Risk Assessment of Water Quality Problems associated with Thermal Stratification: development of a classification system, and application to 19 Queensland weir pools

Meisenhelter, Anna (2006). Risk Assessment of Water Quality Problems associated with Thermal Stratification: development of a classification system, and application to 19 Queensland weir pools Honours Thesis, School of Engineering, The University of Queensland.

       
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Author Meisenhelter, Anna
Thesis Title Risk Assessment of Water Quality Problems associated with Thermal Stratification: development of a classification system, and application to 19 Queensland weir pools
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 2006
Thesis type Honours Thesis
Supervisor Kate O.Brien
Total pages 83
Language eng
Subjects 0904 Chemical Engineering
Formatted abstract
It has been widely documented that prolonged thermal stratification in water storages is detrimental to the water quality within the storage. Stratification inhibits vertical mixing which transports oxygen from the atmosphere through the water column. Further depletion of dissolved oxygen levels arises from microbial activity. Low dissolved oxygen levels in the bottom waters have been linked to the release of nutrients and metals from the storage sediments. Stratification patterns have also been strongly correlated to the establishment and proliferation of blue-green algae blooms.

This report characterises nineteen SunWater weir pools located in Queensland, in terms of their stratification pattern (monomictic, polymictic, permanently well-mixed and permanent stratification) using vertical temperature and dissolved oxygen profiles. Eden Bann Weir, Glebe Weir, Jack Taylor Weir, Jones Weir, Mary River Weir and Tartrus Weir were unable to be classified due to insufficient data measurements.

The temperature difference over the water column was a reasonable indicator of stratification patterns present in the weir pools, however measurements were not always taken at the maximum depth of the weir pool, and the first depth sample was taken up to one meter below the water surface level.

Dissolved oxygen profiles provided a better indicator of water quality problems associated with stratification patterns. The dissolved oxygen concentration was therefore used to classify each weir pool in terms of the risk of water quality problems associated with prolonged stratification. Each weir pool was classified as either having a very low, low, moderate or high risk of water quality problems based on the percentage volume of the weir pool with a dissolved oxygen concentration of less than 3 mg/L. As measurements did not extend to the maximum depth of the weir pool at the time of the sampling, the change in the dissolved oxygen concentration over the unmeasured bottom water is unknown and the percentage volume of the weir pool with less than 3 mg/L of dissolved oxygen may be underestimated.
Keyword Thermal Stratification

Document type: Thesis
Collection: UQ Theses (non-RHD) - UQ staff and students only
 
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Created: Thu, 18 Dec 2014, 16:30:21 EST by Asma Asrar Qureshi on behalf of Scholarly Communication and Digitisation Service