Assessment of groundwater quality for drinking and irrigation purposes: a case study of Peddavanka watershed, Anantapur District, Andhra Pradesh, India

摘要

In India, the quantity and quality of water available for irrigation is variable from place to place. Assessment of water quality has been carried out to determine the sources of dissolved ions in ground-water. Quality of groundwater in a 398 km~2 Peddavanka watershed of a semi-arid region of south India is evaluated for its suitability for drinking and irrigation purposes. The middle Proterozoic Cuddapah Supergroup and Kurnool Group of rocks underlie most of the watershed. The main lithologic units consist chiefly of quartzite, limestone, and shale. Seventy-six water samples were collected from open-wells and bore-holes. Water samples were collected representative of the post-monsoon (winter) and pre-monsoon (summer). The quality assessment is made through the estimation of Ca~(2+), Mg~(2+), Na~ +, K~+, Cl~-, SO_4~(2-), CO_3~(2-), HCO_3~-, total hardness as CaCO_3, TDS, EC, and pH. Based on these analyses, parameters like sodium adsorption ratio, % sodium, residual sodium carbonate, non-carbonate hardness, potential salinity, Kelley's ratio, magnesium ratio, index of base exchange and permeability index were calculated. According to Gibbs' ratio samples in both seasons fall in the rock dominance field. The overall quality of waters in the study area in post-monsoon season is high for all constituents ruling out pollution from extraneous sources.