Williams, B. J. University of Newcastle, brianw@mail.newcastle.edu.au
Cole, B. J. Hunter Water Corporation, coleb@hunterwater.com.au

 
PRELIMINARY INVESTIGATIONS ASSOCIATED WITH MODELLING OF CYANOBACTERIAL BLOOMS IN A SHALLOW RESERVOIR
 
Grahamstown Dam, surface area 2,400 hectares, average depth 6m,supplies about 40-50% of water for Newcastle, Australia (population 300,000). In the last 4 summers there have been three significant blooms of cyanobacteria - in 1996 exceeding 12000 cells/ml. There is some evidence that blooms follow resuspension events and the current research program is focussed on development of real-time models of this process. The 3-D hydrodynamic Princeton Ocean Model has been used to determine bottom currents due to surface wind stress and orbital wave velocities at the bottom have been determined using linear wave theory. The two are combined to compute an effective bottom shear stress. A perspex shear velocity box has been constructed to determine resuspension velocities in the field. The flow in the box is driven by a small bilge pump and has been calibrated using laser doppler velocimetry. Simple drag based lowflow meters are being calibrated for realtime measurement of bottom currents to provide input to a real time predictive model which is to be continuously updated using an iterated extended Kalman filter. A laboratory column 5m high is being used to explore growth characteristics of algae under a variety of nutrient and light gradients.
 
Day: Thursday, Feb. 4
Time: 11:00 - 11:15am
Location: Sweeney Center
 
Code: CS62TH1100S