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Riparian Forest Buffer Inventory and Analysis for the Commonwealth of Virginia Using a Geographic Information Systems Approach

Maintaining healthy forests and wetlands in riparian zones greatly benefits the ecological health of water features. Virginia's Department of Forestry funded a project to inventory and analyze the riparian land cover conditions utilizing a geographic information systems approach and currently available data sources.
Percent of 14 Digit Watershed's Streams buffered on both sides by at least 100 feet of Forest or Wetlands

Percent of 14 Digit Watershed's Streams buffered on both sides by at least 100 feet of Forest or Wetlands

Funding Agency: Virginia Department of Forestry

Water features were taken from the National Hydrography Dataset. Land cover was acquired from the satellite imagery based 1992 National Land Cover Data. Watershed boundaries were provided by the USGS. Air photos were produced by the National Aerial Photography Program and field inventories were done by VA Forestry personnel. An automated algorithm was developed to sample the land cover along transects placed every 300 feet along the water features. These samples were then summarized for each watershed. The algorithm was implemented using a series of extensions for ArcView 3.x.

The inventory shows great variability in the riparian conditions within Virginia. The average watershed has 68.0% of its stream buffered on both sides by at least 100 feet of forest or wetlands, while statewide values range from 0.5% to 99.1%.

The inventory will generate results for buffers at intervals of both at least 100 and 300 feet and for buffers on one side and both sides of water features. The GIS-produced inventory was compared to the results of the field inventories while the production of an inventory via air photo interpretation and fragmentation analysis is on-going. Virginia will use the results to identify and prioritize watersheds for activities to improve riparian buffer conditions.