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Sink

Available with Spatial Analyst license.

Summary

Creates a raster identifying all sinks or areas of internal drainage.

Learn more about how Sink works

Usage

  • A sink is a cell or set of spatially connected cells whose flow direction cannot be assigned one of the eight valid values in a flow direction raster. This can occur when all neighboring cells are higher than the processing cell or when two cells flow into each other, creating a two-cell loop.

  • The Sink tool only supports a D8 input flow direction raster. D8 flow directions can be created using the Flow Direction tool, run with default flow direction type D8.

  • The output of the Sink tool is an integer raster with each sink being assigned a unique value. Sinks are numbered between one and the number of sinks.

  • This tool supports parallel processing. If your computer has multiple processors or processors with multiple cores, better performance may be achieved, particularly on larger datasets. The Parallel processing with Spatial Analyst help topic has more details on this capability and how to configure it.

    When using parallel processing, temporary data will be written to manage the data chunks being processed. The default temp folder location will be on your local C drive. You can control the location of this folder by setting up a system environment variable named TempFolders and specifying the path to a folder to use (for example, E:\RasterCache). If you have admin privileges on your machine, you can also use a registry key (for example, [HKEY_CURRENT_USER\SOFTWARE\ESRI\ArcGISPro\Raster]).

    By default, this tool will use 50 percent of the available cores. If the input data is smaller than 5,000 by 5,000 cells in size, fewer cores may be used. You can control the number of cores the tool uses with the Parallel processing factor environment.

  • See Analysis environments and Spatial Analyst for additional details on the geoprocessing environments that apply to this tool.

Syntax

Sink (in_flow_direction_raster)
ParameterExplanationData Type
in_flow_direction_raster

The input raster that shows the direction of flow out of each cell.

The flow direction raster can be created using the Flow Direction tool, run using the default flow direction type D8.

Raster Layer

Return Value

NameExplanationData Type
out_raster

The output raster that shows all the sinks (areas of internal drainage) on the input surface.

This output is of integer type.

Raster

Code sample

Sink example 1 (Python window)

This example identifies the sinks on an input flow direction Grid raster.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outSink = Sink("flowdir")
outSink.save("C:/sapyexamples/output/outsink01")
Sink example 2 (stand-alone script)

This example identifies the sinks on an input flow direction Grid raster.

# Name: Sink_Ex_02.py
# Description: Creates a raster identifying all sinks or areas of internal drainage.
# Requirements: Spatial Analyst Extension

# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *

# Set environment settings
env.workspace = "C:/sapyexamples/data"

# Set local variables
inFlowDirectionRaster = "flowdir"

# Execute FlowDirection
outSink = Sink(inFlowDirectionRaster)

# Save the output 
outSink.save("C:/sapyexamples/output/outsink02")

Licensing information

  • ArcGIS Desktop Basic: Requires Spatial Analyst
  • ArcGIS Desktop Standard: Requires Spatial Analyst
  • ArcGIS Desktop Advanced: Requires Spatial Analyst

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