GIS Based Groundwater Potential Zone Identification Using AHP for Ponnaniyaru Watershed, Tamil Nadu, India

Abstract

Groundwater is a vital source of water among the other sources due to its quality. An increase in urbanization and population creates tremendous pressure on its quality and quantity. The judicial utilization of Groundwater resources is essential. Though the world is covered by 70% of water, only 2.5% is potable water, so it is necessary to safeguard them for potential use without the water demand. In this study, the Ponnaniyaru river watershed, the sub-basin of the Cauvery River, has an area of 817 sq. km and is located at 12° 47′ 6″ N, 80° 17′ 1″ E, and 13° 15′ 22″ N, 79° 55′ E, as shown in Fig. 24.1. It origins from Kaduvur hills and joins with the Cauvery in West Trichy. The basin is comprised of hard rock terrain, which in turn results in low infiltration and a dry river basin. Water demand is high as the region is semi-arid, and the average temperature is 28 °C. The red loamy soil is predominant in the basin, which has excellent water holding capacity. In recent periods agricultural activities and urbanization have increased drastically in this watershed. GIS and remote sensing are important techniques that could be adopted to analyse the potential groundwater zones and predict possible artificial recharge locations. The artificial recharge system enhances the groundwater potential in the region, but the necessary study has to be carried out to spot the promising areas to set up recharge wells. The geology and geomorphology of the region with a detailed description of the aquifers beneath has to be well understood. The study adopts Saaty’s Analytical Hierarchy Process (AHP), a multi-criteria decision-making approach to determine the weights of the factors. The crucial parameters considered in the study include geomorphology, geology, soil, slope, lineament density, drainage density, land use/land cover, and rainfall. The thematic maps of the parameters are prepared using the ArcGIS tool and are assigned with weights using the AHP technique to determine the potential groundwater zone. After overlaying the factors, the resultant map portrays the potential groundwater zones, which are classified into very poor, poor, moderate, good, and very good zones, and the result is validated with well yield data. With the obtained result, suitable sites for artificial recharge for sustainable groundwater management were identified.