PSU DEP Topographic Wetness Index (TWI) 2020


Identification_Information:
Citation:
Citation_Information:
Originator:Pennsylvania State University
Title:
PSU DEP Topographic Wetness Index (TWI) 2020
Geospatial_Data_Presentation_Form:raster digital data
Online_Linkage: http://www.pasda.psu.edu/
Description:
Abstract:
GIS raster datasets displaying Topographic Wetness Index (TWI) for Pennsylvania by County. TWI raster datasets were derived from 2006-2008 LiDAR (Light Detection and Ranging) elevation points produced by the PAMAP Program. The coordinate system for blocks in the northern half of the state is Pennsylvania State Plane North (datum: NAD83, units: feet); blocks in the southern half are in Pennsylvania State Plane South. Raster spatial resolution is 9.6 ft (approximately 3 m). The TWI, also called Compound Topographic Index (CTI) or Topographic Convergence Index (TCI), is a hydrological-based topographic index that describes the tendency of a cell or area to accumulate and retain water under steady-state conditions. TWI is defined as Ln(Contributing Area/Slope angle).It balances contributing areas capturing the tendency to receive water versus slope angles capturing the tendency to evacuate water. An automated procedure was developed in ArcMap. for the TWI computation. Contributing areas (i.e. cumulative contributing area per unit contour length) were determined based on the D-Infinity model proposed by Tarboton, D. (1997). Lengths were measured considering cell size and whether the direction is adjacent or diagonal. Land surface slope was computed using the Horns method. 
The project was funded by the Pennsylvania Department of Environmental Protection (PADEP) through its Water Program. August 2020.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date:2020
Status:
Progress:Complete
Maintenance_and_Update_Frequency:None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate:-78.399277
East_Bounding_Coordinate:-77.126196
North_Bounding_Coordinate:41.264517
South_Bounding_Coordinate:40.686319
Keywords:
Theme:
Theme_Keyword_Thesaurus:ISO 19115 Topic Categories
Theme_Keyword:geoscientificInformation
Theme_Keyword:imageryBaseMapsEarthCover
Theme_Keyword:inlandWaters
Access_Constraints:None
Use_Constraints:
None
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Department of Geography. Pennsylvania State University
Contact_Electronic_Mail_Address:cxf31@psu.edu
Native_Data_Set_Environment:
Version 6.2 (Build 9200) ; Esri ArcGIS 10.3.1.4959
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Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method:Raster
Raster_Object_Information:
Raster_Object_Type:Grid Cell
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Lambert_Conformal_Conic:
Standard_Parallel:40.88333333333333
Standard_Parallel:41.95
Longitude_of_Central_Meridian:-77.75
Latitude_of_Projection_Origin:40.16666666666666
False_Easting:1968500.0
False_Northing:0.0
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method:coordinate pair
Coordinate_Representation:
Abscissa_Resolution:0.000000026822588594654923
Ordinate_Resolution:0.000000026822588594654923
Planar_Distance_Units:foot_us
Geodetic_Model:
Horizontal_Datum_Name:D North American 1983
Ellipsoid_Name:GRS 1980
Semi-major_Axis:6378137.0
Denominator_of_Flattening_Ratio:298.257222101
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Pennsylvania Spatial Data Access (PASDA)
Contact_Address:
Address_Type:mailing address
Address:
115 Land and Water building
City:University Park
State_or_Province:Pennsylvania
Postal_Code:16802
Country:United States
Contact_Voice_Telephone:(814) 865 - 8792
Contact_Electronic_Mail_Address:pasda@psu.edu
Distribution_Liability:
The USER shall indemnify, save harmless, and, if requested, defend those parties involved with the development and distribution of this data, their officers, agents, and employees from and against any suits, claims, or actions for injury, death, or property damage arising out of the use of or any defect in the FILES or any accompanying documentation. Those parties involved with the development and distribution excluded any and all implied warranties, including warranties or merchantability and fitness for a particular purpose and makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided "as is" and the USER assumes the entire risk as to its quality and performance. Those parties involved with the development and distribution of this data will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation.
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Metadata_Reference_Information:
Metadata_Date:20200916
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Pennsylvania Spatial Data Access (PASDA)
Contact_Address:
Address_Type:mailing and physical address
Address:
115 Land and Water building
City:University Park
State_or_Province:Pennsylvania
Postal_Code:16802
Country:United States
Contact_Voice_Telephone:(814) 865 - 8792
Contact_Electronic_Mail_Address:pasda@psu.edu
Metadata_Standard_Name:FGDC Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version:FGDC-STD-001-1998
Metadata_Time_Convention:local time
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