WMS:Computing Flow Data with TOPAZ: Difference between revisions

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This command will save the current DEM elevations to a TOPAZ formatted input file along with a TOPAZ control file and then start the TOPAZ program. When TOPAZ is finished WMS will automatically read the flow directions (FLOVEC.DAT) and flow accumulations (UPAREA.DAT) computed by [[WMS:TOPAZ|TOPAZ]].
#REDIRECT [[WMS:TOPAZ]]
 
Because WMS is communicating with TOPAZ through disk files you must specify the directory where WMS/TOPAZ perform this interaction. If your specified directory has an unusually long name TOPAZ may have some difficulties. In such cases you will want to specify a directory with a shorter character string length.
 
TOPAZ assumes that all depressions are a function of a lack of resolution in the DEM data and therefore it is not possible to delineate the watershed of a closed basin unless you identify the DEM cell of a natural depression to be a Depression Point from the [[WMS:DEM Point Attributes|DEM Point Attributes]].
 
TOPAZ also creates a file named RELIEF.DAT that has the elevations of the depressionless or filled DEM. TOPAZ (and most grid-based delineation algorithms) assumes that any depression in the DEM is a result of inadequate resolution and not a natural depression. This is true for most depressions, but means that basins for natural depressions cannot be determined. However, with WMS you can define a low point in a natural depression as such and then WMS will flag it so that TOPAZ does not fill the depression and the drainage computed. This is done using the [[WMS:DEM Point Attributes|DEM Point Attributes]] dialog prior to running TOPAZ.
 
==Related Topics:==
* [[WMS:DEM Point Attributes|DEM Point Attributes]]
* [[WMS:TOPAZ|TOPAZ]]
* [[WMS:Importing Flow Directions and Accumulations|Flow Directions/Accumulations]]
* [[WMS:DEM Guidelines|Watershed Delineation with DEMs ]]
 
 
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[[Category:DEMs]][[Category:TOPAZ]]

Latest revision as of 20:08, 26 July 2013

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