Appraisal of groundwater quality in a crystalline aquifer: a chemometric approach

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ORIGINAL PAPER

Appraisal of groundwater quality in a crystalline aquifer: a chemometric approach P. D. Sreedevi 1 & P. D. Sreekanth 2 & S. Ahmed 1 & D. V. Reddy 1 Received: 29 August 2017 / Accepted: 15 March 2018 # Saudi Society for Geosciences 2018

Abstract The purpose of this study is to assess the groundwater quality and identify the processes that control the groundwater chemistry in a crystalline aquifer. A total of 72 groundwater samples were collected during pre- and post-monsoon seasons in the year 2014 in a semi-arid region of Gooty Mandal, Anantapur district, Andhra Pradesh, India. The study utilized chemometric analysis like basic statistics, Pearson’s correlation coefficient (r), principal component analysis (PCA), Gibbs ratio, and index of base exchange to understand the mechanism of controlling the groundwater chemistry in the study area. The results reveal that groundwater in the study area is neutral to slightly alkaline in nature. The order of dominance of cations is Na+ > Ca2+ > Mg2+ > K+ while 2− − for anions, it is HCO−3 > Cl− > NO−3 > SO2− 4 > CO3 > F in both seasons. Based on the Piper classification, most of the groundwater samples are identified as of sodium bicarbonate ( Naþ −HCO−3 Þ type. According to the results of the principal component analysis (PCA), three factors and two factors were identified pre and post monsoon, respectively. The present study indicates that the groundwater chemistry is mostly controlled by geogenic processes (weathering, dissolution, and ion exchange) and some extent of anthropogenic activities. Keywords Groundwater . Crystalline aquifer . Hydrogeochemistry . Chemometric analysis . Semi-arid region

Introduction Groundwater is a vital natural resource, particularly for drinking and irrigation, uses where there are no surface water resources available. The world’s totaled groundwater withdrawal is around 1000 km3 per year, of which about 67% is utilized for irrigation, 22% is for household purposes, and 11% is for the industry (IGRAC 2010; Wada et al. 2010). Two thirds of this is abstracted in Asia, where India, China, Pakistan, Iran, and Bangladesh are the significant consumers (Jac van der 2012). In India, the accessibility of surface water is higher than that of groundwater. However, due to the decentralized availability of groundwater, it is easily accessible and forms the most significant share of India’s irrigation and drinking water supply. Eighty-nine percent

* P. D. Sreedevi [email protected] 1

CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad, Telangana 500 007, India

2

National Academy of Agricultural Research Management (ICAR), Rajendhra Nagar, Hyderabad 500 407, India

of groundwater extracted is utilized in the irrigation sector, making it as the peak group of users in the country, followed by domestic use of which is 9%. Industrial use of groundwater is only 2%. Fifty percent of urban water requirements and 85% of rural household water requirements are also achieved by groundwater (Suhag 2016). In India, groundwater i