Identification of Potential Sites for the Construction of Underground (Subsurface) Dams in Pakistan: A Case Study of Gilgit River Basin

Abstract

A need for existence is water. Water is becoming increasingly scarce as a result of shifting climatic patterns and use practices. Thus, water conservation is of high priority especially in dry regions of Pakistan. Water management by constructing surface reservoirs can help, but again problems like sedimentation and high evaporation rates are of much concern. Therefore, taking into account monsoon rainfall and seasonal river flows, storing water using subsurface dams might be advantageous. To stop subsurface flows and raise groundwater levels (GWLs) in the sediment layers, a subsurface dam can be constructed, improving natural groundwater storage. Due to decreased evaporation, more functionality, cheaper construction costs, lesser danger of pollution, and the potential for using land above the dam, these dams are preferred to surface dams. In order to manage and expand groundwater resources sustainably, underground dams are a viable and efficient option. The purpose of the present study is to develop and assess methods for situating subsurface dams for use in managing water resources. The effectiveness of underground dams is dependent on the ability to find appropriate locations for their construction. Gilgit River Basin was selected as a case study. Subsurface dams are utilized in regions that counter significant shifts in the volume of groundwater flow during the year. Pakistan's semiarid regions, where there is a scarcity of water for domestic and agricultural use, there is an urgent need to investigate more locations that are reasonable for the underground dam’s construction. Geological and hydrological parameters of the land surface are directly responsible for the capability for groundwater. Seven factors— evapotranspiration, hydrological soil texture, land use and land cover, drainage density, rainfall, geology, and slope—were considered, their respective layers were made in Analytic Hierarchy Process (AHP) and ArcGIS techniques employed in creating suitability map. AHP technique was used to define the parameters and give relative importance to each one. Thus, through GIS analysis and AHP technique, all the feature layers were integrated, results were drawn out and the most suitable locations in Gilgit River Basin were identified.