Key Problems on Debris Flow Control Engineering after Wenchuan Earthquake in China

2020 ◽  
Author(s):  
Yanchao Gao ◽  
Songjiang Zhao ◽  
Jiazhu Wang ◽  
Wei Xu
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Large Scale ◽  
Control Measures ◽  
Western China ◽  
Design Parameters ◽  
Disaster Prevention ◽  
Check Dam ◽  
Control Engineering

<p>Strong earthquakes often induce a substantial rise in secondary geohazards. This problem has been studied more after the Great Kanto Earthquake in Japan and the Chichi Earthquake in Taiwan. In western China, after the 2008 M<sub>w</sub>7.9 Wenchuan earthquake, large-scale regional debris flows occurred in 2008, 2009, 2010, 2011, 2013, 2014, and 2019 in the strong earthquake zone. Many control projects have been constructed, including more than 1,000 check dams. Part of the projects were damaged in the subsequent large debris flows. Debris flow after the earthquake is characterized by many loose sources, high frequency and large magnitude. Traditional design parameters and control engineering cannot meet disaster prevention requirements. In the 11 years after the Wenchuan earthquake, our research team continued to investigate the formation of the debris flow in the earthquake area, and summarized the reasons for the failure of the control projects, such as the low estimate of the loose sources and the insufficient design capacity of the check dam. In response to the above problems, we have proposed corresponding solutions, including the optimal combination of different control measures, the design of the dam site and storage capacity, and the structural form of the check dam. This optimization concept has been applied in debris flow prevention such as Qipan gully and Shaofang gully and has achieved good control results. The research provides a reference for subsequent disaster prevention and mitigation in similar earthquake areas.</p>

Relationships among three repeated large-scale debris flows at Pubugou Ravine in the Wenchuan earthquake zone

2014 ◽  
Vol 51 (9) ◽  
pp. 951-965 ◽  
Author(s):  
S. Zhang ◽  
L.M. Zhang ◽  
H.X. Chen
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Large Scale ◽  
Solid Materials ◽  
2008 Wenchuan Earthquake ◽  
Hill Slope ◽  
Earthquake Zone ◽  
The Hill ◽  
Channel Deposits

The 12 May 2008 Wenchuan earthquake in China triggered numerous landslides. Loose landslide materials can easily evolve into deadly debris flows during wet seasons. During the period from 2008 to 2011, three separate large-scale debris flows occurred in the Pubugou Ravine near the epicentre of the earthquake that were among the largest repeated debris flows ever reported. Approximately 1.76 × 106 m3 of sediment was deposited during these three events. This paper aims to (i) analyze the movements of solid materials during the repeated debris flows, (ii) discuss the evolution of the initiation mechanisms of these debris flows, and (iii) evaluate the changing depositional morphology of the debris flow fans and examine the particle sizes of the debris flow materials. To achieve the above research objectives, timely field investigations were undertaken in the past 5 years after each of these debris flow events. Satellite images were used to delineate the boundaries of the initiation areas, the transportation channels, and the deposition zones of these debris flows. With the occurrence of the repeated debris flows, the hill slope deposits gradually evolved into channel deposits and the solid materials in the channels moved toward the gully mouth. Hence, channelized flows gradually became dominant. The debris fan materials of the repeated debris flows became coarser and coarser over time. The three debris flows were all characterized by coarse boulder fronts.

Reanalysis of Flash Floods and Debris Flows on two continents and their management strategies

2021 ◽  
Author(s):  
Juan Daniel Rios-Arboleda
Keyword(s):  
Risk Management ◽  
Developing Countries ◽  
South America ◽  
Debris Flow ◽  
Debris Flows ◽  
Large Scale ◽  
Management Strategies ◽  
Original Analysis ◽  
Risk Management Strategies ◽  
Latitudinal Patterns

<p>This research expands the original analysis of Baker and Costa (1987) including data from Europe and South America with the objective to understand if there are emerging latitudinal patterns. In addition, the threshold proposed by Zimmermann et al. (1997) it is evaluated with the data from tropical zones finding that this is a good predictor.</p><p>Mainly, recent Debris Flow occurred in South America are analyzed with the aim of identifying the best risk management strategies and their replicability for developing countries, particularly, the cases that have occurred in Colombia and Venezuela in the last 30 years are analyzed in order to compare management strategies and understand which are the most vulnerable areas to this phenomenon.</p><p>It is concluded that large-scale and multinational projects such as SED ALP are required in South America to better characterize events that have left multiple fatalities (sometimes hundreds of people) and better understand how to manage the risk on densely populated areas.</p><p>Finally, the use of amateur videos is proposed to characterize these events in nations with limited budgets for projects such as SED ALP, methodology that will be described extensively in later works.</p>

Research on Motion Characteristics and Formation Mechanism of Debris Flow

2014 ◽  
Vol 711 ◽  
pp. 388-391
Author(s):  
Ji Wei Xu ◽  
Ming Dong Zhang ◽  
Mao Sheng Zhang
Keyword(s):  
Debris Flow ◽  
Formation Mechanism ◽  
Debris Flows ◽  
Catchment Area ◽  
Large Scale ◽  
Large Range ◽  
Extreme Rainfall ◽  
Small Catchment ◽  
Rainfall Characteristics ◽  
Motion Characteristics

On July 9 2013, debris flows occurred around Longchi town with large scale and wide harm, which was a great threat to people's life and property as well as reconstruction work. Debris flow ditch in the surrounding town was studied. This paper focused on loose materials, topography and rainfall characteristics, and explored the formation mechanism of debris flow in Longchi town. The result shows that: a small catchment area in valleys also have the risk of large range of accumulation of debris flow, the debris flow is caused by a lot of loose materials in mountains after earthquake and extreme rainfall. Research results contribute to a better understanding of trigger condition of debris flow after earthquake.

Geomorphic effect of debris-flow sediments on the Min River, Wenchuan Earthquake region, western China

2021 ◽  
Vol 18 (9) ◽  
pp. 2427-2440
Author(s):  
Xu-dong Hu ◽  
Li-qin Zhou ◽  
Wei-ming Liu ◽  
Hao Wang ◽  
Lei Cui
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Western China ◽  
Min River

scholarly journals Risk assessment of debris flow based on group decision making – A case study of Luanchuan County, Henan Province, China

2018 ◽  
Vol 175 ◽  
pp. 04025
Author(s):  
Pengyu Chen ◽  
Ying Kong
Keyword(s):  
Risk Assessment ◽  
Decision Making ◽  
Debris Flow ◽  
Group Decision Making ◽  
Debris Flows ◽  
Large Scale ◽  
Group Decision ◽  
Henan Province ◽  
Comprehensive Assessment ◽  
Material Sources

Luanchuan County, located in the mountains of Western Henan Province, is characterized by poor geological environment and abundant material sources and rainfalls. Debris flows have occurred many times in this county, and in some gully debris flows exhibit a large scale, requiring risk assessment. In the multi-factor comprehensive assessment methods for debris flow risk, it is really important to determine the weight of each factor since this affects the reliability of the assessment results. Given that the subjective weighting method can accurately reflect the importance of each factor, in order to improve the reliability of subjective weighting, the group decision making method is used to determine the weight of each factor. Group decision making is realized using the analytic hierarchy process and the data fusion algorithm. In this method, the expert combination weight is determined; on this basis, a model for comprehensive assessment of debris flow risk is established by the linear weighted sum method, and risk assessment is performed for gullies with medium to large-scale debris flows in the study area. The assessment results show that all debris flow gullies face minor to moderate risks. For gullies with high risk degree, it is suggested to timely clear material sources in channels and construct or reinforce retaining dams in order to prevent re-occurrence of debris flows.

scholarly journals Characteristics and Prevention of the Debris Flows following Wenchuan Earthquake in Jushui River Basin, An County, China

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Yonggang Ge ◽  
Jianqiang Zhang ◽  
Xiaojun Guo
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
River Basin ◽  
Debris Flows ◽  
Flash Flood ◽  
River Channel ◽  
Hazard Identification ◽  
Control Mode ◽  
Potential Hazard ◽  
Prevention Measures

After analysing the catastrophic debris flows on August 18, 2012, and on July 9, 2013, in Jushui River basin, An County, the Wenchuan Earthquake seriously striken areas, it was found that they were characterized by the clay soil content of 0.1~1.2%, the density of 1.68~2.03 t/m3, the discharges of 62.2 m3/s to 552.5 m3/s, and the sediment delivery modulus of 1.0~9.4 × 104 m3/km2. Due to intense rainstorm, many large debris flows produced hazard chain, involved in flash flood, debris flow, dammed lake, and outburst flood, and rose Jushui River channel about 1~4 m as well as amplified flood. The hazards and losses mainly originated from the burying and scouring of debris flows, flood inundating, and river channel rise. The prevention of debris flows is facing the intractable problems including potential hazard identification, overstandard debris flow control, control constructions destructing, and river channel rapid rise. Therefore, the prevention measures for the basin, including hazard identification and risk assessment, inhabitants relocating, monitoring and alarming network establishing, emergency plans founding, and river channel renovating, and the integrated control mode for watershed based on regulating the process of debris flow discharge, were recommended for mitigation.

scholarly journals Analysis of River Blocking Induced by a Debris Flow

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Lijuan Wang ◽  
Ming Chang ◽  
Xiangyang Dou ◽  
Guochao Ma ◽  
Chenyuan Yang
Keyword(s):  
Debris Flow ◽  
Return Period ◽  
Debris Flows ◽  
Small Volume ◽  
Disaster Prevention ◽  
Intense Rainfall ◽  
Residential Areas ◽  
The Wenchuan Earthquake ◽  
Movement Characteristics ◽  
Blocking Event

Both the Wenchuan earthquake on May 12, 2008, and the Lushan earthquake on April 12, 2013, produced many coseismic landslides along the Nanya River in Shimian City. Subsequent debris flows that initiated from these landslides and are triggered by intense rainfall become the secondary hazard in the years after the earthquake; in particular, some debris flows led to a serious river blocking event. For example, the Guangyuanbao debris flow which occurred on July 04, 2013, partly blocked the Nanya River, presenting a major threat to the national highway and residential areas. To analyze the pattern of landslide damming, we analyzed numerical simulations of the movement characteristics of the Guangyuanbao debris flow using rainfall intensities with varying recurrence periods of 5, 20, and 50 years. The accuracy of the spreading of the numerical simulation is about 90%. The simulation indicated a small volume of sediment entering the river for a rainfall under 5-year return period. A debris flow induced by rainfall under 20-year return period partly blocked the river, while rainfall under 50-year return period has potential to block the river completely. This proposed analysis of river blocking induced by a debris flow could be used for disaster prevention in earthquake-stricken area.

A review of the classification of landslides of the flow type

2001 ◽  
Vol 7 (3) ◽  
pp. 221-238 ◽  
Author(s):  
Oldrich Hungr ◽  
S. G. Evans ◽  
M. J. Bovis ◽  
J. N. Hutchinson
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Large Scale ◽  
Debris Avalanche ◽  
Basic Material ◽  
Morphological Aspects ◽  
Flow Slides ◽  
Size Limits ◽  
Plastic Clays ◽  
Earth Flows

Abstract As a result of the widespread use of the landslide classifications of Varnes (1978), and Hutchinson (1988), certain terms describing common types of flow-like mass movements have become entrenched in the language of engineering geology. Example terms include debris flow, debris avalanche and mudslide. Here, more precise definitions of the terms are proposed, which would allow the terms to be retained with their original meanings while making their application less ambiguous. A new division of landslide materials is proposed, based on genetic and morphological aspects rather than arbitrary grain-size limits. The basic material groups include sorted materials: gravel, sand, silt, and clay, unsorted materials: debris, earth and mud, peat and rock. Definitions are proposed for relatively slow non-liquefied sand or gravel flows, extremely rapid sand, silt or debris flow slides accompanied by liquefaction, clay flow slides involving extra-sensitive clays, peat flows, slow to rapid earth flows in nonsensitive plastic clays, debris flows which occur in steep established channels or gullies, mud flows considered as cohesive debris flows, debris floods involving massive sediment transport at limited discharges, debris avalanches which occur on open hill slopes and rock avalanches formed by large scale failures of bedrock.

Hazards on Dujiangyan-Wenchuan Highways Induced by Catastrophic Debris Flows on July 10 2013 and Prevention

2014 ◽  
Vol 501-504 ◽  
pp. 2463-2472 ◽  
Author(s):  
Yong Gang Ge ◽  
Qiang Zou ◽  
Jian Qiang Zhang ◽  
Xiao Jun Guo
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Large Scale ◽  
Integrated Management ◽  
Gansu Province ◽  
Chain Process ◽  
Outburst Flood ◽  
Protection Measures ◽  
Traffic Security ◽  
Dangerous Section

After the Wenchuan Earthquake on May 12 2008, the highways from Dujiangyan to Wenchuan, a crucial passage from Chengdu to Sichuan Western Plateau and Gansu province, are always seriously endangered by landslides, debris flows and their following hazards. Hundreds of debris flows from watersheds, gullies and slopes on July 10 2013 produced fatal hazards and destruction on the Highway G213 and the Express Highway from Yingxiu to Wenchuan. The debris flows are characterized by numerous-occurrence, large flux (645~2238m3/s) and large magnitude (5~126×104m3) as well as the hazard chain process which is composed of debris flow, dammed lake and outburst flood. The highways were seriously destructed and blocked in 16 sites, which were induced by 6 collapsed bridges, 3 submerged bridges, 3 buried tunnel entrances, 1 site collapsed highway base and 7 sites buried highway base or bridges, and the traffic was completely interrupted. Based on analyzing the destruction modes of highways, it was found that the large-scale and potential debris flows and the irrational location of some sections, vulnerable protection measures and low resistant capability of highways against debris flows were responsible for huge highway destructions. Considering the active debris flows in the future at least 5~10 years, it was strongly suggested that potential debris flow identification, integrated management of disastrous watershed, dangerous road line altering, increasing and strengthening protection constructions at dangerous section and improving highway reconstruction standard should be carried out for highway protection and traffic security.

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