GRASS5 (OPEN SOURCE GIS for LINUX PC) was used to support the simulations:

•  nested rasters with different resolutions,
•  multiple surface visualization with multiple rendering resolutions combined with masking in NVIZ2.2:

     DEM at combined 10, 4 and 2m resolutions

GRASS5: http://www.geog.uni-hannover.de/grass
  Released under General Public Licence (GPL)
  From "cathedral"  to "bazaar" : OPEN Source development
  Markus Neteler University of Hannover