NHD and LiDAR, a Case Study in Florence County, South Carolina by Dave Arnold

The National Hydrography Dataset (NHD) is a geodatabase representing surface water streams, water bodies, and a number of tables defining relationships and metadata. The hydrographic features are correlated with the certified Watershed Boundary Dataset (WBD). The NHD is maintained and updated via a stewardship process between the United States Geological Survey (USGS) and a principal steward in each state. The NHD was originally created at a scale of 1:100,000 and was later updated to 1:24,000 however, many states are now further increasing the scale, which is broadly defined as local resolution. To create local resolution NHD, Light Detection and Ranging (LiDAR) generated hydrographic break lines are becoming quite common. We will take a look at how state stewards are using LiDAR to update both the NHD and WBD, with a particular emphasis on a pilot project conducted in Florence County, South Carolina in early 2011.

Transcript

1. Creating and Utilizing Local Resolution NHD with LiDAR Derived Hydro in Florence County, South Carolina 2013 Arkansas GIS Conference Rogers, AR – September 12, 2013 Dave Arnold, GISP USGS NHD Region 4 Partner Support With Contributions by Gary Merrill, USGS Geospatial Liaison to SC Veronica Moore, South Carolina
2. 9/15/2013 2
3. Florence County, South Carolina Local Resolution NHD Pilot Feature Attributes - Streams - Stream Banks - Connectors - Waterbodies
4. Hydro Breaklines Lidargrammetry  Lidar Intensity returns are used to create raster stereo pairs  Softcopy Photogrammetry uses LiDAR Stereo Pairs to determine an absolute orientation solution for a 3D intensity image model  Hydro Breaklines are captured with use of a combination of both Automatic and Manual collection techniques.  3D Elevation values assigned to hydro breaklines are the result of x-y-z- values derived from the resulting Lidargrammetry elevation model
5. Hydro Breaklines 3D Breaklines from Intensity Images
6. Hydro Breaklines 2D from Orthoimagery 3D from LiDAR Present Past - 1990 Florence County, SC
7. NHD Stewardship and Partner Support • Principal State Steward • Focal Point for Stewardship in the State • Provides Local Hydrography Knowledge • Approve and Submit all NHD Updates to the USGS • USGS NHD Partner Support • An Advocate for the NHD • Provides Training and is a Technical Point of Contact • Coordinates Overall Activity for One of Four Regions • U.S. Geological Survey • Provides Direction and Overall Management • Maintains, Hosts, and Distributes the NHD Database • Develops Tools to Standardize Editing of the NHD Database
8. NHD Model 2.1 Personal Geodatabase Format • Three Feature Datasets • International Hydrography • Hydrography • WBD • 14 Tables • Metadata and Attribute Storage • Relationship Classes • Metadata Related
9. NHD Data Resolutions • Medium Resolution • Original Product Combined USGS DLGs and EPA RF3 Files • 1:100,000 Scale • Entire United States Except Alaska • High Resolution • Partnership with EPA, USFS, State and Local Agencies • 1:24,000 Scale • Alaska Data at 1:63,360 Scale • Local Resolution • Continued Partnership with State Agencies • Scale Greater Than 1:24,000 • Limited Availability Based on Location
10. Medium Resolution NHD
11. High Resolution NHD
12. The Process
13. Original LiDAR Derived Hydro Four ESRI Shapefiles • Hydrographic Features • Waterbody • Island • Overpass
14. LiDAR Hydrographic Features File HYDRO_TYPE LiDAR FEATURE NHD FEATURE CLASS NHD FTYPE 1 Single Line Feature NHDFlowline Stream or River 2 Dual Line Feature NHDArea 2D Stream or River 5 Hydro Centerline NHDFlowline Artificial Path 7 Single Line Ditch NHDFlowline Canal or Ditch 9 Hidden Stream NHDFlowline Stream or River 10 Hidden Ditch NHDFlowline Canal or Ditch
15. Populating NHDFlowline Feature Class Albers NHD GeoDatabase Schema Used CrossWalk Field Added to NHDFlowline Feature Class to Maintain Hydro_Type Values from Original LiDAR
16. Populate NHDFlowline & NHDWaterbody Simple Data Loader used iteratively to import LiDAR derived hydro lines into NHDFlowline based on HYDRO_TYPE from the LiDAR data. NHDWaterbody populated all at once due to LiDAR data not identifying features.
17. Populate NHDArea Feature Class Create temporary line feature class and use Simple Data Loader to import 2D streams into it.
18. Populate NHDArea Feature Class
19. Populate NHDArea Feature Class Close open line work and then run ‘Feature to Polygon’ to create 2D areas from 1D line work.
20. Populate NHDArea Feature Class Unwanted island polygons removed using Erase function. Features imported into NHDArea feature class.
21. All Data is Imported
22. The Problems
23. Manual Editing and Quality Control NHDFlowline features need FType, FCode, and FlowDir populated. Incorrect line work flowing from water body into 2D area will cause errors.
24. Manual Editing and Quality Control Many LiDAR hydro lines needed to be specifically broken at confluences in order to conform with the NHD geodatabase schema.
25. Manual Editing and Quality Control Much of the LiDAR line work had to be broken at locations where it crossed into water bodies or area features.
26. Manual Editing and Quality Control Improperly broken lines had to be merged to prevent introducing pseudo nodes into the NHD data.
27. The Results
29. Contact Information NHD Website – http://nhd.usgs.gov Stewardship Website - http://usgs-mrs.cr.usgs.gov/stewweb/ Dave Arnold USGS Rolla, Missouri darnold@usgs.gov Veronica Moore City of Sumter Sumter, South Carolina vmoore.vm@gmail.com Gary Merrill USGS Columbia, South Carolina glmerrill@usgs.gov
32. Contact Information NHD Website – http://nhd.usgs.gov Stewardship Website - http://webhosts.cr.usgs.gov/steward Dave Arnold USGS Rolla, Missouri darnold@usgs.gov Gary Merrill USGS Columbia, South Carolina glmerrill@usgs.gov