Tony Yulianto

Landslide potency at Trangkil, Gunung Pati based on the groundwater flow pattern and the value of safety factor

One of strategic approaches in landslide disaster mitigation atTrangkilsettlement area, Gunungpati, Semarang is through the prevention of soil and rock saturation. The investigation of soil and rock saturation is determined based on the shallow groundwater flow pattern and the value of safety factor.The location which prone to landslide on the eastern part with slower groundwater flow is reinforced by the rock characteristics analysis result which show its permeability value is 8.8 x 10-7 cm/s. The slow groundwater flow withinin the loam lithology makes the rock mass is greater, while its lithology could rests on an impermeable claystone. This condition makes the incompact silty loam and peeble mass could easily slide along the claystone surface and based on the analysis of rock characteristics result on the eastern part, the permeability value is smaller than on the western part. The value of safety is 1.372 indicates that the eastern part is an area prone to landslide.