Circulation patterns; their investigation and prediction

Abstract

The effect of wind on the water currents in Rutland Water is being studied with a view to predicting algal distribution patterns so that, by exercising different abstraction options, water treatment problems can be avoided. Investigations using a scale, physical model of the reservoir in a wind tunnel suggest that under most wind directions the circulations tend to separate the water body into three distinct, topographic regions. Water currents in the reservoir itself have been plotted by tracking the paths of drogues using theodolites. This has indicated that in the central basin the circulation may be of the ‘conveyor belt’ type, rather than the solely horizontal type of the model. Surface chlorophyll readings are shown to indicate wind-driven water currents. Algal distribution has been predicted from wind data; however, the analysis requires modification in order to apply to all wind conditions. The effect of wind on the vertical distribution of algae and its implication for abstraction are discussed.