LaharFlow is a tool for modelling the dynamics of lahars on topography. The mathematical model is based on the fluid mechanics of of shallow flows, fluid and granular dynamics, and the morphodynamics of erosion and deposition.

The topography over which lahars flow has a strong effect on their motion. In LaharFlow digital topographic maps are used, with the global freely available 30m SRTM digital elevation model used as the default topographic map. Advanced users are able to upload bespoke digital topographic maps.

Solid material transported by lahars can have a strong influence on the flow dynamics. Lahars span a wide range of regimes, depending on the solids concentration, from hyperconcentrated water flows to lubricated debris flows. LaharFlow includes a novel drag formulation that includes both fluid and granular contributions to the total resistance to flow, and a solids concentration-dependent switching between them. This allows the range of flow regimes to be modelled within LaharFlow.

A manuscript describing the mathematical formulation of the LaharFlow model has been submitted for publication and further publications are in preparation. This page will be updated with the citation once published.

• Model lahars on topography.
• Use SRTM 30m topographic data, or bespoke digital topographic maps for advanced users.
• Model includes a transition between fluid and granular drag formulations to describe.
• Erosion and depostion of solid material is modelled.
• The model includes a morphodynamic link between sediment erosion and deposition and the topographic elevation.
• Simple user interface.
• Graphical output to screen.
• Model flows at a particular volcano.
• Lahar flow paths overlaid on DEM.
• Multiple user-requested plots.
• Export of PDF reports, including graphics.
• Export of model solution to text files.
• Export of model data to kml files.

The LaharFlow model was created by Mark Woodhouse, Andrew Hogg and Jeremy Phillips.

The web interface was developed by Mark Woodhouse, building on the PlumeRise interface developed by Chris Johnson.