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Alaska National Hydrography Dataset (NHD) Tools Demonstration
December 8, 2006
Paul Kimsey, USGS, Denver, CO – Alaska NHD Point-Of-Contact
Viewer and extraction instructions for NHD data at http://nhdgeo.usgs.gov/viewer.htm
- Stewardship
- Working with Carl Markon, USGS Geospatial Liaison for Alaska
- Recommending that the Alaska primary data facilitator would be the AGDC Hydrology Subcommittee which would serve as the Alaska point-of-contact to the USGS
- A state subcommittee (to be created) will have to determine which events will be mirrored in the state instance (copy) of the NHD database
- USGS will provide training to those identified as NHD primary data stewards
- USGS will fund and provide 3 full days of training before they will release the NHD
edit tools
- Follow-up maintenance training will be available through coordination with the primary
steward and the Alaska NHD point-of-contact
- USFS has an agreement with USGS to provide their own training
- USFS work needs integration with other AK entities before going to a national USFS database.
- Certified data stewards pull data, edit data, coordinate with primary steward and other land management agency data stewards who share management responsibilities for adjacent sub-basins with common reaches
- Private organizations can participate in editing if they go through the state steward
process for certification and training.
- The model allows state and local entities to include attributes and events in their instances of the database that would not be included in the national model as data uploads to the national model would strip the extraneous information before ingestion
- Tools are “dummy proof” as they do not allow changes that are not compatible with the national database structure
- Alaska is not adjacent to any other states, however, the St. Croix Pilot Project along the
Maine/New Brunswick, Canada border is working on the “edge match” with regards
to shared hydrographic sub-basins across the US/Canada boundary, this pilot
project is approximately 50 percent completed and if it is successful, can be instrumental
in developing sub-basin hydrography data across the Alaska/Canada border
Carl Markon’s Vision for Stewardship
- Land management agencies to be the official steward for their jurisdiction and perform
their own editing following training and receipt of NHD editing tools
- State and possibly Native entities could be the stewards for lands for which
they are the primary manager
- USGS would the a NHD data steward of last resort
- AGDC Hydrography Subcommittee to coordinate the designation of a primary agency
through Memorandums of Understanding (MOU) which may be state-wide or agency by agency
- An Alaska NHD instance (dataset) will be maintained in-state
- Each individual agency coordinates with those agencies which share sub-basin
responsibility before it goes to the national NHD along with the state
instance.
- This state instance may contain attributes or features which are additional to
the national NHD model
NHD Editing Demonstration
- USGS contracted the current version of the NHD for Alaska
- Data should meet structure and topology requirements
- There will still be numerous content errors, particularly those that require local hydrologic knowledge
- Should the data have topologic issues that have been missed by the contractor, they should notify USGS through Carl Markon
- ComID is unique to each feature and when a feature is deleted, the ComID is retired
- ComIDs are common to entire national database
- Features can have GNIS name and ID but names cannot be added if they do not exist in the GNIS database
- Uploads to the national database will automatically reject any non-GNIS names
- Data is extracted using a UTM projection
- When you add a reach, the edit tool goes out to the national database which is held in Denver and automatically assigns a code
- Artificial paths and connectors are available to “connect” features for which the geometry of the feature is unknown, such as geometry that goes underground or through lakes
- Permanent, intermittent, and ephemeral features are included, however, ephemeral is not well defined
- There are no seasonal features in the NHD model
- Every feature has a reach, flowline, direction and measure, non-participation options are available if direction is unknown
- Contractors are supposed to correct the format, continuity
and structure problems; however, there will still be content errors such as
flow direction, attribute errors, etc.
- AGDC site has the edited copy of each sub-basin (71) that was identified for maintenance using FY04 and 05 funds at http://agdc.usgs.gov/hydro
- 62 sub-basins have been edited by BLM Alaska but are awaiting additional funds in order to submit then to the contractor
- NHD Lines versus NHD flowlines.
- Flowlines have flow and break at each crossing.
- Lines have no flow and no reaches, for example, dams and flumes. Lines cross with no breaks so they are not part of the flow
- Water bodies get 2-D reaches which means that
the NHDWaterbody features are assigned a reach code which includes all lakes
and ponds and the NHD Flowline Artificial Paths inside the waterbodies that
give flow to the water also have ReachCodes
- Shorelines, oceans and lakes
- Shorelines are currently not in the model (agencies could not agree on a standard), but
are planned to be added later
- An ocean is an area, not a water body and therefore do not get reach codes
- Lake shorelines are not routed, but are 2-D.
- Can attach events to an ocean coastline but not to lakes
- Tools only allow temporary reach boundaries
- Official boundaries are national features and will be updated at national level.
- Do not use the boundary to define geometry because it will move
- Feature level metadata by creating a metadata record, all edits are recorded in metadata record
- NHD data has not been leveled since it was moved to geodatabase which means that the “level” is similar to Stream Order but different, as it is used to assist navigation in order to determine what
constitutes a “main river” and what is a tributary
- Only changes will be extracted to master database, does not replicate entire database
- 2 versions of the tools, FS and USGS.
- USGS version works in personal geodatabases
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