Patterns of land degradation and restoration in the Copper Basin, Tennessee, and their influence on soil hydrologic properties

The Copper Basin experienced severe environmental degradation during the late nineteenth and early twentieth century because of copper processing in the area. Emissions of SO₂ from sources near the center of the Basin damaged vegetation in a nearly concentric pattern, with a bare zone of greatest damage in the center. In the 1940s, the Tennessee Valley Authority became concerned about reservoir siltation and began a revegetation program in the basin. Successfully implementing the revegetation plan proved more difficult than had been expected.

After 50 years of revegetation efforts, how effective has this revegetation program been in alleviating severe erosion and siltation problems in the basin and downstream? In this thesis I review the history of land degradation and subsequent revegetation in the Basin. After creating a chronological record of land degradation and restoration, and examining maps and air photos, I classified the Basin into five zones based on the ages of forest cover. In order to test hydrologic recovery, I tested three parameters: runoff generation and sediment detachment by a high intensity rain storm, and the amount of organic matter in the soil. Using a portable rainfall simulator infiltrometer, I conducted tests at selected sites representative of the established categories, and compared the results with those of tests from the Cherokee National Forest outside the Basin.

Results showed the amount of detached sediment generated, an indicator of soil erosion, to decrease with any type of vegetation cover. However, runoff generation did not necessarily decrease under a young forest cover, and low levels of organic matter under young forests show that long periods of time are required before a forest can truly function as a hydrologic regulator. Revegetation, in the short term, is successfully reducing soil erosion in the Basin, but much more time will be needed before the hydrology of the Basin approaches that of a mature forest.