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35 pages, 32787 KiB

Open AccessArticle

Impact-Detection Algorithm That Uses Point Clouds as Topographic Inputs for 3D Rockfall Simulations

by François Noël, Catherine Cloutier, Michel Jaboyedoff and Jacques Locat

Geosciences 2021, 11(5), 188; https://doi.org/10.3390/geosciences11050188 - 27 Apr 2021

Cited by 14 | Viewed by 5223

Abstract

Numerous 3D rockfall simulation models use coarse gridded digital terrain model (DTM raster) as their topography input. Artificial surface roughness is often added to overcome the loss of details that occurs during the gridding process. Together with the use of sensitive energy damping [...] Read more.

Numerous 3D rockfall simulation models use coarse gridded digital terrain model (DTM raster) as their topography input. Artificial surface roughness is often added to overcome the loss of details that occurs during the gridding process. Together with the use of sensitive energy damping parameters, they provide great freedom to the user at the expense of the objectivity of the method. To quantify and limit the range of such artificial values, we developed an impact-detection algorithm that can be used to extract the perceived surface roughness from detailed terrain samples in relation to the size of the impacting rocks. The algorithm can also be combined with a rebound model to perform rockfall simulations directly on detailed 3D point clouds. The abilities of the algorithm are demonstrated by objectively extracting different perceived surface roughnesses from detailed terrain samples and by simulating rockfalls on detailed terrain models as proof of concept. The results produced are also compared to that of rockfall simulation software CRSP 4, RocFall 8 and Rockyfor3D 5.2.15 as validation. Although differences were observed, the validation shows that the algorithm can produce similar results. With the presented approach not being limited to coarse terrain models, the need for adding artificial terrain roughness or for adjusting sensitive damping parameters on a per-site basis is reduced, thereby limiting the related biases and subjectivity. Full article

(This article belongs to the Special Issue Rock Fall Hazard and Risk Assessment)

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8 pages, 1027 KiB

Open AccessCommunication

Introducing Uncertainty in Risk Calculation along Roads Using a Simple Stochastic Approach

by Michel Jaboyedoff, Tiggi Choanji, Marc-Henri Derron, Li Fei, Amalia Gutierrez, Lidia Loiotine, François Noel, Chunwei Sun, Emmanuel Wyser and Charlotte Wolff

Geosciences 2021, 11(3), 143; https://doi.org/10.3390/geosciences11030143 - 22 Mar 2021

Cited by 5 | Viewed by 2620

Abstract

Based on a previous risk calculation study conducted along a road corridor, risk is recalculated using a stochastic simulation by introducing variability into most of the parameters in the risk equation. This leads to an exceedance curve comparable to those of catastrophe models. [...] Read more.

Based on a previous risk calculation study conducted along a road corridor, risk is recalculated using a stochastic simulation by introducing variability into most of the parameters in the risk equation. This leads to an exceedance curve comparable to those of catastrophe models. This approach introduces uncertainty into the risk calculation in a simple way, and it can be used for poorly documented cases to compensate for a lack of data. This approach tends to minimize risk or question risk calculations. Full article

(This article belongs to the Special Issue Rock Fall Hazard and Risk Assessment)

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26 pages, 8755 KiB

Open AccessArticle

Preliminary Modeling of Rockfall Runout: Definition of the Input Parameters for the QGIS Plugin QPROTO

by Marta Castelli, Giulia Torsello and Gianmarco Vallero

Geosciences 2021, 11(2), 88; https://doi.org/10.3390/geosciences11020088 - 14 Feb 2021

Cited by 16 | Viewed by 4973

Abstract

The identification of the most rockfall-prone areas is the first step of the risk assessment procedure. In the case of land and urban planning, hazard and risk analyses involve large portions of territory, and thus, preliminary methods are preferred to define specific zones [...] Read more.

The identification of the most rockfall-prone areas is the first step of the risk assessment procedure. In the case of land and urban planning, hazard and risk analyses involve large portions of territory, and thus, preliminary methods are preferred to define specific zones where more detailed computations are needed. To reach this goal, the QGIS-based plugin QPROTO was developed, able to quantitatively compute rockfall time-independent hazard over a three-dimensional topography on the basis of the Cone Method. This is obtained by combining kinetic energy, passing frequency and detachment propensity of each rockfall source. QPROTO requires the definition of few angles (i.e., the energy angle

ϕ_{p}

and the lateral angle

α

) that should take into account all the phenomena occurring during the complex block movement along the slope. The outputs of the plugin are a series of raster maps reporting the invasion zones and the quantification of both the susceptibility and the hazard. In this paper, a method to relate these angles to some characteristics of the block (volume and shape) and the slope (inclination, forest density) is proposed, to provide QPROTO users with a tool for estimating the input parameters. The results are validated on a series of case studies belonging to the north-western Italian Alps. Full article

(This article belongs to the Special Issue Rock Fall Hazard and Risk Assessment)

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19 pages, 6253 KiB

Open AccessArticle

MATLAB Virtual Toolbox for Retrospective Rockfall Source Detection and Volume Estimation Using 3D Point Clouds: A Case Study of a Subalpine Molasse Cliff

by Dario Carrea, Antonio Abellan, Marc-Henri Derron, Neal Gauvin and Michel Jaboyedoff

Geosciences 2021, 11(2), 75; https://doi.org/10.3390/geosciences11020075 - 9 Feb 2021

Cited by 8 | Viewed by 4181

Abstract

The use of 3D point clouds to improve the understanding of natural phenomena is currently applied in natural hazard investigations, including the quantification of rockfall activity. However, 3D point cloud treatment is typically accomplished using nondedicated (and not optimal) software. To fill this [...] Read more.

The use of 3D point clouds to improve the understanding of natural phenomena is currently applied in natural hazard investigations, including the quantification of rockfall activity. However, 3D point cloud treatment is typically accomplished using nondedicated (and not optimal) software. To fill this gap, we present an open-source, specific rockfall package in an object-oriented toolbox developed in the MATLAB^® environment. The proposed package offers a complete and semiautomatic 3D solution that spans from extraction to identification and volume estimations of rockfall sources using state-of-the-art methods and newly implemented algorithms. To illustrate the capabilities of this package, we acquired a series of high-quality point clouds in a pilot study area referred to as the La Cornalle cliff (West Switzerland), obtained robust volume estimations at different volumetric scales, and derived rockfall magnitude–frequency distributions, which assisted in the assessment of rockfall activity and long-term erosion rates. An outcome of the case study shows the influence of the volume computation on the magnitude–frequency distribution and ensuing erosion process interpretation. Full article

(This article belongs to the Special Issue Rock Fall Hazard and Risk Assessment)

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25 pages, 13485 KiB

Open AccessArticle

New Cadanav Methodology for Rock Fall Hazard Zoning Based on 3D Trajectory Modelling

by Jacopo M. Abbruzzese and Vincent Labiouse

Geosciences 2020, 10(11), 434; https://doi.org/10.3390/geosciences10110434 - 5 Nov 2020

Cited by 8 | Viewed by 2241

Abstract

Most rock fall hazard zoning methodologies are currently based on trajectory modelling, usually performed along 2D slope profiles. For many topographic configurations, this approach cannot provide a realistic description of the way rock fall trajectories and, ultimately, hazard are spatially distributed all over [...] Read more.

Most rock fall hazard zoning methodologies are currently based on trajectory modelling, usually performed along 2D slope profiles. For many topographic configurations, this approach cannot provide a realistic description of the way rock fall trajectories and, ultimately, hazard are spatially distributed all over a slope. This paper presents a new methodology for rock fall hazard zoning, directly applicable to 3D topographies, starting from 3D trajectory simulation results. The procedure is an extension of the Cadanav methodology introduced for hazard zoning along 2D slope profiles. As such, it is fully quantitative and attempts at reducing as much as possible uncertainties and subjective elements affecting current methods for rock fall hazard analysis and zoning. It is also among the first to introduce a “fully-coupled” rock fall intensity-frequency approach. Hazard is estimated by means of “hazard curves”, described at each point of the slope by rock fall intensity-return period couples. These curves may be superimposed on any intensity-return period diagram prescribed in national or regional land use planning regulations, in order to determine which hazardous condition prevails at each point of the slope. The application of the new Cadanav methodology is illustrated for both a theoretical case of simple topography underlying a linear cliff and a real configuration involving a complex topography, characterised by strong three-dimensional features affecting the paths of the blocks. For all topographic models, results obtained for several scenarios involving either localised or diffuse source areas proved that the methodology performs extremely well, providing objective and reproducible results based on a rigorous combination of rock fall energy and return period. Additional tests and real case studies are currently under investigation, for strengthening even further the validation of the approach and extend its applicability to even more complex rock fall scenarios. Full article

(This article belongs to the Special Issue Rock Fall Hazard and Risk Assessment)

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13 pages, 7372 KiB

Open AccessArticle

Risk Assessment of Rock Falls Released from the Former Quarry Near Spitz (Austria)

by Rainer Poisel, Nikolaus Hoedlmoser and Bernhard Grasemann

Geosciences 2020, 10(11), 432; https://doi.org/10.3390/geosciences10110432 - 30 Oct 2020

Cited by 3 | Viewed by 2500

Abstract

In the former quarry near Spitz an der Donau (Austria), many rockfalls have occurred during operation as well as after closure. They have endangered a railway, the Wachau bicycle route, an important road, and the left Danube riverbank. Thus, future detachment scenarios were [...] Read more.

In the former quarry near Spitz an der Donau (Austria), many rockfalls have occurred during operation as well as after closure. They have endangered a railway, the Wachau bicycle route, an important road, and the left Danube riverbank. Thus, future detachment scenarios were investigated and, in addition, weather and occurrence statistics were analyzed to determine the occurrence probabilities of these scenarios. Simulations of possible future rockslides were performed using the Distinct Element Code 3DEC in order to estimate the damage caused by these events. Based on these results, the risks of the scenarios were calculated according to the definition of risk as the product of damage and occurrence probability. By this means, the profitability of mitigation measures (e.g., a massive retaining structure fixed to the ground by bored piles) can be evaluated. Full article

(This article belongs to the Special Issue Rock Fall Hazard and Risk Assessment)

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25 pages, 3446 KiB

Open AccessFeature PaperArticle

Rockfall Research: A Bibliometric Analysis and Future Trends

by Josué Briones-Bitar, Paúl Carrión-Mero, Néstor Montalván-Burbano and Fernando Morante-Carballo

Geosciences 2020, 10(10), 403; https://doi.org/10.3390/geosciences10100403 - 9 Oct 2020

Cited by 62 | Viewed by 10767

Abstract

Rockfall is one of the main phenomena in mountainous environments due to its fast and high speed of movement, its unpredictability, and, therefore, the difficulty of identifying signs of instability and detachment of the blocks. Compared to other types of sliding, the proportion [...] Read more.

Rockfall is one of the main phenomena in mountainous environments due to its fast and high speed of movement, its unpredictability, and, therefore, the difficulty of identifying signs of instability and detachment of the blocks. Compared to other types of sliding, the proportion of rockfall research is smaller and sometimes little known, but, in the last five years, rapid growth in this area has been shown. Therefore, this research aimed to review the intellectual structure of rockfall, through analysis of scientific production using bibliometric techniques that allow its analysis, knowledge, global evolution, and future trends in rockfall. The research methodology consists of three steps: (1) data compilation, (2) software and data cleaning, and (3) analysis, interpretation, and visualization. This analysis focuses on the period from 1975 to 2019. For the data, a total of 811 academic publications were retrieved from the Scopus database. The results indicate an increasing trend of annual publications on rockfall. This analysis reveals the main topics, countries, and most influential institutions in the world that have carried out relevant research in scientific publications; it also shows the journals that have the most publications. VOSviewer software was adopted to evaluate the co-occurrence of author keywords. Currently, the hotspots rockfall issues mainly include: hazard-risk assessment, remote sensing, and rockfall monitoring. Finally, this article analyzes the limitations of current research and proposes a future direction for the development of new research. Full article

(This article belongs to the Special Issue Rock Fall Hazard and Risk Assessment)

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21 pages, 6693 KiB

Open AccessFeature PaperArticle

Simulation of Full-Scale Rockfall Tests with a Fragmentation Model

by Gerard Matas, Nieves Lantada, Jordi Corominas, Josep Gili, Roger Ruiz-Carulla and Albert Prades

Geosciences 2020, 10(5), 168; https://doi.org/10.3390/geosciences10050168 - 7 May 2020

Cited by 20 | Viewed by 4953

Abstract

In this paper, we present the upgraded version of RockGIS, a stochastic program for the numerical simulation of rockfalls and their fragmentation, based on a fractal model. The code has been improved to account for a range of fragmentation scenarios, depending on the [...] Read more.

In this paper, we present the upgraded version of RockGIS, a stochastic program for the numerical simulation of rockfalls and their fragmentation, based on a fractal model. The code has been improved to account for a range of fragmentation scenarios, depending on the impact conditions. In the simulation, the parameters of the fractal fragmentation model that define the sizes of the generated fragments were computed at each impact according to the kinematic conditions. The performance of the upgraded code was verified and validated by real-scale rockfall tests performed in a quarry. The tests consisted of the release of 21 limestone blocks. For each release, the size and spatial distribution of the fragments generated by the impacts were measured by hand and from orthophotos taken via drone flights. The trajectories of the blocks and the resulting fragments were simulated with the code and calibrated with both the volume distribution and the runout distances of the fragments. Finally, as all the relevant rockfall parameters involved were affected by strong uncertainty and spatial variability, a parametric analysis was carried out and is discussed. Full article

(This article belongs to the Special Issue Rock Fall Hazard and Risk Assessment)

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Review

Jump to: Research

16 pages, 6530 KiB

Open AccessEditor’s ChoiceReview

Definitions and Concepts for Quantitative Rockfall Hazard and Risk Analysis

by Didier Hantz, Jordi Corominas, Giovanni B. Crosta and Michel Jaboyedoff

Geosciences 2021, 11(4), 158; https://doi.org/10.3390/geosciences11040158 - 1 Apr 2021

Cited by 32 | Viewed by 4887

Abstract

There is an increasing need for quantitative rockfall hazard and risk assessment that requires a precise definition of the terms and concepts used for this particular type of landslide. This paper suggests using terms that appear to be the most logic and explicit [...] Read more.

There is an increasing need for quantitative rockfall hazard and risk assessment that requires a precise definition of the terms and concepts used for this particular type of landslide. This paper suggests using terms that appear to be the most logic and explicit as possible and describes methods to derive some of the main hazards and risk descriptors. The terms and concepts presented concern the rockfall process (failure, propagation, fragmentation, modelling) and the hazard and risk descriptors, distinguishing the cases of localized and diffuse hazards. For a localized hazard, the failure probability of the considered rock compartment in a given period of time has to be assessed, and the probability for a given element at risk to be impacted with a given energy must be derived combining the failure probability, the reach probability, and the exposure of the element. For a diffuse hazard that is characterized by a failure frequency, the number of rockfalls reaching the element at risk per unit of time and with a given energy (passage frequency) can be derived. This frequency is relevant for risk assessment when the element at risk can be damaged several times. If it is not replaced, the probability that it is impacted by at least one rockfall is more relevant. Full article

(This article belongs to the Special Issue Rock Fall Hazard and Risk Assessment)

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