Redundancy and hierarchical cluster analyses for characterizing geomorphic features contributing to the formation of landslide dams

Landslides frequently produce dams that can cause widespread destruction when breached. Several factors influence the formation of landslide dams. This study used redundant analysis and hierarchical cluster analysis to investigate geomorphic features contributing to the formation of landslide dams. Eight landslide geomorphic features corresponding to the width of the river beneath the landslide and four geomorphic indices were selected to explore the geomorphic characteristics of 28 river-damming and 59 nondamming landslides in Taiwan. The redundancy analysis revealed that the geomorphic features derived for the river-damming landslides differed from those derived for the nondamming landslides. The width of the river beneath the landslide was noted to be strongly correlated with the aspect of nondamming landslides. Hierarchical cluster analysis was used to cluster the river-damming landslides into three clusters based on the geomorphic features influencing dam formation. Based on these clusters, the landslide site may be damming rivers under different geomorphic combination conditions.