Semarang Municipality has an area with geological condition firmly controlled by fault and fold, leading to greater potential of landslide, as may be evidenced in Meteseh, Jabungan, Sukorejo, Karangrejo, and Kandiri Villages. Therefore, a strategy is necessary to mitigate the landslide disaster. One of strategical approaches to such problem is prevention of land and rock saturation. The investigation of the landslide and rock saturation is determined based on shallow groundwater (unconfined) flow pattern. Such strategic pattern is applied to landslide prone area like Trangkil settlement. In determining the potential location of the landslide, a geological mapping is needed to examine the surface position and the direction of the unconfined (phreatic). The potential location of the landslide was mostly found in the east area where the groundwater flow is slow. A slow groundwater flow in clay-silt lithology can causes greater rock mass weight, while this lithology depends on impermeable clay. Such condition has caused non-compacted granule-silt-clay of unit easy to experience a sliding in the direction of the clay surface.