Local Resolution NHD

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• 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 Coordinators Office
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Introduction

• Status of NHD in West Virginia
• 33 sub-basins
• Medium, high resolution NHD complete
• Pilot projects underway for Local
  Resolution (LR) NHD creation

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Local Resolution Pilot Project

• Objectives
• Meet with potential data users
• Develop methods and standards
• Assemble 14800 source data statewide
• Assemble final LR-NHD for two pilot watersheds
• Show benefits of LR-NHD for water resource
  applications

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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
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1. Capture local hydro features

• Statewide aerial photography, 2003
• Contractor digitized hydro features from stereo
  pairs

• Features with visible water only
• Single-lined up to 50ft wide
• Double-lined over 50ft wide
• Lakes/ponds (min. 100ft wide)
• Swamps/marshes
• No name or code attributes
• Correct flow direction
• Edge-matched

Local scale hydro features from SAMB photos
14800 streams
14800 polygons
Sutton Lake, WV
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2. Data prep/revision

• Systematically examine contractors 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.
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3-4. Pre-conflation, conflation

• For pilot watersheds
• USGS routines and NHD Geo-Conflation Toolkit
  (NHDGCT)
• Pre-conflation
• Conflation
• QAQC
• Load into national dataset

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5. Long term maintenance

• Involve interested cooperators
• Encourage NHD stewardship process
• Project communications
• Show benefits of LR-NHD data

Website http//wvgis.wvu.edu/stateactivities/LRNH
D.html
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Benefits of LR NHD

• Common data framework among NHD scales

Sutton Lake
1100,000 scale NHD Medium resolution
124,000 scale NHD High resolution
14800 scale streams Local resolution (approximate
d from SAMB stream data)
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Benefits

• Provides more highly detailed cartographic base

24K NHD streams
Flatwoods WV
LR NHD streams
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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
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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
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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

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Benefits

• Supports WV legislative requirement
• WV Water Resources Protection Act
• Quantify nature and extent of water resources

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Future Considerations

• Completion of LR NHD
• Cartographic issues
• Edge-matching
• Encouraging partnerships
• Data stewardship
• Updates, maintenance

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Thank you!