A method for predicting shallow landslide area in managed and unmanaged forests

Abstract

In recent years, with the decline of forestry in Japan, unplanted areas left after clear-cutting have increased rapidly. As shallow landslides occur frequently in clear-cut and unplanted areas, this study newly constructed a landslide risk prediction model, an improvement of a previous model [Kuroiwa and Hiramatsu, 2004], that considers the forest condition, especially whether the forest root system is decayed or developed following forest harvesting. Using this model, we calculated the shallow landslide area ratio in the Miyagawa Dam basin. It was possible to predict the shallow landslide area ratio with high accuracy compared with previous model application. Thus, the proposed model successfully predicted changes in shallow landslide areas of the basin by considering forest harvesting and rainfall.