Originally published by Scimex

The ongoing wet weather across south-eastern Australia has shown no signs of slowing, with flash and riverine flooding occurring across large regions of NSW and Victoria. The Bureau of Meteorology has warned the Lachlan River could peak in Forbes at the 1952 flood level of 10.8 metres today. Below, Australian experts respond to the ongoing situation.

Organisation/s: Australian Science Media Centre

Funder: N/A

Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Professor Jennifer McKay is Professor of Business Law at the University of South Australia

“The PM mentioned that the planning laws need to be changed to prevent development in flood plains. This is a really positive development and policy position, but it will require an astute legal architecture to achieve this aim.

This possible avenues for  legal  architecture can be commented on and cast in the light of modern legislative norms such as human rights, gender equity, rights of nature and the Sustainable development goals.”

Last updated: 18 Nov 2022 12:11pm

Declared conflicts of interest:

None declared.

Dr Feifei Tong is a Senior Lecturer from Southern Cross University

“The Wilson River catchment at Lismore has 18 named mountains, separated by six significant streams, each descending hundreds of metres over about 50 km. On rainy days, these streams race to meet near the Lismore CBD with coincident peak flows.

For Lismore, about half of the past 110 years can be classified as a flood year, meaning flooding, ranging from ‘minor’ to ‘major’, happened during the year. However, in over 7 of 10 La Niña years, Lismore experienced flood events. In addition, in many of the La Niña years, more than one flooding hit Lismore. An example is that in the last three years, two ‘major’, three ‘moderate’ and two ‘minor’ flooding occurred at Lismore.

Lismore catchment is nationally unique in gauging the impact of climate patterns on river flows. It is a natural laboratory, more accurate than any flood model. Potential research designed to understand past flood events will be helpful to not only Lismore but many other catchments around Australia facing increased heavy rains.”

Last updated: 17 Nov 2022 10:50am

Declared conflicts of interest:

Feifei is conducting a flood study for the Lismore catchment.

Dr Lurion De Mello is a Senior Lecturer in Finance at the Department of Applied Finance at Macquarie University

“It is extremely difficult to say if this is the grand finale. Torrential rain seems to be the situation we are dealing with now compared to prolonged rain. Perhaps a sign of a weakening La Niña.
The bigger picture is should the state and federal govt be putting an action plan to consider permanent relocation and closure of towns around flood plane areas. Would it mean the non-existence of some towns? 

 “

Last updated: 16 Nov 2022 5:04pm

Declared conflicts of interest:

None declared.

Associate Professor Ian Wright is a water scientist from the School of Science at Western Sydney University

“NSW regional communities continue to suffer yet more extreme weather. Many of the towns impacted from flooding this week, such as Bathurst, Forbes, Dubbo and Condobolin, were running out of drinking water just 2.5 years ago. Water storage dams (Wyangala Dam near Cowra, and Burrendong Dam near Dubbo) are today releasing torrents of flood waters. From 2015 to 2020 they were progressively drying out. Burrendong Dam (today 135% capacity) is spilling into the Macquarie River.

The township of Warren is on the Macquarie River floodplain and has been in flood for weeks. Residents know this latest flood water is now heading towards them. Rural industries, such as irrigated agriculture and livestock industries, have suffered with severe water shortages for years. Now sheep and cattle are drowning in flood waters and many crops are under water, or are in paddocks too boggy to harvest.

This adds to economic suffering for farmers, rural communities and has implications for world food security as the world desperately needs Australian grain. This flood crisis seems to have no end – almost like the Black Summer drought and bush fires that burnt for months from winter 2019 to late summer 2020.”

Last updated: 16 Nov 2022 4:29pm

Declared conflicts of interest:

None declared.

Professor Jamie Pittock is from the Fenner School of Environment and Society at The Australian National University

“After months of cogitation, last month the NSW and Federal governments announced $800 million in funding to buy 2,000 flood destroyed homes and help residents in the NSW Northern Rivers region relocate to safer ground. Bizarrely, the same sensible support has not been offered to the residents whose homes have been destroyed in the Hawkesbury-Nepean Valley of Western Sydney in the past two years. We can only hope that the governments act quickly now to extend the benefits from relocating homes from floodplains to the Central West and all regions of NSW.”

Last updated: 16 Nov 2022 4:28pm

Declared conflicts of interest:

None declared.

Dr Nandini Ramesh is a Senior Research Scientist in Natural Hazards from CSIRO’s Data 61 and the University of Sydney

“The current La Niña event is expected to persist through the summer, so the risk of heavy rainfall may not diminish for a few months longer. However, the good news is that it is unlikely that the next year will also have a La Niña event.

At this time of year, we also start to see heavy rainfall associated with the monsoon over northern Australia, so while the current likelihood of heavier-than-normal rainfall is high over eastern Australia, that likelihood is expected to increase over northern Australia in the coming months as well.”

Last updated: 16 Nov 2022 4:27pm

Declared conflicts of interest:

None declared.

Dr Chiara Holgate is a Postdoctoral Research Fellow at the Research School of Earth Sciences at the Australian National University and ARC Centre of Excellence for Climate Extremes

“With several of Australia’s climate drivers acting in their wet phase, more flooding in the coming weeks and months should not come as a surprise and floodplain communities need to be prepared to act quickly. Our research shows that rainfall in eastern Australia is maximised when a particular set of climate drivers act in concert.

This combination of drivers is happening right now – La Nina with a negative Indian Ocean Dipole and positive Southern Annular Mode. These drivers have led to higher than normal rainfall over eastern Australia in recent times that have primed the landscape for flooding. Of course, while the number and extent of floods this year seem unusual in the context of recent decades, it is my understanding that the extent to which it is actually unusual has not yet been scientifically established.”

Last updated: 16 Nov 2022 1:04pm

Declared conflicts of interest:

None declared.

Kimberley Reid is an atmospheric scientist from the ARC Centre of Excellence for Climate Extremes at Monash University

“An atmospheric river has crossed the eastern states due to a strong low pressure system south of Australia. 

The ongoing La Niña means that dams, rivers and soils are already soaked so even a moderate amount of rainfall is likely to cause flooding. These repeated floods will likely continue until La Niña goes away.
 
The negative Indian Ocean dipole should start to decay in the next month which might provide some reprieve for regions west of the Great Dividing Range.”

Last updated: 16 Nov 2022 1:03pm

Declared conflicts of interest:

None.