The modelling of soil slip erosion in the upper Komering area south Sumatra, province Indonesia

Abstract

Field observations and back analyses of soil slips in the tuff area of the Komering river basin showed that the triggering mechanism of soil slips in deep weathered tuffs is the downward percolation of a more or less saturated wetted zone to a critical depth. A combined infiltration and stability model gives the possibility to calculate the probability of failure per area and hence the amount of soil displacement, using a stochastic approach. An estimate of soil slip erosion was dune for three different situations of landuse: ladang (recently prepared), coffee field, secondary forest. A first tentative simulation with the model gives already an insight in the main factors which contribute to the increase in danger for soil slipping in case of deforestation and a transverse into ladang fields. The most sensible parameters in the stability system appeared to be the initial moisture content of water in the soil and the depth of the rootzone.