Predicting water quality and ecological responses

Authors: Fiona Dyer, Sondoss El Sawah, Paloma Lucena-Moya, Evan Harrison, Barry Croke, Alica Tschierschke, Rachael Griffiths, Renee Brawata, Jarrod Kath, Trefor Reynoldson and Tony Jakeman

This project has developed and applied a linked modeling framework to assess climate change impacts on water quality regimes, ecological responses and stream flow. The modelling framework allows managers to explore potential changes in the water quality and ecology of freshwater systems in response to plausible scenarios for climate change and management adaptations. The following regions were selected to illustrate the range of plausible management adaptation alternatives: Goodradigbee region (primarily conservation with little/no management), Upper Cotter region (river regulation), Upper Murrumbidgee region (river regulation), Lower Molonglo region (salt discharge from water quality treatment centre), Yass region (agriculture and salinity). The project models combined these management adaptation alternatives with six climate scenarios representing minor, moderate and major changes in flow characteristics for 1oC and 2oC temperature increases. The predicted responses of macroinvertebrate communities to theoretical scenarios of climate change and/or alternative management adaptations varied across the five regions examined. The strongest predicted effects of management occurred in the Upper Murrumbidgee region where there was the greatest direct impact of management alternatives on flows downstream of Tantangara Dam. In this region, the impacts of the theoretical adaptation alternatives appeared to outweigh the effects of climate change. In the Lower Molonglo region there was a potential effect from management alternatives relative to baseline conditions, illustrating the direct effects of effluent control options for this region. Responses to climate change were predicted to occur in the Upper Cotter, Goodradigbee and Yass regions, with the latter two regions not subject to management adaptation alternatives. The differing responses between regions suggest that within the Upper Murrumbidgee River catchment as a whole, alternative management adaptations should not be uniformly applied in response to climate change.

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