Local Resolution NHD
Photo-Based Revision
for West Virginia
Jackie Strager
Kurt Donaldson
Kevin Kuhn
April 24, 2007
Denver, CO
West Virginia GIS Technical Center
Natural Resource Analysis Center
West Virginia University
WV State GIS Coordinator’s Office
Introduction
• Status of NHD in
West Virginia
– 33 sub-basins
– Medium, high
resolution NHD
complete
– Pilot projects
underway for
Local Resolution (LR)
NHD creation
Local Resolution Pilot Project
• Objectives
– Meet with potential data users
– Develop methods and standards
– Assemble 1:4800 source data statewide
– Assemble final LR-NHD for two pilot
watersheds
– Show benefits of LR-NHD for water resource
applications
LR NHD Process Steps
1. Capture local hydro features
2. Data prep and revision
3. Pre-conflation steps
4. Conflation/QAQC steps
5. Ensure data stewardship
1. Capture local hydro features
• Statewide aerial
photography, 2003
• Contractor digitized
hydro features from
stereo pairs
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Features with visible water only
Single-lined up to 50ft wide
Double-lined
over
50ft wide
Local
scale
hydro features
Lakes/ponds
(min.
100ftphotos
wide)
from
SAMB
Swamps/marshes
1:4800 streams
No name or code attributes
1:4800 polygons
Correct flow direction
Edge-matched
Sutton Lake, WV
2. Data prep/revision
• Systematically examine contractor’s hydro
data for incomplete and missing features
• Close double-lined streams
• Add DLG codes
Approximately 15-20% of
streams were not
adequately captured in
source local datasets.
1:4800 streams in source
Additional 24K streams added
3-4. Pre-conflation, conflation
For pilot watersheds:
• USGS routines and NHD
Geo-Conflation Toolkit
(NHDGCT)
– Pre-conflation
– Conflation
– QAQC
• Load into national dataset
5. Long term maintenance
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Involve interested cooperators
Encourage NHD stewardship process
Project communications
Show benefits of LR-NHD data
Website: http://wvgis.wvu.edu/stateactivities/LRNHD.html
Benefits of LR NHD
• Common data framework among NHD
scales
Sutton Lake
1:100,000 scale NHD
Medium resolution
1:24,000 scale NHD
High resolution
1:4800 scale streams
Local resolution
(approximated from
SAMB stream data)
Benefits
• Provides more
highly detailed
cartographic base
Flatwoods WV
24K NHD streams
LR NHD streams
Benefits
• More accurate source data
Source for 24K NHD:
Big Chimney quad
Last revised: 1976
Source for LR NHD:
2003 Aerial photo
Revised LR NHD streams shown in yellow
Benefits
• Quantifies recent
changes in stream
drainage
24K NHD streams
LR NHD streams
Valley fill area
EPA:
Up to 1,200 miles of streams lost in
multi-state mountaintop-removal
mining region
Active mine permit, Lockwood quad
Benefits
• Supports modeling of flow and hydrology
at detailed local scale
• More accurate stream mileage
for stream mitigation projects,
riparian buffers
• Aids in floodplain mapping and
emergency planning
• More detailed dataset for
resource management and
planning, permitting,
cumulative impact analysis
Benefits
• Supports WV legislative
requirement
– WV Water Resources Protection Act
– Quantify nature and extent of water
resources
Future Considerations
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Completion of LR NHD
Cartographic issues
Edge-matching
Encouraging partnerships
Data stewardship
– Updates, maintenance
Thank you!