Equal area catchment delineation

[toddsams]

Hello,

Does anyone know how I might be able to generate a catchment grid/polygons such that each catchment is equal in area?

Typically, a flow accumulation threshold is set to initiate a stream grid and all other catchments are delineated based on stream junctions. This results in different sized catchments.

Might there be a method to generate a new catchment for equal drainage area intervals?

Todd

[ChristineDartiguenave]

You could use the flow accumulation grid to identify the cells that are a multiple of the number of cells you would like to have in each catchment, and then perform a subwatershed delineation on all these points at once. The issue however is dealing with confluences. There are going to be some jumps in the flow accumulation sequences so you will not be able to get exactly the same areas and may need to some editing to identify the locations of the points to use.

Christine Dartiguenave
Esri Water Resources Team

[toddsams]

Thanks Christine.

Wouldn't this create overlapping watersheds? I am hoping to generate equal/similar area catchments similar to how ArcHydro Tools generates catchments. The polygons that result from Catchment Delineation in ArcHydro Tools do not overlap.

The limitation of ArcHydro Tools is that catchments are delineated at each confluence. This results in many small sliver catchments. I would like to generate catchments that are similarly sized, analogous to how USGS HUC boundaries are represented.

[ChristineDartiguenave]

If you use subwatershed delineation with all input points the resulting subwatersheds will not overlap.

Christine Dartiguenave
Esri Water Resources Team

[toddsams]

My study area is very large and many of my target fac values are "skipped" at flow junctions. Hand editing all of these missing points is unreasonable given the extent of my study region.

Any other suggestions for obtaining roughly equivalent catchment areas using Hydro Tools?