Modeling Flood Peak Discharge Caused by Overtopping Failure of a Landslide Dam

Abstract

Overtopping failure often occurs in landslide dams, resulting in the formation of strong destructive floods. As an important hydraulic parameter to describe floods, the peak discharge often determines the downstream disaster degree. Based on 67 groups of landslide dam overtopping failure cases all over the world, this paper constructs the calculation model for peak discharge of landslide dam failure. The model considers the influence of dam erodibility, breach shape, dam shape and reservoir capacity on the peak discharge. Finally, the model is compared with the existing models. The results show that the new model has a higher accuracy than the existing models and the simulation accuracy of the two outburst peak discharges of Baige dammed lake in Jinsha River (10 October 2018 and 3 November 2018) is higher (the relative error is 0.73% and 6.68%, respectively), because the model in this study considers more parameters (the breach shape, the landslide dam erodibility) than the existing models. The research results can provide an important reference for formulating accurate and effective disaster prevention and mitigation measures for such disasters.

Using a single remote-sensing image to calculate the height of a landslide dam and the maximum volume of a lake

“…12) for calculating the volume of dam debris. In the case of the Baige landslide dam, the prediction outcome is 32.4×10 6 m 3 , while the true value according to a field survey is 30.2 × 10 6 m 3 (Shen et al, 2020). The error is mainly induced by the elevation change of the riverbed in the direction of the vertical channel, which has a great influence on the area of the dam section when the width of the dam is large.…”

“…Fan analyzed a series of dams induced by the 2008 Wenchuan earthquake and found that 43 % of them collapsed within 1 month (Fan et al, 2012). According to Shen's research on the longevity of barrier lakes, nearly 48.3 % of dams will breach within a week and 84.4 % of dams will fail within 1 year (Shen et al, 2020). Most landslide dams are unstable.…”

“…The first category is soil parameters, including the dam material composition and the repose angle of the dam material, which has an unavoidable relationship with the formation and erosion process of the dam. The low permeability and high erodibility of a landslide dam will lead to short longevity and fast breaching (Shen et al, 2020). The second category is hydrological parameters, such as the lake volume, average annual discharge and catchment area, which determine the speed at which the lake surface rises (Cao et al, 2011).…”

“…The landslide surface influences the kinetic energy of the landslide material, which has a great influence on the formation of the landslide dam. Also, the geometric parameters of the dam itself determine the stability of the dam, the maximum volume of the lake and the potential maximum discharge of the breach (Dong et al, 2011;Cao et al, 2011;Shen et al, 2020).…”

“…As water goes through the dam surface, the resulting erosion process will lead to a rapid increase in the discharge, and will finally result in flooding. According to research, this process has a strong relationship with the height of the landslide dam (Federica et al, 2021;Shen et al, 2020;Chen et al, 2004;Braun et al, 2018), which makes it one of the most important parameters related to this hazard.…”