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.

Design Standard of Control Structures Against Debris Flow in Japan

2010 ◽  
Vol 5 (3) ◽  
pp. 307-314 ◽  
Author(s):  
Nobutomo Osanai ◽  
◽  
Hideaki Mizuno ◽  
Takahisa Mizuyama ◽  
Keyword(s):  
Debris Flow ◽  
Flow Control ◽  
Warning Systems ◽  
Technical Standard ◽  
Stone Size ◽  
Control Structures ◽  
Open Type ◽  
Check Dams ◽  
Closed Type ◽  
Structural Measures

Countermeasures to prevent or mitigate sedimentrelated hazards, debris flow in this paper are classified as structural measures or nonstructural measures. The structural measures are Sabo dams, leading dikes, and channels for debris flow control. The nonstructural measures are the designation of areas prone to debris flow, proper land use in the areas, the reinforcement of houses, the creation of warning systems and the evacuation of the inhabitants in case of emergency. A technical standard on debris flow control structures of Japan was revised in 2007. Major revision is that check dams called Sabo dams constructed near houses are changed from closed type Sabo dams to open type Sabo dams because the occurrence frequency is low as once for longer than one hundred years, natural torrent environment should be conserved in ordinary days and sediment trap capacity should be kept until debris flow occurs. Points changed are explained such as the opening of open type dams is as equal as the maximum stone size.

Experimental study on discharge process regulation to debris flow with open-type check dams

Landslides ◽  
2020 ◽  
Author(s):  
Hao Sun ◽  
Yong You ◽  
Jinfeng Liu ◽  
Guangze Zhang ◽  
Tao Feng ◽  
...  
Keyword(s):  
Experimental Study ◽  
Debris Flow ◽  
Discharge Process ◽  
Open Type ◽  
Check Dams ◽  
Type Check

scholarly journals Method to evaluate the effect of inclination angle of steel open-type check dam on debris flow impact load

2018 ◽  
Vol 10 (1) ◽  
pp. 95-115 ◽  
Author(s):  
Toshiyuki Horiguchi ◽  
Yoshiharu Komatsu
Keyword(s):  
Debris Flow ◽  
Natural Disasters ◽  
Inclination Angle ◽  
Impact Load ◽  
Time History ◽  
Check Dam ◽  
Open Type ◽  
Inclination Angles ◽  
The Impact ◽  
Type Check

Although the latest statistics indicate a decrease in the number of victims of natural disasters in Japan, the number of sediment disasters has increased. A countermeasure against natural disasters is provided by the installation of a steel open-type check dam (hereafter, open Sabo dam). The open Sabo dam is expected to capture boulders (more than 1.0 m in diameter) contained in debris flow of which boulders concentrate in front part. When a debris flow impacts an open Sabo dam, the large impact load on the steel pipes are caused by the impact of boulders under debris flow. Therefore, it is important to evaluate the impact of both boulders and the following soil and small gravels including fluid force of the open Sabo dam from the design point of view. Although an open Sabo dam has various shapes especially, the every open Sabo dams is evaluated by the same design method in Japan. It is necessary to propose the load evaluation method in the experiment scale in contrast with different shape of open Sabo dam. This article presents an experimental approach to determine the effect of the front inclination angle of steel open Sabo dams on the impact load. The debris flow impacts 1/40 scale models of steel open Sabo dams which are set in a flow channel flume, and the debris flow load is measured by using three load cells placed horizontally at the back of the Sabo dam model. Different front inclination angles are set for each Sabo dam models. The time history of the impact load is examined by comparing the loads corresponding to four kinds of dams, which are different from the front inclination angles, and decrease of impact load considering the buffering effect of driftwoods in debris flow.

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>

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.

scholarly journals Effectiveness and efficiency of slot-check dam system on debris flow control

2015 ◽  
Vol 3 (9) ◽  
pp. 5777-5804 ◽  
Author(s):  
Y. H. Zou ◽  
X. Q. Chen
Keyword(s):  
Debris Flow ◽  
Flow Control ◽  
River Basin ◽  
Debris Flows ◽  
Check Dam ◽  
Sediment Control ◽  
Sediment Volume ◽  
Check Dams ◽  
Effectiveness And Efficiency ◽  
Set Up

Abstract. Slot-check dam system is commonly used to control sediment transport associated with debris flows and mitigate debris flow hazards. This paper aims to estimate the performance of the slot-check dam system in the field and set up a verification to evaluate the efficiency of a slot-check dam system and each subsystem in debris flow sediment control. Field survey on a group of a series of slot-check dams at Shengou Basin in Yunnan, China reveals that the conserving sediment volume of each dam is related to its relative location in the group, gradually decreasing from upstream to downstream. The cumulative sediment volume within a subsystem of slot-check dams closely related to the characteristics of the catchment controlled by the subsystem. It increases with the controlled catchment area of the most downstream dam in subsystem and the distance from the dam to the upstream most. Evaluation models for the conserving efficiency of a slot-check dam system on debris flow control in a river basin and each subsystem within the group associate to the controlled catchment characteristics have been proposed. The layout principle of a slot-check dam system in a river basin has been developed based on the conserving efficiency of a subsystem of slot-check dams which would allow the slot-check dam system to be designed in a more scientific way.

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