Review of Investigations on Hazard Chains Triggered by River-Blocking Debris Flows and Dam-Break Floods

Abstract

The Tibetan Plateau suffers from various types of geohazards (collapses, landslides, and debris flows.) due to abrupt changes in complex topography and weather conditions. Global warming and frequent high-intensity earthquakes in recent years have exacerbated the situation. Collapses and landslides provide vast amount of soil and debris which are conveyed downstream by runoff caused by extreme rainfalls to form large-scale debris flows; then, the debris flows block rivers and finally form dam-break floods, that is, a hazard chain triggered by debris flows. Along the evolution direction of the hazard chain, the affected areas are constantly amplified. This study first summarizes the related research studies on river blockage, debris-flow dam failure, and the hazard chain triggered by debris flows and then points out the drawbacks of existing research studies. Overall, the research (including mechanism, risk assessment, key prevention, and control technologies) on the hazard chain triggered by debris flows is still in its infancy and is disconnected among single hazard types in the hazard chain; meanwhile, the understanding of the mechanism of debris flow blocking the river is not enough; the established model and discriminant have minimal application scope, and there is no empirical model and dynamic model of debris-flow dam failure. Finally, several key scientific issues of this field were raised: 1) it is necessary to elaborate the coupling mechanism of debris-flow dam formation and construct the discriminant and numerical model of debris flow blocking the river with high precision and a wide application range. 2) It is necessary to further study the failure mechanism of a debris-flow dam, construct the numerical model of the failure process of a debris-flow dam, and accurately simulate the outburst flood hydrograph. 3) It is necessary to clarify the critical transformation conditions and dynamic evolution process of the hazard chain caused by debris flows, complete the accurate quantitative simulation of the whole disaster chain process, then establish a complete risk assessment system of the hazard chain, and finally develop some key prevention and control technologies suitable for the hazard chain.

The vulnerability of buildings to a large-scale debris flow and outburst flood hazard chain that occurred on 30 August 2020 in Ganluo, Southwest China

“…In recent years, the hazard chain of debris flows and outburst floods has become more frequent in high mountain regions due to the impact of climate change and earthquakes (Chen et al, 2022).…”

“…Risk assessment for debris flow-outburst flood hazard chains is crucial to mitigate the damage posed to structures in the confluence zone. Risk analysis should incorporate both the debris flow initiation mechanism and the mechanism that generates the dam-burst flood (Chen et al, 2022). A detailed investigation should be conducted for the exposed elements in the confluence zone and in corresponding disaster reduction measures should be developed (Cui and Guo, 2021).…”

“…The evaluation and mitigation of the multiple risks posed by debris flows and dam-burst floods in a confluence zone require a multi-risk analysis that considers hazard interactions and their cumulative effects on building vulnerability. Most studies on debris flow and dam-burst floods mainly focus on numerical simulations and the evolving processes of hazard chains (Nin et al, 2022;Chen et al, 2022), but studies on the vulnerability of building to hazard chains are scarce. The vulnerability of buildings to the cumulative impact of debris flow and flash flood may differ from the sum or sequence of vulnerability resulting from a single debris flow or flash flood (Kappes et al, 2012).…”

Research on the Evolution Network Model of the Landslide Disaster Chain: A Case Study of the Baige Landslide

“…Large-scale landslides, in particular, account for a significant portion and are prominent research subjects in the field of geological disasters worldwide due to their extensive scale, high destructiveness, and complex causes [8][9][10][11]. Entire slopes of soil mass can transform into debris flows that block rivers, resulting in landslides blocking rivers, which, in turn, lead to the formation of successive barrier lakes, floods, and swellings [12,13] This poses a significant threat to residential areas, farmland, highways, and other infrastructure.…”

Experimental study on whole process of river blockage and dam break under different hydrodynamic conditions

“…Due to natural disasters, such as earthquakes, rainstorms, typhoons and melting glaciers, destructive landslides or debris flows can easily form near mountain valleys (Coussot and Meunier, 1996;Cruden, 2005;Sassa, 2007;Chae et al, 2017;Chen et al, 2022). These material sources would very likely block river channels, causing these to stop flowing and form natural dams (Costa and Schuster, 1988;Fan et al, 2020;Zhong et al, 2021).…”