Watershed Segmentation is the process of dividing a basin into several sub-basins. While calculate watershed basin can obtain larger basins, practical analysis may require dividing larger basins into smaller ones (called sub-basins).

Feature Description

The first step in determining a basin is to identify its pour point. Similarly, watershed also requires identifying pour points for sub-basins. Unlike calculate watershed basin, pour points for sub-basins can be located either on the raster boundary or within the raster. Therefore, the pour point data for watershed can be either the raster data obtained from calculate pour point, or use 2D point datasets representing pour points to divide basins.

Feature Entry

• Spatial Analysis Tab -> Raster Analysis Group -> Hydrology -> Watershed.
• Toolbox -> Raster Analysis -> Hydrology -> Watershed.

Parameter Description

• Flow Direction Data: Select the datasource and dataset containing the direction raster.
• Pour Point Data: Select the datasource and dataset containing the pour point data. The pour point data can be either the calculated pour point raster data or field-collected point datasets.

  Note: The basins extracted by watershed correspond to pour points. If the accumulated water volume of some basins does not meet the set threshold for pour point extraction, these catchments will not appear in the watershed results. Therefore, the watershed results may not cover the entire DEM extent. To obtain basin results covering the full analysis bounds, use calculate watershed basin.

• Filter: Only valid for 2D pour point data. Set filter expressions to select pour points participating in watershed analysis.
• Result Data: Set the datasource name and dataset name for saving results.
• Click the Execute button to perform the prepared analysis. After the execution is completed, the output window will indicate whether the result succeeded or failed.