Flow-R (Flow path assessment of gravitational hazards at a Regional scale) is a distributed empirical model for regional susceptibility assessments of gravitational hazards. It allows for automatic source area delineation and essentially for the assessment of the propagation extent, based on several reliable published empirical runout models on local and regional scales. Up to now, it has been adapted to:

  • Debris flows
  • Snow avalanches
  • Rockfalls
  • Rock avalanches
  • Shallow landslides


Flexible Input Data

The choices of the datasets and the algorithms are open to the user, which makes it compliant for various applications and dataset availability.

Data Exporting

Export the generated outputs for further treatment in a GIS tool.


Flow-R was developed at the University of Lausanne, but Terranum is now in charge of the development and the maintenance.

Even though the software possesses only a simple graphical user interface, it is now widely used in multiple countries around the globe for multi-hazards assessments. Terranum can provide support in various domains:

Specific development

There may be situations where Flow-R needs to be modified in order to meet the requirements of a certain project, or to model a specific behaviour. We are ready to make the necessary adjustments in Flow-R in order to meet your needs.

Nation scale modeling

Flow-R is pretty limited in terms of the spatial extent it can handle, and nation scale modeling requires a significant amount of processing time. Terranum possesses a cluster in order to perform intensive calculations.


We have now various experiences using Flow-R in different conditions, with varying data quality and for multiple hazards. Being the editor of the model, we also know quite well the behaviour of the different algorithms. Moreover, we work with an always improving methodology in order to take into account parameters uncertainty to a certain extent.


Having some help when starting using Flow-R is a time saving option. We have some courses ready and will be happy assisting you.


Horton P, Jaboyedoff M, Rudaz B and Zimmermann M: Flow-R, a model for susceptibility mapping of debris flows and other gravitational hazards at a regional scale. Natural Hazards Earth System Sciences, 13, 869-885, 2013, doi:10.5194/nhess-13-869-2013

Release Notes

0.9.7 (12.05.2016)

Fix of the kml export

The kml export of the results has been fixed.

0.9.6 (13.11.2014)

Linux packaging and bug fixes

Improvement of the packaging for Linux
Bug fixes for the command line and the batch versions.

0.9.5 (18.09.2014)

Bug fixes

Bug fixes related to multithreading.

0.9.4 (15.09.2014)

Bug fixes and minor improvements

Bug fixes related to new features in version 0.9.3.
Set the last opened directory when importing data.

0.9.3 (11.09.2014)

Addition of the variable travel angle approach

Addition of a variable travel angle approach (travel angles defined in a raster file).
The user can now choose the batch file.
Addition of a local user directory to add parameters files.
The working directories definition has been moved to the main frame.
Addition of a control of the provided directories.
Better integration of the data import.
Minor bug fixes.

0.9.2 (13.12.2013)

Addition of algorithms for rock avalanches assessment

Addition of the new inertia algorithm (direction memory) for rock avalanches.

0.9.1 (02.12.2013)

Performance improvement and fix for Windows 8

The processing time was reduced by sorting the source areas by the altitude.
Changes in registry paths for a bug related to Windows 8.
The resulting directory is now explicitly displayed when the calculations are over.

0.9.0 (28.11.2013)

Addition of an installer and switch to MCR R2013b

The Matlab Compiler Runtime version has been changed to R2013b.
An installer was added to place Flow-R in the programs directory and to add an entry in the menu.
The user can now choose where to save storage data and resulting grids.
Allows non round coordinates at data import and manage non overlapping grids more strictly.
Optimization of the processing time, mainly for “connected” source areas.
Improvement of the ascii grids export.
Fix a bug of the spreading plotting.
Directory structure for the parameters files were modified.
Many parameters files were generated to offer a wide possibility to the user without requiring him to edit the xml files.
Improvement of the languages management.

0.8.0 (28.03.2013)

Improvements to the interface and switch to MCR R2012b

The Matlab Compiler Runtime version has been changed to R2012b.
Small improvements to the GUI and its text content to be more consistent with the reference paper.
The tabs navigation has been fixed.
A splash screen was added to let the user know that the MCR is loading.
The command prompt is no more displayed in Windows, but a log frame shows up for messages and errors.
The batch mode has been moved to a separate frame, available through the menu.
The datasets and functions lists were improved for clarity.
The name and content of various parameters files were changed for homogeneization.
The user manual was moved to www.flow-r.org/user-manual
Fix of the results plotting when there is only 1 source area.

0.7.7 (12.03.2013)

Minor cleanup

The obsolete version file has been removed.
The root folder name has been changed from Model to FlowR.
Some cleanup of the source code has been performed.
The About frame has been simplified.

0.7.6 (04.03.2012)

Changes in the threshold and residues management

New GUI to define the preferences.
Preferences are now handled by an ini file instead of the xml file.
The quick mode has been changed for a more consistent stopping check.
The threshold is now applied at a previous stage and the cutted probabilities are given to the closest active cells or, if any, to the residues sum.
Changing the multithreading criteria to allow multithreads on the 2011 binary version.
Lowering of the probability threshold to 0.0003 (better precision)

0.7.5 (07.07.2011)

New spreading algorithm

A new version of the Holmgren algorithm has been added. It allows increasing the height of the central cell to decrease the effect of small elevation differences.

0.7.4 (08.03.2011)

Speed improvement

Speed improvement of the spreading.
Multithreading option for the undeployed version.

0.7.3 (08.02.2011)

Important bugs fixes

Bugs fixes with the command-line and the data formatting.
Removal of imdilate as the image processing toolbox is not included in the compiled version.
Fix of a bug in the connected area version.
Fix of a bug allowing the probabilities to increase above the sources probabilities on flat area.
Addition of the Perla model without conservation of the linear momentum (no correction).
Bug fixed in the Perla model.
Display of the progression in the command window.

0.7.2 (19.11.2010)

Online help and bugs fixes

The help was moved to an online wiki page
Fix of a bug in the data importation
Changes in the command line usage
A bug from version 0.7.1 in Holmgren has been fixed

0.7.1 (22.10.2010)

Command-line option and some improvements

It is now possible to call Flow-R as a command line with options
Removed the use of handles in non-GUI functions
Changes of the background colors to use the OS default colors
Changes of data classes from double to single or logical to spare memory
Possibility to rearrange the order of the cells calculation to spare time
Simplification of use of the translation function
Fix of an error in the Perla model

0.7.0 (11.06.2010)

Linux compatibility and new options

An option to take into account a given value for the source was added
The directions management was completely revisited to be more robust
The model is Linux compatible, with a compiled release (./run_FlowR.sh /opt/matlab/matlab_compiler_runtime/v79)
The Model Compiler Runtime was changed for 7.11
The name was changed from DFGridProb to Flow-R
The GUI was set horizontally
A panel About was added
Limit to the update check every 30 days

0.6.5 (03.08.2009)

Bugs fixes

The .mat files writing has been secured by expliciting the extension.

0.6.4 (18.05.2009)

Avalanches oriented triggering

A triggering mode has been added in order to trigger connected sources area as a whole.
A bug in the case study definition by means of coordinates has been fixed.
The kml output warning in case of a too large area is better handled.
Cells with a height difference of 1000m and more are not considered for the spreading.

0.6.3 (23.03.2009)

Bugs and kml output

A bug concerning the listing of the local flow accumulation has been fixed
The kml output for Switzerland has been improved.
The kml output is available for UTM projections.

0.6.2 (25.02.2009)

Bugs and more and kml output

The GUI units were moved from pixel to points or characters to better display on different screens.
The MCR check has been disabled due to languages issues with paths
Some languages edition
Some GUI modification
Empty river and buffer layers automaticly generated
Every slope angle in percent has been changed to degrees
A bug in the refreshing of the view has been fixed
kml files can be output for Switzerland. Fit only for small areas !
D infinity algorithm fixed
A check of the inputs has been introduced
Local flow accumulation now available for source areas identification

0.6.1 (17.02.2009)

Bugs hunting and xml editor

A bug making impossible to use most of the spreading algorithms has been removed.
A bug in the pit holes management in the Holmgren and Dinf algorithms has been fixed.
A bug in the loop script parser has been fixed.
A bug in the functions listing has been fixed.
An error that slowed down the model has been removed.
All parameters are now saved in an xml file for every run.
A check of the version has been introduced.
A tool to edit XML files has been added : XMLTree or XML Parser by Guillaume Flandin
Change directory commands have been removed.

0.6.0 (16.01.2009)

XML everywhere for more customization

Criteria (parameters) files were moved from txt to xml.
New names for algorithms files and new loop script file system.
Alogrithms options were extracted from the scripts and are now available in xml files.
The energy loss can be set as a function of the flow accumulation

0.5.2 (09.01.2009)


The functions names were changed to clarify their usage.
Options were extracted from the code and moved to an xml file.
Correction of the precision in output files. Fix the area difference between energy and probability results.
Multiple small rewrites in the entire code.

0.5.1 (22.12.2008)

Some small new options

A bug that used to crash the model when the buffer option was disabled has been fixed.
The possibility to add the probabilities of different debrisflows instead of considering only the maximum has been added.
The languages file system was move from csv to xml.
Various algorithms values were extended.

0.5.0 (01.12.2008)

Initial state

Model as developped before the versioning


Rockfall propagation in Flow-R

Introduction of a variable travel angle in Flow-R in order to take into account the effect of forests on rockfall propagation

2014 | Canton of Fribourg, Switzerland

Indicative hazard mapping (Fribourg)

Indicative hazard mapping of debris-flows, snow avalanches, rockfalls and landslides for the Canton de Fribourg

2014-2015 | Canton of Fribourg, Switzerland

Snow Avalanche Runout Computation

Investigation on DEM resolutions effects on the processing of the Norwegian snow avalanche susceptibility maps using α⁄β and Perla's models implemented in RAS and Flow-R

2015 | NVE, Norvège

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