In my watershed I have around 400 basins. I need to find the max flow length in each basin. The "Flow Length" tool creates the flow length for the entire watershed, not for each individual basin.

Is there a way to clip the flow direction raster by using the basins or is there a better workflow?

I am using ArcGIS Pro and I have a Spatial Analyst license.


2 Answers 2


An alternative workflow is to turn your stream network into a polyline dataset and your basins into polygons then its a simple Intersect. The Intersection will cut up the network and assign the basin ID. I would then run a summary statistics grouping by basin ID and summing length.


You could create a tool in modelbuilder:

Add iterator: Iterate through features in ‘basin’ feature class:

Tool - Extract by mask (Input: DEM / 'basin' selection as feature mask / Output:%Name%_DEM)

Tool - Flow Length (Input: %Name%_DEM / Output: %Name%_FlowLength / 'Upstream')

Tool - Mosaic to New Raster (Input Rasters: all %Name%_DEMs)

Result would be a raster with flow lengths limited to the boundaries of each basin.

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