*3.1. Elevation*

Surface elevation plays an important part in groundwater recharge. It is the primary source for triggering the water flow under gravity [99]. Elevation studies highlight the regions contributing to the groundwater flow; i.e., higher slopes allow less water infiltration. Islamabad has variable elevation, as it is composed of both mountainous regions and flat surfaces. The mountainous regions have higher slopes that transfer water from higher elevation to lower elevation. A similar study found designated slope as a very important factor in groundwater recharge [108]. Previous research has indicated that gentle slopes and flat surfaces have higher recharge potential compared to inclined surfaces and higher slopes [100]. Therefore, the inclusion of surface elevation signifies the groundwater flow and determines the flow direction as it induces the flow under gravity [108–110]. A major part of the current study area consists of mountainous regions with high surface elevations. Therefore, it is used as a key factor in the current study.
