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Research finds that Victorian watch catchments may not recover from drought

Percentage of 161 survey catchments showing low spillage before, during, and after the Millennium drought from 1997 to 2010. The shaded areas in 2010 show the percentage of catchments that did not recover from the drought.Credit: Monash University

Australia’s first study by Monash University denies the theory that rivers and groundwater are ultimately replenished after droughts and floods. After the Australian Millennium Drought, one-third of Victoria’s catchments had not recovered from the drought almost eight years later.
In unrecovered catchments, about 80% showed no evidence of immediate recovery.


One-third of the catchments included in the Victorian study did not recover from the severe drought almost eight years later, according to Monash University’s first study in Australia.

Globally, science has the common view that rivers and groundwater supplies will eventually be replenished after periods of severe drought and floods.

The study, led by Dr. Tim Peterson of the Department of Civil Engineering at Monash University, was published today in a prestigious international journal. ScienceIs the world’s first company to challenge this widely accepted view.

Researchers used statistical models of rainfall and river flow in 161 catchments throughout Victoria. Each catchment area has more than 30 years of data and no upstream dams or water extractions. The area surveyed is about the same as the United Kingdom or half of California, USA.

At the end of the drought, Dr. Peterson and colleagues at the University of Melbourne found that some rivers continued to behave as if they were in the drought for years to come, and many had not yet recovered.

Specifically, after the Australian Millennium Drought, 37% of Victoria’s catchments did not recover as part of their rainfall and the number of catchments to be recovered remained stagnant.

This means that 100 mm of precipitation before the 1990 drought produced more river flow than the same 100 mm in 2017. Therefore, the river flow after the drought is reduced by 30%.

The number of catchments with low or very low runoff increased rapidly from 1996 to the end of the summer 2010 drought. By 2011, only 15% of the catchment area had recovered.

The Millennium Drought, considered one of the worst droughts that hit Australia in modern history, crippled the Murray-Darling basin and put extreme pressure on ecosystems, agricultural production and urban water supplies in the southeastern part of the country. Drought. It ended at the 2010 La Niña Meteorological Event.

A catchment or basin is any area of ​​land that captures precipitation, which flows into common outlets such as rivers, streams, bays, and lakes. Almost all water in Victoria comes from river streams.

Dr. Peterson said the rehabilitation of catchments after a severe drought had a significant impact on the world’s long-term water resources program and aquatic environment, especially when climate change was added to the findings.

“Our findings suggest that hydrological droughts can continue indefinitely after meteorological droughts, and the mechanism of recovery remains an open issue,” Peterson said. The doctor said.

“This new discovery looks like a way for catchments to behave naturally. It’s not explained by factors such as land use. It’s more complicated than we thought.”

Each catchment area analyzed for this study has at least 15, 7, and 5 years of river flow observations before, during, and after the Millennium Drought, and extracts of major upstream reservoirs and rivers. There was not.

In all 161 catchments, researchers found that eight years after the drought, 51% of the catchments switched to low or very low runoff. At the end of the drought in 2010, the catchments, mainly in the east, returned to normal runoff (see figure).

Importantly, by mid-2017, almost eight years after the drought, more than one-third of the catchment area was still in low runoff and had not returned to pre-drought behavior.

Dr. Peterson also suggests that evidence suggests that vegetation responded to drought by increasing the proportion of precipitation that plants head towards transpiration, the process of water movement through the plant and evaporation from the leaves. Stated.

“In practice, this means that in response to the millennium drought, the vegetation in the selected catchment area responded by maintaining similar transpiration rates,” he said.

Researchers say the catchment area is more complex than previously thought, and the findings have helped the Water Department make better plans for the future.

Dr. Peterson of the University of Melbourne and his co-authors have worked with the Victorian and National Water Departments to share the findings. More recently, through extensive research on Victorian water and climate initiatives.

He states: “It is exciting that findings are already beginning to be used in water management methods. Currently, water management uses these findings to ensure long-term water supply in difficult and changing climates. We are developing mathematical tools to help you. ”


A better way to understand drought


For more information:
“The basin may not recover from drought,” said TJ Peterson of Monash University in Clayton, Victoria, Australia. Science (2021). science.sciencemag.org/cgi/doi… 1126 / science.abd5085

“River basin at the edge of change” Science (2021). science.sciencemag.org/cgi/doi… 1126 / science.abi8770

Courtesy of Monash University

Quote: Victoria’s watch catchment may not recover from drought, findings (2021, May 13) are https://phys.org/news/2021-05-victoria-catchments-recover-drought. Obtained May 13, 2021 from html

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Research finds that Victorian watch catchments may not recover from drought

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