Long Oral Presentation 11th Australian Stream Management Conference 2024

Understanding the impact of climate change on water quality in South-East Australia (#4)

Jonah Bas 1 , Robert Sargent 1 , Anna Lintern 1 , Serene Tan 1 , Andrew Western 2 , Danlu Guo 3
  1. Monash University, Clayton, VICTORIA, Australia
  2. Infrastructure Engineering, University of Melbourne, Melbourne, Victoria, Australia
  3. College of Engineering, Computing & Cybernetics, Australian National University, Canberra, ACT, Australia
  • As forecasts of future climate indicate reduced average rainfall in South East Australia, understanding the responses of water quality in freshwater ecosystems to these conditions is important. This study aims to understand the impact of climate variability on the behaviour of six water quality constituents (DO, TN, TP, EC, turbidity and pH) at selected sites across Victoria, Australia.
  • Statistical modelling was undertaken on a 27-year period of data that spans the Millennium Drought, used as an analogue for prolonged dry conditions. Linear models were fit, including flow, seasonality, linear trend, and temperature (for DO) as explanatory variables. Model outputs, including trends, coefficients and residuals were assessed during both drought and non-drought periods, to better understand the influence of climate on water quality behaviour.
  • Results indicate that streamflow explained the largest degree of variability in TN, TP, turbidity and EC, suggesting that a drying climate will result in overall reductions in concentrations of TN, TP, and turbidity, and increases in EC. The degree of impact is likely to vary in space, with more arid areas experiencing larger impacts on water quality. Some constituents displayed changes in behaviour not related to flow (including increasing trends in pH and turbidity), suggesting that emergent processes associated with climate change-induced drying may have substantial ramifications for water quality in the future.
  • This research can inform future approaches to understanding, forecasting and managing water quality under climate change, and may aid in designing environmental watering programs for water quality outcomes.
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