The Times Australia
The Times World News

.
Men's Weekly

.

Dams have taken half the water from Australia’s second biggest river – and climate change will make it even worse

  • Written by Jan Kreibich, PhD Candidate, Centre for Ecosystem Science & Water Research Laboratory, UNSW Sydney

The largest wetland on Australia’s second longest river, the Murrumbidgee in the southern Murray-Darling Basin, is drying up. This is bad news for the plants, animals and people who rely on the vast Lowbidgee Floodplain. So it’s important to understand what is going on, and whether we can do anything about it.

Our new research[1] used computer modelling to study past and future river flows. We examined natural flows in the lower Murrumbidgee River between 1890 and 1927, before humans started changing the river. We compared these flows to what happened after big dams went in and more water was taken out for irrigation. Then, we modelled how climate change is likely to influence flows in future.

We found river regulation such as dams and reservoirs cut flows in half over the past three decades. It means periods between life-giving floods on the wetlands are now more than twice as long. With climate change, drying of these vital freshwater ecosystems is likely to accelerate.

Altogether, we predict the annual duration of flood events sustaining these wetlands will drop by as much as 85% by 2075 compared to natural levels, if nothing is done. But there are plenty of things we can do to turn this around, because our research shows the main reason for the decline is river regulation and overextraction.

A large group of pelicans on the Lowbidgee Floodplain in golden light, with some flying in the background
A colony of Australian pelicans gathered on the Lowbidgee Floodplain. Annette Ruzicka

Floods are essential for wetlands

The Lowbidgee Floodplain, in southwestern New South Wales, supports expansive river red gum and black box forests as well as one of the state’s largest lignum shrublands. Lignum’s thick mass of stems forms bushes that make great nesting platforms for waterbirds, attracting thousands of glossy ibis, straw-necked ibis and royal spoonbills. The area is also a breeding ground for Australian pelicans.

The endangered Southern bell frog and threatened native fish such as Murray cod also live here.

Floods bring wetlands to life. But human activities have disrupted the natural cycle of flood and drought. In the Murrumbidgee, 26 big dams and reservoirs now store and divert water, mainly for irrigation. These interventions have more than doubled the time between floods, causing large sections of the wetlands to dry up.

The lack of floods has devastated the floodplain, causing black box and river red gum forests to die. Waterbird numbers also plummeted.

A clip from the aerial waterbird survey of Pollen Creek on the Lowbidgee (Centre for Ecosystem Science)

The Lowbidgee’s cultural significance

The Nari Nari people have lived on the Lowbidgee Floodplain for tens of thousands of years. The land and water has deep cultural and spiritual value.

Evidence of Nari Nari connection to this place is seen in the scar trees cut for canoes and other wooden items, middens of discarded shell and bone, earth mounds and burial sites scattered across the landscape.

After 180 years[2] of dispossession, 880 square kilometres of the floodplain was returned[3] to the Nari Nari Tribal Council[4] in 2019. This allows the original peoples of this land to repair it, reinstating cultural burning for example. But there’s a limit to how much they can do without more water.

One woman gazing at a plant in the Gayini Wetlands of the Lowbidgee Floodplain while another looks on. Nari Nari Elders Kerrie Parker (left) and Mabel Fitzpatrick (right) in the Gayini Wetlands of the Lowbidgee Floodplain. Annette Ruzicka

River regulation and climate change

Few studies have effectively reconstructed such a long history of a river to see where we have come from, and just as importantly, assessed what lies ahead.

We modelled natural flows in the Murrumbidgee River, using data for rainfall and runoff upstream. The rainfall data covers more than a century, from 1890 to 2018, which allowed us to model natural flows back to 1890.

First we established a baseline for natural flows. Then we were able to work out how dams, reservoirs and and water diversions have disrupted these flows over time.

We also considered how climate change might influence river flows in the future under different greenhouse gas emission scenarios.

We found most of the decline (55%) in the Murrumbidgee River’s flows was due to river regulation. But climate change will probably make matters worse, shaving another 7–10% off river flows by 2075, based on average projections.

The average annual duration of floods reaching the floodplain wetlands has dropped from 11.3 days under natural flows to just 4.5 days currently. This could decline further to around 1.7 days as the climate becomes warmer and drier.

Colourful aerial image of the Gayini Wetlands An aerial view of the Gayini Wetlands. Annette Ruzicka

Now is the time to act

Australia’s rivers are at risk, but it’s not too late to act. By reducing over-allocation and returning water to the environment we can protect threatened and endangered species, reduce the impacts of climate change, and honour the cultural heritage of First Nations Peoples.

Managing water releases to mimic natural seasonal flows can also help reinstate the natural cues for native plants, animals and other organisms.

Our research underscores the urgent need to understand our past in order to explore future water management options. It’s clear much of the damage has been done by damming the river and taking out so much water. Now it’s important to restore the balance in favour of the environment, to prepare for future climate change.

The Murrumbidgee River and its major floodplain wetlands are also a warning – a canary in the coal mine so to speak – of what could happen to other river systems worldwide as water demand rises along with projected income and population growth. This is especially concerning for many arid and semi-arid regions, where climate change is increasing temperatures while reducing rainfall.

We wish to acknowledge the contribution of Nari Nari Tribal man and General Manager of Gayini wetlands, Jamie Woods, to this article and the research paper it was based on.

References

  1. ^ Our new research (www.sciencedirect.com)
  2. ^ 180 years (doi.org)
  3. ^ returned (www.unsw.edu.au)
  4. ^ Nari Nari Tribal Council (www.narinari.org)

Read more https://theconversation.com/dams-have-taken-half-the-water-from-australias-second-biggest-river-and-climate-change-will-make-it-even-worse-242192

Times Magazine

Effective Commercial Pest Control Solutions for a Safer Workplace

Keeping a workplace clean, safe, and free from pests is essential for maintaining productivity, protecting employee health, and upholding a company's reputation. Pests pose health risks, can cause structural damage, and can lead to serious legal an...

The Science Behind Reverse Osmosis and Why It Matters

What is reverse osmosis? Reverse osmosis (RO) is a water purification process that removes contaminants by forcing water through a semi-permeable membrane. This membrane allows only water molecules to pass through while blocking impurities such as...

Foodbank Queensland celebrates local hero for National Volunteer Week

Stephen Carey is a bit bananas.   He splits his time between his insurance broker business, caring for his young family, and volunteering for Foodbank Queensland one day a week. He’s even run the Bridge to Brisbane in a banana suit to raise mon...

Senior of the Year Nominations Open

The Allan Labor Government is encouraging all Victorians to recognise the valuable contributions of older members of our community by nominating them for the 2025 Victorian Senior of the Year Awards.  Minister for Ageing Ingrid Stitt today annou...

CNC Machining Meets Stage Design - Black Swan State Theatre Company & Tommotek

When artistry meets precision engineering, incredible things happen. That’s exactly what unfolded when Tommotek worked alongside the Black Swan State Theatre Company on several of their innovative stage productions. With tight deadlines and intrica...

Uniden Baby Video Monitor Review

Uniden has released another award-winning product as part of their ‘Baby Watch’ series. The BW4501 Baby Monitor is an easy to use camera for keeping eyes and ears on your little one. The camera is easy to set up and can be mounted to the wall or a...

The Times Features

Running Across Australia: What Really Holds the Body Together?

How William Goodge’s 3,800km run reveals the connection between movement, mindset, and mental resilience As a business owner, I’ve come to realise that the biggest wins rarely com...

Telehealth is Transforming Healthcare Services in Australia

It has traditionally not been easy to access timely healthcare in Australia, particularly for people who live in remote areas. Many of them spend hours on the road just to see a...

Launchd Acquires Huume, Strengthening Creative Firepower Across Talent-Led Marketing

Launchd, a leader in talent, technology and brand partnerships, has announced its acquisition of influencer talent management agency Huume from IZEA. The move comes as the medi...

Vietnam's "Gold Coast" Emerges as Extraordinary Investment Frontier and Australian Inspired Way of Life

$2 Billion super-city in Vung Tau set to replicate Australia's Gold Coast success story A culturally metamorphic development aptly named "Gold Coast" is set to reshape Vietna...

Choosing the Wrong Agent Is the #1 Regret Among Aussie Property Sellers

Selling your home is often one of the largest financial transactions you’ll make, and for many Australians, it’s also one of the most emotional. A new survey of Australian home se...

Travel Insurance for Families: What Does it Cover and Why it’s Essential

Planning a family trip is exciting, but unexpected mishaps can turn your dream vacation into a stressful ordeal. That’s where travel insurance comes in—it’s your safety net when ...