GROUNDWATER ASSESSMENT AND VULNERABILITY MAPPING OF VINDHYAN GANGA SEDIMENTARY FORMATIONS AROUND MIRZAPUR DISTICT IN INDIA

Abstract

The aim of this study is to assess groundwater resources along the Vindhyan-Ganga sedimentary formation of Mirzapur district in India. Subsurface resistivity data from 12 locations are acquired by performing Vertical Electrical Soundings (VES) in the study area. Quantification of groundwater resources is conducted using groundwater table fluctuation data along with characterization of aquifer system by conducting aquifer tests. Total rechargeable area is calculated by considering slope of the landscape determined by Digital Elevation Model (DEM) prepared using Landsat 8 OLI data. Recharge from surface water sources is determined by considering the capacity of the Upper Khajuri dam, the main irrigation reservoir of the study area. The stage of groundwater development is computed from the annual groundwater use and recharge. On-site measurements for pH, electrical conductivity (EC), total dissolved solids (TDS), and temperature are also performed during the field survey and additional groundwater samples from 10 sites are collected for analyzing other water quality parameters. Heavy metals and other major ions are analyzed using AAS (Atomic Adsorption Spectroscope) and ICP-MS. Principal component analysis (PCA) is performed to establish the correlation amongst the observed groundwater quality parameters. Finding of VES are used to simulate the contaminant movement through vadose zone to the underlying groundwater resources. The classical advection dispersion equation coupled with the Richard equation is numerically simulated at different points using Hydrus simulator for assessing the intrinsic vulnerability of the region. The quantitative estimation of groundwater resources shows that annual total groundwater extraction is 13.89 MCM with the annual groundwater recharge of 51.96 MCM. Majority of the study area showed concentration of Cd, Pb, As, and Fe more than BIS recommended limits. The study area is having patches of high vulnerable zones in the south-eastern and western part. The findings of this study can be used directly in effective management of groundwater resources of the area. This study may also assist in decision making related to planning of industrial locations and groundwater remediation strategies.