Abstract The 2008 Wenchuan earthquake generated a large amount of co-seismic debris, which supplied an abundant material source for post-earthquake debris flow activities, leading to a significant increase in the frequency and magnitude of post-earthquake debris flows. Residents and infrastructures will continue to be threatened by the hazard chain of debris flows in the Wenchuan earthquake-affected areas. Further understanding of the formation mechanism, activity characteristics, and cascading effects of post-earthquake clustering debris flows is of great significance to geohazard prevention and urban planning. This work first analyzed the topographic characteristics, triggering rainfall and material source supply of clustering debris flows based on detailed field investigations and aerial observations. Subsequently, we analyzed the characteristics of debris flow blocking the river for the typical catchments and their influencing factors. Meanwhile, we comprehensively assessed the debris flow blocking river effect in the Xiazhuang catchment based on indicators such as the threshold particle size of dam-forming solid material, the minimum volume of solid material for blocking the river, and the probability of blocking the river. Finally, we used OpenLISEM, a multi-hazard model, to reproduce the hazard chain process of debris flow blocking the river on 20 August 2019 in the Xiazhuang catchment and obtained the movement parameters along the path. Based on the simulation results, we analyzed the dynamic process of debris flow dam formation and flood inundation. The results show that the model performed well in predicting the chain process of debris flow blocking the river. Our work provides further insights and an assessment framework for the hazard chain of post-earthquake debris flow blocking rivers. Research highlights <OrderedList> <ListItem> <ItemNumber>1.</ItemNumber> <ItemContent> The impacts of earthquakes on debris flow activity are still significant after a decade following the Wenchuan earthquake. </ItemContent> </ListItem> <ListItem> <ItemNumber>2.</ItemNumber> <ItemContent> The characteristics of topography, rainfall triggering and material source supply for clustering debris flows were analyzed. </ItemContent> </ListItem> <ListItem> <ItemNumber>3.</ItemNumber> <ItemContent> we comprehensively assessed the debris flow blocking-river effect based on the multiple indicators. </ItemContent> </ListItem> <ListItem> <ItemNumber>4.</ItemNumber> <ItemContent> A multi-hazard model was used to reproduce the hazard chain process of debris flow blocking-rive in the typical catchment. </ItemContent> </ListItem> </OrderedList>

Mechanisms and river blocking effects of clustering debris flows on 20 August 2019 along the Minjiang River, Wenchuan, China

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发表日期：

2025年2月6日

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Yuting Luo,
Ming Chen,
Lijuan Wang,
Yao Tang,
Song Ma

摘要

Abstract

The 2008 Wenchuan earthquake generated a large amount of co-seismic debris, which supplied an abundant material source for post-earthquake debris flow activities, leading to a significant increase in the frequency and magnitude of post-earthquake debris flows. Residents and infrastructures will continue to be threatened by the hazard chain of debris flows in the Wenchuan earthquake-affected areas. Further understanding of the formation mechanism, activity characteristics, and cascading effects of post-earthquake clustering debris flows is of great significance to geohazard prevention and urban planning. This work first analyzed the topographic characteristics, triggering rainfall and material source supply of clustering debris flows based on detailed field investigations and aerial observations. Subsequently, we analyzed the characteristics of debris flow blocking the river for the typical catchments and their influencing factors. Meanwhile, we comprehensively assessed the debris flow blocking river effect in the Xiazhuang catchment based on indicators such as the threshold particle size of dam-forming solid material, the minimum volume of solid material for blocking the river, and the probability of blocking the river. Finally, we used OpenLISEM, a multi-hazard model, to reproduce the hazard chain process of debris flow blocking the river on 20 August 2019 in the Xiazhuang catchment and obtained the movement parameters along the path. Based on the simulation results, we analyzed the dynamic process of debris flow dam formation and flood inundation. The results show that the model performed well in predicting the chain process of debris flow blocking the river. Our work provides further insights and an assessment framework for the hazard chain of post-earthquake debris flow blocking rivers.

Research highlights

The impacts of earthquakes on debris flow activity are still significant after a decade following the Wenchuan earthquake.

The characteristics of topography, rainfall triggering and material source supply for clustering debris flows were analyzed.

we comprehensively assessed the debris flow blocking-river effect based on the multiple indicators.

A multi-hazard model was used to reproduce the hazard chain process of debris flow blocking-rive in the typical catchment.