Local Resolution NHD Local Resolution NHD

Photo-Based Revision Photo-Based Revision

for West Virginiafor West VirginiaJackie Strager

Kurt DonaldsonKevin Kuhn

April 24, 2007Denver, CO

West Virginia GIS Technical CenterNatural 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 features1. Capture local hydro features

2. Data prep and revision2. Data prep and revision

3. Pre-conflation steps3. Pre-conflation steps

4. Conflation/QAQC steps4. Conflation/QAQC steps

5. Ensure data stewardship5. Ensure data stewardship

1. Capture local hydro features

• Statewide aerial photography, 2003

• Contractor digitized hydro features from stereo pairs

Local scale hydro featuresfrom SAMB photos

Sutton Lake, WV

1:4800 streams

1:4800 polygons

• 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

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

• 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

1:100,000 scale NHDMedium resolution

1:24,000 scale NHDHigh resolution

1:4800 scale streamsLocal resolution

(approximated from SAMB stream data)

Sutton Lake

Benefits

• Provides more highly detailed cartographic base

24K NHD streams

LR NHD streams

Flatwoods WV

Benefits

• More accurate source data

Source for 24K NHD:Big Chimney quad Last revised: 1976

Source for LR NHD:2003 Aerial photoRevised LR NHD streams shown in yellow

Benefits

• Quantifies recent changes in stream drainage

24K NHD streams

LR NHD streams

Active mine permit, Lockwood quad

Valley fill area

EPA:Up to 1,200 miles of streams lost in multi-state mountaintop-removal mining region

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

• Completion of LR NHD

• Cartographic issues

• Edge-matching

• Encouraging partnerships

• Data stewardship– Updates, maintenance

Thank you!