Masters Theses

Gary S. Honea

Date of Award

5-1996

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering

Major Professor

Ronald E. Yoder

Committee Members

Roland Mote, Daniel Yoder

Abstract

Much effort is spent trying to relate water quality to management practices. Successes have been achieved, but it has often been difficult to link a change in water quality to a management practice, or to conclusively document actual water quality improvement. This research developed and attempted to prove a concept. That concept was that a systems approach could be used to develop a set of tools necessary to relate surface water quality to the management practices employed and to the responsiveness of the unit in which they are employed.

The operational unit for this research project was a well run dairy farm in Claiborne County, Tennessee. Three indices were developed for each of four contaminants; sediment, phosphorus, nitrogen, and coliform bacteria. Other contaminants could have been selected, but these four were deemed the most important. The indices are the management practice index (MPI), the system response index (SRI), and the standard water index (SWI).

The MPI evaluates how well a unit of land is being managed in terms of whether the proper Best Management Practices (BMPs) are being employed and how effectively they are being employed. The risk that may be associated with a BMP failure is also evaluated. In effect the index indicates how good a job the person is doing to keep contaminants out of the surface water. A high MPI indicates a good job is being done.

The second index is the SRI. It relates the measured level of a contaminant, the worst case potential loading of the contaminant into a stream, and the MPI. It can probably best be used to indicate the probability that a given level of contaminant will occur for a particular worst case and management scheme, or whether a system is likely to change if the worst case or management practices are altered. It can also be viewed as a responsiveness index which gives an indication of how forgiving a particular situation will be for the implemented management practices and the potential worst case loading. A high SRI indicates a responsive system, while a low index indicates a less responsive system. With a low SRI it makes little difference what management practices or system loading are used, as the system will not easily change. Its inverse can also be viewed as the buffering capacity of the system.

The final index is the SWI and is simply a ratio of the measured levels of contaminants to a standard. An SWI greater than one indicates the standard has been exceeded.

Overall the dairy farm MPIs indicated a high level of management. On a scale of 0.0 to 1.0, the overall MPIs were 0.91, 0.88, 0.92, and 0.83 for sediment, phosphorus, nitrogen, and coliform bacteria, respectively. The SRIs for subwatershed B were -0.206, 0.0, -0.055, and 0.005 for sediment, phosphorus, nitrogen, and coliform bacteria, respectively. Although the true ranges for these SRI values are yet undetermined, the values appear low, which would indicate a system that is low in responsiveness, or high in buffering capacity. The measured levels of contaminants are reflected in the SWI values of -0.07, 0.0, -0.15, and 0.99 for sediment, phosphorus, nitrogen, and coliform bacteria, respectively.

Together the three indices suggest a high level of management and a low system responsiveness. The MPI results for coliform bacteria appear questionable since the SWI was near 1.0 (near the standard) even though the MPI was relatively high at 0.86 for subwatershed B.

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