Impeded Flowpaths
The Impeded Flowpaths tool produces a valuable output showing surface depressions across the landscape. Some of these depressions are real, and some are not. You can see in this example that depressions are commonly developed behind roadways causing flow to be backed up.
In reality, these roadways could actually be bridges that have streams or culverts going underneath them or have ditches that would actually direct the flow under or around them. These need to be edited to allow this flow to move through the blockage.
In other cases, there may be natural depressions or artifacts in the DEM that will impede flow. These are visible in the image as smaller pink dots across the landscape. Natural depressions in landscape are common, especially in areas of low relief. These features should be allowed to remain in the model as they provide useful information to watershed planners. Those features that are artifacts are generally small and are not true depressions. These features will not significantly impede the flow and should be allowed to remain in the DEM.
Tool Summary
Input
- Unfilled DEM
Output
- Depth raster (DepthGrid + inHUC)