A geostatistical approach for delineating the potential groundwater recharge zones in the hard rock terrain of Tirunelveli taluk, Tamil Nadu, India

Abstract

Groundwater recharge is an important process in hydrological water balancing where the conservational activity of both surface and subsurface water wealth is indispensable. The present geostatistical study deals with the identification of groundwater productive potential regions of Tirunelveli taluk in the Tirunelveli district of southern Tamil Nadu, India. The surface and subsurface morphological parameters such as geomorphology, lineament density, drainage density, topographic slope, land use/landcover, annual mean rainfall, soil, and subsurface geology were considered as groundwater influencing parameters and those are rejuvenated as thematic layers over the study area for inferring groundwater recharge potential regions. These thematic layers were extracted from the spatial and non-spatial datasets which were collected and downloaded from various sources. The satellite data products like LANDSAT-8, ASTER DEM, and existing published maps such as a geological map from the Geological Survey of India (GSI), topographic maps from Survey of India (SOI), and soil atlas from European digital archives are coming under spatial data categories. The non-spatial data of this study are daily rainfall data, monthly water level data, etc. In this study, the multi-criteria decision-making statistical analytical hierarchical process (AHP) methodology is utilized to achieve the layer weights. These weighted layers are reclassified by assigning ranks according to its relative importance, and those layers are mathematically overlaid for generating groundwater productive potential index map. The indexed groundwater recharge potential maps are reclassified into four classes such as very high, high, moderate, and low recharge potential region based on the cumulative score index (CSI) statistical approach and statistical information of the resultant index map. The net result reveals that around 104.25 km² of the study area comes under the very high potential for groundwater infiltration region. The moderate and low potential regions are situated in the central and middle-eastern part of the study area which covers 49 % of the entire study area.