National Elevation Dataset - Hydrologic Derivatives (NED-H) Kris Verdin EROS Data Center

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) Cataloging Unit #

National Elevation Dataset - Hydrologic Derivatives (NED-H) Detail of Output from Stage 1

National Elevation Dataset - Hydrologic Derivatives (NED-H) NHD 1:100,000 scale streamlines

National Elevation Dataset - Hydrologic Derivatives (NED-H) Sinks identified in Stage 1

National Elevation Dataset - Hydrologic Derivatives (NED-H) NED-H Streamlines generated after filling large sink

National Elevation Dataset - Hydrologic Derivatives (NED-H) Post-processing of large sink features

National Elevation Dataset - Hydrologic Derivatives (NED-H) New sink mask and derived streamlines

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) Pfafstetter Demonstration

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) Stage 2 cooperators USGS – Utah, New York, Cheaspeake Bay area EPA USFS - Alaska State agencies Stage 2 training – Thursday afternoon

National Elevation Dataset - Hydrologic Derivatives (NED-H) 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

National Elevation Dataset - Hydrologic Derivatives (NED-H) Stage 3 Tools Highway overpass/blockage tool Improved flow direction algorithm through flat area Sink clearing tool