Aquifer assessment for agriculture through geophysical, hydrochemical and hydrogeological approaches around Perumattunallur lake, Southern India

Abstract

This study mainly focused on aquifer assessment using 2-D Electrical Resistivity Imaging (ERI), hydrochemical, Geographic Information System (GIS)-based analysis and aquifer yield test for agriculture around Perumattunallur lake, Southern India. It comprises on quantifying aquifer thickness and yields with groundwater quality. The 2-D ERI technique was an attempt to study the geological structural and compare with borewell lithologs. The litho units encompass clay, calcrete weathered gneiss rock and charnockites. It shows that the resistivity of the top layer covered by clay/calcrete with kankar ranges of 1–12 Ωm followed by fine sand with a resistivity range of (10–20 Ωm) and calcrete mixed with gneissic rocks with a resistivity range of 20–120 Ωm. The massive charnockite with a resistivity range of >200 Ωm is observed in the hill ranges, present in the NE–SW direction. The hydrochemical study was attempted for the parameters (i.e., TDS, pH, Na+, K+, Ca2+, Mg2+ and Cl−) from bore well water samples briefly displayed by GIS-based geospatial analysis. The geochemical facies analysis of rock–water interaction study was used for the groundwater quality for agriculture. The pumping test helped to determine the aquifer yields with exact determination of the estimation of groundwater supply for agricultural use. The NW side of the wall is a high yield of water discharge from the lake. The average water yield of the study area is about 245.8 m3/day in summer and 310.6 m3/day in winter through the selected 7 bore wells. The alluvium clay with a calcrete layer occurs at the SE part and the results show as a low yield due to poor porosity. The radius influence of each well to be taken as 150 m was identified using the pumping test. The pumping test gives details about an aquifer of leaky aquifer with complex structure of gneissic rock with fracture/fault zone help for aquifer types. The results of the geophysical, hydrochemical and water yield test are used for groundwater quality and quantity for agriculture purpose and domestic use for the sustainable development of groundwater resources in the surroundings of the lake.