Date of Graduation

8-2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Environmental Dynamics (PhD)

Degree Level

Graduate

Department

Geosciences

Advisor

Sonja Hausmann

Committee Member

John Dixon

Second Committee Member

Cindy Sagers

Third Committee Member

Steve Boss

Fourth Committee Member

Reed Green

Fifth Committee Member

Thad Scott

Keywords

Earth sciences, Biological sciences, Algae, Cyanobacteria, Isotopes, Methyl-iso-borneol, Reservoir ageing, Reservoirs, Sedimentation, Water storage capacity

Abstract

Access to potable water has been arguably one of the most important requisites for the advancement of human civilization on earth. As a result, man in his infinite wisdom devised the dam and formed reservoirs, (man- made lakes), to exploit water resources at will. In all natural lakes and reservoirs changes occur in the water quality parameters as it relates to chemical nutrients, temperature and turbidity over time. These changes are collectively referred to as "Reservoir Ageing", of which sedimentation and eutrophication are primary. Reservoir Ageing has consequences which adversely affect and defeat many of the intended uses of the reservoir. Sedimentation for example, drastically reduces the water storage capacity of the reservoir.

Studies indicate that thirty three percent of Midwestern, southeastern and southwestern reservoirs in the U.S, constructed prior to 1953, have lost from a quarter to half of their original volume and an additional fourteen percent have lost one half to three quarters of their original volume. Ten percent have lost all storage capacity completely. Although most of the consequences of sedimentation are negative, sediments in reservoirs can be useful as scientific tools. Sediments have been used to investigate paleoclimates and paleoecoligical relationships and land use changes in a variety of natural lake systems.

Ageing also results in the proliferation of toxic cyanobacteria which can have negative consequences for humans as in the case of Brazil, where 139 people were killed. In particular reference to my research, Ageing can cause bad taste and foul odor of the drinking water in the reservoir causing consumers millions in additional cost. Several measures such as chemical, physical and biological have been utilized to control some of the consequences of Ageing with varying degrees of success. However, any successful strategy must include the entire watershed within which the reservoir is located.

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