Identification of groundwater recharge potential zones in a study region of South Kerala

Abstract

Groundwater is considered as a precious natural resource which serves as the main source of agriculture and domestic purposes. Kerala state is blessed with around 3000mm rainfall annually because of two prominent monsoon. But the available water is insufficient to meet the demand of people. Increase in population and water demand cause threat to overall water balance. Ground water resource must be managed well to overcome these problems. Ground water recharging is a major requirement for sustainable utilization of water resources. It also becomes highly relevant to assess the water recharge zones and to preserve water quality. This study proposes identification of suitable water recharge sites in Karamana river basin, Thiruvananthapuram, Kerala. Karamana river supplies majority of drinking water in Thiruvananthapuram district. Since its quality is deteriorating day by day, appropriate locations for recharging groundwater is identified using GIS technique. Various thematic maps like soil, slope, drainage, geomorphology and land utilization that affect the groundwater recharge is integrated and weighted overlay analysis is adopted to find the groundwater recharge potential map. Weights are assigned using Analytical Hierarchy Process (AHP) by constructing a pairwise comparison matrix. The result depicts the groundwater recharge potential zones which is divided into very high, high, moderate, low and very low potential areas.