III. c. ii. Calculate the Area of the Watershed
             Estimated time:
             2 minutes
The map is now ready to edit. To delineate the watershed manually, we will draw a polygon that represents the area of land contributing to the given downstream pour point. The ‘Delineate Watershed’ layer is currently empty (no features created yet) and was prepared before being added to the map (for details about how to create this layer see the (link below). In this particular watershed, all of the runoff is being stored in a reservoir that has been created by the construction of an earth dam. The dam will be used as our pour point.
In this exercise, you will:
  • Use the Editor to create a polygon feature in ArcMap.
  • Delineate a watershed using contours and a DEM.
  • Save edits that have been made to the map.
  • Adjust the color scheme of a polygon layer.


                                                   Start VideoDemo
Text Version:
    1. Right click “Delineate Watershed” layer → Open Attribute Table

    2. Right click “area” column → Calculate geometry

    3. In “Property” drop down menu, select area

    4. In “Units” drop down menu select “Acres (US)” → OK (the area of the watershed should be around 1525 acres (+/- 10. If not check the watershed outline and adjust accordingly)

    5. Close Attribute Table