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Recent funding from Water Research Australia to support a consortium of researchers to work on the effect that low reservoir levels has on water quality is providing impetus to better understand the effects of climate change of water storages. These storages are vital for water security and many are also important for irrigation and recreation.
Water quality as reservoirs dry
There is increasing certainty that we can expect a warmer world in the future with surface waters of lakes and reservoirs already warming at rates higher than those of the atmosphere. There is much less certainty, however, about what other changes in climate might be expected and how they may affect water storages. For example, different climate models indicate that rainfall in Southeast Queensland (SEQ) may increase or decrease, depending on the model used and the future time period, although there is widespread consensus that summers will be wetter and winters dryer. Wind speeds are even more difficult to predict with climate models but are important because wind affects mixing in water storages and evaporation from catchments, including the water storages.
There is increasing certainty that we can expect a warmer world in the future; surface waters of lakes and reservoirs around the world are already warming at rates higher than those of the atmosphere.
The weather is changing – what can we expect?
As we link climate models to catchment and water storage models, we are beginning to better understand the ramifications of increasing temperature from climate change. Increases in temperature increase the rate of evaporation of water from catchments, to an extent that we should expect that runoff to many water storages will be substantially reduced by the middle of this century. Elevated water temperature of surface water of storages will also increase the duration when they are thermally stratified and stable (usually 9-10 months of the year in deeper
systems in SEQ), with warm surface waters overlying cooler bottom waters. Reduced duration of water column mixing is important because mixing acts like a renewal mechanism, restoring oxygen in bottom waters, improving water quality, and oxidising potent greenhouse gases like methane that are released from water storages in large quantities.
Climate change will therefore pose new challenges for managing water security. It will mean that we will need to look at all aspects of our water use, and integrate grey (e.g., water treatment plants) and green (e.g., restoring riparian vegetation) infrastructure for water life-cycle assessments at the catchment scale.
NOTE: Original article from the ARI Magazine, Edition 4. Link – Magazine
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