Aquifer geometry and hydrochemical framework of the shallow alluvial aquifers in the western part of the Yamuna River Basin, India

Abstract

The Yamuna basin constitutes a part of the Ganga plain which is one of the most densely populated regions and one of the largest groundwater repositories on the earth. Agricultural activities, population growth, rapid industrialization, and unplanned urbanization in the plain have resulted in various geo-environmental hazards, in particular, deterioration of groundwater quality. This studies the aquifer geometry and geochemical evaluation of groundwater in terms of its suitability for domestic and agricultural uses. Groundwater in the basin occurs in Quaternary alluvium and fractures in highly consolidated Alwar quartzites. Hydrogeological cross sections revealed a two- to three-tier aquifer system down to 100 m below ground level. The aquifer sequence comprises of clay, silt, different grades of sand and gravel in varying proportions. Climatic conditions, weathering and anthropogenic activities control the groundwater chemistry in the basin. The pH and electrical conductivity (EC) of the groundwater is variable (pH = 5.5-8.8; EC = 500-6700 μS/cm). At most places, the groundwater is alkaline, hard, and saline. In general, the groundwater has a composition expressed in equivalent units of Na+>Ca2+>K+>Mg2+ for cations and Ca-Mg-Cl and Ca-Mg-HCO3-. Groundwater with a higher proportion of NO3-, Na+, F-, and K+ at a few sites represents the influence of anthropogenic sources on groundwater composition. An excess of alkali metals (Na+ + K+) over Cl- reflects input from the weathering of sodium- and potassium-rich minerals. The high %Na, EC and sodium adsorption ratio (SAR) values at a few sites restrict its suitability for irrigation. © 2004, CAWQ.