Description:
Deep reservoirs are known to undergo thermal stratification driven by seasonaltemperature changes across the year. Stratified conditions can encourage poor waterquality at depth, particularly with low dissolved oxygen and associated implications fordissolved manganese, iron and other water quality parameters. Ecological impactsdue to cold water discharge can also be exacerbated where stratified conditionsprevent the water column from mixing and thus keeping temperatures artificially lowcompared to warmer surface waters.This study presents the first ever comprehensive information for Lake Bellfield, a keywater supply reservoir located in the Grampians National Park, Victoria, Australia.Three years of temperature monitoring data has been recorded, along with three yearsof meteorological data from a nearby weather station. The thermal profile over time ispresented, along with the associated weather information.Results show that the reservoir does indeed undergo stratification, and that ‘turnover’or mixing event typically occur in late April or early May of each year. The magnitudeof stratification is also shown with temperature extremes between the hypolimnion andepilimnion shown. Further information is presented on the likely predictors of thoseturnover events using the nearby weather station information.Discussion is provided on possible strategies to mitigate water quality and ecologicalissues associated with the thermal stratification.