national elevation dataset - hydrologic derivatives (ned-h)

National Elevation Dataset - Hydrologic Derivatives (NED-H)

Kris VerdinEROS Data [email protected]


NED-H Description

• The National Elevation Dataset-Hydrologic Derivatives

• Multi-layer dataset of topographically-derived data layers of hydrologic significance

• Derived from NED in U.S. Albers projection, 30 m cell size


NED-H Core Data Layers• Raster Layers• Hydrologically

Conditioned DEM• Flow directions• Flow accumulations• Slope• Aspect• Compound Topographic

Index

• Vector Layers• Synthetic Streamlines• Reach Catchments• Metadata


NED-H Rationale

• Responsive to the need for better watershed boundaries for the country

• Serves to integrate two of USGS’ key National Datasets - NED and NHD

• Will provide nation-wide, reliable flow direction dataset


NED-H Cooperators

• USGS Mapping & Water Divisions– EROS team providing core team– Cooperative development of the WBD – NAWQA funded development of Stage 2 tools

• National Weather Service– Bulk processing of Stage 1 data– Using Stage 1 product in AMBER modeling effort

• EPA Office of Research & Development– funding Stage 3 tool development


Development Stages• 3 Stage Plan for development

– Stage 1: Blind Pass Processing • Cataloging Unit used as processing unit• National Weather Service’s National Severe

Storms Lab in Norman, OK• California being done by WRD in Sacramento


Development Stages

• Stage 1 Post-processing

– Stage 1a: Clean-up of sink processing• Digital Dam-break algorithm

– Stage 1b: Attribution of Pfafstetter ID to reach catchments

• Will immediately be useful as input to AMBER modeling


Stage 1a:Digital Dam-break algorithm

• Post-processing of large spurious sink features filled in Stage 1

• Typically, these features are “filled” to allow uninterrupted flow

• Iterative algorithm identifies controlling pour point and breaks the digital dam

• Results in preservation of detail of DEM and improved streamline generation


Cataloging Unit #05020003


Detail of Output from Stage 1


NHD 1:100,000 scale streamlines


Sinks identified in Stage 1


NED-H Streamlines generated after filling large sink


Post-processing of large sink features


New sink mask and derived streamlines


Stage 1b:Pfafstetter Attribution

• Provides unique ID number for every reach catchment – ~1000 per C.U.

• Pfafstetter number carries topological information – no linkage table required

• Numbers developed on catchment basis and transferred onto streamlines


Pfafstetter Demonstration


Development Stages

• Stage 2: Vector Editing– In-depth QA/QC of Stage 1 products by local or

regional stakeholders– ArcView based procedures for Stage 2

cooperators– Output is watershed and subwatershed

delineations for WBD along with areas identified for correction in Stage 3


Stage 2 cooperators

• USGS – Utah, New York, Cheaspeake Bay area

• EPA

• USFS - Alaska

• State agencies

• Stage 2 training – Thursday afternoon


Development Stages

• Stage 3: Raster Editing – Feedback from Stage 2 is incorporated into NED-

H DEM via raster edits where required– Revised DEM and derivatives reflect correct

drainage pattern– Derived streamlines are conflated with NHD for

final transfer of attributes• Reach Code is common attribute


Stage 3 Tools

• Highway overpass/blockage tool

• Improved flow direction algorithm through flat area

• Sink clearing tool

http://edcnts12.cr.usgs.gov/ned-h

national elevation dataset - hydrologic derivatives (ned-h)

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