When there are lakes in your study area, i.e. when your DEM and/or your flow direction map have undefined values, the Topological Optimization operation can improve the results of a previous Flow direction operation and a Drainage network extraction operation to ensure a proper flow through this lake.
Before you can perform this operation, you must have prepared a segment map in which the segments connect the inlet(s) of a lake with the outlet(s) of lake (down flow).
As output, the operation delivers:
It is advised to perform this operation in two or more steps, for more information, refer to Topological optimization : functionality.
The final output of this operation can serve as a new basis for the other hydrologic operations, e.g. to obtain new Strahler or Shreve order numbers, new catchments etc.
Dialog box options:
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Drainage network map: |
Select an input raster map that contains a basic but incomplete drainage network. The input map should be an output map of a previous Drainage network extraction operation, i.e. a map with system domain Bool. Open the list box and select the desired input map or map list, or directly drag a raster map or map list from a Catalog into this box. |
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Flow direction map: |
Select a raster map that is the output of a previous Flow direction operation. |
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Stream segment map: |
Select a segment map that contains one or more segments which connect the inlet(s) of lake(s) with the outlet(s) of lake(s). You should have prepared this segment map manually and beforehand. |
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Output raster map: |
Type a name for the output raster map that will contain an updated drainage network. |
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Description: |
Optionally, type a description for the output map. The description will appear in the status bar of the Main window when moving the mouse pointer over the map in a Catalog, and in the title bar of a map window when the output map is displayed. If no description is supplied, the output map will use its own definition as description. |
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Modified flow direction map: |
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Type a name for the output raster map that will contain updated flow directions. |
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When you click the Show button, the dependent output map will be defined, calculated and shown. When you click the Define button, the dependent output map will only be defined; if necessary the map will be calculated later, for instance when the map is opened to be displayed.
See also: