Prediction of Landslide Dam Formation Affected by Topographical and Geological Conditions

Abstract

Landslide dams are caused by large-scale slope collapse. Predicting their failure is important because hazardous flooding may result downstream when landslide dams burst. Accurate prediction of a landslide-dam formation which means height and length via landslide maps that show two-dimensional figure but does not consider landslide depth is needed for a countermeasure against the sediment disaster caused by landslide dam. In this study, past landslide dam failures were investigated. Relationships between landslide dam formation and the topographical and geological characteristics of the region were established to improve landslide dam analysis for more accurate prediction of dams' structural integrity.

The Impacts of River Channel Blockages Caused by Sliding Embankment Collapses during Earthquakes

“…To simply and accurately predict the deposition shapes of landslide dams created via large soil mass movements that block river channels, we now provide an overview of our earlier predictive formula, as shown in Figure 4 [45].…”

“…However, the reproducibilities of the predictive equations [43] have been questioned; analyses of historical landslide dam behaviors revealed a need for improvement. For example, the correlation coefficients of equations predicting land-slide dam deposition lengths ranged from only 0.16 to <0.7 [44,45].…”

“…We thus developed simple equations that predicted the shape (the deposition height and length) of landslide dams that form after earthquakes and heavy rain in Japan; we referred to historical cases [44,45]. We earlier verified the reproducibilities of these equations during heavy rain [45] by reference to the large landslide dams that formed in the Kii Peninsula during Typhoon 12 (Talas) in 2011 [50]. However, the utilities of these equations when analyzing landslide dams that form after earthquake-induced embankment collapses have not been verified.…”

“…However, the utilities of these equations when analyzing landslide dams that form after earthquake-induced embankment collapses have not been verified. Previous studies [45] developed more detailed predictive equations by reference to the geologies of collapsing mountainsides; they sought to improve the accuracies of deposition shape predictions after earthquakes. However, given the differences in the geologies of the collapsing embankments, application of the detailed predictive equations remains challenging.…”

“…We here discuss the impact (disaster risk) of river channel blockages (landslide dams) triggered by the sliding collapse of embankments near rivers during earthquakes. We newly verify the reproducibility of simple equations that predict river channel blockage shapes [45,50] using examples from the Hanshin-Awaji Earthquake. Further, we confirm the reproducibility of our proposed two-dimensional model [55] for landslide dams with gentle slopes and we predict the dam outflow volumes and the disaster risks in the event of dam formation and breach in the Nigawa Yurino area.…”