Runout Distance Research Articles

UTILIZATION OF STATISTICAL ANALYSIS TO IDENTIFY INFLUENTIAL SLOPE PARAMETERS ASSOCIATED WITH ROCKFALL AT OPEN PIT MINES.

The application of statistical analysis software programs has proven useful for the investigation of rockfall runout distance along a designed slope. Rockfall modeling programs are continually being upgraded with more sophisticated analysis tools, such as the use of the rigid body versus lump mass models. Engineers at mine sites utilizing the software may have varied experience related to these models, their associated input parameters, and how to interpret the generated results. To address this concern, researchers at the Spokane Mining Research Division (SMRD) of the U.S. National Institute for Occupational Safety and Health (NIOSH) investigated the influence of slope height, slope angle, slope material, and rock size for both rigid body and lump mass models in a 2-D statistical analysis program. Based on a literature search and industry input, specific ranges common to that of an open pit mining environment were chosen for each of the input parameters to determine 90% rock runout distance as well as their sensitivity to change. Data collected from this numerical analysis and simulation will be compared to empirical rockfall data gathered through the duration of the Highwall Safety project conducted by NIOSH from 2022-2026.

Face stability analysis of tunnels in saturated soil considering soil-fluid coupling effect via material point method

The stability of the tunnel face has been an important issue investigated by many scholars. To fully study the failure evolution of tunnel face and the hydro-mechanical behavior of surrounding soils in saturated stratum, a two-phase single-point material point method (MPM) considering the fluid–solid coupling effect is adopted to investigate this issue. Firstly, this proposed method is validated by comparing with the results obtained from the existing literatures. Secondly a series of MPM simulations are carried out to study the critical support pressure and failure mechanism of tunnel face in saturated soils. The arching effect range and inclination angle of failure soil in front of tunnel face are analyzed and determined. Finally, the post-failure mechanism of tunnel face is investigated. The run-out distance and the flow-in mass of failed soil in tunnel are calculated through the parametric analysis. The results show that MPM can well predict the whole failure process of tunnel face. The proposed method can provide useful guidance for practical tunnel designs.

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.

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.

Axisymmetric column collapses of bi-frictional granular mixtures

The behaviour of granular column collapses is associated with the dynamics of geohazards, such as debris flows, landslides and pyroclastic flows, yet their underlying physics is still not well understood. In this paper, we explore granular column collapses using the sphero-polyhedral discrete element method, where the system contains two types of particles with different frictional properties. We impose three different mixing ratios and multiple different particle frictional coefficients, which lead to different run-out distances and deposition heights. Based on our previous work and a simple mixture theory, we propose a new effective initial aspect ratio for the bi-frictional granular mixture, which helps unify the description of the relative run-out distances. We analyse the kinematics of bi-frictional granular column collapses and find that deviations from classical power-law scaling in both the dimensionless terminal time and the dimensionless time when the system reaches the maximum kinetic energy may result from differences in the initial solid fraction and initial structures. To clarify the influence of initial states, we further decrease the initial solid fraction of granular column collapses, and propose a trial function to quantitatively describe its influence. Due to the utilization of a simple mixture theory of contact occurrence probability, this study can be associated with the friction-dependent rheology of granular systems and friction-induced granular segregations, and further generalized to applications with multiple species of particles in various natural and engineering mixtures.

Discrete element investigation of the mobility of granular mass flows

The gravitational flows of granular materials are omnipresent in industrial processes such as handling and transportation of material and in natural events such as landslides, rock and snow avalanches; however, their mobilities remain elusive due to the arbitrary slope geometry and the sliding volume. By means of three-dimensional discrete element simulations, this paper investigates the flow mobility characterized by its energy evolution, run-out distance, and movement of the center of mass of granular materials collapse on an inclined-upstream region, then plunge and deposit on a horizontal-downstream region. A specific case of numerical simulation is first compared with a theoretical prediction published previously to validate the capability of this numerical approach for simulating the mobility of granular flows. Based on this theoretical validation, a series of numerical experiments is generated by varying a broad range of values of the inclination angle of the inclined-upstream surface and the volume of granular blocks. The results show that the kinetic energy increases significantly with increasing the inclination angle but slightly increases with the volume of granular materials changing along the inclined direction. In which, the rate of reaching the peak values of the vertical and horizontal kinetic energies on the upstream and downstream regions, respectively, increases linearly with increasing the inclination angle. More interestingly, the flow mobility enhances with increasing the sliding volume, represented via the increase of the run-out distance and the decrease of the apparent friction coefficient which is defined as a ratio of the total drop and horizontal movement of the center of mass. Remarkably, the run-out distance of the flows can be nicely scaled by the maximum kinetic energy in the whole process and in horizontal region. These findings robustly declare the origins of the run-out distance from the spreading stage of granular materials in the downstream area and strongly provide evidence for describing the mobility of granular flows on the complex surface.

Semi-resolved CFD-DEM coupling model for submerged granular collapse

Submerged granular collapse involves strong interaction between fluid and particles, while the widely applied unresolved computational fluid dynamics-discrete element method (CFD-DEM) coupling model cannot accurately simulate the interaction when the particle-grid size ratio is >1/3. Herein, a semi-resolved CFD-DEM coupling model is employed to eliminate the size ratio limitation. This model approximates the ambient fluid variables required by the hydraulic force calculation within an expanded dependent domain, and allocates the particle volume and reacting drag force to fluid within an expanded influential domain. The performance of the semi-resolved model in simulating a submerged granular collapse is studied by comparing the numerical results with the experimental data in detail. Results show that the simulated deposit morphologies, including the surface, residual height, and runout distance of the granular columns, well agree with the measured data. Moreover, since the limitation on the size ratio is eliminated, the numerical simulations well reproduce the details of the collapse-induced fluid flows observed in experiments, especially the evolution of the shear vortex above the interface between fluid and particles.

Structural Relationships Across the Sevier Gravity Slide of Southwest Utah and Implications for Catastrophic Translation and Emplacement Processes of Long Runout Landslides

AbstractThe physical processes that facilitate long‐distance translation of large‐volume gravity slides remain poorly understood. To better understand these processes and the controls on runout distance, we conducted an outcrop and microstructural characterization of the Sevier gravity slide across the former land surface and summarize findings of four key sites. The Sevier gravity slide is the oldest of three mega‐scale (>1,000 km2) collapse events of the Marysvale volcanic field (Utah, USA). Field observations of intense deformation, clastic dikes, pseudotachylyte, and consistency of kinematic indicators support the interpretation of rapid emplacement during a single event. Furthermore, clastic dikes and characteristics of the slip zone suggest emplacement involved mobilization and pressurized injection of basal material. Across the runout distance, we observe evidence for progressive slip delocalization along the slide base. This manifests as centimeter‐ to decimeter‐thick cataclastic basal zones and abundant clastic dikes in the north and tens of meters thick basal zones characterized by widespread deformation of both slide blocks and underlying rock near the southern distal end of the gravity slide. Superimposed on this transition are variations in basal zone characteristics and slide geometry arising from interactions between slide blocks during dynamic wear and deposition processes and pre‐existing topography of the former land surface. These observations are synthesized into a conceptual model in which the presence of highly pressurized fluids reduced the frictional resistance to sliding during the emplacement of the Sevier gravity slide, and basal zone evolution controlled the effectiveness of dynamic weakening mechanisms across the former land surface.

Analytical and Numerical Solutions for Three-Dimensional Granular Collapses

This research paper presents a comprehensive approach to investigating dry granular collapses in three dimensions, by combining analytical, numerical, and experimental methods. The experimental investigation utilised a novel apparatus to study granular collapses in the laboratory. It is demonstrated that a quasistatic understanding of granular collapses can accurately predict the final normalised run-out distances for dynamic granular collapses. Our approach involved establishing a correlation between the angle of repose and the initial aspect ratio of the granular column. It is also shown that the material point method (MPM) is suitable for modelling granular collapses in three dimensions. Our in-house solver was further validated using experimental evidence under an explicit formulation, resulting in good agreement between the numerical and experimental results. The findings demonstrate the effectiveness of our in-house solver for three-dimensional granular collapse modelling.

Particle shape effects on granular column collapse using superquadric DEM

This paper presents a systematic study of particle shape effects on granular collapse using superquadric Discrete Element Method. Superquadrics allow non-spherical shapes to be accurately described by varying shape parameters, namely blockiness and particle aspect ratio. Simulations of low and high column collapse with various particle shapes from spheres to elongated/platy cubes are conducted. We found that the collapse of particles with higher blockiness results in shorter runout distance, increased retained height and more particles stacking along boundary walls. Particle blockiness also has clear influence on critical column aspect ratio and scaling law constants. Elongated and platy particles cause uneven deposit surfaces; however, the effects on runout distance, retained height and scaling law constants are relatively different between these two shapes. Particle sphericity, on the other hand, shows trivial effects on granular collapse. These findings significantly complement the understanding of the exclusive effects of particle shapes on granular collapse response.

Can big data and random forests improve avalanche runout estimation compared to simple linear regression?

Accurate prediction of snow avalanche runout-distances in a deterministic sense remains a challenge due to the complexity of all the physical properties involved. Therefore, in many locations including Norway, it has been common practice to define the runout distance using the angle from the starting point to the end of the runout zone (α-angle). We use a large dataset of avalanche events from Switzerland (N = 18,737) acquired using optical satellites to calculate the α-angle for each avalanche. The α-angles in our dataset are normally distributed with a mean of 33° and a standard deviation of 6.1°, which provides additional understanding and insights into α-angle distribution. Using a feature importance module in the Random Forest framework, we found the most important topographic parameter for predicting α-angles to be the average gradient from the release area to the β-point. Despite the large dataset and a modern machine learning (ML) method, we found the simple linear regression model to yield a higher performance than our ML attempts. This means that it is better to use a simple linear regression in an operational context.

Transform margin source–sink clastic deposystems

Abstract Shelf to basin floor clastic-sediment-routing models for individual structural parts of a transform margin are presented. Using 3D and 2D seismic, gravity and well data from the Guyana, Coromandal, Romanche, Saint Paul and Zenith–Wallaby Perth margins as examples, and drawing from a wide range of analogues, four discrete tectonic segments are recognized as characteristic of all transform margins: (1) the transform margin sensu stricto ; (2) the local pull-apart segment on the transform margin; (3) the margin segment developed from the narrow horsetail splaying off from the transform; and (4) the margin segment developed from the extensional end of the horsetail structure, although there are other transitional variants specific to each margin. The routing of clastic sediments varies markedly across these segments. The shelfal staging area varies in width between the segments, increasing in width between segments 1 and 4, with wider shelves (10–25 km) characterized by significant sediment sorting through longshore drift, and narrower segments (0–10 km) often fed directly from focused fluvio-deltaic systems. The overall deep-water slope gradient decreases from segments (1) to (4), with sediment runout distance from shelf to basin floor increasing. The seafloor topography along the margin is highly variable, with significant sand sequestration on slopes with intra-slope ramps and terraces found in segments (2)–(4), with rapid downslope transitions from tributary slope gullies to slope channel complexes and then ponded intra-slope frontal splay complexes on the intra-slope terraces. Mass-transport deposits (MTDs) are ubiquitous and found as either regional slope MTDs or local collapses of slope channel complex margins. Stratigraphic and/or combination traps are associated with the ramp–terrace transitions. Local sectors show pinned long-lived intra-slope channel complex and canyon development, with prominent long-lived intra-slope stacking of intra-slope sandbodies. The outboard basin-floor- or trough-confined deep-water frontal splays (lobes), and their head area erosion by slope-originated MTDs, are directly controlled by the deposystems of the inboard slope systems. The lateral and vertical evolution of deep-water slope architecture is directly controlled by the inherited seafloor topography, set up by the underpinning crustal fabric across the four segments.

Unravelling the dynamics and hazards of the June 3rd, 2018, pyroclastic density currents at Fuego volcano (Guatemala)

The June 3rd, 2018, eruption of Fuego volcano (Guatemala) produced a complex sequence of small-volume pyroclastic density currents (PDCs) that inundated all sectors around the volcano and propagated >12 km on the southeastern flank, deposited ~50 million m3 of pyroclastic material, and killed at least 430 people in the village of San Miguel de Los Lotes and along the RN-14 road. This eruption has illustrated once again that the behavior of small-volume PDCs remains difficult to predict, demonstrating the need for an improved physical understanding of their generation, transport and depositional processes to ultimately improve assessment of their local hazard potential. In this work, we present preliminary results of an interdisciplinary study of the 2018 PDC deposits of Fuego, integrating: (1) field data of the pristine deposit characteristics recorded immediately after the eruption and after one rainy season, (2) sedimentological data (including grain size distributions and componentry) from samples collected at each lobe front and several exposed stratigraphic sections inside three principal ravines draining the volcano and affected by the eruption (Seca, Ceniza and Las Lajas), (3) preliminary quantification of the observed range of different clast surface textures, shape and vesicularities, as determined by SEM analyses, (4) surface morphological data from high-resolution satellite and aerial photography, and (5) advanced digital terrain model analysis correlated with sedimentological data to reconstruct the sequence of events on June 3rd and propose a conceptual model of PDC generation and emplacement on the SE flank of Fuego. In this model, a sequence of packages of material involved in discrete failure events of a perched mass of pyroclastic material accumulated within an old collapse structure on the upper SE flank, corresponds to the emplacement of a series of pulses of valley-confined PDCs down the Las Lajas channel. Headwall failures and gravitational collapses correlate with specific stratigraphic, sedimentological and textural characteristics of the valley-confined PDC units. The duration of individual granular collapse events serves as a proxy for the mobility of the triggered series of PDCs. Also, our detailed stratigraphic work shows evidence of stacked, massive flow units deposited by rapid stepwise aggradation of successive block-and-ash flow (BAF) pulses and their distribution along the southeastern flank supports the interpretation that the June 3rd PDCs, including the dilute parts of the currents, were largely controlled by the topography. The lack of strong changes in the grain size distributions of the fine sub-populations inside the seven valley-confined BAF lobate front units, together with their high content of fines, imply the presence of a self-limiting attrition process, decreasing the bulk porosity of such long-runout BAFs and lowering their effective friction coefficient during transport to reach longer runout distances. This multi-faceted approach completes previous studies already performed on small-volume PDCs at other volcanoes (Merapi, Colima, Unzen) and opens a unique perspective that will provide a significant step forward in our understanding of how such currents are emplaced.

Does sand promote or hinder the mobility of cohesive sediment gravity flows?

ABSTRACTSediment gravity flows exhibit a large range of flow behaviours, making their flow dynamics hard to predict and the resulting deposits a challenge to interpret. Cohesive sediment gravity flows containing clay are particularly complex, as their behaviour is controlled by the balance of turbulent and cohesive forces. A first set of laboratory lock‐exchange experiments investigated the effect of adding 25% very fine sand by volume to high‐density cohesive sediment gravity flows with strongly suppressed turbulence. This caused these mixed clay–sand flows to become more cohesive, have shorter runout distances, and have lower head velocities than the original pure‐clay flows, despite the increase in density difference and the non‐cohesive properties of the sand. Yield stress measurements confirmed that adding the non‐cohesive very fine sand increases the cohesive strength of dense clay suspensions. This higher cohesive strength outcompetes the enhanced density difference and reduces the flow mobility. A second set of experiments across a larger range of clay concentrations showed that, for low‐density cohesive sediment gravity flows dominated by turbulent mixing, the addition of 25% very fine sand increased the head velocities because of the enhanced density difference and weak cohesive forces. Thus, the addition of very fine sand may increase or decrease the mobility of cohesive sediment gravity flows, depending on the initial type of flow and the balance between turbulent and cohesive forces. In the natural environment, this study proposes that very fine sand can only increase the cohesive strength and reduce the flow mobility of cohesive sediment gravity flows that have a sufficiently strong matrix strength to fully support the sand particles. The contribution of very fine sand to the cohesive strength of high‐density cohesive sediment gravity flows may have important implications for flow transformation on submarine fans, especially in distal regions where transient–turbulent, cohesive flows are particularly common.

Simulating Debris Flow and Levee Formation in the 2D Shallow Flow Model D‐Claw: Channelized and Unconfined Flow

AbstractDebris flow runout poses a hazard to life and infrastructure. The expansion of human population into mountainous areas and onto alluvial fans increases the need to predict and mitigate debris flow runout hazards. Debris flows on unconfined alluvial fans can exhibit spontaneous self‐channelization through levee formation that reduces lateral spreading and extends runout distances compared to unchannelized flows. Here we modify the D‐Claw shallow flow model in two ways that are hypothesized to generate levees. We evaluate these modifications with observations from a large‐scale flume experiment. We investigate model performance when including the effect of two different friction sub‐models, as well as the inclusion of segregation effects on granular permeability. Results show that, for a wide range of plausible model input parameters, simulations including the effects of segregation promoted modeled levee formation, whereas simulations without the effects of segregation did not create levees. Further, using a forward predictive framework, simulations with the effects of segregation were more likely to better model the magnitude of debris flow depth and runout distance, whereas simulation timing of the debris flow was affected by the choice of friction sub‐model. Our results indicate that including the effects of segregation on granular permeability can improve the likelihood of better predictions of debris flow depth and runout prior to an event occurring.

Granular column collapse: Analysis of inter-particle friction effects

The purpose of this paper is to investigate the effects of inter-particle friction on the granular column collapses via the discrete element method (DEM) while eliminating the particle-size effects. As the inter-particle friction increases, the runout distance decreases, the deposit height increases, the force chains tend to be closer to the vertical upward direction, the percentage of the strong force chains become greater and the granular assembly is less susceptible to the external gravity field, thus making the collapse tend to be toppling-dominant flow. The correlation between the initial height and runout distance of particles at the final deposits becomes stronger when the collapse tends to be more toppling-dominant. The motion patterns of the collapse are governed by the inter-particle friction and initial aspect ratio through dimensional analysis and the effective aspect ratio parameter is proposed to classify granular column collapse into three regimes (sliding-dominant, transition, and toppling-dominant collapse).

Propagation Modeling of Rainfall-Induced Landslides: A Case Study of the Shaziba Landslide in Enshi, China

Geological disasters, especially landslides, frequently occur in Enshi County, Hubei Province, China. On 21 July 2020, a large-scale landslide occurred in Enshi due to continuous rainfall. The landslide mass blocked the Qingjiang River, formed a dammed lake and caused great damage to surrounding roads and village buildings. In this study, the geomechanical properties of the landslide mass were obtained through field surveys. A three-dimensional topography model of the slope was established using the particle flow code (PFC) and the numerical parameters of the model were calibrated. A 3D discrete element model (DEM) was used to simulate the propagation of Shaziba landslide, and the dynamic behavior of the landslide was divided into five stages. The simulation results show that the landslide movement lasted approximately 1000 s. The maximum average velocity of the landslide reached up to 7.5 m/s and the average runout distance was about 1000 m. The simulated morphology of the landslide deposits was in good agreement with the field data. In addition, the influence of effective modulus on the calculation results was analyzed. The results indicate that the propagation behavior of a landslide and the morphology of landslide deposits are closely related to the effective modulus in the contact model of the PFC3D.

Long runout distance of a block breccia density flow along a half-graben axis: latest Jurassic rift climax in East Greenland

A basinally isolated breccia–pebbly sandstone couplet occurs in the axial part of the latest Jurassic rift-climax half-graben in Wollaston Forland, East Greenland. Synrift breccias are otherwise restricted to a narrow zone along the scarp of the basin-margin Dombjerg Fault. Towards the north the Dombjerg Fault sidesteps en echelon towards the east where it continues in the Thomsen Land Fault. The breccia part of the couplet was transported by a noncohesive debris flow and the pebbly sandstone by a high-density turbidity flow. The couplet is located about 15 km east of the Dombjerg scarp and flowed southwards along the half-graben axis. It is interpreted to have been derived from the southern end of the Thomsen Land Fault. This gives a runout distance of at least 25 km. Other isolated breccias have been reported towards the south along the half-graben axis, giving a runout distance of up to 40 km along the roughly horizontal half-graben axis. The angularity of the clasts is remarkable and reflects derivation directly from the fault scarp during a single catastrophic event. The occurrence of breccias thus cannot be taken as evidence of short transport and deposition at the foot of a scarp or steep slope.

Predictive models for the run-out distance of clay slopes based on material point method

This paper aims to propose run-out distance predictive models for clay slopes using the material point method (MPM), which can simulate the progressive failure process of slopes considering the strain softening effect of soils. A suite of 100 ground motions is selected from the NGA-West2 database and then scaled for conducting the dynamic analysis of slopes. The permanent slope displacements (D) can be classified into two categories, namely the “un-failure” category with D smaller than 0.4 m and the “failure” category with D in the range of 10 m to 15 m. It is found that peak ground velocity (PGV) exhibits the highest correlation with D for the “un-failure” category, whereas all ground-motion intensity measures (e.g., PGV, peak ground acceleration) are less correlated with D for the “failure” category. Therefore, the run-out distance of collapsed clay slopes is more related to the failure model rather than the triggering shaking intensities. Moreover, thousands of slope models with various slope angles, slope heights (H), soil densities, and peak and residual strength parameters are developed based on MPM. The run-out distances for the slopes being collapsed are then collected. Predictive models for different slope angles are proposed, which predict the run-out distance as a function of H, unit weight, residual cohesion, and residual friction angle. The proposed models are applicable for clay slopes with slope angles in the range of 30° to 45° and H in the range of 10 m to 30 m.

Entrainment maps considering hydrological conditions for mass movement runout modelling: Application to debris-flow bulking at Pizzo Cengalo

Debris flows entrain sediments and water along their flow path and grow significantly in size. Because the entrainment process isn’t well understood and data is rare, hazard and risk assessment with numerical models is challenging. It is known, however, that both for debris flows and rock avalanches, interstitial pore water in flow path substrate can cause increases in pore water pressures when overridden by the flow, which enhances erosion. The entrained water likely also plays a role in the process transition from rock avalanche to debris flow, like in the Pizzo Cengalo event in 2017. We present a framework for producing entrainment maps serving as an input for runout modelling, here illustrated using RAMMS. The entrainment maps consist of spatially-distributed entities with properties such as max erosion depth, and soil water content inferred from land cover and lithology maps. This study serves as a basis for producing duration curves of subsurface water available for entrainment and include it into the entrainment maps. Such hydrologically-informed entrainment maps will be useful to assess the probability of certain runout distances.