Groundwater quality zonation in a shallow weathered rock aquifer using GIS

Abstract

Monitoring of groundwater quality on a regular basis is essential for use in the domestic, agricultural and industrial sectors. Further, it is even more important in rural areas where people make use of groundwater for domestic purposes without prior treatment. This study was carried out with the objective of assessing the groundwater quality based on electrical conductivity (EC), fluoride, nitrate and bromide in a part of Nalgonda district, Andhra Pradesh, southern India. Groundwater samples were collected from 45 locations in January 2010. They were analysed using an ion chromatograph for fluoride, bromide and nitrate concentration in groundwater. EC was measured in the field using a portable digital probe. The groundwater samples were not suitable for drinking and domestic use based on EC, fluoride, nitrate and bromide in 6.7, 57, 22 and 11% of the locations, respectively. Overall, 31% of the locations had suitable groundwater quality. The north-eastern and south-eastern parts of this area had unsuitable groundwater. A total of 378.68 km2 had unsuitable groundwater for drinking and domestic purposes. The source for the increased concentration of these parameters is varied and hence it is essential to restore the groundwater quality in this area. Of the several techniques available, artificial recharge by rainwater harvesting will help to dilute the concentration of these ions and improve the groundwater quality.