Effects of Hydraulic Factors on Near-bank Landslide Susceptibility Analysis in Alishan River Watershed

Near-bank landslide is the primary source of sediment in the mountain rivers. Scouring of slope toe may cause the near-bank landslide, resulting in slope materials collapsing into rivers. Collapsing materials accumulated on the riverbed obstruct the flow, forming barrier lake and greatly destabilizes the river channel, hence, post a threat to the safety of downstream residents and property. The Alishan River watershed was selected as the research areas and utilized logistic regression analysis to assess the landslide susceptibility of near-bank areas. Models considered different factors, including geographical and hydraulic factors, were established. Model assessment used the area under the ROC curve (AUC) values to evaluate the performance. Results of the model with the highest AUC value was then produced the landslide susceptibility map to illustrate the effects of geographical and hydraulic factors in the landslide prediction. The results showed that concave banks and channel sinuosity index contribute to near-bank landslides significantly. Observations of landslide susceptibility map and satellite image revealed that concave banks and flow meandering are often the characteristics of near-bank landslide areas with high susceptibility. The results can serve as a reference for disaster prevention and management in the future.