Landscape Metrics Arranged by Hydrological Proximity to Sites on
Mississippi, Missouri, and Ohio Rivers
Figure 1. Study area in the Upper Mississippi, the Missouri and the Ohio River basins and 447 sampling sites.
Scientists and GIS specialists at the EPA Mid-Continent Ecology Division created a spatial
framework for testing multiple landscape scales of influence upon the water quality and biology
sampled at 447 sites along the Upper Mississippi, the Missouri and the Ohio Rivers (Figure 1).
Project objectives were to define landscape areas that could deliver stressors to the Great Rivers,
and subsequently relate landscape characteristics to the ecological integrity of fish, invertebrate and
plankton communities in the rivers. The National Hydrologic Database (NHDPlus) provided a
uniform and comprehensive database covering the entire study area. Hydrologically-defmed
catchments from NHDPlus were aggregated to create sets of spatially-nested contributing units
expected to be meaningful to river ecology.
Figure 2. Flow lines within 10-km hydrological proximity to a
site as selected by upstream navigation along the NHDPlus
network.
Figure 3. Assemblage of NHDPlus catchments associated with
the flow lines selected within 10-km hydrological proximity to
a site.
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NHDPlus navigation tools and custom scripts helped to select consecutive upstream flow lines
(Figure 2) and the associated catchments (Figure 3). Navigation was limited by user-specified
distances (10, 50 and 100 km) measured along the flow lines of the main channel and contributing
tributaries. In addition we analyzed flooding models and landforms (i.e. slope, elevation) and
delineated nominal valley-full catchments (Figure 4). We also delineated sets of main channel and
tributary riparian buffers nested within the assembled contributing areas (Figure 5).
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Figure 4. Valley-full contributing area extending 10 km upriver from a site.
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~^_^ NHDPlus flowline ^^_
Water
i Tributary riparian /
C^ ~y Main channel riparian
10km network
Figure 5. Main channel and tributary riparian buffers nested within 10-km network watershed as navigated by hydrological proximity
to a site using NHDPlus.
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Landscape metrics in contributing units of various scales are being tested for their importance to
water quality and aquatic habitats within large floodplain river systems. The metrics including land
cover, elevation, slope, imperviousness, and tree canopy were extracted from the 2001 National
Land Cover (NLCD) and the National Elevation (NED) databases for all sets of nested landscape
units contributing to each sample site (Figure 6). These basic metrics were transformed into arrays
of landscape variables arranged by hydrological proximity to each site. The geoprocessing output
provided information for consistent analysis and comparison of stressors and responses at various
spatial scales of terrestrial influence on aquatic habitats sampled along the rivers.
Figure 6. Examples of nested landscape units contributing to a site for which landscape metrics were determined.
For more information contact:
David Bolgrien or Mary Moffett
US EPA Office of Research and Development
Mid-Continent Ecology Division
Tatiana Nawrocki (Arctic Slope Regional Corporation) or Matthew Starry (SRA)
US EPA SES3 Contract
6201 Congdon Boulevard, Duluth, MN 55804
Phone: (218) 529-5000 FAX: (218) 529-5003
E-Mail: moffett.marv@epa.gov or bolgrien.dave@epa.gov
This abstract does not necessarily reflect USEPA policy.
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