Seasonal variation in quality of rural groundwater in Kachi, Dutse Local Government Area, Jigawa State, based on physicochemical characteristics and water quality index

Abstract

Groundwater is a key source of water for domestic and rural use, yet its quality is highly influenced by seasonal fluctuations and local geochemical processes. This study provides a comprehensive assessment of seasonal groundwater quality in the study area by integrating physico-chemical parameters, Water Quality Index (WQI), Pollution Index (PI), and Principal Component Analysis (PCA). Water samples were collected from selected boreholes during wet and dry seasons and analysed using standard laboratory procedures, with results compared against WHO drinking water guidelines. Seasonal variation was pronounced: pH ranged from 7.10 (wet) to 7.54 (dry), while electrical conductivity (EC) varied significantly from 426 µS cm⁻¹ (dry) to 2645 µS cm⁻¹ (wet). Major ions such as Na⁺ (55.78–767.97 mg L⁻¹), K⁺ (62.24–799.12 mg L⁻¹), Ca²⁺ (875.60–911.86 mg L⁻¹), Mg²⁺ (139.66–447.29 mg L⁻¹), Cl⁻, SO₄²⁻, PO₄³⁻, and HCO₃⁻ frequently exceeded permissible limits in multiple wells. WQI (68.5–414.8 dry; 185.5–596.3 wet) and PI confirmed that the majority of samples were unsuitable for drinking, with more severe deterioration during the wet season due to surface runoff, recharge, and solute mobilisation. PCA revealed that dry season water chemistry was largely controlled by salinity enrichment and mineral dissolution, whereas wet season patterns reflected ion redistribution and increased nutrient influence, indicating the combined effect of geogenic and anthropogenic factors. These results highlight significant spatial and seasonal heterogeneity in groundwater quality and emphasise the urgent need for routine monitoring, appropriate treatment strategies, and sustainable management practices to ensure safe water supply and protect public health in rural communities.