scholarly journals Classification and susceptibility assessment of debris flow based on a semi-quantitative method combining of the fuzzy C-means algorithm, factor analysis and efficacy coefficient

2020 ◽  
Author(s):  
Zhu Liang ◽  
Changming Wang ◽  
Songling Han ◽  
Kaleem Ullah Jan Khan ◽  
Yiao Liu
Keyword(s):  
Factor Analysis ◽  
Debris Flow ◽  
Human Activity ◽  
Land Use Planning ◽  
Debris Flows ◽  
Field Investigation ◽  
Matter Source ◽  
Susceptibility Analysis ◽  
Fuzzy C Means ◽  
Fuzzy C Means Algorithm

Abstract. The existence of debris flows not only destroys the facilities, but also seriously threatens human lives, especially in scenic areas. Therefore, the classification and susceptibility analysis of debris flow are particularly important. In this paper, 21 debris flow catchments located in Huangsongyu town ship, Pinggu District of Beijing, China were investigated. Besides field investigation, geographic information system, global positioning system and remote sensing technology were applied to determine the characteristics of debris flows. This article introduced clustering validity index to determine the clustering number, and the fuzzy C-means algorithm and factor analysis method were combined to classify 21 debris flow catchments in the study area. The results were divided into four types: scale-topography-human activity closely related, topography-human activity-matter source closely related, scale-matter source-geology closely related and topography-scale-matter source-human activity closely related debris flow. And 9 major factors screened from the classification result were selected for susceptibility analysis, using both the efficacy coefficient method and the combination weighting. Susceptibility results showed that the susceptibility of 2 debris flows catchments were high, 6 were moderate, and 13 were low. The assessment results were consistent with the field investigation. Finally, a comprehensive assessment including classification and susceptibility evaluation of debris flow was obtained, which was useful for risk mitigation and land use planning in the study area, and provided reference for the research on related issues in other areas.

scholarly journals Classification and susceptibility assessment of debris flow based on a semi-quantitative method combination of the fuzzy <i>C</i>-means algorithm, factor analysis and efficacy coefficient

2020 ◽  
Vol 20 (5) ◽  
pp. 1287-1304 ◽  
Author(s):  
Zhu Liang ◽  
Changming Wang ◽  
Songling Han ◽  
Kaleem Ullah Jan Khan ◽  
Yiao Liu
Keyword(s):  
Factor Analysis ◽  
Debris Flow ◽  
Human Activity ◽  
Land Use Planning ◽  
Debris Flows ◽  
Risk Mitigation ◽  
Field Investigation ◽  
Matter Source ◽  
Susceptibility Analysis ◽  
Major Factors

Abstract. The existence of debris flows not only destroys the facilities but also seriously threatens human lives, especially in scenic areas. Therefore, the classification and susceptibility analysis of debris flow are particularly important. In this paper, 21 debris flow catchments located in Huangsongyu Township, Pinggu District, Beijing, China, were investigated. Besides field investigation, a geographic information system, a global positioning system and remote-sensing technology were applied to determine the characteristics of debris flows. This article introduced a clustering validity index to determine the clustering number, and the fuzzy C-means algorithm and factor analysis method were combined to classify 21 debris flow catchments in the study area. The results were divided into four types: debris flow closely related to scale–topography–human activity, topography–human activity–matter source, scale–matter source–geology and topography–scale–matter source–human activity. Nine major factors screened from the classification result were selected for susceptibility analysis, using both the efficacy coefficient method and the combination weighting. Susceptibility results showed that the susceptibility levels of 2 debris flow catchments were high, 6 were moderate and 13 were low. The assessment results were consistent with the field investigation. Finally, a comprehensive assessment including classification and susceptibility evaluation of debris flow was obtained, which was useful for risk mitigation and land use planning in the study area and provided a reference for the research on related issues in other areas.

scholarly journals Discharge of landslide-induced debris flows: case studies of Typhoon Morakot in southern Taiwan

2014 ◽  
Vol 2 (1) ◽  
pp. 315-346
Author(s):  
J.-C. Chen ◽  
M.-R. Chuang
Keyword(s):  
Debris Flow ◽  
Case Studies ◽  
Debris Flows ◽  
Maximum Flow ◽  
Field Investigation ◽  
Typhoon Morakot ◽  
Flow Discharge ◽  
Modeling Software ◽  
Southern Taiwan ◽  
Deposition Depth

Abstract. Three debris-flow gullies, the Hong-Shui-Xian, Sha-Xin-Kai, and the Xin-Kai-Dafo gullies, located in the Shinfa area of southern Taiwan were selected as case studies of the discharge of landslide-induced debris flows caused by Typhoon Morakot in 2009. The inundation characteristics of the three debris flows, such as the debris-flow volume, the deposition area, maximum flow depth, and deposition depth, were collected by field investigations and simulated using the numerical modeling software FLO-2D. The discharge coefficient cb, defined as the ratio of the debris-flow discharge Qdp to the water-flow discharge Qwp, was proposed to determine Qdp, and Qwp was estimated by a rational equation. Then, cb was calibrated by a comparison between the field investigation and the numerical simulation of the inundation characteristics of debris flows. Our results showed that the values of cb range from 6 to 18, and their values are affected by the landslide ratio The empirical relationships between Qdp and Qwp were also presented.

scholarly journals Debris-flow activity in five adjacent gullies in a limestone mountain range

2015 ◽  
Vol 42 (1) ◽  
Author(s):  
Klaus Schraml ◽  
Markus Oismüller ◽  
Markus Stoffel ◽  
Johannes Hübl ◽  
Roland Kaitna
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
National Park ◽  
Regional Scale ◽  
Field Investigation ◽  
Mountain Range ◽  
Sediment Sources ◽  
Aerial Vehicle ◽  
Flow Activity ◽  
Local Variability

Abstract Debris-flows are infrequent geomorphic phenomena that shape steep valleys and can repre-sent a severe hazard for human settlements and infrastructure. In this study, a debris-flow event chro-nology has been derived at the regional scale within the Gesäuse National Park (Styria, Austria) using dendrogeomorphic techniques. Sediment sources and deposition areas were mapped by combined field investigation and aerial photography using an Unmanned Aerial Vehicle (UAV). Through the analysis of 384 trees, a total of 47 debris-flows occurring in 19 years between AD 1903 and 2008 were identified in five adjacent gullies. Our results highlight the local variability of debris-flow activi-ty as a result of local thunderstorms and the variable availability of sediment sources.

scholarly journals Triggering conditions and depositional characteristics of a disastrous debris flow event in Zhouqu city, Gansu Province, northwestern China

2011 ◽  
Vol 11 (11) ◽  
pp. 2903-2912 ◽  
Author(s):  
C. Tang ◽  
N. Rengers ◽  
Th. W. J. van Asch ◽  
Y. H. Yang ◽  
G. F. Wang
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Field Investigation ◽  
Gansu Province ◽  
Northwestern China ◽  
Catastrophic Event ◽  
Catchment Areas ◽  
Triggering Conditions ◽  
Geomorphological Features ◽  
Triggering Rainfall

Abstract. On 7 August 2010, catastrophic debris flows were triggered by a rainstorm in the catchments of the Sanyanyu and Luojiayu torrents, Zhouqu County, Gansu Province northwestern China. These two debris flows originated shortly after a rainstorm with an intensity of 77.3 mm h−1 and transported a total volume of about 2.2 million m3, which was deposited on an existing debris fan and into a river. This catastrophic event killed 1765 people living on this densely urbanised fan. The poorly sorted sediment contains boulders up to 3–4 m in diameter. In this study, the geomorphological features of both debris flow catchment areas are analyzed based on the interpretation of high-resolution remote sensing imagery combined with field investigation. The characteristics of the triggering rainfall and the initiation of the debris flow occurrence are discussed. Using empirical equations, the peak velocities and discharges of the debris flows were estimated to be around 9.7 m s−1 and 1358 m3 s−1 for the Sanyanyu torrent and 11 m s−1 and 572 m3 s−1 for the Luojiayu torrent. The results of this study contribute to a better understanding of the conditions leading to catastrophic debris flow events.

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 Debris flow and landslide processes on manmade landscapes

2019 ◽  
Vol 265 ◽  
pp. 04009
Author(s):  
Darya Bobrova ◽  
Ekaterina Kazakova ◽  
Svetlana Rybalchenko ◽  
Sergei Kudriavtcev
Keyword(s):  
Debris Flow ◽  
Human Activity ◽  
Economic Activity ◽  
Debris Flows ◽  
Road Construction ◽  
Anthropogenic Activity ◽  
Early Stages ◽  
Landslide Processes ◽  
And Storage ◽  
Settlement Areas

Currently the human activity is one of the important factors of debris flow and landslide formation. In some cases, human activity leads to the formation of previously non-existing debris flow and landslide complexes, which increases the areal percentage of exposure of settlement areas to dangerous processes. Most often, anthropogenic debris flows and landslides are confined to the mountainous territory, which is associated with the extraction of minerals, road construction, construction of buildings and structures and storage of soil in floodplains and watercourses on weak mountain slopes. The authors propose to divide the anthropogenic genetic class of debris flows and landslides into three categories, depending on the degree of influence of anthropogenic activity on the formation of debris flow and landslide processes and their characteristics. The usage of this classification allows to determine and evaluate possible consequences of debris flows and landslides at the early stages of economic activity planning

scholarly journals A multivariate statistical method for susceptibility analysis of the debris flow in Southwest China

2019 ◽  
Author(s):  
Feng Ji ◽  
Zili Dai
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Loose Material ◽  
Southwest China ◽  
Quantitative Prediction ◽  
The Tibetan Plateau ◽  
Type I ◽  
Quantification Theory ◽  
Susceptibility Analysis ◽  
Dadu River

Abstract. Southwest China is characterized by many steep mountains and deep valleys due to the uplift activity of the Tibetan Plateau. The 2008 Wenchuan Earthquake left large amounts of loose materials in this area, making it a severe disaster zone in terms of debris flow. Susceptibility is a significant factor of debris flow for evaluating its formation and impact. Therefore, it is in urgent need to analyze the susceptibility of debris flows in this area. At present, the susceptibility analysis models of the debris flow in Southwest China is mainly based on qualitative methods. Little quantitative prediction model is found in the literature. This study evaluates 70 typical debris flow gullies as statistical samples, which are distributed along the Brahmaputra River, Nujiang River, Yalong River, Dadu River, and Ming River respectively. Nine indexes are chosen to construct a factor index system and then to evaluate the susceptibility of debris flow. They are the catchment area, longitudinal grade, average gradient of the slope on both sides of the gully, catchment morphology, valley slope orientation, loose material reserves, location of the main loose material, antecedent precipitation, and rainfall intensity. Then, an empirical model based on the quantification theory type I is established for the susceptibility prediction of debris flows in Southwest China. Finally, 10 debris flow gullies on the upstream of the Dadu River are analyzed to verify the reliability of the proposed model. The results show that the accuracy of the statistical model is 90 %.

scholarly journals Formation-Evolutionary Mechanism Analysis and Impacts of Human Activities on the 20 August 2019 Clustered Debris Flows Event in Wenchuan County, Southwestern China

2021 ◽  
Vol 9 ◽  
Author(s):  
Yu Li ◽  
Xing-nian Liu ◽  
Bin-rui Gan ◽  
Xie-kang Wang ◽  
Xing-guo Yang ◽  
...  
Keyword(s):  
Debris Flow ◽  
Human Activities ◽  
Debris Flows ◽  
Large Scale ◽  
Field Investigation ◽  
Mitigation Measures ◽  
Southwestern China ◽  
Economic Losses ◽  
Mechanism Analysis ◽  
Prediction And Prevention

Characterized by large scale, high frequency, and strong destructiveness, debris flow has become the most noticeable geohazards throughout the world, especially in the mountainous areas of southwestern China. On August 20, 2019, large-scale heavy rainfall pummeled Wenchuan County, Sichuan Province, Southwestern China, which resulted in a cluster of debris flows (the “8·20” clustered debris flows event), and caused considerable economic losses (approximately 3.4 billion RMB were lost) and heavy casualties (48,862 people were displaced, 16 people died and 22 people went missing). Based on field investigation, image data interpretation, mechanism analysis, and other methods, this study reveals the formation mechanism, dynamic evolutionary process, and impacts of human activities on the “8·20” clustered debris flows event. Results from a comprehensive analysis indicate that the occurrence of short-term, high-intensity rainfall and the excessive supply of solid material were the main factors that triggered this catastrophic event. With the debris flow flowing into the main river, this event presented an extremely apparent disaster chain effect. It is also found that improper site selection and inadequate design of human activities played a crucial role in the movement process of the debris flow that directly aggravated the losses. Finally, to improve debris flow prediction and prevention, some early warning and mitigation measures are discussed.

Hydrologic conditions leading to debris-flow initiation

1990 ◽  
Vol 27 (6) ◽  
pp. 789-801 ◽  
Author(s):  
K. A. Johnson ◽  
N. Sitar
Keyword(s):  
Debris Flow ◽  
Pore Pressure ◽  
Debris Flows ◽  
Field Investigation ◽  
Hydrologic Response ◽  
Storm Events ◽  
Hillslope Hydrology ◽  
Antecedent Moisture ◽  
Pressure Pulses ◽  
Flow Activity

Mitigation of the hazards posed by debris flows requires an understanding of the mechanisms leading to their initiation. The objectives of this study were to evaluate and document the hydrologic response of a potential debris-flow source area to major rainstorms and to evaluate whether traditional models of hillslope hydrology can account for the observed response. A field site in an area of previous debris-flow activity was instrumented and monitored for two winter seasons. Hydrologic responses for a wide variety of antecedent conditions were recorded, including two storm events that produced well-defined positive pore-pressure pulses at the site and initiated numerous debris flows in the immediate vicinity of the site. The observed hydrologic response was highly dependent on antecedent moisture conditions which can be characterized by soil matric suction measurements. The pressure-head pulses observed had a magnitude of approximately 50 cm of water, were transient, traveled downslope, and exhibited some spatial variability. Traditional models of hillslope hydrology do not fully account for the positive pore-pressure pulses observed high on the hillslope. Key words: debris flow, hillslope hydrology, pore pressure, antecedent moisture, tensiometer, piezometer, field investigation.

scholarly journals Simulation of Debris-Flow Runout Near a Construction Site in Korea

2020 ◽  
Vol 10 (17) ◽  
pp. 6079 ◽  
Author(s):  
Byung-Gon Chae ◽  
Ying-Hsin Wu ◽  
Ko-Fei Liu ◽  
Junghae Choi ◽  
Hyuck-Jin Park
Keyword(s):  
Debris Flow ◽  
Landslide Susceptibility ◽  
Debris Flows ◽  
Source Area ◽  
Flow Path ◽  
Construction Site ◽  
Landslide Prediction ◽  
Runout Distance ◽  
Susceptibility Analysis

This study analyzed landslide susceptibility and numerically simulated the runout distance of debris flows near a construction site in Korea. Landslide susceptibility was based on a landslide prediction map of the study area. In the prediction map, 3.5% of the area had a 70–90% landslide probability, while 0.79% had over 90% probability. Based on the landslide susceptibility analysis, debris flows in four watersheds were simulated to assess possible damage to the construction site. According to the simulations, debris flow in Watershed C approaches to within 9.6 m of the site. Therefore, the construction site could be impacted by debris flow in Watershed C. Although the simulated flows in Watersheds A and D do not directly influence the construction site, they could damage the nearby road and other facilities. The simulations also show that debris runout distance is strongly influenced by the volume of debris in the on-slope source area and by the slope angles along the debris-flow path.

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