There is not a direct way to find the area for each of the catchment basins in a watershed map. To add your request to our suggestion file for this feature, please email us at surfersupport@goldensoftware.com

However, there is a workaround. The simplest workflow for determining the area of each watershed basin would be to export the watershed layer to GSB (or any vector file format) and then import the GSB file back into Surfer as a base map.  The area for each polygon can then be found on the Info page in the Properties window. 

The steps required for this workflow are provided below:

1. In the Contents window, uncheck the box next to each axis and any other map layer besides the Watershed layer.  Only the watershed layer should be visible on the page.
2. Click the File | Export command.
3. In the Export dialog, change the Save as type field to GSB Golden Software Boundary (*.gsb).
4. Enter a name for the file and click Save.
5. In the Export Options dialog, ensure the Scaling source is set to Map.
6. Click OK to complete the export.
7. If needed, click the Map to select it.
8. Click the Home | Add to Map | Layer | Base command.
9. In the Import dialog, select the GSB file and click Open.
10. If a Surfer Warning dialog appears asking if you want to expand the map limits, click No.
11. In the Contents window, expand the Base(vector) layer and click on one of the polygons.
12. In the Properties window, click the Info tab.
13. The Perimeter and Area are both listed in the Geometry section. Make sure the Coordinate system is set to Map, so that the units are in map units.

If you wish to add the perimeter and area of all the basins to the Attribute Table (which can then be exported to a file, you can follow these steps in addition to the steps above:

1. In the Contents window, click the Base(vector) layer to select it.
2. Click Map Tools | Layer Tools | Open Attribute Table
3. In the Attribute Table, click the Add Geometry Attributes button.
4. Check the geometry attributes you would like added (Perimeter & Area)

      5. Choose the units you would like the geometry added in.

      6. Click OK and the geometries for each object are added to the Attribute Table.

Updated November 18, 2021