Topological Optimization

When a DEM and/or a flow direction map have undefined values, e.g. when there are lakes in the study area, 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.

As input, this operation requires:

• an existing output map of the Drainage Network Extraction operation,
• an existing output map of the Flow Direction operation,
• a segment map with one or more segments that connect the inlet(s) of a lake with the outlet(s) of lake (down flow).

As output, the operation delivers:

• a new continuous drainage network raster map, and
• a new flow direction raster map.

The 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.