Australia’s water quality trends over two decades
- 1School of Engineering, College of Engineering, Computing and Cybernetics, The Australian National University, Canberra, ACT, Australia (danlu.guo@anu.edu.au)
- 2University of Maryland Center for Environmental Science, Cambridge, Maryland, United States
- 3U.S. Environmental Protection Agency Chesapeake Bay Program Office, Annapolis, Maryland, United States
- 4Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain
- 5Department of Environment and Science, Queensland State Government, Brisbane, QLD, Australia
- 6INRAE, L'institut Agro, UMR 1069 SAS, Rennes, France
- 7Water Research Centre, School of Civil and Environmental Engineering, UNSW Sydney, NSW, Sydney, Australia
- 8Science and Innovation Group – Hydrology Research, Bureau of Meteorology, Canberra, ACT, Australia
- 9Department of Infrastructure Engineering, The University of Melbourne, Melbourne, VIC, Australia,
- 10Research Institute for the Environment and Livelihoods, Charles Darwin University, NT, Darwin, Australia
- 11National Centre for Groundwater Research and Training (NCGRT), SA, Adelaide, Australia
- 12Department of Civil Engineering, Monash University, Melbourne, VIC, Australia
Water quality of rivers and streams can vary over time due to changing hydro-climatic conditions in the interaction with catchment physio-geographic conditions and local human activities. This study is the first exploration of long-term river water quality trends across Australian continent, consolidating 375 catchments with contrasting climate, hydrology, land use and land cover. We focused on five key water quality parameters and estimated their flow-normalized trends over 2000-2019 using the Weighted Regressions on Time, Discharge, and Season method (WRTDS). For each parameter, about half of nation’s catchments have significant trends, which are generally within ±10% per annum relative to the first year (2000). Except for TSS, there is no systematic non-linearity nor abrupt changes over time, while for TSS many catchments had a systematic shift from increasing to decreasing trends since around 2010. A random forest model was developed and found that catchment land characteristics, along with baseline water quality, can explain over a third of the spatial variation of the trends of EC, TN, TP and TSS (32-51% explained), but had limited explanatory power for DO (22% explained). These findings will provide critical information on the waterway health, thereby facilitating natural resources management for Australia.
How to cite: Guo, D., Zhang, Q., Minaudo, C., Liu, S., Dupas, R., Zhang, K., Bende-Michl, U., Duvert, C., and Lintern, A.: Australia’s water quality trends over two decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13703, https://doi.org/10.5194/egusphere-egu24-13703, 2024.
