Spatial Limiting Froude

Spatial Limiting Froude#

Overview#

The Spatial Limiting Froude layer is used to set a limiting Froude number for individual FLO-2D grid elements. For example, overland flow on a gentle slope will become subcritical so a limiting Froude value of 0.9 can be assigned. If the limiting Froude is exceeded, the cell roughness n-value is incrementally increased and maintains numerical stability that might occur for severe supercritical flow. For further discussion on the limiting Froude numbers refer to the FLO-2D Data Input Manual.

Digitize or Copy Data#

  1. Select the Froude Areas layer and click Toggle Editing.

  2. Create or copy the polygons that represent the Froude areas to the layer and save them.

../../../_images/spatia002.png ../../../_images/spatia002a.png

Sample Data#

  1. Click the Sampling Froude Numbers button.

../../../_images/spatia003.png

  1. Once the process is complete OK to close it.

../../../_images/spatia004.png

Troubleshooting#

  1. Create the limiting Froude polygons if they are missing from the Froude Areas layer.

  2. If the Grid layer is empty, create a grid system and try again.

  3. If a Python appears during the sampling process, the attribute table may be missing. Save and reload the project into QGIS and try again.