Hydrogeochemical assessment of spring water resources around Melamchi, Central Nepal

Abstract

Abstract Groundwater in the hills and mountains is manifested as springs, the major water sources for people in Nepal's mountainous regions. The aim of this study was to investigate the seasonal variations of in-situ groundwater physicochemical parameters, evaluate groundwater hydrochemistry with respect to water types, and identify groundwater chemistry control mechanisms by analyzing spring water. The area's geology is dominated by schist and gneiss. Depression and fracture springs occur widely. The study involved observation of seasonal variations in in-situ physicochemical parameters, pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), and temperature, and major ion concentrations – Ca2+, Mg2+, Na+, K+, HCO3−, Cl−, SO42− – to describe the water's chemical characteristics. The seasonal variations in physicochemical parameters arose mainly from monsoonal precipitation and its interactions with host rocks. Chemical analysis showed that Ca-HCO3 type water dominated, indicating shallow aquifer groundwater processes. The relative abundance of cations was, in order, Ca2+ > Na+ > Mg2+ > K+ and of anions HCO3− > Cl− > SO42−. Lithological contributions from the interactions of rocks with water across spring flow networks were the major mechanisms controlling spring water chemistry.