Author(s): Hatma Suryatmojo; Nia Amalia Septiani; Danang Sri Hadmoko; Ngadisih
Linked Author(s): Hatma Suryatmojo
Keywords: Landslide; Soil hydraulic properties; Infiltration rate; Soil porosity; Saturated hydraulic conductivity
Abstract: Landslide is one of the hydro-meteorological disaster type in Indonesia and tend to increase year by year. Tectonic conditions in Indonesia that form of a high morphology, intensive fractures, fragile volcanic rocks and supported by a very intensive geomorphological processes and wet tropical climate, causing the potential for landslides to be high. A huge landslide was occurred in Banaran village, Pulung sub-district, Ponorogo District in April 1st, 2016. Many factors that influence the occurrence of landslides, but there are three main factors causing landslides are: extreme rainfall, landslide topography, and soil hydraulic properties. This study intends to investigate the soil hydraulic properties focusing in the soil porosity, infiltration rate and hydraulic conductivity. Nine experimental plots were established to investigate the change of soil hydraulic properties based on differences of topography. The surface soil disturbance associated with intensification of farming and forest cover changes have increased infiltration characteristics, soil compaction and hydraulic conductivity within the near surface profile. Soil compaction has changed the soil pore distribution and has affected soil moisture characteristics. In the disturbed near surface profile (0-50 cm deep) tend to increase the number of macro-pores and the porosity. There were low surface K values on middle-plot compared to upper-plot and down-plot. Reductions in surface K may increase the frequency of surface runoff. Forest and surface soil disturbances have altered the typical surface hydrological pathways, thereby creating the conditions for more water infiltrated and increased the landslide hazard potency. The increase of soil water content led to the rise of the pore pressure and soil weight which could cause soil vulnerability to the movement. Controlling the surface soil profile activities would effective to reduce the portion of water enter to the sub surface soil and reduce the landslide potency.
Year: 2018