Debris Flow Propagation Research Articles

Comparison of Different Numerical Methods in Modeling of Debris Flows—Case Study in Selanac (Serbia)

Flow-type landslides are not typical in this region of the Balkans. However, after the Tamara cyclone event in 2014, numerous such occurrences have been observed in Serbia. This paper presents the initial results of a detailed investigation into debris flows in Serbia, comparing findings from two programs: RAMMS DBF and Geoflow SPH. Located in Western Serbia, the Selanac debris flow is a complex event characterized by significant depths in the initial block and entrainment zone. Previous field investigations utilized ERT surveys, supplemented by laboratory tests, to characterize material behavior. Approximately 450,000 m3 of material began to flow following an extreme precipitation period, ultimately traveling 1.2 km to the deposition zone. For validation purposes, ERT profiles from both the deposition zone and the source area were utilized, with particular attention given to areas where entrainment was substantial, as this had a significant impact on the final models. The first objective of this research is to conduct a detailed investigation of debris flow using field investigations: geophysical (ERT) and aerial photogrammetry. The second objective is to evaluate the capacity of two debris flow propagation models to simulate the reality of these phenomena. The GeoFlow-SPH code overestimated the maximum propagation thickness in comparison to the RAMMS model. The numerical results regarding final depths closely align, especially when considering the estimated average depth in the deposition zone. The results confirm the necessity of using multiple simulation codes to more accurately predict specific events.

Influence of runoff on debris flow propagation at a catchment scale: a case study

Influence of runoff on debris flow propagation at a catchment scale: a case study

Morphological characteristics and conditions of drainage basins contributing to the formation of debris flow fans: an examination of regions with different rock strength using decision tree analysis

Abstract. Debris flows cause severe disasters that can result in human casualties and the collapse of houses. The establishment of early warning systems in basins with high debris flow risks is needed to reduce the negative impacts of debris flow disasters. Because debris flows often form debris flow fans near the mouths of valleys, debris flow fans are regarded as important topographical elements that indicate the occurrence of debris flows. The presence or absence of a debris flow fan makes it possible to clarify the morphological conditions of the contributing area that has generated debris flows. These morphological conditions may depend on rock strength, which controls the weathering activity and grain size of sediments. In this study, we investigated the morphological conditions of a drainage basin that contribute to the formation of debris flow fans using decision tree analysis. The analysis was conducted at two sites with clear differences in rock strength due to geological processes: Neogene sedimentary rock and Paleogene accretionary complex sites. As a result of decision tree analysis using data sets containing a total of 158 basins, the thresholds of morphological parameters needed for forming debris flow fans differed depending on the geological features. When the relief ratio was less than 0.29 at the Paleogene accretionary complex site, coarse-grained sediments were less likely to pass out of the valley, resulting in the absence of debris flow fans. On the other hand, at Neogene sedimentary rock sites, short basins were determined to form debris flow fans, even if the relief ratio was less than 0.36, because the sediments were fine-grained and tended to flow downstream. In contrast, morphological factors that influence the presence or absence of debris flow fans were common at both sites. The first, second, and third most important morphological factors were the relief ratio, most frequent slope gradient, and basin length, respectively. Therefore, these morphological factors are considered important in evaluating debris flow risks. This study demonstrates that the decision tree analysis is an effective tool for determining the hierarchy and threshold of morphological factors that classify the presence or absence of debris flows that reach valley mouths.

Uncertainty in measuring the role of climate change on debris-flow triggering on volcanoes - bulk-density, temperature and moisture analysis at Unzen Volcano (Japan)

As climate change creeps into the 21st century, the intensity of debris flows due to heavy and concentrated rainfall has increased in mountainous regions of Japan and East Asia. However, the relationship between climate change and an increase in debris flows is likely to be non-linear. Rainwater infiltrates more quickly into porous material, and the lack of vegetation cover increases evaporation and the temperature of surface sediments. In addition, periodic gully collapses bring fresh layers of porous material that increase the distance between the surface and the vadose zone. Therefore, to understand the relationship between volcanic debris flows (or lahars), parameters such as density, porosity, temperature, and moisture retention must be captured in detail in both time and space. The aim of this paper is to assess the role of loose, coarse, and porous sediments in lahar triggering. The present study was conducted at Unzen volcano in the Tansandani Guly between 31 May and 1 June 2023, 30 years after the last eruption. The dacite material is composed of a matrix of sand and coarse sand mixed with larger fractions and blocks, therefore traditional density measurement methods could not be applied, and a photogrammetric based method was used. In the field, sets of SfM-MVS photographs were taken before and after digging a hole in the sediments so that the measured mass could be compared to the volume of the hole in the sediments. After the sediments were dried, the dry and wet density, bulk density and porosity of the sample were calculated. When compared to the temperature data collected in the field, the following results were obtained: (1) The porosity of the volcanic material was highest in the lower reaches, followed by the upper reaches, and lowest in the middle reaches. This may be because fine sand washed out of the upstream area by rainfall is currently stored in the midstream area, which may facilitate debris flow generation. In addition, the downstream area has a high porosity, which may be due to the surrounding vegetation preventing the influx of new fine sand from the channel wall. (2) Because of the higher porosity and the lack of organic matter and vegetation cover, the increase in temperature acts more directly on the decrease in water content than in mountainous areas. Consequently, empirical equations for the potential for mudslides in volcanic areas with respect to surface temperature and soil moisture need to be developed for hazard and disaster risk management purposes.

Bivariate analysis of short-duration extreme rainfalls. Application to the study of the debris floods (alluviums) in the Funchal region (Madeira Island)

Intense rainfalls and debris floods are familiar occurrences in Madeira Island (Portugal); but, understanding how intense rainfall relates to this type of floods is limited. This research seeks to characterise extreme rainfall events measured at the Funchal rain gauge station and to analyse their relationship with the region’s debris flood records. Contrary to other studies, a multivariate approach was performed to describe those relationships. To identify the extreme hourly rainfall events, the annual maximum series (AMS) technique was applied to a record of hourly time-series data covering a period of 34 years. By applying bivariate copula analysis to coupled AMS and cumulative rainfall series, joint and conditional return periods were calculated. The results suggested that the extreme rainfall events causing debris flood events tend to have higher return periods than those with no debris flow generation. The exceptionality of the late February 2010 deadly event is reaffirmed. This work assists our understanding as to how intense rainfall events relate to debris flood events, and shows the benefit of copulas in providing new insights in hydrologic studies.

Effect of lithological and geotechnical characteristics on the generation of debrisflows in Matmata, southeastern Tunisia

The Matmata region, located in the south of Gabès (Tunisia), experienced significant damage during the floods of the Beni zelten wadi on November 11, 2017. These floods, exacerbated by the steep slopes and underlying soil conditions, led to the occurrence of debris flows, posing a threat to road infrastructure. The generation of debris flows is closely linked to intense rainfall events that surpass the soil capacity to retain water. To gain insights into the behaviour of the soil samples, various characteristics were analysed, including texture, clay mineralogy, grain size distribution, and Atterberg limits. The results showed that the mean liquid limit values ranged from 38% to 62%, while the mean plasticity index of the materials in the landslide-prone areas varied from 18% to 27.9%. These findings indicate presence of clay formations and highlight a significance of the increased soil clay content as contributing factors to landslide development. The X-ray Diffraction analysis revealed that gypsum, quartz, phyllosilicate and calcite minerals were the most abundant minerals identified in the soil samples. This work shows the importance of clay mineral and geotechnical parameters of the soils in the occurrence of landslides and predicting debris flows occurrences in the Matmata region.

Effects of bed sediment conditions on debris flow propagation from the two-phase flow modelling perspective

Debris flows are classical two-phase flows that are greatly affected by bed sediment conditions. However, the underlying mechanism remains uncertain from either a theoretical or numerical perspective. Here an existing depth-averaged two-phase continuum flow model is further improved by incorporating the effects of pore-fluid pressure and bed sediment conditions. By numerical simulation of the USGS experiments, we have numerically reproduced the mechanism that “the coarser the bed sediments and the larger the basal pore pressure, consequently the larger the erosion rates”. Moreover, an additional mechanism for this phenomenon has been revealed. Specifically, debris flows on steep slopes are likely to fall into a high shear stress regime, under which conditions the sediment transport capacity always takes a maximum value and is independent of the sediment size. Therefore, the sediment settling velocity that is proportional to the sediment size affects the erosion rate directly. It is also observed that the added potential energy due to a net erosion has positive effects on the kinetic energy of the debris flow. Notably, coarse and fine particles exhibit distinct roles in energetics and the former is characterized by more intensive interactions with the water phase, which should be appropriately considered in the modeling. Finally, particle size coarsening is observed in the head region, which is attributed to the hiding/exposure mechanisms of nonuniform sediments. These findings can enhance the understanding of the mechanism between the bed conditions and debris flow.

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 as a process: a history informed hazard planning approach applied to the 2018 post-fire debris flows, Montecito, California

Historical information about floods is not commonly used in the US to inform land use planning decisions. Rather, the current approach to managing floods is based on static maps derived from computer simulations of the area inundated by floods of specified return intervals. These maps provide some information about flood hazard, but they do not reflect the underlying processes involved in creating a flood disaster, which typically include increased exposure due to building on flood-prone land, nor do they account for the greater hazard resulting from wildfire. We developed and applied an approach to analyze how exposure has evolved in flood hazard zones in Montecito, California, an area devastated by post-fire debris flows in January 2018. By combining historical flood records of the past 200 years, human development records of the past 100 years, and geomorphological understanding of debris flow generation processes, this approach allows us to look at risk as a dynamic process influenced by physical and human factors, instead of a static map. Results show that floods after fires, in particular debris flows and debris laden floods, are very common in Montecito (15 events in the last 200 years), and that despite policies discouraging developments in hazard areas, developments in hazard zones have increased substantially since Montecito joined the National Flood Insurance Program in 1979. We also highlight the limitation of using conventional Flood Insurance Rate Maps (FIRMs) to manage land use in alluvial fan areas such as Montecito. The knowledge produced in this project can help Montecito residents better understand how they came to be vulnerable to floods and identify action they are taking now that might increase or reduce their vulnerability to the next big flood. This science-history-centric approach to understand hazard and exposure evolution using geographic information systems (GIS) and historical records, is generalizable to other communities seeking to better understand the nature of the hazard they are exposed to and some of the root causes of their vulnerabilities, in other words, both the natural and social processes producing disasters.

Triggering conditions, runout, and downstream impacts of debris flows following the 2021 Flag Fire, Arizona, USA

Debris flows pose a serious threat to communities in mountainous areas, particularly in the years following wildfire. These events have been widely studied in regions where post-wildfire debris flows have been historically frequent, such as southern California. However, the threat of post-wildfire debris flows is increasing in many regions where detailed data on debris-flow physical properties, volume, and runout potential are sparse, such as the Southwest United States (Arizona and New Mexico). As the Southwest becomes more vulnerable to these hazards, there is an increasing need to better characterize the properties of post-wildfire debris flows in this region and to identify similarities and differences with nearby areas, particularly southern California, where there is a greater abundance of data. In this paper, we study the characteristics and downstream impacts of two post-wildfire debris flows that initiated following the 2021 Flag Fire in northern Arizona, United States. We gathered data regarding soil hydraulic properties, rainfall characteristics, watershed response, and debris-flow initiation, runout, volume, grain size, and downstream impacts during the first two monsoon seasons following the containment of the Flag Fire. We also applied established debris-flow runout and volume models that were developed in southern California to our study watershed and compared the output with observations. In the first monsoon season following the fire, there were two post-wildfire debris flows, one of which resulted in damage to downstream infrastructure, and one major flood event. We found that, while more intense rainfall is required to generate debris flows at our study site compared to southern California, burned watersheds in northern Arizona are still susceptible to debris flows during storms with low recurrence intervals in the first year following fire. During the second monsoon season, there were no major runoff events, despite more intense storms. This indicates that the temporal window for heightened debris-flow susceptibility at our study area was less than one year, due to the recovery of soil hydraulic properties and vegetation regrowth. We also found that the debris-flow properties at our study site, such as volume, mobility, and grain size distribution, may differ from those in other regions in the western United States, including southern California, potentially due to regional differences in rainfall characteristics and sediment supply. Differences in rainfall characteristics and sediment supply may have also influenced the performance of the debris-flow runout and volume models, which overpredicted the observed runout distance by 400 m and predicted a volume more than 17 times greater than what was observed.

An integral assessment of landslide dams generated by the occurrence of rainfall-induced landslide and debris flow hazard chain

Landslides caused by rainfall are one of the most frequent causes of disasters in tropical countries and mountainous terrain and can block rivers generating landslide dams. This paper presents a methodology for the estimation of the obstruction of water streams generated by rainfall-induced shallow landslides. The spatial distribution of the landslide hazard was estimated in terms of the Factor of Safety (FoS) values using the deterministic method with physical basis SLIDE (Slope - Infiltration - Distributed Equilibrium). The rainfall regimes of the study area were estimated by means of a simple scaling Log Normal Model. Subsequently, the resulting areas with a high hazard level that could detach and reach the riverbed were identified as sources for the simulation of the debris flow runout using the Rapid Mass Movement Simulation model with its debris flow module, (i.e., RAMMS-DF), estimating zones of the riverbed that should be analyzed in detail. Finally, the effects of river channel obstructions generated after debris flow movement were analyzed by means of the Iber, a well-known, physically based 2D hydraulic model and their possible changes on the river hydraulic. In order to generate a workflow that allows the application of the SLIDE methodology and the preparation of inputs for the subsequent processes of debris flow propagation and hydraulic modeling of the river corridor of analysis, a Python-based toolbox was created. Our results highlight the changes in the fluvial dynamics in the corridor of the river of analysis after the landslide dams generated by the occurrence of rainfall-induced landslide and debris flow hazard chain for the different return periods. In all cases, the material deposited in the river channel was sufficient to change the hydraulic regime of the river corridor, showing longer delay times in the transit of the flow, in addition to the decrease in the specific flow. This would imply a water shortage in the study basin of the hydroelectric project; however, in the scope of this project it is not possible to really determine the real effects that could be generated by this event.

Methodology for assessing pipeline failure probability due to a debris flow in the near field

Aboveground transmission oil pipelines can cross debris flow-prone areas. Currently, there are no available methodologies to assess pipeline failure status with the different pipeline arrangements (location, direction, and segment lengths) and different operating conditions. For solving the research gap, this study proposes a novel methodology to simulate the cascade processes of debris flow propagation, the impact of debris flow on pipelines, and pipeline failure. With consideration of different pipeline arrangement and operating conditions. We introduce the polar coordinate system to set up locations and directions scenarios for the first time. Also, we use the 3-D debris flow simulation model (DebrisInterMixing solver in OpenFOAM) coupled with a modified pipeline mechanical model considering operating conditions for the first time. The proposed methodology shows the different trends of pipeline failure probability with the increase of pipeline segment length for the different pipeline locations and directions. The result shows, for the pipelines of 30° the tensile stress has a more moderate increase rate with the increase of pipeline segment length, and the pipeline failure probability keeps 0 at the 5-m location. At 5 m and 15 m locations, the failure probabilities of the pipelines of 60° and 90° start to increase when the segment length is 13–14 m, while for other pipelines the segment length is 17–19 m. The findings of this study can support the decisions of government authorities, stakeholders, and operators for risk assessment, prioritization of hazard mitigation measures and emergency planning, or concerning decisions regarding pipeline siting during the design, routing, construction, operation, and maintenance stage.

Exploring the Application of a Debris Flow Likelihood Regression Model in Mediterranean Post-Fire Environments, Using Field Observations-Based Validation

Post-fire geomorphic processes and associated risks are an important threat in Mediterranean environments. Currently, post-fire mass movement prediction has limited applications across the Mediterranean despite the abundance of both forest fires and landslide/debris flow disasters. This work applies a debris flow generation likelihood model to evaluate the probability of mass movement phenomena in different catchments of a burnt area, after a catastrophic fire near Schinos (Attica, Greece) in 2021. Then, it uses field observations from the area, recording mass movement phenomena after high-intensity rainfall events, to validate the results. The findings show that the model is successful in determining the probability of debris flow generation in the 21 basins of the study area, ranging from 0.05 to 0.893. The probability values show a statistically significant correlation (sig. = 0.001) with the actual debris flow occurrences in the area, and satisfactory results in terms of the model’s predictive ability, functioning well within the particular geo-environmental characteristics of the Mediterranean environment. The results establish the reliability of the approach as a tool to assess mass movement risks in a region with an abundance of post-fire related hazards and disastrous events.

Keynote lecture. A general two phase depth integrated model considering pore water pressure and dewatering

Debris flows can be considered a type of landslide with large velocities and long run-out distances. There are many types of debris flows, depending on the properties of the solid and fluid components of the mixture. The triggering and propagation of debris flows can be studied using a single 3D mathematical model. The computational cost can be very high because of their length, and depth-integrated models provide a good combination of accuracy and cost. Both types of models can be combined in the analysis, using 3D models for initiation and at singular points where more accuracy is wanted. As in a chain where the strength is never higher than that of the weaker link, we have to ensure that all the models are accurate enough in a joint model. This paper deals with a new depth-integrated model which can take into account the changes caused by dewatering in a debris flow.

Study of debris-flow initiation through the analysis of seismic signals

Monitoring data gathered in the headwaters of the Gadria catchment, eastern Italian Alps, have been analysed to study debris-flow initiation. The active channel, located at 2200 m a.s.l., was instrumented with a geophone, a time-lapse video camera and a rain gauge. The peak amplitude and duration of the seismic signals and their frequency content were analysed and compared with video images. Results showed that different seismic sources produced signals with different characteristics and that it is possible to discriminate the most intense runoff by analysing the combination of peak amplitude and duration of the seismic signal. The further development of this research would be to create an algorithm able to automatically classify the seismic sources and identify intense channel processes that can generate debris flows. In perspective, the combination of seismic detection in the initiation area with monitoring just above the infrastructures at risk could represent an effective solution to expand the lead time of an early warning system.

Debris flow seismo-acoustic wave in a finite layer waveguide

The seismo-acoustic wave detection is a popular method to detect debris flows. It has been successfully used in different early warning systems worldwide. However, more information is embedded in the signals related to flow conditions. This research uses theoretical derivation to connect signals with debris flow propagation speed. We assume debris flow generates seismo-acoustic stress acting on a river bed and the seismo-acoustic waves propagate in a finite layer waveguide below the channel. Then, the propagation of seismo-acoustic stress was solved with the elastic wave equations along the channel. For any fixed point in this waveguide, the frequency of the recording signal can be translated as a function of debris flow propagation speed and seismo-acoustic wave velocity. The result shows that there is a Doppler-like property for a recorded signal where debris flow propagation speed can cause a frequency shift. This result also indicates that different superior frequency bands would be recorded from different media.

Numerical modeling of debris flows using basic equations in generalized curvilinear coordinate system and its application to debris flows in Kinryu River Basin in Saga City, Japan

Each year, structures installed in rivers and valleys (e.g., bank protections, bridges, and sabo dams) are damaged by debris flows; therefore, it is necessary to predict the flow characteristics of debris flows accurately to design river and valley structures that are robust against such debris flows. In recent years, several two-dimensional models have been developed to simulate debris flow. However, the basic equations in the numerical simulation models are in the Cartesian coordinate system, and the shape of each numerical analysis grid is square or rectangular. It is impossible to use numerical grids that match the horizontal shape of the river or valley structures, such as bank protections and sabo dams, when employing square or rectangular grids. This makes it difficult to calculate the fluid forces acting on river or valley structures. In this study, the basic equations of debris flow are provided in the generalized curvilinear coordinate system and a numerical simulation model of debris flow designed using an orthogonal curved grid along the horizontal shape of rivers and valleys is developed. Numerical simulations of a periodical meandering valley are conducted using the basic equations in the generalized curvilinear and Cartesian coordinate systems; the difference between the two results is discussed. Further, numerical simulations of the debris flow that occurred in the Kinryu River Basin in Saga City, Japan, in 2019 are performed using the basic equations in the generalized curvilinear and Cartesian coordinate systems, and the difference between the two simulation results is discussed. The numerical simulation results of debris flow in a periodical meandering channel suggest a slow propagation of debris flow when equations in the Cartesian coordinate system are used; this is attributed to the rough boundaries of debris flow when a square grid is used, which causes numerical energy dissipation that does not exist physically. The inundation areas and land surface deformation of debris flow in Kinryu River Basin were reproduced well by the developed numerical analysis model; the basic equations were written in the generalized curvilinear coordinate system. The development and decrescence of debris flows were reproduced using the developed model; the first debris flow in Kinryu River Basin was stopped in the upstream mild slope area, while the second flowed into the residential area. Reproducing the flow depth, velocity, and discharge could be improved by the model using basic equations in the generalized curvilinear coordinate system, as compared with those reproduced using basic equations in the Cartesian coordinate system. When the Cartesian coordinate system was used, the volume of the debris flow was evaluated to be small and the travel distance of the debris flow was evaluated to be short; thus, the debris flow does not arrive at the residential area and the risk of debris flows is underestimated.

A new two-layer two-phase depth-integrated SPH model implementing dewatering: Application to debris flows

Debris flows can be considered a type of landslide with large velocities and long run-out distances. There are many types of debris flows, depending on the properties of the solid and fluid components of the mixture. The triggering and propagation of debris flows can be studied using a single 3D mathematical model. The computational cost can be very high because of their length, and depth-integrated models provide a good combination of accuracy and cost. Both types of models can be combined in the analysis, using 3D models for initiation and at singular points where more accuracy is wanted. As in a chain where the strength is never higher than that of the weaker link, we have to ensure that all the models are accurate enough in a joint model. This paper deals with a new depth-integrated model which can take into account the changes caused by dewatering in a debris flow. An important limitation of existing two-phase models allowing different velocities of solid and water particles is that when water abandons the mixture, porosity decreases and tends to zero. Here, a two-layer model is introduced, including an unsaturated upper layer on top of a saturated layer.

SPH numerical modelling of landslide movements as coupled two-phase flows with a new solution for the interaction term

In this paper, the theoretical framework is a depth-integrated two-phase model capable of considering many essential physical aspects such as reproducing the propagation of debris flows with soil permeability ranging from high to low and considering the pore-water pressure evolution. In this model, the pore fluid is described by an additional set of depth-integrated balance equations in order to take into account the velocity of pore fluid. The model employs a frictional rheological law for the granular material, and the interstitial fluid is treated as a Newtonian fluid. A drag law describes the interaction between interstitial fluid and grains. The variables of permeability, porosity, and drag force are included in the governing equations to consider the interaction between the phases. This paper aims to extend a generalized two-phase depth-integrated model to enhance the description of the interaction between the two phases and their respective movements. It allows us to increase our understanding of the mechanism behind natural rapid landslides. To evaluate the developed approach, a set of dam-break problems has been performed. These simulations provide interesting information in simple and controlled situations on the landslide propagations with different degrees of soil permeability and the interaction between solid and fluid phases. The extended model has also been applied to simulate the dynamics of the Acheron rock avalanche, which is an appropriate benchmark to examine the applicability of the model to real cases.

Effect of lithological and geotechnical characteristics on the generation of debris flows in the arid basin of Mirave, Peru

Studies concerning the debris flows in mountain areas are relevant because of their potential negative effects on the human communities and infrastructure in their areas of influence. To advance the understanding of the theoretical basis, this study qualitatively analyzes the effect of lithological characteristics and soil type on the generation of debris flows in the arid basin of Mirave, in southern Peru, as a consequence of extensive rainfall. Two debris flow events are evaluated, which occurred in the studied area in March 2015 and February 2019. The method used to achieve the objective combines the use of satellite images, field data collection, and lab tests results to estimate the relative importance of the abovementioned characteristics in the generation of debris flows. The results suggest that the poor presence of clay and the predominance of sandy-loamy structured soils in the Mirave Basin make them unstable when erosion occurs. In addition, the features of broken down materials generated from residual and colluvial soils in the primary area of study are one of the main causes of debris flows in the region.
 Keywords: arid basin, debris flows, geotechnical characteristics, lithology.