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Service Description: The TWI is a physically based index or indicator of the effect of local topography on runoff flow direction and accumulation. The index is a function of both the slope and the upstream contributing area.The computation of TWI is performed using both geographic information systems (GIS) and Python, a programing software used to enhance computing capabilities. The indices help identify rainfall runoff patterns, areas of potential increased soil moisture, and ponding areas. Illinois State Water Survey generated the index to the Illinois counties of DuPage and Will (see report at http://hdl.handle.net/2142/98495), but has subsequently generated the index for all Illinois counties. The DEM used for this county was derived from LiDAR acquired in 2017. While TWI is usually viewed in raster format, ISWS is distributing a version in polygon format for easier access and use.

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Service Item Id: 89c579d040a4452f9bf3f73eabb4cfa3

Copyright Text: Gewalt Hamilton Associates, Inc.

Spatial Reference: 103037  (6455)  LatestVCSWkid(0)


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Spatial Reference: 103037  (6455)  LatestVCSWkid(0)

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Spatial Reference: 103037  (6455)  LatestVCSWkid(0)

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Supported Image Format Types: PNG32,PNG24,PNG,JPG,DIB,TIFF,EMF,PS,PDF,GIF,SVG,SVGZ,BMP

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Comments: The TWI is a physically based index or indicator of the effect of local topography on runoff flow direction and accumulation. The index is a function of both the slope and the upstream contributing area.The computation of TWI is performed using both geographic information systems (GIS) and Python, a programing software used to enhance computing capabilities. The indices help identify rainfall runoff patterns, areas of potential increased soil moisture, and ponding areas. Illinois State Water Survey generated the index to the Illinois counties of DuPage and Will (see report at http://hdl.handle.net/2142/98495), but has subsequently generated the index for all Illinois counties. The DEM used for this county was derived from LiDAR acquired in 2017. While TWI is usually viewed in raster format, ISWS is distributing a version in polygon format for easier access and use.
Subject: Topographic Wetness Index
Category:
Keywords: Wetness,Index,TWI
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Supported Query Formats: JSON, geoJSON, PBF

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Supports Datum Transformation: true



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