I'm a GIS specialist with a good background in watershed hydrology and geomorphology theories. In a project, I should analyse coastal and inland catchments separately. I have some neighbourhood coastal catchments and want to use archydro tool in ArcGIS to create flow accumulation.
In the archydro manual, esri suggested the users append coastal catchments (Overview of archydro terrain preprocessing workflows Page 8 of 13):
Append Coastal Catchments. This is an optional step that should be done for larger DEM with a large portion of coastal areas – areas defined as not draining into the “streams”. This function defines coastal catchments and appends them to the catchment feature class.
Why a user should append coastal catchments while the catchments logically have separate drainage area.
Thanks for advanced