Watershed (Ready To Use)

Summary

Determines the contributing area above each input point. A watershed is the upslope area that contributes flow.

Usage

• Tools in the Ready To Use toolbox are ArcGIS Online geoprocessing services that use hosted data and analysis capabilities in ArcGIS Online.

• A watershed feature will be returned for each input point.

• Output watershed features are the complete upstream area that contributes flow. For example, an input point, or pour point, on the Mississippi River in Louisiana will create a watershed feature including areas from New York to Montana into western Canada.

• No watershed feature will be returned if the pour point does not fall within the extent of the specified data source.

• If no point identification field is specified, the unique ID field will be used by default.

• There is limit of 1,000 input point features or 30 minutes per request. If more than 1,000 input features are provided, the service will immediately return and error and stop processing the output. If the run time exceeds 30 minutes, the service will terminate and return an error.

• The pour point identification field must be of type integer or string. It is most useful to use a field consisting of unique values.

• This tool creates an output feature layer containing the watershed polygons. The polygon features layer will contain various fields including the following:

  • PourPtID—The values supplied in the point identification field if specified. If no values are specified, it corresponds to the unique ID field from the input points feature layer.
  • Data Resolution—The resolution of the pre-processed data (in native units) used internally to generate the output.
  • Area Square Kilometers—The area in square kilometers for each watershed.

• The default snapping distance is the resolution of the data in the specified database multiplied by 5.

• The optional output of snapped points contains a PointID field. This field contains the values supplied in the pour point ID field. This is used to relate the input pour points to their watersheds.

• To provide feedback on this service, visit the Hydro forum.

Parameters

Dialog

Label	Explanation	Data Type
Input Points	The point features that will be used for calculating watersheds. These are referred to as pour points, because it is the location where water pours out of the watershed.	Feature Set
Point Identification Field (Optional)	An integer or string field used to identify the input points. The default is to use the unique ID field.	String
Snap Distance (Optional)	The maximum distance the location of an input point will be moved. Interactive input points and documented gage locations may not align exactly with the stream location in the DEM. This parameter allows the service to move the point to a nearby location with the largest contributing area. By default, the snapping distance is calculated as the resolution of the source data multiplied by 5.	String
Snap Distance Units (Optional)	The linear units that will be used for the snap distance. Meters—The units are meters. This is the default. Kilometers—The units are kilometers. Feet—The units are feet. Yards—The units are yards. Miles—The units are miles.	String
Data Source Resolution (Optional)	Specifies the source data resolution that will be used in the analysis. The values are an approximation of the spatial resolution of the digital elevation model used to build the foundation hydrologic database. Since many elevation sources are distributed in units of arc seconds, an approximation is provided in meters for easier understanding. Blank—The hydrologic source, built from a 3-arc second data source, which is approximately 90-meter resolution elevation data, will be used. Finest—The finest resolution available at each location from all possible data sources will be used. This is the default. 10 meters—The hydrologic source, built from a 1/3 arc second data source, which is approximately 10-meter resolution elevation data, will be used. 30 meters—The hydrologic source, built from a 1-arc second data source, which is approximately 30-meter resolution elevation data, will be used. 90 meters—The hydrologic source, built from a 3-arc second data source, which is approximately 90-meter resolution elevation data, will be used.	String
Generalize (Optional)	Specifies whether the output watersheds will be smoothed into simpler shapes or conform to the cell edges of the original DEM. Unchecked—The edges of the polygons will conform to the cell edges of the original DEM. This is the default. Checked—The polygon boundaries will be smoothed into simpler shapes.	Boolean
Return Snapped Points (Optional)	Specifies whether a point feature at the watershed's pour point will be returned. If snapping is enabled, this may not be the same as the input point. Unchecked—No point features will be returned. This is the default. Checked—A point feature will be returned.	Boolean

Derived Output

Label	Explanation	Data Type
Output Watershed	The output watershed.	Feature Set
Output Snapped Points	The output snapped points.	Feature Set

Python

arcpy.agolservices.Watershed(InputPoints, {PointIDField}, {SnapDistance}, {SnapDistanceUnits}, {DataSourceResolution}, {Generalize}, {ReturnSnappedPoints})

Name	Explanation	Data Type
InputPoints	The point features that will be used for calculating watersheds. These are referred to as pour points, because it is the location where water pours out of the watershed.	Feature Set
PointIDField (Optional)	An integer or string field used to identify the input points. The default is to use the unique ID field.	String
SnapDistance (Optional)	The maximum distance the location of an input point will be moved. Interactive input points and documented gage locations may not align exactly with the stream location in the DEM. This parameter allows the service to move the point to a nearby location with the largest contributing area. By default, the snapping distance is calculated as the resolution of the source data multiplied by 5.	String
SnapDistanceUnits (Optional)	The linear units that will be used for the snap distance. Meters—The units are meters. This is the default. Kilometers—The units are kilometers. Feet—The units are feet. Yards—The units are yards. Miles—The units are miles.	String
DataSourceResolution (Optional)	Specifies the source data resolution that will be used in the analysis. The values are an approximation of the spatial resolution of the digital elevation model used to build the foundation hydrologic database. Since many elevation sources are distributed in units of arc seconds, an approximation is provided in meters for easier understanding. Blank—The hydrologic source, built from a 3-arc second data source, which is approximately 90-meter resolution elevation data, will be used. FINEST—The finest resolution available at each location from all possible data sources will be used. This is the default. 10m—The hydrologic source, built from a 1/3 arc second data source, which is approximately 10-meter resolution elevation data, will be used. 30m—The hydrologic source, built from a 1-arc second data source, which is approximately 30-meter resolution elevation data, will be used. 90m—The hydrologic source, built from a 3-arc second data source, which is approximately 90-meter resolution elevation data, will be used.	String
Generalize (Optional)	Specifies whether the output watersheds will be smoothed into simpler shapes or conform to the cell edges of the original DEM. True—The polygon boundaries will be smoothed into simpler shapes. False—The edges of the polygons will conform to the cell edges of the original DEM. This is the default.	Boolean
ReturnSnappedPoints (Optional)	Specifies whether a point feature at the watershed's pour point will be returned. If snapping is enabled, this may not be the same as the input point. True—A point feature will be returned. False—No point features will be returned. This is the default.	Boolean

Derived Output

Name	Explanation	Data Type
WatershedArea	The output watershed.	Feature Set
SnappedPoints	The output snapped points.	Feature Set

Environments

This tool does not use any geoprocessing environments.