You may need to manually draw or edit a catchment due to imperfect or incomplete terrain data, preliminary design limitations, etc.

When automated catchment delineation is subsequently used for adjacent catchments, the software will:

1. Prevent overlapping catchments: Automated catchments will respect manually created catchments and not overlap them. Manually created catchments in this case includes those originally created automatically but subsequently manually altered.
2. Protect manually drawn catchments: Manual catchments will not be redrawn when using automated delineation to update catchments.
3. Provide flexibility:
   1. A catchment that has been manually modified can be reset as an automated catchment.
   2. For catch basins with multiple connected catchments, one of these catchments may be automatically delineated, and the rest manual. (This applies to case where there is additional contributing area outside terrain model boundary.)

Catchments can be set to Manual or Automatic using the Delineation Mode property, found in the catchment Property Grid.

This field is automatically set to Automated or Manual based on how catchment created:

For catchments created with automatic delineation, Delineation Type = Automatic.

When a catchment is created manually (i.e., by selecting from the Layout ribbon, importing via ModelBuilder) Delineation Mode = Manual.

You can edit Delineation Type property as desired.

When automated catchment delineation is performed, (including right-click updates), there is no modification to - or overlap with - catchments with Delineation Type = Manual.