Debris Flow Basins Research Articles

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.

Variation in Debris-Flow-Prone Areas with Ecosystem Stability: A Case Study of the Qipan Catchment in the Wenchuan Earthquake Region

The spatial distribution of vegetation in a basin has a far-reaching influence on the potential for sediment separation and transport capacity. However, many landslides induced by strong earthquakes have greatly changed the existing pattern, which further increases the probability of debris flow in a basin during heavy rainfall and has a significant impact on the stability of the basin. Thus, this study selected the debris flow basin in the Qipan catchment of the Wenchuan earthquake area as the research object. Multisource and high-precision remote sensing images were used to analyze the land use changes in the basin, and the index of connectivity (IC) was introduced to analyze the evolution of sediment transport capacity. An ecosystem stability assessment method suitable for post-earthquake debris flow basins was proposed. Through quantitative assessment of the ecosystem stability of the basin after the Wenchuan earthquake in 2008 and the two debris flow events after the earthquake, the dynamic relationship between the debris-flow-prone area and the ecosystem stability of the basin was revealed. The results showed that the stability of the ecosystem in the Qipan catchment increased annually, indicating a stable and substable state. The spatial distribution characteristics were lower in the north and south and greater in the middle. By comparing the evaluation results with the actual terrain change trend, the accuracy and feasibility of the evaluation method are verified. The results of this study provide a scientific basis for the formulation of regional disaster prevention strategies and help to accelerate the improvement of regional stability in debris-flow-prone areas.

Copula-Based Probabilistic Hazard Assessment Model for Debris Flow Considering the Uncertainties of Multiple Influencing Factors

This paper proposes a probabilistic hazard assessment model for debris flows considering the uncertainties of multiple influencing factors based on copula approaches. Fifty-nine rainfall-induced debris flows occurred between 2001 and 2009 in Taiwan are taken as an illustrative example to validate the proposed approaches. A copula-based probabilistic model is developed to model the joint probability distribution of debris-flow volume V and its influencing factors (e.g., rainfall intensity, RI and landslide area, AL). The developed model is then used to make probabilistic prediction of debris-flow volume for a specific hazard level, and compared with the empirical approaches. The proposed probabilistic model is also used to develop the exceedance probability charts of quantities for a specific debris-flow basin. Results show that the developed V–RI–AL probabilistic model can provide reasonable estimates of debris-flow volume in Taiwan for a specific probability level of 0.94, and show better predictive performance than the empirical relationships by using an independent debris-flow dataset in Taiwan for validation. The developed multivariate joint probabilistic model can also provide the exceedance probability of debris flows through considering the uncertainties of debris flow and its influencing factors, providing a preliminary reference for hazard assessment of the debris flows.

The evolution of glacial lake and glaciers and their potential impact on glacial debris flow activity in the Palong Zangbu catchment in Southeastern Tibet

Due to warm and humid air currents of the Indian Ocean and the southwest monsoon, the Palong Zangbo catchment in southeastern Tibet has developed oceanic glaciers in the valley, and the activity of glacial debris flows has been gradually intensified under neotectonic activity, frequent earthquakes, climate change, and extreme rainfall. In this paper, the topographic and morphological data of the debris flow basin, the dynamic evolution characteristics of glaciers and glacial lakes were analyzed by using multisource long-term series of remote sensing images. Simultaneously, the distribution of moraines and landslide sources were extracted based on satellite image. In addition, climate change in the study area was analysed using temperature and rainfall data from the last 40 years, revealing that the average temperature in the study area from May to October presented a fluctuating tendency as a whole, especially after 2013, when the temperature gradually increased. As these temperature changes led to continuous melting of the glaciers in the study area, the glacier area decreased from 8,300 km2 in 1988–4,584 km2 in 2019, which decreased nearly 45%. However, the number and area of glacial lakes in the study area gradually increased under a power-law trend, which further led to a significant increase on the possibility of glacial lake rupture in the study area. Due to the joint effects of earthquakes, glacier melting and glacial lake collapse, the debris flows in the study area were well developed, and a total of 122 debris flows were found with varying channel lengths, areas and material sources. Importantly, the characteristics of the glaciers, glacial lakes and climate change in the study area have indicated that the glaciers have retreated, the number of glacial lakes has increased, and the risk of debris flow in this basin will increase in the future. Therefore, it is necessary to strengthen monitoring and early warnings on floods due to glacial lake collapses and debris flows in the study area to improve the risk management of debris flows and floods and the prevention and mitigation of disasters.

DEBRIS FLOW RELIEF OF THE MALAYA PAIPUDYNA BASIN (THE POLAR URAL MOUNTAINS)<a href="#FN1"><sup>1</sup></a>

We studied the debris flow relief of the Malaya Paipudyna basin, the Polar Ural Mountains. Based on the analysis of remote sensing data and field surveys, we established that 14 debris flow basins are located on the territory. We found traces of five slushflow occurrence in the streams in the spring of 2021. Typical landforms for different morphodynamic zones of debris flow basins were identified. The initiation zones of debris flows are mainly represented by catchment funnels on the slopes of the Bolshoi and Maliy PaIpudynskii ranges. The transit zones V-shaped bottom incisions alternate with box- and trough-shaped transverse profile. Within the debris flow fans, two generations of accumulative debris flow relief are clearly distinguished. Young accumulation zones are represented by pebble-boulder ridges up to 0.5 m high, localized directly in the near-channel areas of debris flow fans. Usually, they are either devoid of soil and vegetation cover, or are overgrown only by herbs. Ancient debris flow fans are triangular in shaped with convex transverse profile, consisting of a system of ridges and hollows, and overgrown with shrubs. The area of young accumulation zones for each debris flow basin is no more than 0.03 km2, the area of ancient accumulation zones is 0.4 km2. Debris flow fans are superimposed on the bottom of the trough valley of Malaya Paipudyna, which is mainly the surface of glacial accumulation. Probably, the formation of these fans began after the degradation of the last extensive glaciation of the territory. We calculated the morphometric features of the debris flow basins.

The distribution law and coupling factors of debris flows in the G318 Linzhi–Lhasa section of the Sichuan–Tibet traffic corridor

In recent years, debris flow disasters have occurred frequently along the highway, causing river blockages and road interruptions, which seriously threaten the safety of people's lives and property. Highway G318 is an important throat project linking Sichuan and Tibet; at the same time, it is an important channel for the economic development of Sichuan and Tibet and the transportation of national defense materials. Taking the Linzhi–Lhasa Section of Highway G318 as an example, this study analyses the distribution law and characteristics of coupling factors of debris flows in the study area (under its topographical, hydrometeorological, geological, and structural conditions) using remote sensing interpretation, field surveys, and mathematical statistics. The research shows that: (1) The types and quantity of debris flows in the region show statistical laws under the factors of the slope, slope aspect, drainage area, and gradient of the gully. The vegetation coverage in the upper reaches of the Nyang River valley gradually decreases, and the average debris flow disaster density is 0.529/km, which is the most densely distributed area of debris flow. (2) The distribution density of regional debris flows in narrow valleys is greater than that in wide valleys, and those in the Nyang River basin are greater than those in the Lhasa River basin. (3) By comparing the tectonic geological map and the debris flow distribution map, it was found that the debris flow distribution is controlled by faults, and 71% of the debris flow basins have faults. (4) There is a significant positive correlation between the gradient of the material source area and the gradient of the debris flow gully, as well as a close positive correlation between the rainfall and the fault density, and a close negative correlation between the average gradient and the drainage area. Due to the unique topography and geomorphology of different regions, a difference in meteorology and hydrology occurred. This further affected the topography, geomorphology, and distribution of debris flow disasters. Based on the study of the distribution law of regional debris flow and geological environmental factors, this study provides strong support for regional debris flow prevention and related research.

Rockfalls change the runout and frequency of debris flows at Punta Nera (Eastern Italian Alps)

In the Dolomitic region, many debris flow basins have headwaters characterized by extremely steep slopes of bare outcropping rock. Cliffs are commonly incised by multiple chutes which rapidly deliver runoff at their base where the channels incise scree deposits. Debris flows mobilize and transport sediment along such ephemeral channels following intense summer convective rainstorms. In the debris flow basin of Punta Nera, a series of rockfalls, which occurred in the upper part of the headwater between 2013 and 2016, caused dramatic changes in the debris flow dynamics. Starting from the summer of 2014, the runout of debris flow events increased so much that it reached the national road, which runs at the toe of the debris flow fan, attracting media attention and prompting the adoption of protective measures. Here, we use newspaper reports, direct observations, aerial and terrestrial photograph, monitoring data and topographic surveys to document the rockfalls and the debris flow activity. The sudden increase in sediment availability changed the magnitude of events, their runout and the critical conditions for debris-flow occurrence.

Application of physical models to improve the mitigation structures of debris flow in a case study

Debris flows are a phenomenon in mountains areas, where a large amount of mobile rock material, large amounts of water and steep slopes meet together. They are characterized by high capacity of sediment transport, high concentration of sediment with wide range of grain sizes and high front-velocity. To improve the protection measures against debris flow, it is necessary to know the processes of debris flows and its interaction with structures of the measures. By investigation of the mitigation structures in experimental scaled physical models it is possible to understand the functionality of the structures under different scenarios as well as optimization of the structures. For the protection of the counties Agarn und Leuk in Valais in Switzerland a multi-level debris flow basin system has been designed. By means the physical model in scale of 1:55 the functionality and the dimensions as well as the details of the structures could be optimized.

Multifractal Features of Particle-Size Distribution and Their Relationships With Soil Erosion Resistance Under Different Vegetation Types in Debris Flow Basin

Understanding the influence of vegetation types on soil particle-size distribution (PSD) is essential to evaluate the effects of sediment control by vegetation restoration. In this work, we studied the effects of different vegetation types, including bare land, meadow, shrub and forest on soil PSD in Jiangjiagou gully, Yunnan province, China. A total of 60 soil samples were collected and analyzed for soil particle size distribution using the laser diffraction method. Fractal theory was used to calculate multifractal parameters. The volume fraction of silt particles in shrub and forest is significantly higher than that in bare land, meadow, whereas the total volume fraction of sand particles in bare land and meadow exceed that in shrub and forest. The soil particle size distribution along soil layers has no significant difference in each vegetation type. The volumetric fractal dimension is significantly higher in forest and shrub than in bare land and grassland, but there is no significant difference between forest and shrub. In addition, soil erosion resistance exhibits significant differences of forest > shrub > grassland > bare land. Multifractal parameters are highest in bare land except for multifractal spectrum values (f (αmax) and f (αmin)) and the maximum value of singularity index (αmin). All generalized dimensions spectra curves of the PSD are sigmoidal, whereas the singular spectrum function shows an asymmetric upward convex curve. Furthermore, soil erosion resistance has significant relationships with multifractal parameters. Our results suggest that multifractal parameters of the soil PSD can predict its anti-ability to erosion. This study also provides an important insight for the evaluation of soil structure improvement and the effects of erosion control by vegetation restoration in dry-hot valley areas.

Long-term hillslope erosion and landslide–channel coupling in the area of the catastrophic Wenchuan earthquake

Approximately 200,000 landslides were triggered by the 2008 Wenchuan earthquake and subsequent strong rainfall events, and the amount of landslide sediment delivered to the channels within catchments depended on the amount of landslide debris generated by the earthquake and the amount of post-earthquake rainfall. To better understand long-term hillslope erosion and the long-term changes in landslide–channel coupling, this study quantifies the coupling degree of landslide–channel by defining a landslide-channel coupling index (LCCI) and estimates the long-term hillslope erosion driven by landslides within 12 debris flow basins. We track landslide activity using multiyear imagery from 2008 to 2019, and the landslide ratio, landslide new regeneration ratio, and landslide reactivated ratio indicate that the overall landslide activity decayed following the Wenchuan earthquake. The calculation results of the coupling index illustrate that the coupling degree of landslide–channel in the study area follows a power law trend of decay over time. However, due to the influence of landslide activity, the coupling index decreased significantly in the first 5 years after the Wenchuan earthquake and then decreased slowly. The hillslope erosion driven by landslides is estimated using a conservative statistical model. The result shows that the landslide-driven hillslope erosion has decayed following a power law, and elevated levels of erosion may last for an unexpectedly long period. In addition, the landslide–channel coupling degree affects the movement of landslide sediment to channels. While the coupling degree of landslide–channel and the amount of landslide sediment supplied to the channels have decreased significantly in recent years, abundant landslide sediment could still be delivered to the channels when strong rainfall occurs in this region. Furthermore, a considerable amount of sediment appears to remain within the tributary channels and trunk channels, which means the activity of debris flow may last longer period than hillslope erosion.

Morphometric analysis of debris flow basin of Harsovska river (Southwest Rila, Bulgaria)

The analysis of morphometric properties of a river basin and identification of the correlation between the specific topography and the processes of debris flow is crucial for identifying the areas with a high ecological risk. Results of the fieldwork and analysis in the GIS environment show the high risk of debris flow for the Harsovska river basin.

Long-term changes in the landslide sediment supply capacity for debris flow occurrence in Wenchuan County, China

After the Wenchuan earthquake, a large number of landslides in debris flow basins continued to provide loose debris for channels and further affected the occurrence of debris flows. Evaluating the landslide sediment supply capacity in debris flow basins requires understanding the landslide activity and the coupled relationship between the landslide and the channel. In this study, we proposed a model based on the landslide area density index (PAls) and the landslide connectivity (ICl) to evaluate the capacity of the landslide sediment supply for channels in 46 sub-catchments in the study area. The capacity of the landslide sediment supply for channels generally decreased from 2008 to 2018, but due to the influence of heavy rainfall, the actual capacity of the landslide sediment supply for channels in the study area may gradually diminish in an unstable way, and it may arrive at the pre-earthquake level by 2025 without the influence of extreme rainfall. However, higher debris flow activity may last longer than 2025 because sufficient gully materials are still accumulated in the channel. The sediment transport capacity of landslides was divided into five levels: extremely, high, moderate, slight and low. The capacity of the landslide sediment supply for channels changed from extreme levels and high levels to moderate levels and slight levels after the first 5 years of the Wenchuan earthquake and was then dominated by low levels. Simultaneously, the regions with higher landslide sediment supply capacities gradually changed from along the Minjiang River regions to the upper and middle reaches of the debris flow basin from 2008 to 2018. Hongchun gully, which is in the study area, was chosen as an example to compare the assessment results and field investigation. The long-term evolution of landslides is an important reason for the decrease in the sediment supply capacity of landslides.

Debris flow magnitude, frequency, and precipitation threshold in the eastern North Cascades, Washington, USA

We examine the magnitude, frequency, and precipitation threshold of the extreme flood hazard on 37 low-order streams in the lower Stehekin River Valley on the arid eastern slope of the North Cascades. Key morphometric variables identify the magnitude of the hazard by differentiating debris flood from debris flow systems. Thirty-two debris flow systems are fed by basins 10°. Five debris flood systems have larger drainage areas and debris fans with slopes 7–10°. The debris flood systems have Melton ruggedness ratios from 0.42–0.64 compared to 0.78–3.80 for debris flow basins. We record stratigraphy at seven sites where soil surfaces buried by successive debris flows limit the age of events spanning 6000 years. Eighteen radiocarbon ages from the soils are the basis for estimates of a 200 to1500-year range in recurrence interval for larger debris flows and a 450 ± 50-year average. Smaller events occur approximately every 100 years. Fifteen debris flows occurred in nine drainage systems in the last 15 years, including multiple flows on three streams. Summer storms in 2010 and 2013 with peak rainfall intensities of 7–9 mm/h sustained for 8–11 h triggered all but one flow; the fall 2015 event on Canyon Creek occurred after 170 mm of rain in 78 h. A direct link between fires and debris flows is unclear because several recent debris flows occurred in basins that did not burn or burned at low intensity, and basins that burned at high intensity did not carry debris flows. All but one of the recent flows and fires occurred on the valley’s southwest-facing wall. We conclude that fires and debris flows are linked by aspect at the landscape scale, where the sunny valley wall has flashy runoff due to sparse vegetation from frequent fires.

Природные наледи селевых бассейнов Среднего и Южного Сахалина

The article deals with the ice mounds formation processes in the mudflow basins. Small natural frosts are widespread on the territory of Middle and Southern Sakhalin within the slope and small valley debris flow basins, along with dangerous slope exogenous processes (debris flows, landslides, erosion, etc.), often having a paragenetic nature of the current. The mechanism of ice data formation is due to the hydro/meteorological features of the territory, as well as disturbance of the thermal, hydrological or hydrogeological regime of the debris flow basin. The main reason for the formation of natural ice mounds in the valley debris flow basins is disturbance of the hydrological regime of the catchment basin during debris flow formation, which mainly contributes to the annual solid runoff of first order watercourses. Scum of slope debris flow basins are formed in case of violation of the thermal regime of the surface and soil of the debris flow basin due to climatic anomalies, as well as damage to natural heat-insulating coverings: snow and soil-vegetable. It is also possible to form sloping ice as a result of a violation of the hydrogeological regime of the catchment basin under anthropogenic impact or the development of dangerous exogenous slope processes with a sufficient depth of rock capture. Cryogenic processes of ice formation affect debris flow and channel processes.

Using morphometrics to distinguish between debris flow, debris flood and flood (Southern Carpathians, Romania)

Debris flows and debris floods are rapid mass movements that occur in rugged mountain areas. The differences between them consist in the quantity of water input, which in turn influences the type of flow. For practical reasons, these two process types should be differentiated because different remedial measures should be applied for planning purpose. Due to the lack of historical data covering a long period of time, a morphometric analysis of the factors that control the flow type was chosen for the present study. Only those morphometric parameters with the most important role were selected. Based on statistical analyses, we noticed that only six parameters have a substantial contribution to debris flow occurrences. These are: Melton number, basin relief ratio, basin length, basin area, fan slope and source area ratio. The results show debris flow basins are characterized by Melton ratio > 0.55, basin relief ratio > 0.4, basin length < 1.7 km and basin area < 1.1 km2, debris flood basins by 0.3 < Melton ratio < 0.55, 0.2 < basin relief ratio < 0.4, 1.7 km < basin length < 5.1 km and 1.1 < basin area < 8.2 km2, while flood basins correspond to values of Melton ratio < 0.3, basin relief ratio < 0.2, basin length > 5.1 km and basin area > 8.2 km2.

Runoff‐generated debris flows: Observation of initiation conditions and erosion–deposition dynamics along the channel at Cancia (eastern Italian Alps)

AbstractIn the Dolomitic region, abundant coarse hillslope sediment is commonly found at the toe of rocky cliffs. Ephemeral channels originate where lower permeability bedrock surfaces concentrate surface runoff. Debris flows initiate along such channels following intense rainfall and determine the progressive erosion and deepening of the channels. Sediment recharge mechanisms include rock fall, dry ravel processes and channel‐bank failures. Here we document debris flow activity that took place in an active debris flow basin during the year 2015. The Cancia basin is located on the southwestern slope of Mount Antelao (3264 m a.s.l.) in the dolomitic region of the eastern Italian Alps. The 2.5 km2 basin is incised in dolomitic limestone rocks. The data consist of repeated topographic surveys, distributed rainfall measurements, time‐lapse (2 s) videos of two events and pore pressure measurements in the channel bed. During July and August 2015, two debris flow events occurred, following similarly intense rainstorms. We compared rainfall data to existing rainfall triggering thresholds and simulated the hydrological response of the headwater catchment with a distributed model in order to estimate the total and peak water discharge. Our data clearly illustrate how debris entrainment along the channel is the main contributor to the overall mobilized volume and that erosion is dominant when the channel slope exceeds 16°. Further downstream, sediment accumulation and depletion occurred alternately for the two successive events, indicating that sediment availability along the channel also influences the flow behaviour along the prevailing‐transport reach. The comparison between monitoring data, topographical analysis and hydrological simulation allows the estimation of the average solid concentration of the two events and suggests that debris availability has a significant influence on the debris flow volume. © 2020 John Wiley &amp; Sons, Ltd.

DEBRIS FLOW CHECK CONSTRUCTIONS SITUATED NEAR THE MOUTH OF RIVERS OF THE SAKHALIN ISLAND

The significant part of roads and railways of the Sakhalin Island are located in the coastal zone of the sea, in the lower part of the debris flow transit zone. Debris flows cause blockages and damage to the roadways. In some areas of the island are sites where the number of debris flow basins is 30-40 per km. Basically, these are slope debris flows, which are formed annually during precipitation of liquid precipitation, and whose volume can reach 500 m3. At the same time, debris flows can play an important role in the formation of beaches and protection from abrasion due to the removal of material to the mouth of the rivers. Transport of debris flow material to the coastal zone on the Sakhalin Island is carried out on the coasts of the Gulf of Patience, the Gulf of Aniva, the Tatar Strait, etc. Beach savings are the best of its natural protection against destruction. Therefore, the need to build seepage facilities is due not only to the need to protect the roadway, but also the importance of transporting debris flow material to the beach area. Characteristics of debris flows in the coastal zone of the island differ in a number of parameters, such as the volume of debris slides, the frequency of formation of debris flows, the type of debris flows, the size of carried fragments of rocks; therefore, when choosing a debris flow protection facility, it is necessary to be guided both by the parameters of debris flows and by the role of debris flows in the formation of beaches. The paper examines the current state of water chute and debris flows chute under the roads in the near-mouth parts of debris flow rivers, as well as the expediency of selecting debris flow protection structures depending on the characteristics of debris flows.

Evolution of debris flow basins on the slopes of marine terraces of the coast of Magadan oblast and Sakhalin Island.

Evolution of debris flow basins on the slopes of marine terraces of the coast of Magadan oblast and Sakhalin Island.

Relation between basin morphometric features and dynamic characteristics of debris flows – a case study in Siberia, Russia

Extreme and prolonged rainfall in the Tunka Ridge caused several debris flows in the vicinity of the Arshan village (Siberia, Russia) on June 28, 2014. These debris flows, in spite of similar geological conditions, had different velocity, peak discharge and alluvial fan volume values. The flow velocity was from 3.5 m/s to 19.6 m/s, the peak discharge ranged from 63 m3/s to 13566 m3/s, and the alluvial fan volume varied from 4.13×103 to 8.45×105 m3. Such a great range of values is due to the morphometric parameters of the debris flow basins. The article deals with the influence of morphometric parameters of debris flow basins, such as the basin area, the average slope, Melton ratio, relief ratio on the debris flow velocity, peak discharge and volume of alluvial fans. In this debris flow event the average values of slope angle and total basin relief of the debris flow basins did not affect the values of debris flow velocity, peak discharge and alluvial fan volume. The highest correlations were observed with the debris flow basin area that was connected with the water inflow volume into the debris flow basins during the rainfall. The unequal water distribution among debris flow basins also had an impact on the debris flow velocity, peak discharge and volume of alluvial fans.

Regional debris flow susceptibility analysis based on principal component analysis and self-organizing map: a case study in Southwest China

A method was developed to analyze the susceptibilities of 541 regional basins affected by debris flows at the Wudongde Dam site in southwest China. Determining susceptibility requires information on source material quantity and occurrence frequency. However, the large number of debris flows can hinder the individual field investigation in a each small basin. Factors that may trigger debris flows can be identified using remotely sensed interpretation information. Susceptibility analysis can then be conducted based on these factors. In this study, SPOT5 satellite imagery, digital elevation models (DEM), a lithology distribution map, and rainfall monitoring data were used to identify 12 debris flow trigger factors: basin relief ratio, slope gradient in the initiation zone, drainage density, downslope curvature of the main channel, vegetation coverage, main channel aspect, topographic wetness index, Melton’s ruggedness number, lithology, annual rainfall, form factor, and cross-slope curvature of the transportation zone. Principal component analysis was used to obtain the eight principal components of these factors that contribute to susceptibility results. Then, a self-organizing map method was adopted to analyze the principal components, which resulted in a debris flow susceptibility classification. Field validation of 26 debris flow basins was used to evaluate the errors of the susceptibility classification, as well as assess the causes of such errors. The study found that principle component analysis and self-organizing map methodologies are good predictors of basin susceptibility to debris flows.