GIS based groundwater quality mapping in southeastern part of Anantapur District, Andhra Pradesh, India

Groundwater is used for domestic, industrial water supply and for irrigation all over the world. Although three-fourth of earth is being surrounded by sea only a little portion of it can be used for drinking purpose. The study area lies in the Southeastern part of Anantapur District, Andhra Pradesh. The area is located in the survey of India toposheets No's 57 F/14, F1l5, J/3, J/4 lying between East 77° 30′ -78° 15′ longitudes and 14° 0′ -14° 30′ North latitudes. Geologically, it is underlain mainly by Peninsular gneisses of Archean age and comprises pink granites, schists and composite gneisses (equivalents of the Dharwars), intruded by a few pegmatite dykes. Major geomorphic units are denudational hills, dissected pedimonts, pediplain and alluvium. The study area experiences a semiarid climate. The study area faces water scarcity as well as water quality problems. Hence, a Geographic Information System (GIS) based assessment of spatiotemporal behaviour of groundwater quality has been carried out in the region. A surface map was prepared in the Arc GIS 9.3 (spatial analyst module) to assess the quality in terms of spatial variation and it showed that the high and low regions of water quality varied spatially during the study period. All the other parameters analysed are in adherence to desirable limits of WHO and Indian Standards for drinking water. Hence the groundwater in the study area is not suitable for drinking purpose. The spatial analysis of groundwater quality patterns of the study area shows seasonal fluctuations and these spatial patterns of physical and chemical constituents are useful in deciding water use strategies for various purposes.