Groundwater Potential Zones and Storage Capacity of Aquifer in Parsa District, Nepal

Dependency on groundwater in southern flatlands (Terai) of Nepal is high because of its reliability. Random excessive pumping may cause depletion of groundwater. Combination of Multi-Criteria Decision Analysis (MCDA) technique like Analytical Hierarchy Process (AHP) with Geographical Information System (GIS) tool aids in identifying the ground- water potential zones in different environmental settings. The study was conducted in Parsa district and provides a basis for the availability of groundwater. The objective of this study is to map the groundwater potential zones and calculate the storage capacity of an aquifer up to 50 m depth. A new theme of groundwater potential zones was obtained from seven different themes by using weighted overlay tool. Potential groundwater storage capacity of shallow aquifer was obtained by the help of thickness of aquifer and porosity of permeable layer. Permeable layer depths were interpolated using ordinary Kriging. An area of about 14.67 km2 , 213.26 km2 , 840.90 km2 and 284.18 km2 of study realm exhibited poor, moderate, good, and very good groundwater potential zone respectively. Approximately70 % of total study area has a permeable layer between 9.21 to 11.79 m within depth of 50 m of shallow aquifer as obtained by ordinary Kriging method. A totalof 5072.84 million cubic meters of water can be stored in the permeable layer of shallow aquifer up to 50 m depth. The chances of establishing groundwater potential storage zone were better in regions that had non-residential areas, flatlands, low surface drainage density, high rainfall and fertile soil based on weighted overlay.