Spatiotemporal dynamics of land use change and agrochemical-driven water quality degradation

Land Use and Land Cover (LULC) transitions exert major influence on water resources, particularly in fragile Himalayan basins. This study analyzes four decades (1979–2018) of LULC change and its implications for riverine water quality in North Kashmir, India. Using multi-temporal Landsat imagery integrated with Geographic Information System (GIS) techniques, substantial declines in agriculture (−55 %) and dense forest (−25–37 %) were detected, accompanied by sharp increases in horticulture (+35–55 %) and built-up areas (+200–290 %). Seasonal water sampling (April, July, August, and October 2020) revealed pronounced nutrient enrichment, with nitrate, ammoniacal nitrogen, and phosphorus peaking during intensive horticultural activity in July–August. Correlation and Principal Component Analysis (PCA) indicated that fertilizer-driven enrichment (PC1, 64 % variance) and hydrological variability (PC2, 21 %) were the dominant factors influencing water quality. The composite Water Quality Index (WQI) classified water as good to moderate in April but moderate to poor in late summer, reflecting agrochemical stress. These findings demonstrate the effectiveness of integrating remote sensing, GIS, and statistical modeling to evaluate coupled landwater dynamics in mountain ecosystems.