Date of Award

8-1975

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Civil Engineering

Major Professor

Bruce A. Tschantz

Committee Members

Donald E. Overton, Clement Burdick III, John I. Sewell, Roger A. Minear

Abstract

In order to promote stripped coal as an economically and environmentally acceptable fuel source, it is essential to assess properly the societal (external) cost of extracting coal by strip mining. One of the elements contributing to the damage function associated with the societal costs on the production side of extracting coal by means of stripping, is the change impacted on the watershed hydrologic environment. One of the most important such watershed hydrologic changes in terms of the watershed response is peak flow due to its potential to cause serious damages.

The objective of this study is to determine the quantitative relationships between change in peak and mean daily flow and the associated coal strip mining in a given watershed.

The study of the effects of strip coal mining on the watershed hydrologic changes is a system cause-and-effect relationships problem. Watershed hydrologic processes are complex, and the addition of the strip mining factor adds to the complexity of the process. This complexity renders mathematical watershed modeling the only effective approach for determining the impact of strip mining on the hydrologic environment.

The New River Watershed, which has a drainage area of 382 square miles and is located in the southern Appalachian Region in Tennessee, was selected for study because this portion of the watershed has been intensively (intensified locally by the form of multi-seam cut) and extensively (intensified mining being carried out over the basin) mined for coal and long-term hydrological data and other related information were available. The Tennessee Valley Authority Daily Streamflow Model, which has been successfully applied to stimulate daily streamflow for watersheds with various drainage areas and characteristics in the Tennessee Valley Region, was chosen to simulate different watershed conditions in term of degree of mining disturbance. Four watershed study time periods, representing different accumulated mining disturbance levels and ranging from 0 to 5 percent of the total watershed area disturbed in the New River Watershed, were selected for analyzing progressive effects of stripping on streamflow.

The model, with successful reproduction of the daily streamflow for the four watershed study periods, has demonstrated the following strip mining impacts on streamflow:

1. The early stages of mining has significantly affected storm runoff during peak flow periods. The storm runoff increased, for example, as much as 14 percent for a stormflow with a 10-year return period.

2. As mining intensified locally by multi-seam cut, the increase for the same storm runoff was leveled off to only 8 percent;

3. As mining intensified and extensified over the watershed, the increase in the storm runoff increased to 18 percent; and

4. Daily flow increased by 30 percent in a normal water year with the watershed being extensively mined.

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