Characteristics of the disastrous debris flow of Chediguan gully in Yinxing town, Sichuan Province, on August 20, 2019

Abstract

On August 20, 2019, at 2 a.m., a disastrous debris flow occurred in Chediguan gully in Yinxing town, China. The debris flow destroyed the drainage groove and the bridge at the exit of the gully. In addition, the debris flow temporarily blocked the Minjiang River during the flood peak, flooding the Taipingyi hydropower station 200 m upstream and leaving two plant workers missing. To further understand the activity of the debris flow after the Wenchuan earthquake, the characteristics of this debris flow event were studied. Eleven years after the Wenchuan earthquake, a disastrous debris flow still occurred in the Chediguan catchment, causing more severe losses than those of earlier debris flows. In this paper, the formation mechanism and dynamic characteristics of this debris flow event are analysed based on a drone survey, high-definition remote sensing interpretations and other means. The catastrophic debris flow event indicates that debris flows in the Wenchuan earthquake area are still active. A large amount of dredging work in the main gully could effectively reduce the debris flow risk in the gully. In addition, it is also important to repair or rebuild damaged mitigation measures and to establish a real-time monitoring and early warning system for the high-risk gully.

Mechanistic Analysis and Numerical Simulation of the 2021 Post‐Fire Debris Flow in Xiangjiao Catchment, China

“…Large, severely burned areas (Wall et al., 2020), short‐term heavy rainfall (Staley et al., 2020), and steep terrain (N. Li et al., 2021) created favorable conditions for debris flow. The area of moderate and high severity burned area in Xiangjiao catchment has reached 32.6 km 2 , the peak 30‐min rainfall intensity has reached 20.2 mm h −1 , and the mean hillslope angle is 29°.…”

Impact of glacier changes and permafrost distribution on debris flows in Badswat and Shishkat catchments, Northern Pakistan

“…We analyzed data from a large number (16) of meteorological stations located at high and low elevations to reduce the uncertainties associated with short-term fluctuations on trend analysis results. Rainfall is one of the dominant debris flow triggering agents in mountainous terrains (Iverson et al, 2011;Li et al, 2021). Solid grains typically comprise 50%-70% of the volume of debris flows (Iverson, 1997;Iverson et al, 2011).…”

Impact Pressure Influence of Flood on Bridge Deck under Sediment Deposition Conditions: An Experimental Study

“…One potential damage stems from the fact that as debris flow evolves downstream, its components change, and volume and inertia increase, resulting in an exceptionally high impact pressure directly exerted on bridges [13,14]. Investigations have revealed that the impact pressure of debris flows is influenced by many factors including front velocity, flow depth, bulk density, liquid volume fractions, solid volume fractions, and the interaction between debris flows and obstructions [15][16][17][18], and both laboratory experiments and in situ tests have been conducted to physically explain and quantify the impact pressure of debris flow on bridge decks, piers foundation, and abutment [10,19,20]. Additionally, numerical simulations have aided vulnerability analysis of bridge structures [21], and hybrid models have been utilized to simulate both horizontal and vertical forces exerted on bridge decks by debris flow [22].…”