Burn a Stream or Raise a Wall in WhiteboxTools
Often it is necessary to re-condition a DEM by burning streams or raising walls to force a watershed to be delineated with known streams or boundaries (example: NHD streams or WBD HUC boundaries). WhiteboxTools provide a couple of convenient tools for burning a stream or raising a wall which inlcude FillBurn, RaiseWalls, and BurnStreamsAtRoads.
This tools burns a stream into an existing DEM (Figure 1). The stream alignment needs to be provided as a vector shapefile. The resulted DEM is shown in Figure 2.
This tools burns a wall with a specified height above an existing DEM ground (Figure 3). The wall alignment needs to be provided as a vector shapefile. An optional breach line may be needed so the area surrounded by the newly erected walls will not become depressed. The re-conditioned DEM with the new wall is shown in Figure 4.
The watersheds delineated after and before the wall is burned are shown in Figure 5. It is obvious the new wall blocks the flow coming from the upstream side, which results in a much smaller watershed.
This tool is convenient to burn a stream crossing an roadway embankment if the DEM or LiDAR does not pick up the crossing where there is a culvert or a bridge. Two vector shapefiles are required: one for stream alignment and the other for roadway. The stream alignment should connect to the existing stream on either side of the roadway. The burned stream is along the stream alignment and its length is determined by the Road Embankment Width value (half of it on either side of the roadway, Figure 7). It appears that the value of Road Embankment Width must be provided, and otherwise, the output DEM is the same as the input DEM.
Figure 7 is only for illustration purpose to show the function of BurnStreamsAtRoads. The stream alignment (the solid blue line) does not actually connect to a stream to the upper side of the roadway in this example.
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