Identification of groundwater potential zones of Alappuzha (Kerala) in South India integrating AHP and GIS

Groundwater is one of the important natural resources that is essential to sustain the life on Earth. Crisis related to groundwater and other water resources is becoming severe in the recent years. Controlled use of water recourses and management of groundwater aquifers in indispensable. This study has been carried out to identify groundwater recharge or groundwater potential area of Alappuzha, Kerala, South India. Groundwater potential signifies the total quantity of water that occupying in the aquifer, and it varies from one area to another due to change in aquifer properties. Investigation on the groundwater potential study is done by Analytical Hierarchy Process (AHP) and also incorporating Geographical Information System (GIS). Eight thematic GIS layers including geology, geomorphology, soil, rainfall, slope, drainage density, land use/ land cover (LULC) and lineament density were chosen. Pair-wise comparison technique was employed to assign weight and rank to these layers and the weighted sum of all these layers aided to create the groundwater potential zone (GWPZ) map of Alappuzha. The map classified the study area in to five zones, very high, high, moderate, poor and very poor. In Alappuzha very high potential zone is extends up to 106 km² about 8% of the study area. High potential zones spread over 755.4 km² (59%) of the area. 311.9 km² (24%) of Alappuzha is occupied by moderate GWPZ. The poor and very poor GWPZ covers about 85.01 km² (7%) and 16.9 km² (1.2%), of the study area respectively. The least unsuitable for subsurface recharge was identified along the coastal stretch, characterized by high drainage density and intense discharge rate.