What's New – New surface roughness (Manning) parameters for DynamicFlood

DynamicFlood computations need information about the surface roughness for each of the land cover classes available in the Scalgo Live land cover map.  We use so-called Manning numbers to parameterize this. Today, we updated the Manning numbers for all countries where DynamicFlood is available, except Sweden which was recently updated independently. The new values reflect a generally more conservative approach to surface roughness.

The Mannings numbers can be seen in the surface roughness section of the documentation, but for your convenience we have replicated them below:

The values were chosen based on an evaluation and synthesis of relevant literature (Arcement, 1989, Papaioannou et al, 2018, HEC-RAS 2D User's Manual, N-V240 Vannhåndtering, MSB2260).

This change was also recorded in the DynamicFlood changelog.

How does this release affect your computations?

The new numbers will be applied to all new workspaces, created after the update. Workspaces created before the update will retain the previous numbers.

If you need to create a new workspace that uses the same numbers as an old workspace, you can import the Manning numbers from the old workspace (using the "+" icon under Select Manning in the Run hydrodynamic engine dialog).

Likewise, if you would like to update an old workspace to use the new numbers, you can import the numbers from a new workspace.