Spatial assessment of groundwater quality based on minor ions

Use of water for domestic, agricultural and industrial purpose depends on the desirable range of concentration of various ions. As the suitability of groundwater for different use depends on concentration of several ions, delineation of a region having groundwater of suitable quality relies on integrating the quality of groundwater with respect to each ion. This can be brought out with the aid of advanced tools such as GIS (geographical information system). This study was carried out with the objective of assessing the groundwater quality based on EC (electrical conductivity), fluoride, bromide and nitrate using GIS techniques and the regions requiring attention for groundwater treatment was identified in a part of Nalgonda district, Andhra Pradesh, southern India. Forty five groundwater samples were collected and their EC, fluoride, nitrate and bromide concentration was analysed. Groundwater was not suitable for consumption in 6.6% of the samples based on EC. Fluoride, nitrate and bromide concentration in groundwater was not permissible as per BIS and WHO standards in 57%, 22% and 11% of the groundwater samples respectively. The areas having groundwater suitable or unsuitable for domestic use was delineated using GIS. The groundwater samples collected from 69% of the locations exceeded the desirable limit for drinking for atleast one parameter. The groundwater was unsuitable for domestic use in the northeastern and southeastern parts of this area. The source for the concentration of these parameters exceeding the limit is different for each parameter. Hence it is important to take a suitable collective measure in improving the groundwater quality. Considering the various options available for redeeming the groundwater quality, artificial recharge of groundwater by rainwater harvesting will be suitable to reduce the concentration of all ions in this area.