Earthquakes and heavy rainfall result in the formation of landslide dams following a massive collapse or landslide. Clarifying geomorphic changes to landslide dams following overtopping is important for mitigation of future disasters. However, past modeling experiments have not provided adequate information about geomorphic changes at landslide dams in actual scale. Recently, detailed geomorphic data before and after the landslide dam overtopping erosion by LiDAR was acquired, and it came to be able to understand the detailed shape of the water channel that has been caused along with the erosion. Therefore, we used aerial photographs, and LiDAR data sets to analyze the geomorphic changes of some landslide dams formed during the 2004 Chuetsu earthquake, the 2008 Iwate and Miyagi inland earthquake and so on. In this study, we also presented new method for describing geomorphic change of water channel. We used slope stability analysis for slope collapse at side slope of water channel. Then, we verified this method with the LiDAR data sets.

Key wordsFlandslide dam, overtopping erosion, slide slope collapse