Journal of Geography, Environment and Earth Science International

Groundwater quality plays a decisive role in sustaining irrigated agriculture, particularly in regions where intensive farming depends heavily on subsurface water resources. This study assessed the suitability of groundwater for irrigation in Udham Singh Nagar district, Uttarakhand, India, using the Irrigation Water Quality Index (IWQI), with emphasis on electrical conductivity (EC) as a primary indicator of salinity hazard. A total of 82 groundwater samples were collected from hand pumps distributed across seven developmental blocks of the district and adjoining areas. The samples were analysed for key physicochemical parameters, including EC, total dissolved solids (TDS), sodium adsorption ratio (SAR), major ions (Na⁺, Cl⁻ and HCO₃⁻), nitrate, boron and pH, following standard analytical procedures. The FAO-based irrigation suitability assessment indicated that 78.08% of the samples posed no salinity risk based on EC, while 21.92% showed slight to moderate salinity. Similarly, 73.17% of the samples were classified as safe based on TDS, while the remaining 26.83% exhibited slight to moderate restriction. All groundwater samples recorded SAR values below 3.0, indicating the absence of sodium-related toxicity and minimal risk to soil infiltration. However, spatial analysis revealed localised salinity concerns in areas such as Kashipur, Rudrapur, Sitarganj and nearby localities. The IWQI results further showed that 42.4% of the groundwater samples fell under moderate irrigation restriction, 54% under high restriction and 3.6% under severe restriction. These findings indicate that, although groundwater is generally suitable for irrigation, its use requires appropriate management practices, including controlled irrigation scheduling, adequate leaching and good soil drainage, to prevent long-term salinisation. The study highlights notable spatial variability in irrigation water quality within the Tarai region and supports the usefulness of IWQI as a practical decision-support tool. The outcomes provide guidance for sustainable irrigation planning, crop selection and groundwater management under increasing agricultural intensification.