You can create a catchment based on the terrain of a specified surface.
The catchment's flow path can be created at the same time you create the catchment. It is drawn between the specified discharge point and the hydraulically most distant point that is calculated.
The flow path is created using the settings specified in the CreateCatchmentsFromSurfaces command settings.
The Create Catchment From Surface command only creates areas flowing to a point. For catchment areas flowing to a boundary, use the Create Catchment From Object command.
If the input parameters result in a valid catchment, the catchment is created in the drawing using the specified catchment style.
If the input parameters do not result in a valid catchment or flow path, the AutoCAD Text Window may display the following errors:
Issue | Solution |
---|---|
A catchment is not created for the selected discharge point The specified location results in a catchment with no area |
The calculation algorithm used may not result in a valid catchment for each selected discharge point. In order for this command to produce a catchment area, the surface triangle edges must form a channel that slopes toward the discharge point. It may be useful to run the Water Drop command and find a path that runs close to a location of interest, such as a location where you might want a catch basin or grate. Selecting a point along the path as the discharge point will typically yield a catchment area. If the command encounters a "flat edge" or small aberration that conflicts with the general trend of the surface leading to the discharge point, it will stop and a catchment will not be created. If the Create Catchment From Surface command does not work for a particular point, you may need to manually draw a polyline and use the Create Catchment From Object command. This may be the case if you are trying to get an area that flows to a property line or wetland boundary. |