling stations during February, August, and December 2025 and analysed for nine physicochemical and biological parameters. Land use/land cover classification was conducted using satellite imagery and GIS techniques, while Pearson correlation and Redundancy Analysis (RDA) were used to evaluate relationships between LULC and water quality parameters within 500, 1,000 and 1,500 m river buffer zones. The results showed that grassland was the dominant land cover type (63.63%), followed by cropland (17.76%) and forest (11.42%). Turbidity, biochemical oxygen demand (BOD5) and faecal coliform concentrations exceeded Tanzania's standards at several sampling locations, indicating water quality degradation. Pearson correlation and RDA revealed that cropland and built-up areas were significantly positively associated (p < 0.01) with turbidity, nutrients, BOD5, and faecal coliforms, while forests, wetlands, and grasslands contributed to improved water quality conditions. The strongest LULC influence occurred within the 500 m riparian buffer zone. The study emphasises the significance of sustainable management and protection of the river ecosystems.