Seasonal variations in physicochemical characteristics of the River Gomati from Pilibhit to Jaunpur District, Uttar Pradesh, India

Rivers with high water quality are essential for human survival, aquatic ecosystems, agriculture, and industry. This study assesses the water quality in the Gomati River using physicochemical parameters, the Water Quality Index (WQI), and statistical techniques to support sustainable resource management. Seasonal variations in water quality were assessed across fourteen sites in pre- and post-monsoon periods (of year 2022). While parameters such as pH, total alkalinity (TA), total dissolved solids (TDS), and total hardness (TH) generally complied with BIS (Drinking Water Specification, Second Revision IS:10500:2012, Bureau of Indian Standards, New Delhi, 2012) and WHO (Guidelines for Drinking Water Quality, World Health Organization, Geneva, 2017) standards, concerning levels of dissolved oxygen (DO: 3.9–5.2 mg/L), biological oxygen demand (BOD: 10.9–26 mg/L), and chemical oxygen demand (COD: 14.7–40 mg/L) were recorded, particularly in the pre-monsoon period and downstream of urban centers like Sitapur, Lucknow, and Jaunpur. WQI classified sites near Lucknow as ‘Very Bad’ to ‘Poor’ before the monsoon, with post-monsoon improvements attributed to dilution, except at selected locations (S-4, S-5, S-9, S-10, and S-11), where water remained poor in both the seasons. Despite localized pollution, the river exhibited resilience due to self-purification and reduced industrial discharges post-COVID-19 lockdowns. Cluster Analysis (CA) indicated that the pre-monsoon pollution was concentrated downstream of major cities, while the post-monsoon mobilization affected further downstream locations. Municipal and industrial wastewater discharges were identified as the primary pollution sources. Principal Component Analysis (PCA) identified key factors influencing water quality, explaining 75.2% and 79.8% of variance in pre- and post-monsoon data, respectively. Electrical conductivity (EC), TDS, pH, and temperature were significant pre-monsoon contributors, while EC, COD, and temperature had a greater influence post-monsoon. These findings emphasize the urgent call for effectual wastewater management policies in urban-adjacent areas to prevent further environmental degradation of the Gomati River.