Identifying Groundwater Recharge and Discharge Zones Using GIS Layers One of the most important GIS layers in this process is topography, often represented using a Digital Elevation Model. Elevation controls the direction of surface water flow and strongly influences groundwater movement. Areas with higher elevation typically act as recharge zones, where water moves downward into the subsurface. Lower-lying areas, valleys, and depressions often serve as discharge zones, where groundwater emerges