Gis Approach to Identify the Influence of Rock Water Interaction and Land Use Land Cover on Groundwater Quality Degradation

Abstract

Groundwater is an important source of water available at any desired location with the requirement of less treatment. Its quality has been declining, which may be ascribed to both anthropogenic activities and gigantic natural processes. Maintaining groundwater quality is a significant issue as still many people depend on it for agricultural and even drinking purposes. The present study pertains to spatial analysis of the groundwater resources of 23 Mandals of Sri Potti Sreeramulu Nellore district located in Andhra Pradesh, a region which has been reported to have fast quality decline. Geological classes belonging to Toposheets numbered 57 M, 57 N, and 57O are used to develop the geology map. More than 90% of the area is underlain by quartzite, gneisses, hornblende schists and mica schists. LISS-III images of IRS P6 Resources at II are used for land use classification. Chemical data of 57 groundwater observation wells evenly distributed in the area has been obtained from Groundwater and Groundwater audit department Nellore, for the year 2016. Spatial distribution maps are developed for each quality parameter of available data for both pre-monsoon and post-monsoon seasons by inverse distance weighted interpolation method using ArcGIS. Even though the wells of pre-monsoon are showing maximum concentrations, its spatial distribution is more in post-monsoon (more than acceptable and permissible limits). It is observed that rock-water interaction is one cause in reducing water quality in some areas. This indicates the source of the groundwater pollution to be geogenic. The study also attempts to tie up the land use classes present in the area to the groundwater quality distribution in the region. So in this study, satellite data from the LISS-III sensor along with the collateral information derived from the field and other sources have been used to identify the sources of pollution behind the quality degradation of groundwater.