Flow-R (Flow path assessment of gravitational hazards at a Regional scale) is a distributed empirical model for regional susceptibility assessments of debris flows, developed at the University of Lausanne. It was successfully applied to different case studies in various countries.

The model was also found relevant to assess other natural hazards such as rockfall or snow avalanches. It allows for automatic source area delineation and for the assessment of the propagation extent. The choices of the datasets and the algorithms are open to the user, which makes it compliant for various applications and dataset availability.

Two versions are available

Flow-R 1.0 (Unil)

The Matlab-based version of Flow-R is free of charge and available on the download page. Any use is allowed.

Flow-R 2.0 (Terranum)

Flow-R 2.0 has been written from scratch in C++ and is much faster (about 45x) and more efficient in terms of memory management.


When you need support, please first read the FAQ section and the reference paper. Many aspects are covered in terms of methodology and practical details. When you don't find the relevant answer, you can contact us. We can also provide expertise and make intensive computation on a cluster for a country-scale map production for example.


Version 2.0 released (14.12.2020)

I am pleased to announce the release of Flow-R version 2.0! Flow-R 2.0 has been written from scratch in C++ by Terranum, which makes it much faster (about 45x) and more efficient in terms of memory management (large spatial areas). Among the new features, this version now allows managing several consecutive runs through a queuing system. Flow-R 2.0 also offers greater flexibility in terms of input data by supporting all common types of raster files and saves the results as GeoTIFF or shapefiles. In addition, it is possible to individually extract the reach perimeter of each source cell. Several versions are available, as well as a demo. The page https://www.terranum.ch/en/products/flow-r/ provides all the necessary information.

Version 0.9.8 released (27.01.2018)

This release contains a new variable angle approach for rockfall with a travel angle that can change along the propagation. The runtime was upgraded to R2017b.

Modelling for large regions ? (22.04.2015)

When it comes to production of maps on a large region with Flow-R, a desktop computer is not anymore suitable. We, at Terranum, have a cluster on which Flow-R can run on multiple computers. It thus allows us to provide modelling for large regions. If you consider outsourcing the production for a large region, we would be glad to assist (contact pascal.horton@terranum.ch).

Error in a figure (07.01.2015)

There is an error in the figure of the relationship between the slope and the contributing area for the identification of the debris-flow source areas. However, the equations and the implementation in Flow-R are correct. Read more.

Version 0.9.6 released (13.11.2014)

This release is mostly a bug-fix release. A couple of issues related to new functionalities were removed.

Version 0.9.3 released (11.09.2014)

A new version has been released with several improvements of the user experience and two main enhancements. The enhancements are : a new inertial algorithm for rock avalanches assessment, and a new variable travel angle approach to take into account for example the effect of the forest on rockfalls propagation. See the release notes for more details.