The Create Watersheds tool creates water catchment areas for each point in an input layer.
The Nova Scotia Salmon Association is attempting to increase Atlantic salmon populations by improving habitat connectivity in areas with hydroelectric dams. The Create Watersheds tool is used to determine how much habitat is made accessible with the construction of a fishway at a chosen dam.
Many storm drains are connected to rivers, lakes, oceans, or other waterways, making anything entering the drain a potential pollutant for areas downstream. The Create Watersheds tool can be used to determine where the water entering a storm drain comes from.
A single input of point features is required. The points can be loaded through the input drop-down menu or created using the Draw tool. A watershed will be calculated for each point.
Use Search distance to nearest drainage to correct points that are not located directly on a drainage line. Distances can be measured in Miles, Yards, Feet, Kilometers, or Meters. To use the exact location of your input points, specify a search distance of zero.
The results are two layers containing the watersheds and the adjusted input points. The watershed layer will contain the same attributes as the points and four additional fields:
- PourPtID—The unique ID field from the input points feature.
- Area Square Kilometers or Area Square Miles—The area of the watershed. The units of the area field will depend on the Units setting on your profile.
- Description—Describes the source database used in the analysis. US30m, which is derived from the 30m NHDPlusV2.1 for the continental United States, and the 90m HydroSHEDS for the world between 60 degrees North and 56 degrees South, plus some areas in Canada and Alaska north of 60 degrees.
- DataResolution—The data source resolution that was used in the analysis.
If Use current map extent is checked, only the features in the current map extent will be used to compute watersheds. If unchecked, all features in the input layer will be analyzed, even if they are outside the current map extent.
- The input must be point features.
- You must be granted the elevation analysis privilege to use Create Watersheds.
How Create Watersheds works
The Create Watersheds tool uses a hosted digital elevation model (DEM) to create water catchment areas. The resolution of the DEM used depends on the location of the analysis and will be recorded in the DataResolution field of the result layer.
For the result watersheds to be relevant, the input points must be located on drainage lines. The Search distance to nearest drainage option will move the input points to the nearest drainage line within the search distance. If you do not specify a search distance, the tool will compute and use a conservative search distance.
For analysis purposes, drainage lines have been precomputed by Esri using standard hydrologic models. If there is no drainage line within the search distance, the location containing the highest flow accumulation within the search distance is used.
Use Create Watersheds to determine the upstream contributing area, or watershed, based on one or more points along drainage lines. Other tools may be useful in solving similar but slightly different problems.
Map viewer analysis tools
If you are trying to determine the flow path downstream from your points, use the Trace Downstream tool.