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How To: Find sinks and internal drainage areas using elevation data

Summary

Instructions provided describe how to find sinks and internal drainage areas using elevation data.

Procedure

Before using the Hydrology toolset, a surface raster is needed. If only contours or a TIN are available, they will need to be converted to a raster, using either the Topo to Raster tool or the TIN to Raster tool.

Note:
The 3D Analyst extension is required to use the TIN to Raster tool. The Spatial Analyst extension is required to use the Topo to Raster tool, as well as the hydrology tools used in the methodology described below.


Once a surface raster is available, proceed to steps 1 and 2.

  1. Create a flow direction raster (Spatial Analyst > Hydrology > Flow Direction).
    [O-Image] Flow Direction tool
  2. Create a sink raster (Spatial Analyst > Hydrology > Sink).
    [O-Image] Sink Tool

    The output is a raster with a unique value assigned to each sink. Sinks are numbered between one and the total number of sinks.

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