Simulating the effect of check dam collapse in a debris-flow channel

Abstract. Debris flows often cause devastating damage to property and can injure or kill residents in mountainous areas. The construction of check dams in debris flow valleys is considered a useful strategy for mitigating the damages downstream. In this paper, a new type of spillway structure with lateral contraction was proposed to distribute debris flows after the check dam storage filled up. Four different lateral contraction ratios of the spillway were considered in experiments that investigated debris flow patterns, scour characteristics, and energy dissipation rates when debris flows passed through the spillway. The results indicated that lateral contraction considerably influenced the extension of debris flow nappes. The drop length of the nappe at η = 0.7 (η means lateral contraction ratio) was approximately 1.4 times larger than at η = 0.4. The collision, friction, and mixing forces between the debris flow nappes and debris flows in downstream plunge pools dissipated much of the debris flow kinetic energy, ranging from 42.03 % to 78.08 % at different contraction ratios. Additionally, based on a dimensionless analysis, an empirical model was proposed to predict the maximum scour depth behind the check dam. It indicated that the results calculated by the model exhibited good agreement with the experimental results.

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Evaluation and Governance Design of Risk Factor of Debris Flow on Gunmaling

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.90-93.3151 ◽

2011 ◽

Vol 90-93 ◽

pp. 3151-3154

Author(s):

Lei Nie ◽

Li Na Xu ◽

Yan Xin Yu

Keyword(s):

Debris Flow ◽

Correlation Method ◽

Mature Stage ◽

Check Dam ◽

Effect Measure ◽

Gray Correlation ◽

Medium Risk ◽

Reduce Risk ◽

Total Capacity ◽

Set Up

Abstract: It is analyzed and obtained the result that the debris flow is currently in mature stage with medium risk and high occurrence through the gray correlation method of fractal research and effect measure of debris flow gully. Therefore, it is necessary to take corresponding governance measures. In this article, check dam is used as main preventive engineering measures to set up two check dams in the passing area of debris flow, with total capacity about 2800m3 and design reservoir capacity of flood once per 50 years. Construction of the check dam will effectively reduce risk of debris flow.

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Sediment-trapping eﬀectiveness of check dams with multiple debris-flow surges: Experimental study

10.5194/egusphere-egu21-9144 ◽

2021 ◽

Author(s):

Jiangang Chen ◽

Xi'an Wang ◽

Huayong Chen

Keyword(s):

Debris Flow ◽

Field Investigation ◽

Sediment Deposition ◽

Disaster Mitigation ◽

Check Dam ◽

Sediment Trapping ◽

Check Dams ◽

The Relationship ◽

Debris Flow Hazard ◽

Deposition Morphology

<p>A series of check dams were constructed for debris-flow hazard mitigation in China. Based on the results of field investigation, check dam has a significant impact on the geomorphology of debris flow gully, especially the upstream and downstream of a check dam. According to the relationship between the sediment deposition thickness and the check dam height, the running status of a check dam can be divided into three states: without sediment deposition, half of the storage capacity with sediment deposition, and full of sediment deposition. With the accumulation of sediment transport, the running state of a check dam gradually changed and the sediment-trapping effect of check dams has gradually weakened, leading to the loss of part of the disaster mitigation effect, increasing the risk of downstream infrastructure and human security. Therefore, experiments with multi-surges of debris flows were carried out to study the geomorphic and sediment-trapping e&#64256;ectiveness of check dams. The results showed that with the increase of the sediment amount with multi-surges, the deposition slope in the downstream dam approached or even exceeded that of upstream dam. For one surge, deposition morphology has slightly difference in the cascade dams. At last, a method for calculating the reduction coefficient of deposition slope considering the check dam height and sediment amount with multi-surges is proposed.</p>

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Characteristics of a Debris Flow Disaster and Its Mitigation Countermeasures in Zechawa Gully, Jiuzhaigou Valley, China

Water ◽

10.3390/w12051256 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1256 ◽

Cited By ~ 2

Author(s):

Xing-Long Gong ◽

Kun-Ting Chen ◽

Xiao-Qing Chen ◽

Yong You ◽

Jian-Gang Chen ◽

...

Keyword(s):

Debris Flow ◽

Debris Flows ◽

Peak Discharge ◽

Dam Failure ◽

Check Dam ◽

Jiuzhaigou Earthquake ◽

Property Losses ◽

Jiuzhaigou Valley ◽

Engineering Projects ◽

Debris Flow Disaster

On 8 August 2017, an Ms 7.0 earthquake struck Jiuzhaigou Valley, triggering abundant landslides and providing a huge source of material for potential debris flows. After the earthquake debris flows were triggered by heavy rainfall, causing traffic disruption and serious property losses. This study aims to describe the debris flow events in Zechawa Gully, calculate the peak discharges of the debris flows, characterize the debris flow disasters, propose mitigation countermeasures to control these disasters and analyse the effectiveness of countermeasures that were implemented in May 2019. The results showed the following: (1) The frequency of the debris flows in Zechawa Gully with small- and medium-scale will increase due to the influence of the Ms 7.0 Jiuzhaigou earthquake. (2) An accurate debris flow peak discharge can be obtained by comparing the calculated results of four different methods. (3) The failure of a check dam in the channel had an amplification effect on the peak discharge, resulting in a destructive debris flow event on 4 August 2016. Due to the disaster risk posed by dam failure, both blocking and deposit stopping measures should be adopted for debris flow mitigation. (4) Optimized engineering countermeasures with blocking and deposit stopping measures were proposed and implemented in May 2019 based on the debris flow disaster characteristics of Zechawa Gully, and the reconstructed engineering projects were effective in controlling a post-earthquake debris flow disaster on 21 June 2019.

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