A high-level aerial photograph can provide an overview of relatively large areas. The infrared aerial photo of downtown Wheeling shows the Ohio River and lower Wheeling Creek as they appeared in 1991. Can you see the coal barge moving up the river past the railroad bridge? That bridge is no longer there. Compare a closer view of the six sites with the color photograph and topographic map below. Left: High-level aerial photograph over Wheeling, WV. Photo: Courtesy of Dr. Ben Stout
Low-level aerial photographs are
particularly useful for identifying features near sampling sites. Local features, as well
as the distance from the Ohio River, may have an impact on the site's water quality.
Photo: Courtesy of Dr. Ben Stout
A topographic map can help to
locate features near stream sites and to document the location of stream sites for future
reference. In addition, it can provide measures for identifying stream gradient, stream
order, distance from the mouth, distance to the headwaters, watershed area, and amount of
forested land. Topographic maps are available from the U.S. Geological Survey. Photo: Courtesy of Dr. Ben Stout
Compare information provided by the three types of images. Which image is best? Do all contribute useful information?
Consider these questions: What are some of the differences that occur at sites 2.6, 5.4, 6.2, 7.4, 10.6, and 12.0 km (1.6, 3.6, 3.9, 4.6, 6.6, 7.5, mi., respectively) upstream of the Ohio River. Compare the forest canopy, distance from the stream to nearby roads and buildings, and amount of "green space" around the streams in each photograph. How do these visual attributes compare with the biological community data presented in Scenario #1?
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