How To: Identify ridgelines from a DEM

Summary

The instructions provided describe how to identify ridgelines from a DEM. Spatial Analyst and the Hydrology Toolset can be used to identify and extract ridgeline features from an elevation raster (DEM) in the same manner as a stream network can be created by reversing the DEM cell values.

Procedure

This workflow uses Map Algebra and the Hydrology Toolset to derive ridgeline features from a DEM.

Fill the DEM using the Fill tool in the Hydrology Toolset.

Note:
For more information on the Fill tool read Creating a depressionless DEM.

Switch the high/low values in the Fill DEM by using the Raster Calculator to multiply the Fill DEM by -1.
Run the Flow Direction tool using the output raster from step 2 as the 'Input surface raster' and checking 'Force all edge cells to flow outward'.
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Note:
For more information on this tool read Flow Direction (Spatial Analyst).
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Run the Flow Accumulation tool using the output raster from step 3 as the 'Input flow direction raster'.

• Make sure to set the output data type to Integer, rather than Float.
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Flow Accumulation tool
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Note:
For more information on this tool read Flow Accumulation (Spatial Analyst).
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Set the Flow Accumulation threshold and create the stream network raster using the Raster Calculator.

For 9.3.1:

For 10.0:
Create a Stream Order raster using the stream network raster (step 5) for the 'Input steam raster' and the Flow Direction raster (step 3) for the 'Input flow direction raster'.
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Note:
For more information on this tool read Stream Order (Spatial Analyst).
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Create a ridgeline shapefile by running the Stream to Feature tool with the Stream Order raster as the 'Input stream raster'.
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Note:
For more information on this tool read Stream to Feature (Spatial Analyst).
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Last Published: 5/5/2016

Article ID: 000011289