What is RAS-Flood

RAS-Flood  is an assembly of three complementary generic software utilities which map and assess, by virtual case study,  ‘in-channel’ catchment solutions to fluvial flooding :-

  1.  Routine GIS feature creation from Lidar point-cloud to describe the catchment digitally (Globalmapper is hard to beat)
  2.  Moderated pragmatic stream Bathymetry to 1M grid from stage 1 (Atrepo point-smoothing interpolation methodology)
  3.  2D Mesh creation and flow computation  (HECRAS 2D courtesy USACE)

g40-ap40-varch1-gis  g40-ap40-varch2-bathym  g40-varch3-mesh



How long does it take to produce indicative hydrographs from catchment rainfall for comparison of alternative intervention and landuse measures?

Allow a day per 10 sq km for stage 1 (2.5 GHz x 8GB hardware) and 15 minutes per stream for stage 2.    Stage 3 mesh creation within the perimeter and with breaklines from stage 1 is automated and takes only a few minutes. However allow an hour or so to check over such geometry manually.

Then, with geometric data saved and terrain, bathymetry & (initially say) 24 hour rainfall loaded, the testing of an ‘Unsteady-Flow’ plan to yield indicative hydrographs can be set to take less than an hour (per 100 sq km). A cloud server running the flow analysis code is available on request (email gaw1@cantab.net)



Will catchment flood alleviation measures be considered by policy-makers to provide ‘public good’ and thereby eligible for ‘public funds’ ?

Hard to say, but there is talk of putting a solid value per cubic metre of ‘blue-green’ extreme event flood water storage.


What does it cost and is there a limit to catchment size ?

Data and code are free to download; likewise to provide a steer on any stream bathymetry overlay.  Useful results to date on 2 sqkm to 1000 sqkm catchments


RAS-Flood Methodology        More on Virtual Case Study        Acknowledgements







Download tests:   canal map                          g40-fbridges