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

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 effectiveness 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>

Planning method and application case of debris-flow check dams in water and soil conservation

2020 ◽  
Author(s):  
Jiangang Chen ◽  
Huayong Chen ◽  
Xiaoqing Chen
Keyword(s):  
Debris Flow ◽  
Flash Flood ◽  
Hazard Mitigation ◽  
Extreme Rainfall ◽  
Solid Material ◽  
Field Investigation ◽  
Disaster Mitigation ◽  
Soil Restoration ◽  
Engineering Practice ◽  
Check Dams

<p>Check dams are transverse structures build across gullies and they are very important engineering measure in soil restoration hazard mitigation. After three successive earthquakes in China, a considerable number of solid material was deposited in gullies. With the extreme rainfall, a numerous of flood and debris flow events were trigged, some of them caused serious secondary disasters. In the past 12 years after the Wenchuan earthquake, based on the debris-flow prevention method by controlling debris-flow magnitude and avoiding blocking river, a series of check dams were constructed to regulate the water and soil erosion. The operation status of check dams needs to be investigated and summarize the engineering practice experience. Based on the results of field investigation, the shape and size characteristics of the dam opening were analyzed, and then established a classification system of the opening clogging types. Moreover, in August 20, 2019, Flash floods and mudslides occurred in Wenchuan County, causing more than 30 people dead, buried the G213 highway, and damaged a bridge. These disasters bring new thinking for future hazard mitigation. Geotechnical measures can quickly reduce the disaster risk of flash flood and debris flow, and now it has formed a set of perfect design standards. However, the disaster mitigation effect of the vegetation measures are not fully studied. Thus, the integrated disaster mitigation effect of the above two methods will be investigated in the future work.</p>

Study on the Effect of Debris Flows from Guanba River on Qiong Lake, Sichuan, China

2012 ◽  
Vol 599 ◽  
pp. 709-715 ◽  
Author(s):  
Xue Li Wei ◽  
Yun Long Qi ◽  
Qian Gong Cheng ◽  
Ning Sheng Chen
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Environmental Problem ◽  
Water Area ◽  
Sediment Deposition ◽  
Disaster Mitigation ◽  
Mountain Slope ◽  
Change Pattern ◽  
Push Forward ◽  
Deep Water Area

Sediment deposition caused by debris flows and floods is an important process controlling the evolution and regression of lake, and even a pervasive environmental problem. Qiong Lake is regards as a “bright phearl of the altiplano” in the Yunnan Plateau, and because debris flows construct a vital links between mountain slope and Qiong Lake, so the debris flows drove by rainfall will control the evolution rule of rift lakes. Based on the data of lake shorelines of Qiong Lake, it was found that the shoreline was push forward by 665 m since 1998. In addition, in the recent 30 years, turbidity current deposits have generated underwater levee and other landscapes in the deep water area of Qiong River. This paper has analyzed the matter migration process induced by debris flows, and presented the regime change pattern of debris flow along river channel and corresponding mechanical mechanism, mainly revealed the submarine transportation and deposition pattern of debris flow. The above studies provide a helpful way of comprehending the formation mechanism of turbidity flow induced by debris flow, and the transportation pattern. Based on severe sediment deposition catastrophes in this kind of rift lakes from debris flows and floods, disaster mitigation must be planned and appropriate engineering countermeasures put in place as soon as possible.

Soil erosion and sediment interception by check dam in watershed under extreme rainstorm on the Loess Plateau, China

2020 ◽  
Author(s):  
leichao bai
Keyword(s):  
Soil Erosion ◽  
Loess Plateau ◽  
Sediment Deposition ◽  
Delivery Ratio ◽  
Construction Technology ◽  
Check Dam ◽  
The Loess Plateau ◽  
Check Dams ◽  
Hydrological Station ◽  
Extreme Rainstorms

<p>The magnitude of soil erosion and sediment reduction efficiency of check dams under extreme rainstorms are long-standing concerns. This paper aims to use check dams to deduce the amount of soil erosion under extreme rainstorms in watersheds and to identify the difference of sediment intercepting efficiency of different types of check dams. Based on the sediment deposition of 12 check dams with 100% sediment intercepting efficiency and sub-catchment clustering by taking 12 check dams-controlled catchments as standard separately, the amount of soil erosion caused by an extreme rainstorm event on July 26<sup>th</sup>, 2017 (named “7·26” extreme rainstorm) was deduced in the Chabagou watershed in the hill and gully region of the Loess Plateau. The differences of sediment intercepting efficiency among check dams in the watershed were analysed according to the field observation 17 check dams. The results showed that the average erosion intensity under the ‘7·26’ extreme rainstorm was approximately 2.03×10<sup>4 </sup>t·km<sup>-2</sup>, which was 5 times that in the second erosive rainfall in 2017 (4.15×10<sup>3 </sup>t·km<sup>-2</sup>) and 11-384 times that in 2018 (0.53×10<sup>2 </sup>t·km<sup>-2</sup> - 1.81×10<sup>3 </sup>t·km<sup>-2</sup>). Under the ‘7·26’ extreme rainstorm, the amount of soil erosion in the Chabagou watershed above Caoping hydrological station was 4.20×10<sup>6</sup> tons. The sediment intercepting efficiencies check dams with drainage canals (including the destroyed check dams) and with drainage culverts was 6.48% and 39.49%, respectively. The total actual sediment amount trapped by the check dam was 1.11×10<sup>6</sup> tons, accounting for 26.36% of the total soil erosion amount. In contrast, 3.09×10<sup>6</sup> tons of sediment was inputted to the downstream channel, and the sediment deposition in the channel was 2.23×10<sup>6</sup> tons, accounting for 53.15% of the total amount of soil erosion. The amount of sediment transport at the hydrological station was 8.60×10<sup>5</sup> tons. The sediment delivery ratio (SDR) under the “7·26” extreme rainstorm was 0.21. The results indicated that the amount of soil erosion was huge, and the sediment intercepting efficiency of check dams was greatly reduced under extreme rainstorms. It is necessary to strengthen the management and construction technology standards of check dams to improve the sediment intercepting efficiency and flood safety in the watershed.</p>

scholarly journals Rainfall Warning Model for Rainfall-Triggered Channelized Debris Flow Based on Physical Model Test—A Case Study of Laomao Mountain Debris Flow in Dalian City

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1083
Author(s):  
Yuzheng Wang ◽  
Lei Nie ◽  
Chang Liu ◽  
Min Zhang ◽  
Yan Xu ◽  
...  
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Effective Means ◽  
Field Investigation ◽  
Disaster Mitigation ◽  
Physical Model Test ◽  
Comparison Results ◽  
Geomechanical Analysis ◽  
Critical Rainfall ◽  
Debris Flow Initiation

Debris flows are among the most frequent and hazardous disasters worldwide. Debris flow hazard prediction is an important and effective means of engineering disaster mitigation, and rainfall threshold is the core issue in debris flow prediction. This study selected the Laomao Mountain debris flow in Dalian as the research object and explored the relationship among the percentage of coarse sand content of soil, rainfall conditions and the critical rainfall values that induce debris flows on the basis of field investigation data, combined with the results of a flume test, soil suction measurement and geomechanical analysis. The new multi-parameter debris flow initiation warning models were obtained through the mathematical regression analysis method. The critical rainfall values of debris flows in this area were calculated by the previous research on the mechanism of hydraulic debris flow initiation (HIMM). Lastly, the multi-parameter debris flow initiation warning models were compared and analyzed with the critical rainfall values obtained using the HIMM method and the rainfall information available in historical rainfall data, and the reliability of the models was verified. The comparison results showed that the new multi-parameter debris flow initiation warning models can effectively modify the traditional intensity–duration model and have certain reliability and practical values. They can provide an effectual scientific basis for future work on the monitoring and prediction of debris flow disasters.

scholarly journals Influence of check dams on debris-flow run-out intensity

2008 ◽  
Vol 8 (6) ◽  
pp. 1403-1416 ◽  
Author(s):  
A. Remaître ◽  
Th. W. J. van Asch ◽  
J.-P. Malet ◽  
O. Maquaire
Keyword(s):  
Debris Flow ◽  
Source Area ◽  
Disaster Mitigation ◽  
Hazard Mapping ◽  
Geometrical Parameters ◽  
Equilibrium Equations ◽  
Numerical Work ◽  
Check Dams ◽  
Flow Intensity ◽  
Definition Of

Abstract. Debris flows are very dangerous phenomena claiming thousands of lives and millions of Euros each year over the world. Disaster mitigation includes non-structural (hazard mapping, insurance policies), active structural (drainage systems) and passive structural (check dams, stilling basins) countermeasures. Since over twenty years, many efforts are devoted by the scientific and engineering communities to the design of proper devices able to capture the debris-flow volume and/or break down the energy. If considerable theoretical and numerical work has been performed on the size, the shape and structure of check dams, allowing the definition of general design criteria, it is worth noting that less research has focused on the optimal location of these dams along the debris-flow pathway. In this paper, a methodological framework is proposed to evaluate the influence of the number and the location of the check dams on the reduction of the debris-flow intensity (in term of flow thickness, flow velocity and volume). A debris-flow model is used to simulate the run-out of the debris flow. The model uses the Janbu force diagram to resolve the force equilibrium equations; a bingham fluid rheology is introduced and represents the resistance term. The model has been calibrated on two muddy debris-flow events that occurred in 1996 and 2003 at the Faucon watershed (South French Alps). Influence of the check dams on the debris-flow intensity is quantified taking into account several check dams configurations (number and location) as input geometrical parameters. Results indicate that debris-flow intensity is decreasing with the distance between the source area and the first check dams. The study demonstrates that a small number of check dams located near the source area may decrease substantially the debris-flow intensity on the alluvial fans.

scholarly journals Field Investigation of Debris Flow Hazard Area on the Roadside and Evaluating Efficiency of Debris barrier

2015 ◽  
Vol 25 (4) ◽  
pp. 439-447
Author(s):  
Jong Hyun Lee ◽  
Jung Yub Lee ◽  
Sang Won Yoon ◽  
Young Suk Oak ◽  
Jae Jeong Kim ◽  
...  
Keyword(s):  
Debris Flow ◽  
Field Investigation ◽  
Hazard Area ◽  
Debris Flow Hazard

scholarly journals Analysis of Debris Flow Reduction Effect of Check Dam Types considering the Mountain Stream Shape: A Case Study of 2016 Debris Flow Hazard in Ulleung-do Island, South Korea

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Man-Il Kim ◽  
Namgyun Kim
Keyword(s):  
South Korea ◽  
Debris Flow ◽  
Observation Point ◽  
Mountain Stream ◽  
Check Dam ◽  
Open Type ◽  
Flow Reduction ◽  
Check Dams ◽  
Closed Type ◽  
Type Check

Ulleung-do is a volcanic island located 130 km east of the Gangwon-do province of South Korea. It is characterized by steep slopes covered with effusive rocks released from multiple volcanic activities. Having accumulated deep colluvium, Ulleung-do Island manifests a high vulnerability to landslides frequently caused by heavy rains or typhoons, debris flow, rockfall, and other disaster hazards in mountainous areas. Therefore, facilities and residential areas located in the lower areas of the island sustain widespread damage. Hence, the installation of check dams designed to reflect the area’s local conditions is required to avoid further damage. In line with that, this study analyzes the disaster cases in Ulleung-do’s mountain areas and the effect of check dams in debris flow reduction for each type using the KANAKO-2D model. At observation point 1, the result shows that the maximum rate of debris flow is reduced by 48.5% with an open-type check dam installed and 62.9% with a closed-type check dam installed from the level without a check dam. For observation point 2, the maximum flow depth decreases by 49.7% with an open-type check dam and 77.4% with a closed-type check dam. Thus, this study suggests that the simple installation of check dams in a mountain stream that has experienced debris flow effectively mitigates damage brought by various disasters.

scholarly journals Direct field observations of massive bedload and debris-flow depositions in open check dams

2018 ◽  
Vol 40 ◽  
pp. 03003 ◽  
Author(s):  
Guillaume Piton ◽  
Firmin Fontaine ◽  
Hervé Bellot ◽  
Frédéric Liébault ◽  
Coraline Bel ◽  
...  
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Time Lapse ◽  
Bedload Transport ◽  
The Other ◽  
Field Observations ◽  
Sediment Trapping ◽  
Check Dams ◽  
Protection Systems ◽  
Detention Basins

Sediment detention basins, also called SABO dams, are key facilities in flood protection systems of mountain catchments, specifically in torrents prone to massive bedload transport or debris flows. A better understanding of the processes generating sediment trapping is required to optimize their functioning. Two monitoring stations have been implemented in the French Alps on two torrents: the Manival (Saint-Nazaire-Les-Eymes) and the Claret (Saint-Julien-Mont-Denis). Time-lapse photos show an event depositing 10,000 m3of debris flow in a basin in less than six minutes and several events partially filling the other basin with gravel, impairing its capacity to store debris flows later. After a presentation of the catchments, this paper qualitatively analyzes the dynamics of the depositions. It highlights and stresses the consistency and differences between bedload and debris-flow deposition. Overall, despite clear differences of geomorphic activity, deposits tend to fill the trap basins just enough to enable the sediment transport continuity reestablishment through the basin. The open check dams thus play a role only provided that this continuity precondition is completed. These observations enhance our comprehension of massive sediment trapping in torrents and our capacity to better adjust trap maintenance and design to the objective sought in each site.

scholarly journals Evaluating an optimum slit check dam design by using a 2D unsteady numerical model

2018 ◽  
Vol 40 ◽  
pp. 03027 ◽  
Author(s):  
Su-Chin Chen ◽  
Samkele Tfwala
Keyword(s):  
Optimal Design ◽  
Debris Flow ◽  
Numerical Solutions ◽  
Decision Makers ◽  
Check Dam ◽  
Storm Events ◽  
Check Dams ◽  
Aerial Vehicle ◽  
The Many ◽  
Steep Slopes

Debris flow could be catastrophic to residents and property located at their downstream. As a result, engineers have designed several structural countermeasures, such as check dams. Regardless of the many investigations on check dams, uncertainty with respect to their design is still persistent. Against this backdrop, the study aims to assess the efficiency and determine an optimal design of slit check dams for mitigating debris flow and sediment-laden flows in steep channels. The study uses an actual slit check dam located at Landao creek, a tributary to the Beng-gai River in the central range of Taiwan. The creek has an average slope of 7 degrees, while its d50 is approximately 100 mm. Steep slopes, extreme precipitation, poor geologic formations, debris flow and landslides characterise the catchment. Concerning the slit check dam design; there were six rectangular concrete piers (width = 1.5 m, length = 4 m, depth = 8 m), linearly spaced at 1 m in a 180° alignment layout, with the middle 2 piers height reduced by 2.5 m. We evaluated the performance of this configuration and further tested two additional configurations by cutting a single pier and three piers at the centre in a 2D model, Nays-2DH. Hydrograph of a selected storm was used for upstream boundary conditions. Surveys using an unmanned aerial vehicle were conducted pre- and post-storm events to validate numerical solutions. Scour and deposition profiles from the different pier configurations formed the basis of our assessment. The numerical computations yielded valuable results and may provide better understanding in the optimal design of slit check dams. Our findings are of paramount importance to engineers and decision makers with regard to debris flow mitigation, especially in a typhoon prone region like Taiwan.

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