Author(s): I. H. Fisher
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Keywords: No Keywords
Abstract: To maintain water quality in lakes at levels suitable for various human purposes, thedistribution of nutrient and algal concentrations must be subjected to deliberate human intervention. Various scientifically-based numerical models are available to predict the effects of such human intervention, but generally they have not been subjected to sufficient1y comprehensive comparisons against field data, for their validity to be accepted by management. It is argued that lake circulation is the appropriate point at which to commence such a comprehensive comparison, because it is the set of processes which can be effectively decoupled from the total set of transport/biogeochemical processes. Although attempts have been made to validate circulation models of large lakes, these have not used data from spatial scales similar to those implicit in the models. No comparable attempts have been reported for shallow lakes of medium size, yet these constitute a major source of water for human use. A strategy is proposed for the collection of water velocity data suitable for comparison with models of circulation in lakes of medium size. After justifying the use of Eulerian rather than lagrangian techniques, the spatial distribution of sensors and their deployment are considered. Because a substantial number of sensors is seen to be necessary, cost is a major criterion for sensor selection. Considering cost and other criteria, including the need to measure velocities of order 10 mm s`-1, thes uspension wire velocity sensor is the most satisfactory sensor for the purpose of validation. Recent development for sustained operation in the field is described. Development of a monitoring network in northern New South Wales is in progress. Typical results from a relatively deep site during stratified conditions demonstrate the applicability of the approach.
Year: 1985