Debris Flow Disaster Research Articles

The Effect of Temporal Characteristics on Developing a Practical Rainfall-Induced Landslide Potential Evaluation Model Using Random Forest Method

With the unique rainfall patterns of typhoons, plum rains, and short-term heavy rainfalls, the frequent landslide and debris flow disasters have caused severe loss to people in Taiwan. In the studies of landslide susceptibility, the information of factors used for analysis was usually annual-based content, and it was assumed that the same elements from different years were independent between each year. However, the occurrence of landslides was usually not simply due to the changes within a year. Instead, landslides were triggered because the factors that affected the potential of landslides reached critical conditions after a cumulative change with time. Therefore, this study had well evaluated the influence of temporal characteristics and the ratios of antecedent landslide areas in the past five years in the landslide potential evaluation model. The analysis was conducted through the random forest (RF) algorithm. Additional rainfall events of 2017 were used to test the proposed model’s performance to understand its practicality. The analysis results show that in the study area, the RF model had considerably acceptable performance. The results have also demonstrated that the antecedent landslide ratios in the past five years were essential to describe the significance of cumulative change with time when conducting potential landslide evaluation.

A study of the disaster model and movement process simulation of debris flow in the Zhixi River of Deqin County

Deqin County is one of the areas suffering the most serious geological disasters in Yunnan Province. Based on the development characteristics of the debris flow in the Zhixi River, this study identifies five disaster-generating modes for the debris flow in the Zhixi River: Collapse - clastic flow, rock landslide-clastic flow, soil-rock mixture landslide-clastic flow, loose accumulation layer -bedrock contact surface landslide-clastic flow and landslide in loose accumulation layer-clastic flow. The FLO-2D model is used to simulate the debris flow movement in the Zhixi River under the rainstorm cycle of 10, 20, 50 and 100 years, and the maximum flow velocity, the maximum accumulation depth, the accumulation distance and the volume scale in different rainfall return periods are quantitatively analyzed. The results show that the debris flow is characterized by high acceleration, fast velocity, strong destructive force, and long circulation area when it erupts. When the debris flow occurs once in 100 years, its maximum velocity reaches 3.07 m/s, the maximum mud depth is 2.27 m , the volume of debris flow washed out is 84419 m3, and the disaster area reaches 91600 m2. The results provide quantitative data reference for the prevention and control of debris flow disasters in Zhixi River, and also provides an important basis for the design of disaster prevention and mitigation projects in Deqin County.

Temporal changes in the debris flow threshold under the effects of ground freezing and sediment storage on Mt. Fuji

Abstract. Debris flows are one of the most destructive sediment transport processes in mountainous areas because of their large volume, high velocity, and kinematic energy. Debris flow activity varies over time and is affected by changes in hydrogeomorphic processes in the initiation zone. To clarify temporal changes in debris flow activities in cold regions, the rainfall threshold for the debris flow occurrence was evaluated in Osawa failure at a high elevation on Mt. Fuji, Japan. We conducted field monitoring of the ground temperature near a debris flow initiation zone to estimate the presence or absence of seasonally frozen ground during historical rainfall events. The effects of ground freezing and the accumulation of channel deposits on the rainfall threshold for debris flow occurrence were analyzed using rainfall records and annual changes in the volume of channel deposits since 1969. Statistical analyses showed that the intensity–duration threshold during frozen periods was clearly lower than that during unfrozen periods. A comparison of maximum hourly rainfall intensity and total rainfall also showed that debris flows during frozen periods were triggered by a smaller magnitude of rainfall than during unfrozen periods. Decreases in the infiltration rate due to the formation of frozen ground likely facilitated the generation of overland flow, triggering debris flows. The results suggest that the occurrence of frozen ground and the sediment storage volume need to be monitored and estimated for better debris flow disaster mitigation in cold regions.

Study on debris flow risk monitoring and Early Warning in Nujiang Prefecture, Yunnan Province, China

Debris flow is the mainly the geological disasters in Nujiang Prefecture, while precipitation is the trigger of it, how to implement debris flow forecast based on precipitation monitoring data or forecast data is a hot issue in current debris flow disaster research field. Because of the special geomorphology in Nujiang Prefecture, due to the influence of human activities, geological disasters occur frequently, severely affect the local economic development. As a demonstration area of geological disaster monitoring and early warning in Yunnan Province, to build a well-developed geological disaster warning system, it is very important to spread it to other parts of Yunnan province. Based on the analysis of the current situation of geological disasters in Nujiang Prefecture, adopt appropriate monitoring method and calculation method to select the primary sites for debris flow monitoring and early warning in the Nu River basin for research.

Debris Flow Risk Reduction in Malaysia: From Science-Policy to Multi-Stakeholder Actions

Debris flows remained the deadliest and disastrous geological disasters in Malaysia. The two-decade records from 1995 until 2015 highlighted at least 23 events have occurred regardless of fatalities, and locations. The fatal event was induced by a typhoon recorded in Keningau, Sabah in 1996 with the highest human losses of 302, and economic losses of RM 458.9 million. To date, Malaysia has no dedicated national policy, framework, and standard operating procedure to address this sediment-related disaster in a holistic manner. Moreover, a dedicated, responsible government agency for managing debris flow risk reduction remained elusive. This study aims at providing insights for debris flow disaster risk reduction (DRR) by addressing risk governance, including multi-sectoral agencies roles and responsibilities for different triggering factors, i.e., earthquakes, and intense and prolonged rainfall, and DRR investment towards co-developing an integrated national action plan for reducing current risk, preventing future risk, and strengthening resilience. This study explores various methods to better understand local profiles and suitable methods to assess geological hazard risk processes, activities and impact towards redefining a comprehensive risk assessment method in Malaysia. A case study of recent event in Mesilau watershed induced by the earthquake and rainfall, as a result of 2015 Sabah Earthquake was selected for this study. This study elaborates the significance uses of scientific- and social-based study in promoting science-policy and multi-stakeholders action planning for reducing sediment-based disaster risk in the near future. This includes: (i) the mapping and characterizing the watershed area, (ii) modelling the past debris flow event, and (iii) engaging with the community and stakeholder to gather more local inputs.

Analysis of material supply characteristics of debris flow based on land use types in the upper Min River, China

Land-use type is a natural choice of human social and economic activities. This study investigates the typical debris flow gullies of the upper Min River and analyses the supply characteristics and activity of its material sources under various land-use types using multi-stage remote sensing images data and geographic information system software. The results demonstrate the following: (1) the land-use type does not restrict the loose material source of debris flow near the fault zone; (2) the degree of cultivated land, forest (grass) land, bare land, and urban and rural construction land promote debris flow disaster formation in different channels far from the fault zone; (3) the gully exhibits significant influence on human engineering activities, and there are more loose material sources between the bare land and urban and rural construction land; (4) more loose material sources are observed in forest (grass) land and cultivated land in debris flow channels with vegetation development. In summary, before the Wenchuan earthquake, the debris flow source centroid is far from the debris flow channel, but after the earthquake, the debris flow material source centroid is near the debris flow channel.

Debris flow hazard assessment of the Eryang River watershed based on numerical simulation

The middle reach of Taohe River, in the south part of Gansu Province, China is severely threatened by debris flow hazard. Eryang River is an important branch of Taohe River. On May 10, 2012, many debris flows were triggered by extreme heavy rainfall (1% frequency), resulting in serious losses of human lives and properties. In order to recognize the hazard of debris flows in small watersheds, six key debris flow gullies in Eryang watershed, Lalonggou, Zhalonggou, Yizigou, Jiehagou, Lalugou, Paizuigou, were selected as the research area. The numerical simulation software FLO-2D was used to analyze the debris flow movement and accumulation characteristics of each debris flow gully under the actual ‘5.10’ rainfall conditions, so as to reconstruct the ‘5.10’ debris flow disaster scenario. Numerical simulation results show that the flow speed increased to the maximum after 15-30 minutes since the outburst. The flow lasted for about 3 hours. The speed in the moving section was very high, and decreased sharply at the gully-mouth, then deposits accumulated in the river valley. According to the satellite images and field investigations, the simulation results were compared with the actual situations. The comparison shows the simulation effect is good, the deposition area, the discharge process, and the main damage area were well-reconstructed by FLO-2D simulation. Then, the same method and parameters are used to simulate the accumulation range, depth and velocity of debris flows under the precipitation of 2 % and 0.2 % frequency (fifty and five hundred years rainfall, respectively), and then the risk zoning map is produced using the simulation data. The potentially threatened houses and properties were outlined. The threatened area is 37900m2 and 60500m2 under 2% and 0.2% rainfall frequencies. There are 22 houses in the highest hazard level. This provides direct reference to the local government to control the debris risk. This work also provides a practical approach for the debris flow hazard assessment.

Engineering Planning Method and Control Modes for Debris Flow Disasters in Scenic Areas

Compared with debris flows in other areas, debris flows in scenic areas not only seriously threaten residents, tourists, roads, walkways, and other infrastructure, but also cause considerable damage to the landscapes and ecosystems of these areas. Extreme rainfall events in the future will increase the complexities and challenges involved in debris flow control in scenic areas. Currently, the systematic planning of the entire scenic area is not considered in the treatment of debris flows. It is not possible to realize the rapid planning of any debris flow gully control project in a scenic area and to quantify the volume of debris flow material retained by each engineering structure. Based on field investigations and data collected from debris flow control projects in gullies in Jiuzhaigou Valley, China, an engineering planning method for debris flow control projects in scenic areas is herein proposed, and the challenges confronting existing control projects in scenic areas are discussed. Moreover, based on the example of Jiuzhaigou Valley, corresponding control engineering schemes for debris flow gullies in Xiajijie Lake Gully, Zhuozhui Gully, Xuan Gully, Pingshitou Gully, and West-Zhuozhui Gully are formulated. Four control modes for debris flow disasters in scenic areas are proposed, namely, “blocking + deposit stopping,” “deposit stopping,” “blocking,” and “drainage + deposit stopping,” which provide a systematic control strategy for post-earthquake debris flow disaster management in Jiuzhaigou Valley and other similar scenic areas.

Research on Promoting Mine Soil Pollution Prevention and Greening Based on Big Data

Mineral resources are the important material basis of economic and social development, and the contribution and influence of mining industry to our country is great, but the exploitation of mineral resources in a long period, high intensity and large scale brings great pressure to the ecological environment. Mining will damage the land, produce a large amount of solid waste and occupy the land. At the same time, it will easily lead to collapse and debris flow disaster, but also cause soil and water pollution. Mine pit drainage will lead to the decline of groundwater level in many areas, spring discharge reduced or even dried up, seriously affecting the local ecological environment. Protecting ecological environment, dealing with climate change and maintaining energy and resource security are the common challenges facing the world. Writing ecological civilization into the Constitution, green mine construction has risen to national strategy [1]. Under the background of industrial civilization turning to ecological civilization, green mine construction is a general direction and an important way and inevitable requirement to realize the high quality development of mining industry. Is also our country realizes from the mining country to the mining power transformation only way! To promote the real green development of mine soil based on big data.

Soil mass domination in debris-flow disasters and strategy for hazard mitigation

Soil mass domination in debris-flow disasters and strategy for hazard mitigation

Aggravation of debris flow disaster by extreme climate and engineering: a case study of the Tongzilin Gully, Southwestern Sichuan Province, China

Aggravation of debris flow disaster by extreme climate and engineering: a case study of the Tongzilin Gully, Southwestern Sichuan Province, China

Quantitative analysis of artificial dam failure effects on debris flows – A case study of the Zhouqu ‘8.8’ debris flow in northwestern China

Artificial dams are one of the most common hydraulic structures for mitigating debris flow disasters in alpine valley regions. However, performance alteration and failure after successive debris flows can lead to dam failure, releasing large amounts of materials within a very short time; moreover, the contribution of artificial dam failures to debris flows is poorly understood. This study quantitatively analyzed the artificial dam failure effects based on the numerical simulations of the Zhouqu '8.8' debris flow, with three scenarios: all nine dams failed (S1); no dams were ever built (S2); all nine dams remained intact (S3). The results showed that artificial dam failures had a significant amplifying effect on the magnitude of a debris flow. The maximum velocity and flow depth decreased by 20% and 11.2% if all the dams did not collapse; comparison of S1 and S2 showed that discharge and velocity at the front of the debris flow increased by 54.6% and 89%, the bulk density and yield stress increased by 3.3% and 5.7%, due to artificial dam failures. This could increase the destructive capacity of a debris flow and the possibility of a river blockage. A single artificial dam failure could locally amplify the magnitude of debris flow. Overall, on the catchment scale, the magnitude of a debris flow was dominated by topography and channel geometry, which can reduce the amplification effect of dam failures at locations where the channel was curved. However, where the channel was straight and flat, the flow velocity and discharge increased cumulatively by 3 m/s and 637 m3/s due to cascading failure. In addition, a comprehensive scheme combining ecological and engineering measures to mitigate debris flow disasters is discussed. This quantitative study is important and urgent needed to understand the amplification effect of dam failures and to implement debris flow mitigation in alpine valley regions.

New insights into the delayed initiation of a debris flow in southwest China

On 6 July 2020, 3 h 40 min after rainfall stopped, a delayed debris-flow disaster occurred due to colluvium deposits in a hollow region (CDH) in the Chenghuangmiao Gully, Sichuan Province, China, resulting in 4 deaths and 27 injuries. This study explores the initiation process of the delayed debris flow and the cause for the delay. Field investigations, catchment geometry interpretation, laboratory tests, theoretical calculations, and fluid–solid coupling numerical simulation were performed to obtain landslide parameters and understand the mechanisms of the event. Results show that (1) the event was a giant low-frequency viscous debris flow. (2) It was initiated by the delayed landslide process under the influence of back-end confluence. (3) The debris-flow discharge in the main gully increased over 19.5 min. (4) The seepage process inside the CDH continued for 3 h 20 min after the rainfall stopped before the pore pressure and reduction in strength were sufficient to initiate the debris flow. This research provides new insights on delayed debris-flow disasters and can be a reference for improving disaster management systems, especially monitoring and early warning systems, thereby avoiding future casualties.

Risk Assessment of Debris Flow Disaster Based on Principal Component Analysis

Debris flow disasters have the characteristics of large energy, strong explosiveness, and great harm. They cause irreversible damage to the environment and at the same time, seriously threaten the safety of human life and property. Therefore, it is essential to evaluate the risk of debris flow. In this paper, nine factors such as the basin area, the length of the main ditch, and the cutting density of the basin along the Jinsha River are used to calculate the cumulative contribution rate to screen the principal components using the principal component analysis method, and then comprehensively score the linear combination of independent principal components. Therefore, the risk assessment of each debris flow channel is carried out, and the results obtained are compared with the methods in different documents, which shows that this method has better applicability and feasibility. This method of determining weights overcomes the shortcomings of the subjective method of determining weights and is more reasonable and objective. The research results can provide decisionmaking references for relevant departments and industries.

The rescue and relief plan based on the risk assessment of debris flow in Yunnan Province, China

Nowadays, natural disasters occur frequently in the world, causing a large number of casualties and economic losses. As a typical natural disaster caused by non-human activities, debris flow can not be fully prevented in advance. Therefore, timely emergency rescue and relief work after the disaster is particularly important. This paper takes Yunnan Province, a province with severe debris flow disaster, as an example to discuss the formulation of a reasonable and effective debris flow rescue and relief program, so as to ensure that the rescue and relief work can be carried out in an orderly manner and avoid greater losses caused by disasters. This paper uses a combination of qualitative analysis and quantitative analysis to study the deployment of personnel and material resources in the debris flow rescue and relief plan. First, we select the five influencing factors of the 24 ​hours precipitation, the number of rainstorm days in the month, the precipitation and the altitude of the month, and the terrain slope when the debris flow disaster occurs. We obtain the weight of each influencing factor through the Analytic Hierarchy Process (AHP), and use Fuzzy Evaluation Method to evaluate the risk of debris flow disaster index. Then through qualitative analysis, we concluded that debris flow rescue and disaster relief requires 3 types of rescue team personnel and 6 types of emergency supplies. According to the three indicators of the debris flow risk evaluation index, the affected population, and the direct economic loss of the disaster, the rescue personnel are dealt with through the Radial Basis Function neural network (RBFNN), so as to construct a debris flow rescue and disaster relief plan. Finally, taking the mud-rock flow event in Gongshan County, Nujiang Prefecture, Yunnan Province on May 31, 2018, as an example, a relevant plan for the event was formulated according to the rescue and relief plan constructed in this paper, and the feasibility of the plan was evaluated by comparing with the actual disaster relief data of the event.

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

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.

Quantitative Prediction of Outburst Flood Hazard of the Zhouqu “8.8” Debris Flow-Barrier Dam in Western China

In recent years, the intensified influences of global climate change and human activities have increased the frequency of large-scale debris flow disasters. As a result, main river channels often become blocked, thus forming a disaster chain of rivers dammed by debris flow followed by outburst flooding. In order to quickly and easily reveal the dynamic process of a debris flow dam breach, and quantitatively predict the outburst flood hazard, this study takes the Zhouqu “8.8” debris flow barrier dam in Western China as an example. Based on a stability assessment, China Institute of Water Resources and Hydropower Research’s Dam Breach Slope (DBS-IWHR), China Institute of Water Resources and Hydropower Research’s Dam Breach (DB-IWHR), and Hydrologic Engineering Center’s River Analysis System (HEC-RAS) were integrated to simulate the development of dam breach, breach flood, and outburst flood evolution, respectively, under different scenarios. The simulated peak discharge flow of the actual spillway was 317.15 m3/s, which was consistent with the actual discharge of 316 m3/s. The results under different scenarios showed that, with the increased inflow of the barrier lake, the erosion rate of the dam increased, the peak discharge of the dam break flood increased, the peak arrival time shortened, and the downstream flooding area increased. These findings could provide scientific support for risk management and emergency decision-making with respect to barrier dam failure.

Analysis of the acceptable risk preferences of debris-flow disasters for three-category populations and their demographic characteristics in China

Debris flows are abrupt geological hazards frequently resulting in destructive disasters in mountain areas. Thus, analysis of the acceptable risk of debris-flow disasters should be attentively considered, whereas the crucial problem of the acceptable disaster risk is how to know what the risk levels of debris-flow disasters are acceptable for the public. Thence, the questionnaire investigation of the acceptable risk preferences for different populations in various regions can be such a solution. The acceptable disaster risks are not only taking into account people's acceptance, but also related to government's disaster-reduction strategy and also referred to expert’s professional evaluation. Therefore, the establishment of guidelines and criterions for the acceptable risks of debris-flow disasters need all participations from multiple populations and different regions. In this survey, three-category populations including ordinary people, experts/scholars and administrators across China joined the questionnaire investigation. Five indicators (disaster-affected toll, death toll, death rate, personal direct economic loss, and total direct economic loss) were used to describe the acceptable risks of debris-flow disasters. Incorporated with frequency analysis, this work has explained the demographic characteristics for the acceptable risk preferences. The results indicate that ordinary people have relatively low acceptable risks, experts/scholars have slightly high acceptable risks and administrators have acceptable risks between both of them. Educational level, occupation, and income were the dominatingly demographic factors for the interpretations of the acceptable risk preferences.

Risk Assessment of Debris Flow in Strong Earthquake Area

The construction and operation of the Jiuzhaigou County bidding section of the Jiumian Expressway is affected by debris flow disasters. It is important to scientifically and reasonably evaluate the debris flow risk in the engineering area. Therefore, according to the data of topography, meteorology, hydrology and regional geological structure of the project area, 12 influencing factors, such as regional geological disasters, loose material reserves along the gully and maximum punching amount at one time, are selected as the evaluation indexes of debris flow risk assessment. Based on the catastrophe progression method, a mutation model of debris flow risk assessment suitable for the project area was established. The debris flow risk assessment mutation model was used to evaluate the debris flow risk of 8 trenches in the project area, and the applicability of the model is verified by comparing the actual occurrence history of debris flow in the trench with the evaluation results. The analysis results show that the risk of debris flow in four gullies of Gangou and Xiaganzuo in the bid section project area of Jiuzhaigou County of Jiumian Expressway is extremely dangerous, and the debris flow risk of Shangganzuo gully is severe. These five debris flow gullies are the key objects of debris flow prevention and control during the construction and operation of Jiuzhaigou County bidding section of the Jiumian Expressway.

Debris Flow Numerical Simulation Model Comparison with Field Events in Kuala Kubu Baru and Lentang, Malaysia

Debris flow is one of Malaysia’s natural disasters which could cause casualties and serious infrastructure damage. Precisely predicting the factors associated with the occurrence of debris flow such as the run-out lengths, velocities and thickness of alluvial deposits can greatly mitigate damage, minimize or even avoid the aftermaths of the occurrence. Applying numerical simulation models explaining debris flow deposition would be a valuable tool in forecasting potential debris flow activity and providing criteria for designing protective measures. Comprehensive studies of available records of past debris flow events from relevant sources and site investigations have been carried out in order to assemble field information for the particular debris flow event in Malaysia. A number of calamitous debris flow events occurred in Malaysia have been closely observed and studied. The well-documented events, i.e. Lentang and Kuala Kubu Baru debris flow disasters occurred on 2nd November 2004 and 10th November 2003, respectively were simulated using the Kanako 2D (Ver.2.04) simulation model software. The results obtained from the numerical simulation model were compared with the real events in order to evaluate their predictive capabilities. The results showed an accuracy of more than 93% was obtained from the simulation model as compared to the real in-situ measurements. A positive simulation result will become a valuable method to predict potential debris flow hazard behavior of the same type and characteristics.