WMS:Mapping Tables: Difference between revisions

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A '''mapping table''' or '''map table''' is used by WMS to link values within a project. There are multiple ways this can be accomplished:
A '''mapping table''' or '''map table''' is used by WMS to link values within a project. There are multiple ways this can be accomplished:
*For [[WMS:GSSHA|GSSHA]], WMS assign model parameter values to grid cells by linking parameter values to index maps.  
*For distributed models, WMS assign model parameter values to grid cells by linking parameter values to index maps. See [[WMS:WMS Supported File Formats|File Formats]] for the different mapping parameters. The [https://gsshawiki.com/Mapping:Mapping_tables GSSHA Wiki] also discusses this.
*For [[WMS:GIS|GIS]], this is done by creating a lumped average based on the percentages of land use values or soil types within a basin.
*For lumped parameter models, a lumped average (or area-weighted average) is created based on the percentages of land use values or soil types within a basin. A mapping table must be imported prior to computing the composite curve numbers. For a [[WMS:Land Use|land use]] or [[WMS:Soil|soil type coverage]], the mapping table may be set up interactively by selecting each polygon and assigning the appropriate parameters. The [[WMS:Compute GIS Attributes|''Compute GIS Attributes'' dialog]] then uses the mapping tables created using those coverages, or manually via a text file.  


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This can be done with either a lumped average or This is used for [[WMS:Land Use|Land Use coverages]] and [[WMS:Soil|Soil Type coverages]].
different depending on whether composite curve numbers or runoff coefficients are being computed. A mapping table must be imported using the '''Import''' button prior to computing the composite curve numbers. The radio group above the mapping window specifies whether the land use or soil type mapping table is displayed. For a land use or soil type coverage the mapping table may be set up interactively by selecting each polygon and assigning the appropriate parameters. Such files can then be exported and later imported. For grid attributes, define a land use or soil type table by defining a land use or soil type coverage and then using the '''Attributes''' command from the ''Feature Objects'' menu (in the Map module) to define individual polygon attributes that constitute the table. See [[WMS:Land Use|Land Use coverages]] and [[WMS:Soil|Soil Type coverages]] for information on assigning parameters to land use and soil type polygon coverages. See [[WMS:WMS Supported File Formats|File Formats]] for the different mapping parameters.
==Composite CN Table==
Because land use tables with corresponding CNs vary from text to text and agency to agency, WMS supports a user definable method for relating land use to CNs. This is done through a simple table file that is imported prior to computing the composite CN. The file scsland.tbl is an example of such a file and was created from a table given in the [[WMS:References#Handbook of Hydrology|Handbook of Hydrology]]. This file can be edited to supply user defined values or a new table with the same format can be created. See [[WMS:Land Use Files|Land Use Files]] to view the format of the table.
==Runoff Coefficient Table==
{{main|WMS:Soil Type Runoff Coefficient Files}}
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==Related Topics==
==Related Topics==
* [[WMS:Compute GIS Attributes|Compute GIS Attributes]]
* [[WMS:Land Use|Land Use]]
* [[WMS:Land Use|Land Use]]
* [[WMS:Soil Type|Soil Type]]
* [[WMS:Soil Type|Soil Type]]
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[[Category:WMS Map|T]]
[[Category:WMS Map|T]]
[[Category:External Links]]

Revision as of 21:55, 18 December 2019

A mapping table or map table is used by WMS to link values within a project. There are multiple ways this can be accomplished:

  • For distributed models, WMS assign model parameter values to grid cells by linking parameter values to index maps. See File Formats for the different mapping parameters. The GSSHA Wiki also discusses this.
  • For lumped parameter models, a lumped average (or area-weighted average) is created based on the percentages of land use values or soil types within a basin. A mapping table must be imported prior to computing the composite curve numbers. For a land use or soil type coverage, the mapping table may be set up interactively by selecting each polygon and assigning the appropriate parameters. The Compute GIS Attributes dialog then uses the mapping tables created using those coverages, or manually via a text file.

Related Topics