Characterization and quality assessment of groundwater for irrigation in the Bhopalgarh tehsil of Jodhpur district, Rajasthan, India

In present study, the quality of groundwater for irrigation in Bhopalgarh tehsil of Jodhpur district, Rajasthan was examined. Bhopalgarh tehsil bounded by Nagaur district to the north and east, Pipar city tehsil to the south, Jodhpur tehsil to the southwest and Bawadi tehsil to the west. Georeferenced sixty water samples of tube well/open well were collected from different villages where the waters are being used for irrigation for last few years. The water samples were analyzed for various chemical properties like EC, pH, major cations: Na+, Ca2+, Mg2+, K+ and anions: CO32-, HCO3-, Cl- and SO42-. Subsequently, residual sodium carbonate (RSC), sodium adsorption ratio (SAR), adjusted SAR, potential salinity and Mg/Ca ratio were also calculated. The quality of irrigation water was categorized on the basis of salinity (EC), sodicity (SAR) and alkalinity (RSC) into 4 salinity (C-1 to C-4) classes, 4 sodicity (S-0 to S-3) classes and 3 alkalinity (A-1 to A-3) classes, respectively. Besides this, the quality of irrigation water was also categorized on the basis of the EC, SAR and RSC into six classes viz. good, High-SAR saline, marginally saline, marginally alkali, alkali and highly alkali. The results showed that 21.66 percent water samples were good, 15 percent water samples were marginally saline, 48.33 percent water samples were High-SAR saline, 8.33 percent water samples were marginally alkali, 3.33 percent water samples were alkali and 3.33 percent water samples were highly alkali in nature and it is found that most of the irrigation water came under high-SAR saline category.