Debris Flow Hazard Research Articles

Check dam storage capacity calculation based on high-resolution topogrammetry: Case study of the Cutou Gully, Wenchuan County, China

Debris flows are a common natural trigger of disasters in mountainous areas, and check dams are standard structural measures for controlling debris flows. Despite their prevalence in debris flow-prone areas worldwide, the capacity of check dams is still calculated using empirical formulas, which lead to large calculation errors. This paper proposes a new method that uses GIS to calculating the design storage capacity of a check dam in the debris flow-prone Cutou Gully in Wenchuan County, China. Large-scale digital surface models derived from unmanned aerial vehicle imagery and ground surveys identify local topographic changes in the debris flow path and develop appropriate maintenance plans for check dams. The measured storage capacity of the check dam is determined by analyzing the DEM differences. This study uses the newly proposed method to calculate the design storage capacity of the check dam. The accuracy of the calculation results was evaluated using the checkpoint method, and the results showed that the design and measured siltation surface errors ranged from −1.16–2.96 m, with a root mean square error of 0.93 m. The design capacity of the check dam is 33.6× 104 m3, and the actual capacity is 36.7× 104 m3, with an absolute error of 3.1× 104 m3 and relative error of 8.6%. The results prove the validity of the proposed calculation method; moreover, this study shows that the new method is accurate, easy to operate, and highly efficient for visualizing the spatial distribution of the siltation depth behind the check dam. This work will help improve future engineering decisions, design strategies, and find optimal design solutions to minimize the risk of debris flow hazards.

POSSIBILITIES OF THE SAGA GIS IN THE STUDY AND MAPPING OF THE DEBRIS FLOW HAZARD OF THE BAIKAL MOUNTAIN COUNTRY

The possibilities and limitations of SAGA GIS for processing DEM and remote sensing materials of free access in the interests of specialized mapping of debris flow hazard in the Baikal region are considered. The results of processing the SRTM and ASTER GRID DEMS, as well as the spectrosonal images obtained from the Landsat-8 and Sentinel-2 satellites in the SAGA environment are compared. The most effective tools of GIS-analysis of territories from the point of view of the potential hazard assessment of debris flows based on remote sensing data are determined.

Mitigation of Debris Flows—Research and Practice in Hong Kong

ABSTRACT Dense urban development on a hilly terrain coupled with intense seasonal rainfall and heterogeneous weathering profiles give rise to acute debris-flow problems in Hong Kong. The Geotechnical Engineering Office (GEO) of the Hong Kong SAR Government has launched a holistic research and development (R&D) programme and collaborated with various tertiary institutes and professional bodies to support the development of a comprehensive technical framework for managing landslide risk and designing debris-flow mitigation measures. The scope of the technical development work includes compilation of landslide inventories, field studies of debris flows, development and calibration of tools for landslide run-out modelling, back analysis of notable debris flows, physical and numerical modelling of the interaction between debris flows and mitigation measures, formulation of a technical framework for evaluating debris-flow hazards, and development of pragmatic mitigation strategies and design methodologies for debris-flow countermeasures. The work has advanced the technical understanding of debris-flow hazards and transformed the natural terrain landslide risk management practice in Hong Kong. New analytical tools and improved design methodologies are being applied in routine geotechnical engineering practice.

Revealing the Importance of Capillary and Collisional Stresses on Soil Bed Erosion Induced by Debris Flows

AbstractClimate change is increasing the frequency of extreme rainfall events and the snow cover to melt at high altitudes, which may exacerbate the threat posed by debris flows. Soil bed erosion, the process by which the bed material fails under loadings from a debris flow, is perhaps the most important momentum exchange process that governs the destructive potential of debris flows. Existing erosion theories adopt saturated soil mechanics to describe the failure of soil bed and place a strong emphasis on the basal friction induced shear stress as the driving mechanism. However, soil beds in nature are rarely saturated and field observations have hinted at the importance of collisional stresses as a driving mechanism. In this study, an unsaturated soil mechanics framework is used to characterize soil bed erosion by collisional flows. Experiments were conducted to model the erosion of unsaturated sandy beds with a wide range of initial matric suction values, which is a measure of capillary stresses, by gravel flows. Contrary to the existing literature, the rate of erosion does not increase linearly but demonstrates a parabola‐like relationship with the bed water content because the shear strength of unsaturated soil is governed by capillary stresses. The importance of collisional stresses on soil bed erosion is demonstrated by a newly proposed dimensionless number. Findings indicate that existing erosion models largely underestimate channel bed erosion, especially for soil beds with low water content, and stress the importance of hydro‐mechanical coupling to advance the current state of debris flow hazard delineation.

HAZARD ASSESSMENT OF DEBRIS FLOW ALONG ZIRE-BOMI SECTION OF SICHUAN-TIBET RAILWAY

Debris flow is one of the most developed disaster types in the Tibetan Plateau, and poses a certain threat to the construction of Sichuan-Tibet Railway and the safety of life and property due to its sudden outbreak, violent movement process, and strong destructive characteristics. Geological hazard assessment is part of the effective measures in the management and prevention of disaster prevention and mitigation. For reasonably quantifying the spatial distribution characteristics of debris flow hazard along the railway line, the paper takes the Zire-Bomi section of the Sichuan-Tibet Railway within Linzhi City as the experimental area. We apply the Bayesian optimization algorithm based random forest(TBOR) and gradient boosting tree model(TBOG)to quantify the debris flow hazard values of the route section and identify the hazard levels. The input information of the two models includes 172 historical hazard points and 11 feature parameters. The output information is the outbreak probability of debris flow for each prediction unit. Lastly, the ROC-AUC method is employed to test the evaluation outcomes of the two prediction algorithms. The findings reveal that in the TBOR and TBOG models, the overall debris flow hazard level of the Zire-Bomi line section of the Sichuan-Tibet Railway is relatively high. The proportion of hazard zones inside the high-higher hazard interval of the two models reaches 56.439% and 66.580% respectively, corresponding to the highest hazard point densities of 12.577/(102km2) and 12.940/(102km2)respectively. Compared to the ROC-AUC values derived from the TBOG model, the TBOR model computes 0.89, which is higher than that of TBOR at 0.83. Therefore, the TBOR model has better prediction accuracy. The research findings can provide necessary reference for the construction of disaster prevention and mitigation protection projects along Sichuan-Tibet Railway and the hazard evaluation of other line sections.

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.

A multi-source data fusion modeling method for debris flow prevention engineering

The Digital Elevation Model (DEM) data of debris flow prevention engineering are the boundary of a debris flow prevention simulation, which provides accurate and reliable DEM data and is a key consideration in debris flow prevention simulations. Thus, this paper proposes a multi-source data fusion method. First, we constructed 3D models of debris flow prevention using virtual reality technology according to the relevant specifications. The 3D spatial data generated by 3D modeling were converted into DEM data for debris flow prevention engineering. Then, the accuracy and applicability of the DEM data were verified by the error analysis testing and fusion testing of the debris flow prevention simulation. Finally, we propose the Levels of Detail algorithm based on the quadtree structure to realize the visualization of a large-scale disaster prevention scene. The test results reveal that the data fusion method controlled the error rate of the DEM data of the debris flow prevention engineering within an allowable range and generated 3D volume data (obj format) to compensate for the deficiency of the DEM data whereby the 3D internal entity space is not expressed. Additionally, the levels of detailed method can dispatch the data of a large-scale debris flow hazard scene in real time to ensure a realistic 3D visualization. In summary, the proposed methods can be applied to the planning of debris flow prevention engineering and to the simulation of the debris flow prevention process.

Debris-Flow Hazard Assessments: A Practitioner's View

ABSTRACTSubstantial advances have been achieved in various aspects of debris-flow hazard assessments over the past decade. These advances include sophisticated ways to date previous events, two- and three-dimensional runout models including multi-phase flows and debris entrainment options, and applications of extreme value statistics to assemble frequency–magnitude analyses. Pertinent questions have remained the same: How often, how big, how fast, how deep, how intense, and how far? Similarly, although major life loss attributable to debris flows can often, but not always, be avoided in developed nations, debris flows remain one of the principal geophysical killers in mountainous terrains. Substantial differences in debris-flow hazard persist between nations. Some rely on a design magnitude associated with a specific return period; others use relationships between intensity and frequency; and some allow for, but do not mandate, in-depth quantitative risk assessments. Differences exist in the management of debris-flow risks, from highly sophisticated and nation-wide applied protocols to retroaction in which catastrophic debris flows occur before they are considered for mitigation. Two factors conspire to challenge future generations of debris-flow researchers, practitioners, and decision makers: Population growth and climate change, which are increasingly manifested by augmenting hydroclimatic extremes. While researchers will undoubtedly finesse future remote sensing, dating, and runout techniques and models, practitioners will need to focus on translating those advances into practical cost-efficient tools and integrating those tools into long-term debris-flow risk management.

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

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.

Debris-Flow and Debris-Flood Susceptibility Mapping for Geohazard Risk Prioritization

ABSTRACT Regional-scale assessments for debris-flow and debris-flood propagation and avulsion on fans can be challenging. Geomorphological mapping based on aerial or satellite imagery requires substantial field verification effort. Surface evidence of past events may be obfuscated by development or obscured by repeat erosion or debris inundation, and trenching may be required to record the sedimentary architecture and date past events. This paper evaluates a methodology for debris-flow and debris-flood susceptibility mapping at regional scale based on a combination of digital elevation model (DEM) metrics to identify potential debris source zones and flow propagation modeling using the Flow-R code that is calibrated through comparison to mapped alluvial fans. The DEM metrics enable semi-automated identification and preliminary, process-based classification of streams prone to debris flow and debris flood. Flow-R is a susceptibility mapping tool that models potential flow inundation based on a combination of spreading and runout algorithms considering DEM topography and empirical propagation parameters. The methodology is first evaluated at locations where debris-flow and debris-flood hazards have been previously assessed based on field mapping and detailed numerical modeling. It is then applied over a 125,000 km2 area in southern British Columbia, Canada. The motivation for the application of this methodology is that it represents an objective and repeatable approach to susceptibility mapping, which can be integrated in a debris-flow and debris-flood risk prioritization framework at regional scale to support risk management decisions.

Forecasting the Frequency and Magnitude of Postfire Debris Flows Across Southern California

AbstractSouthern California has a long history of damaging debris flows after wildfire. Despite recurrent loss, forecasts of the frequency and magnitude of postfire debris flows are not available for the region like they are for earthquakes. Instead, debris flow hazards are typically assessed in a reactive manner after wildfires. Such assessments are crucial for evaluating debris flow risk by postfire emergency response teams; however, time between the fire and first rainstorm is often insufficient to fully develop and implement effective emergency response plans like those in place for earthquakes. Here, we use both historical distributions of fire and precipitation frequency and empirical models of postfire debris flow likelihood and volume to map the expected frequency and magnitude of postfire debris flows across southern California. We find that at least small debris flows can be expected almost every year, while major debris flows capable of damaging 40 or more structures have a recurrence interval between 10 and 13 years, a return interval that is comparable to a magnitude 6.7 earthquake. A sensitivity analysis to possible future changes in current fire and precipitation regimes indicates that debris flow activity in southern California is more sensitive to increases in precipitation intensity than increases in fire frequency and severity. Projected increases in rainfall intensity of 18% result in an overall 110% increase in the probability of major debris flows. Our results, in combination with an assessment of exposure, can be used to prioritize watersheds for further analysis and possible prefire mitigation.

Role of the Rheological Parameters in Debris Flow Modelling

Nowadays, the debris flow model has become an essential part of risk analysis and impact engineering. Coupled with field observations and historical records, these models have proven powerful tools to understand the behaviour of debris flow in complex terrain. However, their application poses several new challenges to scholars and engineers. A detailed understanding of the debris flow phenomena requires a sound knowledge of the shallow water equation and rheological model used to simulate the debris flow hazard. In this study, important rheological models used to analyse the debris flow process and their limitations have been highlighted. Furthermore, the suitability of the Voellmy-Salm rheological model has been studied for 2D pyroclastic flow taking different combinations of the coefficient of friction namely coulomb friction coefficient \\i,and turbulent coefficient of friction £ using IMEX SFLOW 2D dynamic continuum model. It was found that velocity and runout distances are significantly influenced by the variation of the coefficient of the turbulent friction © at a large scale. It is then concluded that the identification of a suitable rheological model is necessary to simulate the precise behaviour of complex and heterogeneous debris flow

Back calculation and hazard prediction of a debris flow in Wenchuan meizoseismal area, China

On August 20, 2019, many catastrophic debris flows broke out in meizoseismal area of Wenchuan M s 8.0 earthquake in China under the influence of continuous heavy rainfall. This paper takes the Chutou gully debris flow event occurred on August 20, 2019 as an example. The 3-D numerical simulation software, RAMMS, is used to back calculate the event and predict the future hazard. Coulomb and viscous turbulent friction, μ and ξ are calibrated in RAMMS. Numerical simulation reveals the movement process of Chutou gully from the aspects of flow depth, velocity, discharge, and run-out solid materials volume. The simulation results show that more than two-thirds of the solid materials are still deposited in the main channel, which could provide material basis for the re-occurrence of high hazard debris flow. In addition, based on the intensity and probability of debris flow, the hazard of debris flow is divided into high, middle, and low degrees. According to the simulation results and hazard assessment model, the hazard map of Chutou gully debris flow in various rainstorm return periods (20, 50, 100, and 200 years) is established, which can provide guidance for the future land-use planning and debris flow prevention works.

The relationship of human activities and rainfall-induced landslide and debris flow hazards in Central China

Human activities have been recognized as one of the significant influencing factors on natural hazard, yet studies of quantitative relationship between human activities and natural hazard have been limited. The relations of human activities and hazards (landslide and debris flow) induced by heavy rainfall are quantitatively analyzed in this study and suggestions are provided for the integrated hazard mitigation management in the study area of Central China. The results show that human activities index (HAI) is an effective indicator to characterize spatiotemporal changes of human activities. The relations of rainfall-induced landslide, debris flow hazards and human activities are significant as shown in spatial distribution. The probability of rainfall-induced landslide, debris flow hazards is highly correlated with the intensity of human activities and the changes of HAI. However, in terms of temporal relations, human activities have more direct impact on rainfall-induced landslide hazard than on rainfall-induced debris flow hazard, as the frequency of landslide hazard shows a 2-year delay with HAI changing, in general, according to the cross-wavelet transform analysis. In comparison, no significant correlating period is shown between the changing human activities and the frequency of rainfall-induced debris flow hazard. Specifically, there are three types of time relationship between the changing human activities and rainfall-induced landslide, debris flow hazards in the affected counties: (1) concurrent changing, accounting for 30% of landslide and 18% of debris flow; (2) lagging relationship, accounting for 54% of landslide and 30% of debris flow; (3) no direct relationship, accounting for 16% of landslide and 52% of debris flow. The results in this study suggest that HAI is a simple and effective index for the local governments to manage human impacts on rainfall-induced landslide and debris flow hazards, and integrated prevention measures are suggested to be executed when HAI reaches 0.072. In addition, the types of human activities also impact landslide, as the ratio of Economy factor to Land use factor (E/L) is significantly (P < 0.05) higher in counties with concurrent relationship of changing human activities and frequency of rainfall-induced landslide hazard. The results should assist the policy-making for integrated mitigation of rainfall-induced landslide and debris flow hazards at local/regional level, while balancing economic development and natural hazard.

Forecasting and Seismic Detection of Proglacial Debris Flows at Mount Rainier National Park, Washington, USA

ABSTRACT The glaciated Mount Rainier volcano in southwestern Washington State (United States) has a rich history of outburst floods and debris flows that have adversely impacted infrastructure at Mount Rainier National Park in the 20th and 21st centuries. Retreating glaciers leave behind vast amounts of unconsolidated till that is easily mobilized during high-precipitation-intensity storms in the fall months, and during outburst floods during warm summer months. Over 60 debris flows and outburst floods have been documented between 1926 and 2019 at Mount Rainier. Debris-flow activity has led to the closure of campgrounds and visitor destinations, which has limited visitor access to large swaths of the park. This paper documents efforts to characterize and seismically monitor debris flows, map hazards, and develop forecasting approaches for wet and dry weather debris flows. Using the day-of and historic antecedent weather conditions on past debris-flow days, we developed a debris-flow hazard model to help predict those days with a higher relative hazard for debris-flow activity park-wide based on prevailing and forecasted weather conditions. Debris flows are detected in near-real-time using the U.S. Geological Survey Real-time Seismic Amplitude Measurement (RSAM) tool. If an event is detected, we can then provide evacuation alerts to employees and visitors working and recreating in the areas downstream. Our goal is to accurately forecast the debris-flow hazards up to 7 days ahead of time and then use RSAM to detect debris flows within minutes of their genesis.

Quantitative Analysis of the Debris Flow Societal Risk to People Inside Buildings at Different Times: A Case Study of Luomo Village, Sichuan, Southwest China

Debris flows, which cause massive economic losses and tragic losses of life every year, represent serious threats to settlements in mountainous areas. Most deaths caused by debris flows in China occur in buildings, and the death toll is strongly dependent on the time people spend indoors. However, the role of time spent indoors in the quantitative analysis of debris flow risk has been studied only scarcely. We chose Luomo village in Sichuan atop a debris flow alluvial fan to study the influence of the temporal variation in the presence of people inside buildings on the societal risk. Two types of days (holidays vs. workdays) and two diurnal periods (daytime vs. nighttime) were considered in our risk evaluation model. A questionnaire survey was conducted for each family in the village, and the probability of the temporal impact of a debris flow on every household was calculated based on the average amount of time each member spent in the house. The debris flow hazard was simulated with FLO-2D to obtain the debris flow intensity and run-out map with return periods of 2, 10, 50, and 100 years. The risk to buildings and societal risk to residents were calculated quantitatively based on the probabilities of debris flow occurrence, the probability of the spatial impact, and the vulnerabilities of buildings and people. The results indicated that societal risk on holidays is always higher than that on weekdays, and societal risk at night is also much higher than that in the daytime, suggesting that the risk to life on holidays and at night is an important consideration. The proposed method permits us to obtain estimates of the probable economic losses and societal risk to people by debris flows in rural settlements and provides a basis for decision-making in the planning of mitigation countermeasures.

Hazard Assessment of Debris Flows by Statistical Analysis and GIS in Central Taiwan

This paper aims to build an analytical process of assessing debris-flow hazards using multivariate analysis and geographic information system (GIS) techniques. The watershed of the Chen-Yu-Lan River is investigated in this study. Factors that are believed to be critical in the occurrence of debris flow are identified and considered in the assessment of debris-flow hazards. These factors used for assessing the debris-flow hazard are: (1) rock formation, (2) fault length, (3) naked-land area, (4) slope angle, (5) slope aspect, (6) stream slope, (7) watershed area, (8) form factor, and (9) cover and management factor. Using the spatial analysis feature of GIS, the indexes of these factors are calculated. By using principal component analysis (PCA) and discriminant analysis (DA) of all indexes according to each factor, the discriminant function of overall debris-flow hazard at any particular creek in the Chen-Yu-Lan River may be assessed. The applicability of the proposed approach for hazard assessment of debris-flow in the watershed of the Chen-Yu-Lan River has been confirmed with other researches and field observations in recent debris-flow events.

Debris Flow Modelling Using RAMMS Model in the Alpine Environment With Focus on the Model Parameters and Main Characteristics

Debris flows are among the natural hazards that can occur in mountainous areas and endanger people’s lives and cause large economic damage. Debris flow modelling is needed in multiple applications such as design of protection measures or preparation of debris flow risk maps. Many models are available that can be used for debris flow modelling. The Rapid Mass Movement Simulation (RAMMS) model with its debris flow module, (i.e. RAMMS-DF) is one of the most commonly used ones. This review provides a comprehensive overview of past debris flow modelling applications in an alpine environment with their main characteristics, including study location, debris flow magnitude, simulation resolution, and Voellmy-fluid friction model parameter ranges, (i.e. μ and ξ). A short overview of each study is provided. Based on the review conducted, it is clear that RAMMS parameter ranges are relatively wide. Furthermore, model calibration using debris-flow post-event survey field data is the essential step that should be done before applying the model. However, an overview of the parameters can help to limit the parameter ranges. Particularly when considering the similarity between relevant case studies conducted in similar environments. This is especially relevant should the model be applied for estimating debris-flow hazard for potential future events. This model has been used mostly in Europe, (i.e. Alpine region) for modelling small and extremely large debris flows.

Pure risk premium rating of debris flows based on a dynamic run-out model: a case study in Anzhou, China

Debris flow risk is growing with the current increases in landscape exploitation and extreme precipitation events associated with global warming. Insurance is an efficient approach to cope with disasters. Based on the quantitative assessment, the debris flow hazard was obtained by a dynamic run-out model (FLO-2D), and the pure risk premiums of debris flow disaster were rating in a high-risk region (Anzhou) in Sichuan, China. Simulation results indicated that disastrous debris flows would reoccur every 5 years on average under the contemporary climatic and geological conditions of the study area. The mountain region experienced a wider area affected by debris flows than plains and hills; however, its area affected by low debris flow depth (d < 0.1 m) accounts for a larger proportion (56.69% and 22.60%, respectively). The probability of sub-basins with basin slopes of 5°–10° experiencing serious debris flows was pretty close to the probability of sub-basins with slopes of 25°–35°, which are considered to be susceptible to trigger debris flows. Furthermore, for relatively flat sub-basins (slopes < 25°), the part closer to source was more susceptible to higher flow depth. Risk assessment results showed that the significant spatial difference between the distribution of debris flow risk and hazard largely linked to the distribution of at-risk element (buildings). The pure risk premium of Anzhou was rated as 0.69–25.48‰ depending on the proportion of at-risk buildings to insured buildings, which highlights the need to encourage or require more low-risk and secure buildings to participate in insurance schemes to share the debris flow risk of the entire region.

Risk Assessment of Highway in the Upper Reaches of Minjiang River under the Stress of Debris Flow

The southwest mountainous area is a frequent debris flow disaster area in China, which poses a serious threat to the regional roads and greatly affects the normal traffic operation and the safety of residents’ lives and property. The debris flow risk assessment of highway can quantify the threat degree of debris flow to the roads. In this paper, from the perspective of villages and towns, taking the upper reaches of Minjiang River as the research area, four factors including road network density, highway disaster resistance capacity, population density and highway cost are selected, and the weight is obtained by using entropy weight method, and the debris flow vulnerability evaluation results of highway are obtained by weighted calculation. Four indexes of debris flow density, shape factor, relative height difference and annual rainfall are selected to evaluate the debris flow hazard of highway by using the information method. Based on the vulnerability and hazard evaluation results, the risk of highway debris flow is evaluated, and the results are classified and discussed. The results show that: the risk of debris flow on the upper reaches of Minjiang River is relatively low, the overall spatial distribution shows a trend of high in the East and low in the west, and the overall risk of township roads in Wenchuan county is the highest; The risk of debris flow is generally high within -10 to 30 km from the central fault zone of Longmenshan.