naa a22 4500 510755720 CHVBK 20180411083121.0 cr unu---uuuuu 180411e20130501xx s 000 0 eng 10.1007/s12594-013-0090-y doi (NATIONALLICENCE)springer-10.1007/s12594-013-0090-y Spatial variations of groundwater vulnerability using cluster analysis [Elektronische Daten] [N. Subba Rao, P. Surya Rao, D. Deva Varma] An investigation on quality of groundwater has been carried out in the river basin of Varaha located in Visakhapatnam District, Andhra Pradesh to find out the factors that are responsible for spatial variations of water vulnerability. The study area is underlain by the Precambrian rocks of Eastern Ghats over which the Recent Formations occur. Groundwater is a prime source for drinking and irrigation. The quality of groundwater is fresh and brackish with dominance of the latter. Groundwater samples are categorized into two major clusters A and B, using the dendrogram of cluster analyses. Out of these two major clusters, five sub-clusters I to V in the pre-monsoon season and six sub-clusters I to VI in the post-monsoon season are identified. The sub-clusters I to IV of pre-monsoon and I to V of post-monsoon seasons of the cluster A are characterized by less mineralized groundwater compared to those of V of pre-monsoon and VI of post-monsoon seasons of the cluster B, which represent highly mineralized groundwater. The low to high mineral content follows gradually from upstream to the downstream area, being higher in post-monsoon season in both the clusters A and B, depending upon the source, mineral dissolution, and precipitation, solubility and leaching of ions, ion exchange and adsorption processes. Spatial distributions of the sub-clusters give clues to understand the factors that cause variations of groundwater vulnerability at a specific site, vis-a-vis local and regional lithological and non-lithological influences. As a result, the quality of groundwater on a regional scale changes from Na+ > Mg2+ >Ca2+ > K+: HCO 3 − > Cl− > SO 4 2− > NO 3 − > F− in the cluster A to Na+ > Mg2+ >Ca2+ > K+: Cl− > HCO 3 − > SO 4 2− > NO 3 − > F− in the cluster B, following the topography. The classification of the area into the zones of relative groundwater vulnerability with respect to drinking water quality of the chemical composition of the sub-clusters helps the planners to identify the specific locations, where the inferior quality of groundwater can occur, for taking the remedial measures. Geological Society of India, 2013 Cluster analysis nationallicence Spatial variations nationallicence Groundwater vulnerability zones nationallicence Groundwater quality nationallicence Andhra Pradesh nationallicence Subba Rao N. Department of Geology, Andhra University, 530 003, Visakhapatnam, India aut Surya Rao P. Department of Geology, Andhra University, 530 003, Visakhapatnam, India aut Deva Varma D. Department of Geology, Andhra University, 530 003, Visakhapatnam, India aut Journal of the Geological Society of India Springer-Verlag 81/5(2013-05-01), 685-697 0016-7622 81:5<685 2013 81 12594 https://doi.org/10.1007/s12594-013-0090-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s12594-013-0090-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Subba Rao N. Department of Geology, Andhra University, 530 003, Visakhapatnam, India aut NATIONALLICENCE 700 1- Surya Rao P. Department of Geology, Andhra University, 530 003, Visakhapatnam, India aut NATIONALLICENCE 700 1- Deva Varma D. Department of Geology, Andhra University, 530 003, Visakhapatnam, India aut NATIONALLICENCE 773 0- Journal of the Geological Society of India Springer-Verlag 81/5(2013-05-01), 685-697 0016-7622 81:5<685 2013 81 12594 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer