Temperature stratification in the lower River Murray, Australia: implication for cyanobacterial bloom development

The relationship between temperature stratification of the water column, river discharge and meteorological forcing was examined for the lower River Murray by using a combination of field measurements and a simple mixing criterion. Wind was found to be the dominant variable affecting the degree of temperature stratification under low flow conditions typical of summer. The results of a three-month intensive study were used in conjunction with six years of historical data to determine the stratification potential of the lower River Murray and its implication for water quality and cyanobacterial bloom development. The physical characteristics and therefore stratification behaviour of the water column in the river section studied are not conducive to sustained blooms at any time of the year because of a combination of strong winds and sufficiently high river discharges.