20240220 10410900 1.0 TRUE Adams_STWI.tif GIS raster dataset displaying Topographic Wetness Index (TWI) for south Adams County, PA. This TWI raster was derived from the 2006-08 PAMAP LiDAR DEM data. The TauDEM extension (D-Infinity tools) for ArcMap was used to create flow direction, slope, and contributing area rasters. TWI was then calculated using the following equation: Ln (Contributing Area/Slope). The methodology was described by Cody Fink in his 2013 thesis entitled Dynamic Soil Property Change in Response to Natural Gas Development in Pennsylvania. TWI results in a dimesionless raster and should be displayed using a red (low values representing no flow) to blue (high, representing high probability flowpaths) color gradient. TWI results vary depending on raster size and analysis options so value thresholds for probability-based overland flowpaths for water should be field verified. Jamie Shallenberger, SRBC, and Cody M. Fink.