Characteristics Of Debris Flow Research Articles

Characteristics of debris flow dynamics and prediction of the hazardous area in Bangou Village, Yanqing District, Beijing, China

Abstract Debris flow is one of the most common types of geological disasters in China. Owing to the influence of topography, geomorphology, geological conditions, human activity, and rainfall debris flow disasters frequently occur in the mountainous areas of Beijing. The research on debris flow in the Beijing area focuses on rainfall and risk evaluation, material sources, and early warning and prevention of debris flow. However, there are few studies on the development characteristics of single-gully debris flow and the prediction of hazardous areas in the Beijing area. Therefore, we chose the debris flow of Bangou Village in Yanqing District of Beijing as the research object. We analyzed the recharge conditions in the ditch domain and predicted the extent of the hazardous area around the gully, providing suggestions for control measures. The dynamic reserves of the loose deposits in the debris flow gully, currently in the development stage, were estimated as 15.48 × 104 m3, representing four supply sources: artificial deposits, alluvium and diluvium, residual slope deposits, and collapse. The peak flow is 24.49 m3/s for a 10-year rainfall event, 27.64 m3/s for a 20-year rainfall event, 31.79 m3/s for a 50-year rainfall event, and 34.93 m3/s for a 100-year rainfall event. The total amounts of solids washed out by a debris flow from the preceding events are 0.70 × 104 m3, 0.79 × 104 m3, 0.91 × 104 m3, and 1.00 × 104 m3, respectively. The size of the debris flow is small, with a maximum hazardous area of 0.2810 km2. We conclude that a small debris flow outbreak in the Bangou Village gully is possible. We expect that the results of this study will provide basic information and help improve debris flow research in Beijing.

Study on debris flow discharge characteristics of check dam spillway

After a check dam is filled with sediment, the debris flow will flow out from the spillway. Insufficient discharge capacity of the spillway can lead to debris flow scouring the dam's shoulder and foundation. Therefore, it is necessary to study the discharge capacity of the spillway. It is of great importance for further optimizing the structural design of the check dam. This article analyzes discharge characteristics of debris flow of a spillway through a series of flume experiments. According to the motion states, it can be divided into five stages: contact stage of the spillway, flushing and climbing stage, increasing and reflux stage, stable discharge stage, and final discharge stage. We analyzed the influencing factors of the discharge capacity, including the type of spillway, bulk density of debris flow, scale of debris flow, flume gradient, and effective opening width of the spillway. Furthermore, we derived a calculation formula of discharge for the spillway based on Bernoulli's principle. Finally, we considered the influence of the ratio of flow area and Froude number to the discharge coefficient and established a calculation method of discharge. Consequently, we compared the calculated results with the measured results and found them to be in good agreement. Our research results provide a quantitative calculation method for the design of spillways and energy dissipation and erosion prevention projects under check dams, which is beneficial for improving engineering value and for better serving disaster prevention and reduction efforts.

Analysis and evaluation of development characteristics of debris flow in Longshougou

Long Shougou is located at the exit of Hei he River in Zhang ye City, which is directly facing the reservoir of Long Shougou Hydropower Station. Through site survey, UAV flight and indoor simulation calculation, the development characteristics and risk of Long Shougou debris flow were analyzed and evaluated. The results show that: Long Shougou debris flow is in the "development period", belonging to "small", "easy" and "high frequency" debris flow; The length of Long Shougou Channel is 1.70 km, the circumference is 3.76 km, the area is 0.72 km2 , the relative height difference is nearly 584 m, the longitudinal gradient is 342.27 ‰, and the overall bending coefficient is 1.14; Gully sediments are mainly gully bed deposits and slope collapse deposits, with total reserves of 20.94 ×104 m3 and dynamic reserves of 7.76 ×104 m3 ; Calculated according to the designed rainstorm frequency of 1%, the flow velocity of debris flow at the gully mouth is 2.64m /s, the total amount of primary overflow is 17,296.41m3 , the primary outflow of solid matter is 7956.35m3 , and the overall impact pressure of debris flow is 16.32kPa. The maximum impact force of a single stone is 2.56kN according to 0.5m; It is suggested to consider the impact of the annual inflow of debris flow on the water quality of the Longshou hydropower station reservoir and the impact on the power station switching station near the Gulou port, and do a good job in the relevant sediment discharge measures.

A dataset of the distribution and characteristics of debris flows along the National Highway 318 in the Sino-Nepalese transport corridor (2022)

Due to the unique geographical and geological conditions in the Sino-Nepal transportation corridor, there is a lack of reliable and comprehensive data on debris flow distribution data in the region. This dataset is compiled based on early identification of debris flows and field surveys, integrating Digital Elevation Models (DEM) and geological maps. It provides a catalog and detailed feature information of debris flows within the corridor along the National Highway 318 between China and Nepal from 1990 to 2022. Precipitation and temperature parameters are derived from 30 years (1980–2009) of interpolated data from national meteorological stations. Fault distribution information is sourced from the 1:50,000 digital geological maps published by the China Geological Survey. Terrain information is obtained from NASA's Shuttle Radar Topography Mission (SRTM) data, which provides a global DEM at a resolution of 12.5 m. Within the geographical coordinates of 28.0°–29.4°N and 85.1°–88.9°E, a total of 255 debris flow records have been extracted, covering an area of 1660.73 km². We primarily employed hydrological analysis methods in ArcGIS for the extraction of debris flow basins. Considering the limitations in DEM accuracy, we made necessary manual corrections with reference to Google Earth imagery. The dataset comprises three files: a vector file depicting the main distribution range of debris flows along the National Highway 318 in the Sino-Nepalese transport corridor; a vector file containing the catalog of debris flows; and a document detailing the parameters and characteristics of the debris flows.The dataset has undergone on-site field surveys and confirmation to ensure its reliability. Therefore, it can serve as a foundational dataset applicable to debris flow studies in the region.

CFD-DEM numerical investigation of the effects of water content and inclination angle on interactions between debris flows and slit dam

Debris flows, composed of sediment–water mixtures, can pose significant risks to downstream populations and infrastructure in mountainous regions. Slit dams have been demonstrated as being effective measures for decreasing the destructivity of debris flows. Reliable evaluations of the interactions between debris flows and slit dams are challenging if the complicated component characteristics of debris flows, such as the water content, are not considered. Here, a multi-scale study of debris flows impacting a slit dam is conducted via computational fluid dynamics and discrete element method (CFD-DEM) simulations to understand the influences of the water content (controlled by solid volume fraction in this study) and the channel inclination angle on flow–slit dam interactions. The results indicate that both the initial solid volume fraction and the channel inclination angle have significant effects on the impact kinematics of flow–slit dam interactions and regulation functions of the slit dam: (i) For gentle slopes, the deposition of debris flows is primarily influenced by flume basal friction, and the normalized peak total impact forces have little difference for a given inclination angle, whereas for steep slopes, an overtopping can occur, further result in the increasing of the normalized peak total impact forces with the increase of solid volume fraction. (ii) The run-up height and retention efficiency are also analyzed to provide a scientific reference for optimizing the design of slit dams.

Susceptibility of Landslide Debris Flow in Yanghe Township Based on Multi-Source Remote Sensing Information Extraction Technology (Sichuan, China)

The extraction of real geological environment information is a key factor in accurately evaluating the vulnerability to geological hazards. Yanghe Township is located in the mountainous area of western Sichuan and lacks geological survey data. Therefore, it is important predict the spatial and temporal development law of landslide debris flow in this area and improve the effectiveness and accuracy of monitoring changes in landslide debris flow, this article proposes a method for extracting information on the changes in landslide debris flows combined with NDVI variation, which is based on short baseline interferometry (SBAS-InSAR) and optical remote sensing interpretation. In this article, we present relevant maps based on six main factors: vegetation index, slope, slope orientation, elevation, topographic relief, and formation lithology. At the same time, different remote sensing images were compared to improve the accuracy of landslide debris flow sensitivity assessments. The research showed that the highest altitude of the region extracted by multi-source remote sensing technology is 2877 m, and the lowest is 630 m, which can truly reflect the topographic relief characteristics of the region. The pixel binary model’s lack of regional restrictions enables a more accurate estimation of the Normalized Difference Vegetation Index (NDVI), bringing it closer to the actual vegetation situation. The study uncovered a bidirectional relationship between vegetation coverage changes and landslide deformation in the study area, revealing spatial–temporal evolution patterns. By employing multi-source remote sensing technology, the research effectively utilized changes in multi-period imagery and feature extraction methods to accurately depict the development process and distribution characteristics of landslide debris flow. This approach not only offers technical support but also provides guidance for evaluating the vulnerability of landslide debris flow in the region.

Preliminary Investigation on the Kinetic Characteristics of the Glacial Debris Flows in Tianmo Valley, Tibet Plateau, China

AbstractGlacial debris flows occurring on the Tibetan Plateau consistently result in significant property damage and loss of human life. A comprehensive field investigation was conducted in Tianmo valley along the Sichuan‐Tibet Highway to reveal the dynamics of a debris flow that occurred on 11 July 2018. Furthermore, a depth‐averaged multiphase debris flow model was proposed and employed to reconstruct the characteristics of the debris flow. The model derivation, implementation, evaluation, and application were presented to demonstrate its performance. The Voellmy model was chosen because it adequately accounts for both basal frictional effects and the entrainment phenomenon. The entrainment processes, the ice melting, and the lubrication effect, were also taken into consideration. Based on the numerical results combined with field investigation data, the kinetic characteristics of the glacial debris flow were analyzed. The Tianmo valley has a small area, but the volume and erosion rate of debris flows were much larger than that of two‐phase debris flows in the same location due to ice melting. The simulation results demonstrated that the glacial debris reached a peak velocity of 20 m/s. Additionally, the volume of the debris flow increased by 50% due to the erosion over a short runout distance of approximately 4,000 m. This increase was a result of the high velocity and abundant entrainment sources on the slope. This study aims to improve understanding of the high velocity and destructive potential of debris flows in the Tianmo valley.

ВКЛАД НГМС РК В СЕЛЕВУЮ БЕЗОПАСНОСТЬ СТРАНЫ

In this paper, the scientific activities of the National Hydrometeorological Service of Kazakhstan to study the origin, development and degradation of debris flows, carried out with the aim of reducing the damage caused by debris flows, are presented over a long period. The features of precipitation, emptying of surface and intraglacial reservoirs, mineralogical and granulometric compositions of debris rocks, geomorphological conditions of debris flow formation, recurrence and characteristics of debris flows were studied. Methods for computation of the viscosity and plasticity of debris-flow mass, used in mathematical modeling of debris flow formation have been developed. A method for ultra-short-term forecasting of catastrophic debris flows caused by rainfall, based on data on preliminary soil moisture, the position of the zero isotherm and seasonal snow line, and current actual meteorological information has been developed. The feasibility of this method is tens of times greater than the feasibility of the method for short-term forecasting of debris flows caused by rainfall, which was used previously. The computation of the characteristics of debris flows is based on the discovery of an ambiguous dependence between the density of debris-flow mass and the slope of way of debris flow. A debris-flow hazard map for the territory of the Republic of Kazakhstan has been developed. A concept for protection against debris flows of Almaty city under climate changing has been proposed. A geological and geomorphological method has been developed for determining the genesis of fan, which allows optimizing the work on assessing the risk of urbanization of territories located in the mountain and foothill zones.

Feature Extraction Algorithm of Massive Rainstorm Debris Flow Based on Ecological Environment Telemetry

In order to accurately extract the characteristics of debris flow caused by group rainstorms, effectively identify the on-site information of debris flow, and provide a scientific basis for debris flow monitoring, early warning and disaster control, this paper proposes a method for extracting the characteristics of heavy rainstorm debris flow using multiregional ecological environment remote sensing. In the ecological environment where debris flows occur frequently, remote sensing data of heavy rainstorm debris flows are preprocessed using remote sensing technology, providing an important basis for the feature extraction of debris flows. The kernel principal component analysis method and Gabor filters are innovatively used to extract the spectral and texture features of rainstorm and debris flow remote sensing images, and the convolutional neural network structure is improved based on the open source deep learning framework, integrating multilevel features to generate debris flow feature maps. The improved convolution neural network is then used to extract the secondary features of the fusion feature map, and the feature extraction of heavy rainstorm debris flow is realized. The experiment shows that this method can accurately extract the characteristics of heavy rainstorm debris flow. Fused remote sensing images of debris flow effectively ameliorate the problem of insufficient informational content in a single image and improve image clarity. When the Gabor kernel function has eight different directions, the feature extraction effect of the debris flow image in each direction of the heavy rainstorm is the best.

Risk assessment of debris flow disaster in mountainous area of northern Yunnan province based on FLO-2D under the influence of extreme rainfall

The stratum in Yunlong mountain area is unstable, and it is more likely to have extreme damage to the mountain in extreme rainfall weather, and even cause the occurrence of mountain disasters such as debris flow. This paper conducted field geological surveys and used the FLO-2D professional simulation system to scientifically evaluate the risk probability of three debris flow in Yunlong County. The risk prediction before and after engineering control was compared for the county’s urban areas.This paper uses construction drawings and remote sensing images to assist in positioning methods for debris flow simulation. After dividing the debris flow simulation grid, the control project is added to the simulation project in the form of a plug-in, and specific engineering parameters are imported into the simulation project file by modifying its properties. The setting of the control project in numerical simulation is completed, solving the problem of setting engineering measures. By this method, the probability analysis of debris flow under three different rainfall frequencies of 1%, 2% and 5%, namely once in 20 years, once in 50 years and once in 100 years, is simulated, and the flow and sedimentation characteristics of debris flow before and after engineering control are compared. The results show that under 5% rainfall frequency, the simulated results before engineering control were compared with the actual deposition range, and the evaluation accuracy is within a reasonable error range. After debris flow engineering control, the proportion of high risk areas of debris flow in urban areas decreased significantly, especially when the frequency of rainfall was once in 100 years, and the area of non-danger areas increased by 5.92% compared with that before control. In the end, this paper combines the depth of mud, the velocity of mud and the outbreak frequency to get the debris flow risk assessment map before and after engineering treatment, and puts forward suggestions for further prevention and control measures of debris flow disaster. The research results of this paper will provide good guidance for the occurrence and control of debris flow hazards under the influence of extreme rainfall in the mountainous area of northern Yunnan.

Effects of material composition on deposition characteristics of runoff-generated debris flows

Effects of material composition on deposition characteristics of runoff-generated debris flows

Application of remote sensing monitoring to the spatiotemporal variation in debris flow activity in the catastrophic Wenchuan seismic area

Debris flows are typical compounded geohazards with long-term activity in earthquake-stricken areas. Numerous debris flows were simultaneously induced by subsequent extreme precipitation and caused serious property losses and casualties. Monitoring the dynamic variation in debris flow activity and its decay process over time is key for debris flow risk management and mitigation of the impact of debris flows. In this study, the spatiotemporal variation in debris flow activity of the Wenchuan seismic area over the past ten years was monitored based on multiperiod satellite data and field monitoring. The hillslope landslide sediment delivery to the channel gradually decreased, and the area with higher sediment transfer potential gradually changed from southern Wenchuan County to the northern area, which caused the area with high susceptibility to debris flows to gradually move towards northern Wenchuan County. Impacted by the decrease in available materials and coarsening of channel materials, the power of rainfall runoff required for driving debris flows gradually increased. This resulting debris flow is more likely to occur in this basin with a larger catchment area, longer channel length, and higher elevation difference. The changes in the debris flow activity index indicated that the debris flow activity evolves with an impulse type, and it may last for decades. The decay processes of the debris flow activity were summed up in three periods, i.e., high-activity period (2008–2015), unstable period (2015–2035), and recession period (after 2035), based on the dynamic evolution of material, hydrodynamics, and the coefficient of debris flow activity. Simultaneously, the active characteristics of debris flows in different periods were revealed, which is of great significance to the risk management of debris flows in the next period.

Characteristics of debris flows recorded in the Shenmu area of central Taiwan between 2004 and 2021

Abstract. The data of debris-flow events between 2004 and 2021 in the Shenmu area Taiwan are presented and discussed in this paper. A total of 20 debris-flow events were observed in 18 years. Debris flows in the Shenmu area usually occurred in the Aiyuzi Stream during the rainy season, May to September, and about once per year between 2009 and 2017. The rainfall thresholds from the observed data are proposed to be Imax⁡ (maximum hourly rainfall), R24 (24 h accumulated rainfall), and Rt (effective accumulated rainfall) of 9, 23, and 67.8 mm, respectively. The rainfall data also imply that the trend curves of intensity–duration (I–D) were different before and after 2009, which is due to the extreme rainfall event of Typhoon Morakot in 2009. The I–D curve obtained from the post-2009 data is proposed as the baseline of the debris-flow I–D relationship in the study area. The extreme rainfall event also influenced the flow speed (average 14.3 m s−1 before 2010 and 4.46 m s−1 after 2010) and the occurrence frequency of debris flows (1.83 times per year before 2009 and 0.75 times after 2009). Recent findings have indicated that the ground surface vibrational signals of debris flows are potentially useful for debris-flow early warning in terms of accumulated energy, and the characteristic frequency of debris flows in the study area was below 40 Hz. The dataset and the rainfall thresholds in this study permit comparison with other monitored catchments and are useful for global debris-flow datasets.

Characterization of Environmental Seismic Signals in a Post‐Wildfire Environment: Examples From the Museum Fire, AZ

AbstractThe 2019 Museum Fire burned in a mountainous region near the city of Flagstaff, AZ, USA. Due to the high risk of post‐fire debris flows and flooding entering the city, we deployed a network of seismometers within the burn area and downstream drainages to examine the efficacy of seismic monitoring for post‐fire flows. Seismic instruments were deployed during the 2019, 2020, and 2021 monsoon seasons following the fire and recorded several debris flow and flood events, as well as signals associated with rainfall, lightning and wind. Signal power, frequency content, and wave polarization were measured for multiple events and compared to rain gauge records and images recorded by cameras installed in the study area. We use these data to test the efficacy of seismic recordings to (a) detect and differentiate between different energy sources, (b) estimate the timing of lightning strikes, (c) calculate rainfall intensities, and (d) determine debris flow timing, size, velocity, and location. We then calculate forward models of seismic signals associated with debris flows and rainfall to better interpret our results and characterize these events. Our observations and modeling show that we can differentiate between these sources and that seismic data can provide insight into post‐fire debris flow characteristics, including relative particle sizes and velocity.

Impact mechanisms and morphological characteristics of Nam Pam debris flow - flash flood catchment

Understanding the mechanisms and damages caused by debris flows and flash floods is crucial for proposing effective mitigation conterneasures. This study aims to clarify the impact mechanisms and morphological characteristics of a debris flow and flash flood event that occurred from the night of August 2, 2017 to the early morning of August 3, 2017, in Nam Pam commune, Muong La district, Son La province. The study involved field surveys and analysis of the morphological characteristics of the sub-catchments within the Nam Pam stream catchment. The morphological characteristics of the catchment area were analysed by quantifying the relationships between parameters such as area, slope, elevation, length, Melton coefficient... contributing to supplementing the database for identifying high-risk catchment areas prone to debris flows. The 2017 flash flood event in the Nam Pam stream catchment was a multi-hazard phenomenon resulting from rainfall-induced geological transformations. The transformation process started from higher elevations, with widespread landslides caused by rainfall transforming into concentrated "debris flows" in the primary sub-catchment channels, then transitioning into "debris flow-flash floods" in the secondary sub-catchments, followed by "flash floods-debris flows" in the tertiary sub-catchments, and ultimately transforming into "flash floods" in the fourth-order catchment area.

Impact Characteristics of Viscous-Dominated Debris Flow on Circular Cylinder

Impact Characteristics of Viscous-Dominated Debris Flow on Circular Cylinder

The mechanisms of high mobility of a glacial debris flow using the Pudasaini-Mergili multi-phase modeling

Glacial debris flows with high mobility and long run-out distance have posed a growing threat to human life and critical infrastructure under climate change. The dynamics and mobility of glacial debris flows are related to many physical factors, among which initial ice/water content, phase transition, and entrainment might be the most important. A typical glacial debris flow occurred on 10 September 2020 near Namcha Barwa Peak in Tibet Plateau and travelled about 10 km under no precipitation condition. The major unsolved mechanical questions for the high mobility of this glacial debris flow include: What is the primary water source of this glacial debris flow? How do the water and ice affect the dynamics of the glacial debris flow? Which physical factor dominates the high mobility characteristics of the glacial debris flow? To answer these questions and deepen our understanding, we adopted the Pudasaini and Mergili (2019) advanced multi-phase mass flow model implemented in the computational tool (r.avaflow) to back-calculate this event. Through well-designed numerical experiments, we revealed that the initial water content is the major water source of this glacial debris flow event. We analyzed the impact of the initial ice/water fraction, phase transition, and entrainment on the mobility of the glacial debris flow. Results show that the initial ice/water content and entrainment are critical to the mobility of the glacial debris flow in the initial and later transport stage, respectively, while the phase transition only plays a minor role. Our study promotes mechanical understanding of the high mobility of this kind of glacial debris flow events.

Risk assessment of debris flow along the northern line of the Sichuan-Tibet highway

Debris flow occurs frequently in mountainous areas due to the special geographical and geological environment, causing significant damage to linear infrastructure. However, a systematic assessment of debris flow risk to the national highway is limited by the lack of regional vulnerability data. Based on a detailed inventory of debris flow and highway structure characteristics, this study presents a comprehensive regional risk assessment framework on the northern line of the Sichuan-Tibet Highway in China. The proposed framework consists of three main procedures: (1) debris flow hazard analyses by the weight-of-evidence method, (2) analyses of physical vulnerability using 12 vulnerability indexes, and (3) risk calculation which considers the natural attributes of debris flow and the social characteristics of a linear highway. The predictive performance was evaluated through receiver operating characteristic (ROC) curves, and the validation results showed that areas under the ROC curves were 83.77%. The risk zoning map indicated that the high-risk areas were particularly distributed in Dege County and Daofu County, with a high disaster frequency and a low highway protection standard. The regional risk assessment framework supports decision-making for disaster prevention and highway rehabilitation in mountainous areas.

Multi-scale flume investigation of the influence of cylindrical baffles on the mobility of landslide debris

Debris flows travel downslope at high speed and often cause damage to the infrastructure of societies around the world. With increasing extreme rainfall events and urbanization in mountainous regions, effective structural countermeasures are in increasing demand. Over recent years, engineers have proposed the installation of an array of cylindrical columns, called baffles, to reduce the velocity of debris flows in catchments. However, existing design methods are highly empirical in nature, so it is unclear whether they are adequate or over designed, and appropriate specifications and arrangement of cylindrical baffles have still not been suggested. Moreover, previous experimental studies have predominantly modeled debris flows as dry granular flows at a laboratory scale. In this study, to investigate the effect of cylindrical baffles on the dynamic characteristics of debris flow, a series of small-scale flume tests was conducted using a flume equipped with devices to measure the flow interaction between baffles and the dynamic loads of debris flow. In addition, to investigate the scale effect of debris flows and cylindrical baffles on flow characteristics, large-scale tests were also performed according to different numbers of rows of baffles for similar baffle configurations confirmed by small-scale tests. Using the small- and large-scale test results, this study analyzed the energy dissipation and dynamic impact characteristics according to the height and number of rows of baffles. The analysis results showed that the use of baffles increased the energy dissipation of debris flows, and an additional row of baffles produced greater effects on the energy dissipation in the debris flows. Based on the test results, the average dynamic pressure coefficient for cylindrical baffles was 0.31.

Debris flow characteristics of the compound channels with vegetated floodplains

Compound cross-sections with vegetated floodplains are a common type of cross-section in debris-flow gullies. Floodplain vegetation participates in large-scale debris flow events and regulates debris-flow discharge. Extensive research has been conducted on the water flow characteristics of compound rivers. However, few studies have investigated the debris flow characteristics of compound channels in mountainous areas, particularly those of debris flow and flash flood inundation areas with vegetation. This study discusses the section characteristics of debris flow gullies with vegetated floodplains, gully evolution processes, and their influence on debris flow. The results show that the compound debris flow gully with a vegetated floodplain is formed in the gully from the mature stage to the old-mature stage. The compound sections are developed in flow areas with a gentle slope, which can be bilateral floodplain, unilateral floodplain, and multi-main gully floodplain types. Owing to the vegetation of the floodplain, the roughness of the channel increases, which makes the beach roughness coefficient much larger than that for the main channel. In the integrated Manning coefficient method, the error in resolving the flow velocity and discharge is large and cannot reflect the difference in velocities of the floodplain and main channel, therefore the sectional splitting method is most applicable. Influencing debris flow movement, limiting channel migration, and retaining debris flow to the main channel were the main contributions of the riparian forest zone.