Modeled flowpaths for Pennsylvania Hydrography Dataset (PAHD) - Allegheny County


Identification_Information:
Citation:
Citation_Information:
Originator:Pennsylvania Bureau of Geological Survey , Department of Conservation and Natural Resources
Publication_Date:20230920
Title:
Modeled flowpaths for Pennsylvania Hydrography Dataset (PAHD) - Allegheny County
Geospatial_Data_Presentation_Form:vector digital data
Other_Citation_Details:
Suggested citation: Fehrs, E. R., 2023, Modeled PAHD for Allegheny County: Pennsylvania Geological Survey, 4th ser., DR 23-02.0, scale 1:2,400, geodatabase.
Description:
Abstract:
The Modeled_PAHD_Flowpath geometries are the result of a conflation study that incorporated elevation data and preexisting hydrography. These geometries were produced using QL2 lidar deliverables (published in 2020) and preexisting elevation-derived hydrography that had also been generated from QL2 lidar deliverables (published in 2015). The workflow involved four main steps: (1) use the most recently available QL2 lidar to create a geomorphon derivative delineating channelized structures identified from the elevation surface, (2) compare the monotonicity of these channelized features with equivalent geometries in the 2015 Allegheny County Hydrography Dataset to evaluate which feature better conformed to the elevation surface, (3) use a TPI product to better winnow out "false channels" picked up in heavily urbanized areas, and (4) ultimately use monotonicity values to evaluate the legitimacy of all geometries.This workflow has a number of weaknesses; for instance, it is nearly impossible to winnow out channelizations adjacent to road features based on elevation characteristics of these lines. The Pennsylvania Bureau of Geological Survey (PaGS) therefore does not recommend using these geometries as a cartographic product without a manual review of the geometries. Please reach out to PaGS if you would like to provide critique of techniques used or this product, or you would like to learn more about the developing PAHD workflow.
Purpose:
An intermediate product of the Pennsylvania Hydrography Dataset (PAHD) generation. This product is the result of a conflation study with existing hydrography originated by the Allegheny County Division of Computer Services Geographic Information Systems Group. This product is not intended to be a finalized component of the Pennsylvania Hydrography Dataset (PAHD): these are provisional data that have undergone no manual refinement. The Modeled_PAHD_Flowpath geometries represent an intermediate product that was created from a workflow that was examining, among other things, the application of conflation steps, monotonicity, and Topographic Positioning Index (TPI) products toward an automated elevation-derived hydrography (EDH) workflow.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date:20230920
Currentness_Reference:
publication date
Status:
Progress:Complete
Maintenance_and_Update_Frequency:As needed
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate:-80.379012
East_Bounding_Coordinate:-79.642261
North_Bounding_Coordinate:40.693548
South_Bounding_Coordinate:40.181714
Keywords:
Theme:
Theme_Keyword_Thesaurus:None
Theme_Keyword:hydrography, elevation-derived hydrography, EDH, conflation, flowpaths, Allegheny County, lidar, Pennsylvania
Theme:
Theme_Keyword_Thesaurus:ISO 19115 Topic Categories
Theme_Keyword:boundaries
Theme_Keyword:elevation
Theme_Keyword:inlandWaters
Place:
Place_Keyword_Thesaurus:None
Place_Keyword:Allegheny County, Pennsylvania, Pittsburgh
Access_Constraints:None
Use_Constraints:
The provisional data contained in the geodatabase may be used provided that credit for the original (unaltered) data is given to the Pennsylvania Bureau of Geological Survey, Department of Conservation and Natural Resources. Users shall clearly indicate the source of the data. Users who modify the data in any way are obligated to describe the types of modifications they have made. Users are not to misrepresent this Pennsylvania Bureau of Geological Survey (or PaGS) data, nor to imply that changes they (users) have made were approved by the PaGS.These data are public information and, as such, the data may be used as a reference source and may be interpreted by organizations, agencies, units of government, or others based on needs; however, each user is responsible for the appropriate application of the data. Federal, state, or local regulatory bodies are not to reassign to PaGS any authority for the decisions they make using these data.The data are not meant for site-specific analysis at scales finer (i.e., larger, more detailed) than 1:2,400. Users are not to misrepresent the data by presenting it at scales for which it is not intended, nor to imply that presentation at such scales is approved by the PaGS.Not for commercial resale.Distribution LiabilityThese data files and accompanying documentation are provided "as is," and the user assumes the entire risk as to their quality and performance.The Commonwealth of Pennsylvania makes no guarantee or warranty concerning the accuracy of information contained in the geographic data or accompanying documentation. The Commonwealth of Pennsylvania further makes no warranties, either expressed or implied, as to any other matter whatsoever, including, without limitation, the completeness or condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user.Although these data have been processed successfully on a computer system at the Department of Conservation and Natural Resources, the Commonwealth of Pennsylvania makes no warranty, expressed or implied, regarding the use of the data files or accompanying documentation on any other computer system, nor does the act of distribution constitute any such warranty.Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the Commonwealth of Pennsylvania government or any agency thereof.The user shall save the Commonwealth of Pennsylvania harmless and indemnify it from any suits, claims, or actions arising out of the use of or any defect in the data files or accompanying documentation. The Commonwealth of Pennsylvania assumes no legal liability for the accuracy, completeness, or usefulness of the data files and accompanying documentation. In no event shall the Commonwealth of Pennsylvania have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the geographic data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Department of Conservation and Natural Resources
Contact_Person:Pennsylvania Bureau of Geological Survey
Contact_Address:
Address_Type:mailing and physical
Address:
3240 Schoolhouse Rd
City:Middletown
State_or_Province:PA
Postal_Code:17057
Country:US
Contact_Voice_Telephone:717-702-2017
Contact_Electronic_Mail_Address:RA-NR-TOPO_MAINDESK@pa.gov
Data_Set_Credit:
Conflation dataset generation and preparation--Ellen R. Fehrs, Pennsylvania Bureau of Geological Survey
Native_Data_Set_Environment:
Version 6.2 (Build 9200) ; Esri ArcGIS 10.8.1.14362
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Data_Quality_Information:
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator:Allegheny County Division of Computer Services Geographic Information Systems Group
Title:
Allegheny County Lidar and Terrain Products (2017)
Online_Linkage: https://www.pasda.psu.edu/download/alleghenycountyimagery2017/
Type_of_Source_Media:onLine
Source_Citation_Abbreviation:
Allegheny County Lidar and Terrain Products (2017)
Source_Contribution:
Hydrography deliverables produced from QL2 lidar flown by Pictometry in 2015. Products used in the creation of Modeled PAHD Flowpaths include the county-commissioned hydrography geometries (Breakline_ArtificialPaths, Breakline_Culverts, and Breakline_StreamCenterlines) overlying the study area.
Source_Information:
Source_Citation:
Citation_Information:
Originator:Allegheny County Division of Computer Services Geographic Information Systems Group
Title:
Pennsylvania Western Lidar 2020 QL2; DEM - South
Online_Linkage: https://www.pasda.psu.edu/download/usgs/LiDAR2020/By_County/Bare_Earth_DEM/Mosaic/
Type_of_Source_Media:onLine
Source_Citation_Abbreviation:
Pennsylvania Western Lidar 2020 QL2; DEM - South
Source_Contribution:
Derivatives produced from QL2 lidar flown by NV5 Geospatial in 2020.
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Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method:Vector
Point_and_Vector_Object_Information:
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type:String
Point_and_Vector_Object_Count:53091
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Lambert_Conformal_Conic:
Standard_Parallel:39.93333333333333
Standard_Parallel:40.96666666666667
Longitude_of_Central_Meridian:-77.75
Latitude_of_Projection_Origin:39.33333333333334
False_Easting:1968500.0
False_Northing:0.0
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method:coordinate pair
Coordinate_Representation:
Abscissa_Resolution:0.0003280833333333333
Ordinate_Resolution:0.0003280833333333333
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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Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label:Modeled_PAHD_flowpaths
Entity_Type_Definition:
Geometries produced by conflating existing 2015 Allegheny County hydrography with geomorphon derivatives created from 2020 QL2 lidar.
Entity_Type_Definition_Source:
Pennsylvania Geological Survey
Attribute:
Attribute_Label:OBJECTID
Attribute_Definition:
Internal feature number.
Attribute_Definition_Source:
Esri
Attribute_Domain_Values:
Unrepresentable_Domain:
Sequential unique whole numbers that are automatically generated.
Attribute:
Attribute_Label:Shape
Attribute_Definition:
Feature geometry.
Attribute_Definition_Source:
Esri
Attribute_Domain_Values:
Unrepresentable_Domain:
Coordinates defining the features.
Attribute:
Attribute_Label:FCode
Attribute_Definition:
This field is based on the U.S. Geological Survey's National Hydrography Dataset "FCode" field. "Feature Codes" are numerical signifiers associated with specific feature types. As this is preliminary data, the only FCode value included for this dataset is 33401, a.k.a. culvert features. Not all culverts in this dataset are represented by the 33401 FCode: only those features which had already been manually included in the 2015 Allegheny County Hydrography Dataset are included here. This is because the point of this study was to produce geometries from an entirely automated process. In the future, the Pennsylvania Geological Survey will research ways to identify, "break out," and represent culvert features without manual intervention.
Attribute_Definition_Source:
Pennsylvania Geological Survey
Attribute_Domain_Values:
Codeset_Domain:
Codeset_Name:33401
Codeset_Source:Pennsylvania Geological Survey
Attribute:
Attribute_Label:Avg_Slope_preSmooth
Attribute_Definition:
Average slope of the flowpath geometry before 3D smoothing was applied to ensure monotonicity. Culverts (FCode 33401) do not have this value, as they were not evaluated for conflation based on monotonicity. 
Attribute_Definition_Source:
Pennsylvania Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
Slope is returned as a percentage value, or grade, and is calculated differently for each geometry type that supports this property. A value of -1 indicates the feature is vertical.
Attribute:
Attribute_Label:Avg_Slope
Attribute_Definition:
Average slope of the flowpath geometry after 3D smoothing was applied to ensure monotonicity. Culverts (FCode 33401) do not have this value, as they were not evaluated for conflation based on monotonicity.
Attribute_Definition_Source:
Pennsylvania Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
Slope is returned as a percentage value, or grade, and is calculated differently for each geometry type that supports this property. A value of -1 indicates the feature is vertical.
Attribute:
Attribute_Label:Avg_Slope_Diff
Attribute_Definition:
The difference between the average slope values of flowpath geometries before and after 3D smoothing has been applied to ensure monotonicity. In theory, the greater the difference between these values, the more the z-values of the line have been altered to fit a monotonic model of flow. Some level of alteration is expected for modeled geometries to "flow" perfectly downslope, but abnormally large values (i.e. differences greater than 5-m) suggest either an artificial barrier structure (e.g. culvert or bridge) or a flowpath that is does not fit channelization in the elevation surface.
Attribute_Definition_Source:
Pennsylvania Geological Survey
Attribute_Domain_Values:
Unrepresentable_Domain:
Slope is returned as a percentage value, or grade, and is calculated differently for each geometry type that supports this property. This field represents the difference of two slope values.
Attribute:
Attribute_Label:Shape_Length
Attribute_Definition:
Length of feature in internal units.
Attribute_Definition_Source:
Esri
Attribute_Domain_Values:
Unrepresentable_Domain:
Positive real numbers that are automatically generated.
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Distribution_Information:
Distributor:
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
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:20230912
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Department of Conservation and Natural Resources
Contact_Person:Pennsylvania Bureau of Geological Survey
Contact_Address:
Address_Type:mailing and physical
Address:
3240 Schoolhouse Rd
City:Middletown
State_or_Province:PA
Postal_Code:17057
Country:US
Contact_Voice_Telephone:717-702-2017
Contact_Electronic_Mail_Address:RA-NR-TOPO_MAINDESK@pa.gov
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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