Construction of the deep-seated landslide susceptibility model using watershed-aspect slope unit

Situating at the tectonic plate junction, the geological conditions in Taiwan is fragile and unstable. The heavy rainfall of typhoons and frequent earthquakes often caused landslide disasters, resulting in significant loss of lives and properties.

Objective of this research aims to construct deep-seated landslide susceptibility model based on discriminant analysis and innovated slope unit. The study area is the Wushe reservoir basin in Central Taiwan with records of frequent deep-seated landslides.

This research uses the slope unit derived using watershed combined with slope aspects as the analysis unit, which has been edited referring to high resolution DEM, aerial photos, and satellite images. The hypothesis testing and Pearson correlation coefficient analysis were conducted on geological, geographical, and hydrological factors derive from DEM. A total of six significant factors were selected to construct the landslide susceptibility model by discrimination analysis. The six significant factors include standard deviation of elevation, river density, average slope angle, geological category, hypsometric integral, and geological structure density. It was found that slope angle and standard deviation of elevation are more important among these factors.

Stratified sampling based on K-mean analysis is carried out based on the standard deviation of elevation and average slope angle, and the discrimination function is used to construct deep-seated landslide susceptibility model in the research area. The ROC curve is used to evaluate the results, and the estimated results compared relatively well with the mapped scarps of the deep-seated landslide.