Evaluation of groundwater quality in northern Indo-Gangetic alluvium region.

The northern Indo-Gangetic alluvium region is known for intensive agricultural and industrial activities. Groundwater is the main source used for drinking, irrigation and industrial purposes in this region. Groundwater quality assessment is an essential component for its safer use. Thus, the measurements on various water quality parameters were carried out on surface water and groundwater samples of dug wells, bore wells and hand pumps at different sites spread over an area of about 2150 km(2). Influence of soil on hydrochemistry of groundwater was investigated through analyzing soil characteristics at selected sites in the region. Water quality classification was investigated through calculating the base-exchange, meteoric genesis, Langelier saturation and Ryznar stability indices. Groundwater sources were evaluated according to various criteria for their drinking and domestic, irrigation (salinity, chlorinity and sodicity), and industrial (saturation index) uses. Soil-water interactions and impact on groundwater quality was evaluated using ion flux coefficient (cf). Results of this study show that the groundwater in the study region is mainly of Na-HCO(3) and shallow meteoric water percolation type. Low cf values observed for NO(3), PO(4), Ca and metals indicate their lower mobility from soil matrix to groundwater. About 4-19% of the groundwater samples showed levels of TDS, hardness, alkalinity, Cl, F, SO(4), Ca, Mn, Pb, Cr and Fe above their respective permissible limits. Majority of samples violating the drinking water guidelines belong to shallow depth aquifer. Correlations between various parameters lead to interpretation of the results of analysis and suggesting the ionic species present in the groundwater sources. Contamination of some groundwater aquifers with F, Pb and Cr indicates natural and anthropogenic influences.