  Citation: Jenifer, M.A.; Jha, M.K. A Novel GIS-Based Modeling Approach for Evaluating Aquifer Susceptibility to Anthropogenic Contamination. Sustainability 2022, 14, 4538. https://doi.org/10.3390/ su14084538 Academic Editor: Salvador García-Ayllón Veintimilla Received: 14 February 2022 Accepted: 31 March 2022 Published: 11 April 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). sustainability Article A Novel GIS-Based Modeling Approach for Evaluating Aquifer Susceptibility to Anthropogenic Contamination M. Annie Jenifer 1 and Madan Kumar Jha 2, * 1 VIT School of Agricultural Innovations and Advanced Learning, Vellore Institute of Technology, Vellore 632014, India; anniejenifer@vit.ac.in 2 AgFE Department, Indian Institute of Technology, Kharagpur 721302, India * Correspondence: madan@agfe.iitkgp.ac.in Abstract: Population growth, increasing urbanization and industrialization, mismanagement, and climate change are accountable for the rising depletion and pollution of groundwater worldwide. Consequently, water security, food security, and environmental security are in jeopardy, leading to a severe concern for the sustainable water supply on the Earth. The contamination of groundwater, a complex and hidden resource, is difficult to detect and treat. Therefore, it is essential to evaluate aquifer’s propensity for contamination to protect this precious resource. In this paper, a novel approach integrating the GWQI (Groundwater Quality Index), AVI (Aquifer Vulnerability Index), and geospatial modeling is proposed to explore aquifer susceptibility to contamination, applied to an unconfined aquifer. The Groundwater Quality Index (GWQI) was developed by the conventional method and the Analytic Hierarchy Process (AHP), whereas the Aquifer Vulnerability Index (AVI) was developed using a modified DRASTIC model. It was found that the spherical semi-variogram along with simple Kriging is suitable for interpolating concentrations of groundwater quality parameters. Geospatial modeling indicated that the AHP-based GWQI map is more accurate than the conventional method. The integration of the best GWQI and AVI resulted in an Aquifer Susceptibility Index (ASI) map, which revealed that >80% of the study area falls under ‘severe’ to ‘very severe’ susceptible zones, while about 20% of the area falls under ‘moderate’ or ‘minimum’ susceptible zones. The validation results confirmed that the developed ASI map is reliable. The ASI map can serve as a useful tool for planners and decision makers to devise sustainable aquifer management programs to protect vital groundwater resources from contamination and ensure a safe and reliable water supply under climate change. Keywords: groundwater pollution; aquifer susceptibility index; groundwater quality index; aquifer vulnerability index; geospatial modeling; AHP; modified DRASTIC 1. Introduction A major share of freshwater comes from groundwater, which is a significant and reli- able source for human consumption, supplying nearly half of the drinking water demand in the world. Groundwater also supports irrigated agriculture, groundwater-dependent ecosystems, and the socio-economic development of a country [1]. However, about 30% of the world’s principal aquifers are under escalating stress due to over-exploitation of groundwater [2]. As of 2010, two-thirds of the total global groundwater is abstracted in Asia, with India, China, Pakistan, Iran, and Bangladesh being major consumers. India ranks first in the world by abstracting 251 km 3 of groundwater per year, which is over a quarter of the total groundwater withdrawals in the world [3]. On the other hand, water quality is another important aspect of sustainable water management. The indiscriminate dumping of various solid wastes, improper disposal of liquid wastes from diverse industries, and biomedical wastes from hospitals as well as the excessive use of chemical fertilizers and pesticides in agricultural fields have led to the contamination of groundwater resources in Sustainability 2022, 14, 4538. https://doi.org/10.3390/su14084538 https://www.mdpi.com/journal/sustainability