scholarly journals r.avaflow & r.randomwalk: two complementary and comprehensive open source GIS simulation tools for the propagation of rapid geophysical mass flows

2016 ◽  
Author(s):  
Martin Mergili ◽  
Matthias Benedikt ◽  
Julia Krenn ◽  
Jan-Thomas Fischer ◽  
Shiva P Pudasaini
Keyword(s):  
Open Source ◽  
Open Source Software ◽  
Flow Model ◽  
Rock Avalanche ◽  
Two Phase ◽  
Simulation Tools ◽  
Physically Based ◽  
Open Source Gis ◽  
Mass Flows ◽  
Geophysical Mass Flows

We present two GIS model applications for simulating the propagation of rapid geophysical mass flows: r.avaflow employs an advanced physically-based two phase flow model intended for in-detail case studies, r.randomwalk a conceptual model suitable for studies at various scales. Both tools are implemented in open source software environments serving for the needs of both research and practice. They offer a range of visualization, validation, parameter sensitivity analysis and parameter optimization functions. Some of the key functionalities of both tools are demonstrated for the Acheron rock avalanche in New Zealand.

scholarly journals r.avaflow & r.randomwalk: two complementary and comprehensive open source GIS simulation tools for the propagation of rapid geophysical mass flows

2016 ◽  
Author(s):  
Martin Mergili ◽  
Matthias Benedikt ◽  
Julia Krenn ◽  
Jan-Thomas Fischer ◽  
Shiva P Pudasaini
Keyword(s):  
Open Source ◽  
Open Source Software ◽  
Flow Model ◽  
Rock Avalanche ◽  
Two Phase ◽  
Simulation Tools ◽  
Physically Based ◽  
Open Source Gis ◽  
Mass Flows ◽  
Geophysical Mass Flows

We present two GIS model applications for simulating the propagation of rapid geophysical mass flows: r.avaflow employs an advanced physically-based two phase flow model intended for in-detail case studies, r.randomwalk a conceptual model suitable for studies at various scales. Both tools are implemented in open source software environments serving for the needs of both research and practice. They offer a range of visualization, validation, parameter sensitivity analysis and parameter optimization functions. Some of the key functionalities of both tools are demonstrated for the Acheron rock avalanche in New Zealand.

scholarly journals r.avaflow & r.randomwalk: two complementary and comprehensive open source GIS simulation tools for the propagation of rapid geophysical mass flows

2016 ◽  
Author(s):  
Martin Mergili ◽  
Matthias Benedikt ◽  
Julia Krenn ◽  
Jan-Thomas Fischer ◽  
Shiva P Pudasaini
Keyword(s):  
Open Source ◽  
Open Source Software ◽  
Flow Model ◽  
Rock Avalanche ◽  
Two Phase ◽  
Simulation Tools ◽  
Physically Based ◽  
Open Source Gis ◽  
Mass Flows ◽  
Geophysical Mass Flows

We present two GIS model applications for simulating the propagation of rapid geophysical mass flows: r.avaflow employs an advanced physically-based two phase flow model intended for in-detail case studies, r.randomwalk a conceptual model suitable for studies at various scales. Both tools are implemented in open source software environments serving for the needs of both research and practice. They offer a range of visualization, validation, parameter sensitivity analysis and parameter optimization functions. Some of the key functionalities of both tools are demonstrated for the Acheron rock avalanche in New Zealand.

scholarly journals r.avaflow v1, an advanced open-source computational framework for the propagation and interaction of two-phase mass flows

2017 ◽  
Vol 10 (2) ◽  
pp. 553-569 ◽  
Author(s):  
Martin Mergili ◽  
Jan-Thomas Fischer ◽  
Julia Krenn ◽  
Shiva P. Pudasaini
Keyword(s):  
Open Source ◽  
Programming Languages ◽  
Rock Avalanche ◽  
Two Phase ◽  
Fluid Mixture ◽  
Complex Process ◽  
Process Chains ◽  
Mass Flows ◽  
Definition Of ◽  
Gis Software

Abstract. r.avaflow represents an innovative open-source computational tool for routing rapid mass flows, avalanches, or process chains from a defined release area down an arbitrary topography to a deposition area. In contrast to most existing computational tools, r.avaflow (i) employs a two-phase, interacting solid and fluid mixture model (Pudasaini, 2012); (ii) is suitable for modelling more or less complex process chains and interactions; (iii) explicitly considers both entrainment and stopping with deposition, i.e. the change of the basal topography; (iv) allows for the definition of multiple release masses, and/or hydrographs; and (v) serves with built-in functionalities for validation, parameter optimization, and sensitivity analysis. r.avaflow is freely available as a raster module of the GRASS GIS software, employing the programming languages Python and C along with the statistical software R. We exemplify the functionalities of r.avaflow by means of two sets of computational experiments: (1) generic process chains consisting in bulk mass and hydrograph release into a reservoir with entrainment of the dam and impact downstream; (2) the prehistoric Acheron rock avalanche, New Zealand. The simulation results are generally plausible for (1) and, after the optimization of two key parameters, reasonably in line with the corresponding observations for (2). However, we identify some potential to enhance the analytic and numerical concepts. Further, thorough parameter studies will be necessary in order to make r.avaflow fit for reliable forward simulations of possible future mass flow events.

scholarly journals Physically-based modelling of granular flows with Open Source GIS

2012 ◽  
Vol 12 (1) ◽  
pp. 187-200 ◽  
Author(s):  
M. Mergili ◽  
K. Schratz ◽  
A. Ostermann ◽  
W. Fellin
Keyword(s):  
Open Source ◽  
Regional Scale ◽  
Rock Avalanche ◽  
Granular Flows ◽  
Travel Distance ◽  
Type Model ◽  
Distributed Models ◽  
Physically Based ◽  
Open Source Gis ◽  
Statistical Relationships

Abstract. Computer models, in combination with Geographic Information Sciences (GIS), play an important role in up-to-date studies of travel distance, impact area, velocity or energy of granular flows (e.g. snow or rock avalanches, flows of debris or mud). Simple empirical-statistical relationships or mass point models are frequently applied in GIS-based modelling environments. However, they are only appropriate for rough overviews at the regional scale. In detail, granular flows are highly complex processes and physically-based, distributed models are required for detailed studies of travel distance, velocity, and energy of such phenomena. One of the most advanced theories for understanding and modelling granular flows is the Savage-Hutter type model, a system of differential equations based on the conservation of mass and momentum. The equations have been solved for a number of idealized topographies, but only few attempts to find a solution for arbitrary topography or to integrate the model with GIS are known up to now. The work presented is understood as an initiative to integrate a fully physically-based model for the motion of granular flows, based on the extended Savage-Hutter theory, with GRASS, an Open Source GIS software package. The potentials of the model are highlighted, employing the Val Pola Rock Avalanche (Northern Italy, 1987) as the test event, and the limitations as well as the most urging needs for further research are discussed.

scholarly journals r.avaflow v1, an advanced open source computational framework for the propagation and interaction of two-phase mass flows

2016 ◽  
Author(s):  
Martin Mergili ◽  
Jan-Thomas Fischer ◽  
Julia Krenn ◽  
Shiva P. Pudasaini
Keyword(s):  
Open Source ◽  
Programming Languages ◽  
Rock Avalanche ◽  
Two Phase ◽  
Fluid Mixture ◽  
Complex Process ◽  
Process Chains ◽  
Mass Flows ◽  
Definition Of ◽  
Gis Software

Abstract. r.avaflow represents an innovative open source computational tool for routing rapid mass flows, avalanches or process chains from a defined release area down an arbitrary topography to a deposition area. In contrast to most existing computational tools, r.avaflow (i) employs a two-phase, interacting solid and fluid mixture model; (ii) is suitable for modelling more or less complex process chains and interactions; (iii) explicitly considers both entrainment and stopping i.e. the change of the basal topography; (iv) allows for the definition of multiple release masses and/or hydrographs; and (v) serves with built-in functionalities for validation, parameter optimization and sensitivity analysis. r.avaflow is freely available as a raster module of the GRASS GIS software, employing the programming languages Python and C along with the statistical software R. We exemplify the functionalities of r.avaflow by means of two sets of computational experiments: (1) generic process chains consisting in bulk mass and hydrograph release into a reservoir with entrainment of the dam and impact downstream; (2) the prehistoric Acheron rock avalanche, New Zealand. The simulation results are generally plausible for (1) and, after the optimization of two key parameters, reasonably in line with the corresponding observations for (2). However, we identify some potential to enhance the analytic and numerical concepts. Further, thorough parameter studies are necessary in order to make r.avaflow fit for reliable forward simulations of possible future mass flow events.

scholarly journals Depth-Integrated Two-Phase Modeling of Two Real Cases: A Comparison between r.avaflow and GeoFlow-SPH Codes

2021 ◽  
Vol 11 (12) ◽  
pp. 5751
Author(s):  
Seyed Ali Mousavi Tayebi ◽  
Saeid Moussavi Tayyebi ◽  
Manuel Pastor
Keyword(s):  
Rock Avalanche ◽  
Two Phase ◽  
Simulation Code ◽  
Simulation Tools ◽  
Mesh Free ◽  
Particle Hydrodynamics ◽  
Landslide Evolution ◽  
Smoothed Particle ◽  
Hazard And Risk ◽  
Comparison Of The Results

Due to the growing populations in areas at high risk of natural disasters, hazard and risk assessments of landslides have attracted significant attention from researchers worldwide. In order to assess potential risks and design possible countermeasures, it is necessary to have a better understanding of this phenomenon and its mechanism. As a result, the prediction of landslide evolution using continuum dynamic modeling implemented in advanced simulation tools is becoming more important. We analyzed a depth-integrated, two-phase model implemented in two different sets of code to stimulate rapid landslides, such as debris flows and rock avalanches. The first set of code, r.avaflow, represents a GIS-based computational framework and employs the NOC-TVD numerical scheme. The second set of code, GeoFlow-SPH, is based on the mesh-free numerical method of smoothed particle hydrodynamics (SPH) with the capability of describing pore pressure’s evolution along the vertical distribution of flowing mass. Two real cases of an Acheron rock avalanche and Sham Tseng San Tsuen debris flow were used with the best fit values of geotechnical parameters obtained in the prior modeling to investigate the capabilities of the sets of code. Comparison of the results evidenced that both sets of code were capable of properly reproducing the run-out distance, deposition thickness, and deposition shape in the benchmark exercises. However, the values of maximum propagation velocities and thickness were considerably different, suggesting that using more than one set of simulation code allows us to predict more accurately the possible scenarios and design more effective countermeasures.

Development of Assessment Criteria for Various Open Sources GIS Software Packages

2021 ◽  
pp. 398-412
Author(s):  
Shahriar Shams
Keyword(s):  
Open Source ◽  
Open Source Software ◽  
Assessment Criteria ◽  
Significant Development ◽  
Analysis And Design ◽  
Advantages And Disadvantages ◽  
Software Packages ◽  
Open Source Gis ◽  
Gis Software

There has been a significant development in the area of free and open source geospatial software. Research has flourished over the decades from vendor-dependent software to open source software where researchers are paying increasing attention to maximize the value of their data. It is often a difficult task to choose particular open source GIS (OGIS) software among a number of emerging OGIS software. It is important to characterise the projects according to some unified criteria. Each software has certain advantages and disadvantages and it is always time consuming to identify exactly which software to select for a specific purpose. This chapter focuses on the assessment criteria enabling developers, researchers, and GIS users to select suitable OGIS software to meet their requirements for analysis and design of geospatial application in multidisciplinary fields. This chapter highlights the importance of assessment criteria, followed by an explanation of each criteria and their significance with examples from existing OGIS software.

A two-fluid model for avalanche and debris flows

2005 ◽  
Vol 363 (1832) ◽  
pp. 1573-1601 ◽  
Author(s):  
E. Bruce Pitman ◽  
Long Le
Keyword(s):  
Debris Flows ◽  
Fluid Model ◽  
Solid Material ◽  
Fluid Inertia ◽  
Two Phase ◽  
Engineering Research ◽  
Mass Flows ◽  
Two Fluid Model ◽  
Two Fluid ◽  
Geophysical Mass Flows

Geophysical mass flows—debris flows, avalanches, landslides—can contain O (10 6 –10 10 ) m 3 or more of material, often a mixture of soil and rocks with a significant quantity of interstitial fluid. These flows can be tens of meters in depth and hundreds of meters in length. The range of scales and the rheology of this mixture presents significant modelling and computational challenges. This paper describes a depth-averaged ‘thin layer’ model of geophysical mass flows containing a mixture of solid material and fluid. The model is derived from a ‘two-phase’ or ‘two-fluid’ system of equations commonly used in engineering research. Phenomenological modelling and depth averaging combine to yield a tractable set of equations, a hyperbolic system that describes the motion of the two constituent phases. If the fluid inertia is small, a reduced model system that is easier to solve may be derived.

scholarly journals Back calculation of the 2017 Piz Cengalo–Bondo landslide cascade with r.avaflow: what we can do and what we can learn

2020 ◽  
Vol 20 (2) ◽  
pp. 505-520 ◽  
Author(s):  
Martin Mergili ◽  
Michel Jaboyedoff ◽  
José Pullarello ◽  
Shiva P. Pudasaini
Keyword(s):  
Debris Flow ◽  
Flow Model ◽  
Rock Avalanche ◽  
Simulation Software ◽  
Process Models ◽  
Model Parameters ◽  
Two Phase ◽  
Three Phase Flow ◽  
Glacier Ice ◽  
Future Work

Abstract. In the morning of 23 August 2017, around 3×106 m3 of granitoid rock broke off from the eastern face of Piz Cengalo, southeastern Switzerland. The initial rockslide–rockfall entrained 6×105m3 of a glacier and continued as a rock (or rock–ice) avalanche before evolving into a channelized debris flow that reached the village of Bondo at a distance of 6.5 km after a couple of minutes. Subsequent debris flow surges followed in the next hours and days. The event resulted in eight fatalities along its path and severely damaged Bondo. The most likely candidates for the water causing the transformation of the rock avalanche into a long-runout debris flow are the entrained glacier ice and water originating from the debris beneath the rock avalanche. In the present work we try to reconstruct conceptually and numerically the cascade from the initial rockslide–rockfall to the first debris flow surge and thereby consider two scenarios in terms of qualitative conceptual process models: (i) entrainment of most of the glacier ice by the frontal part of the initial rockslide–rockfall and/or injection of water from the basal sediments due to sudden rise in pore pressure, leading to a frontal debris flow, with the rear part largely remaining dry and depositing mid-valley, and (ii) most of the entrained glacier ice remaining beneath or behind the frontal rock avalanche and developing into an avalanching flow of ice and water, part of which overtops and partially entrains the rock avalanche deposit, resulting in a debris flow. Both scenarios can – with some limitations – be numerically reproduced with an enhanced version of the two-phase mass flow model (Pudasaini, 2012) implemented with the simulation software r.avaflow, based on plausible assumptions of the model parameters. However, these simulation results do not allow us to conclude on which of the two scenarios is the more likely one. Future work will be directed towards the application of a three-phase flow model (rock, ice, and fluid) including phase transitions in order to better represent the melting of glacier ice and a more appropriate consideration of deposition of debris flow material along the channel.

scholarly journals Develop Direct Geo-referencing System Based on Open Source Software and Hardware Platform

2015 ◽  
Vol XL-5/W7 ◽  
pp. 295-297
Author(s):  
H. S. Liu ◽  
H. M. Liao
Keyword(s):  
Open Source ◽  
Open Source Software ◽  
Processing System ◽  
Hardware Platform ◽  
Position Information ◽  
Open Source Gis ◽  
Camera Position ◽  
Software And Hardware ◽  
Gps Tracks ◽  
Gis Software

Direct geo-referencing system uses the technology of remote sensing to quickly grasp images, GPS tracks, and camera position. These data allows the construction of large volumes of images with geographic coordinates. So that users can be measured directly on the images. <br><br> In order to properly calculate positioning, all the sensor signals must be synchronized. Traditional aerial photography use Position and Orientation System (POS) to integrate image, coordinates and camera position. However, it is very expensive. And users could not use the result immediately because the position information does not embed into image. To considerations of economy and efficiency, this study aims to develop a direct geo-referencing system based on open source software and hardware platform. <br><br> After using Arduino microcontroller board to integrate the signals, we then can calculate positioning with open source software OpenCV. In the end, we use open source panorama browser, panini, and integrate all these to open source GIS software, Quantum GIS. A wholesome collection of data – a data processing system could be constructed.

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