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Floods can be a disaster for humans – but for nature, it's boom time

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Wednesday, November 9, 2022

ShutterstockHumans, as a rule, do not like floods. And three years of La Niña rains have meant Australians have had more than enough of floods. But Australia’s plants and animals have evolved alongside periodic floods, as they have for fire. For them, floods are a boon. These pulses of water are vital to the health of most river floodplain ecosystems. For some native fish, floods create new habitat as the waters fill floodplains, wetlands and creeks. Many trees like river red gums need periodic flooding too. Floods trigger a huge spike in growth. Nutrient-rich sediment is washed downstream and out on to floodplains. This is a boon to algae and aquatic plants at first, and, once the water evaporates, to grasses, shrubs and trees. Herbivores such as wallabies and wombats feast on the new growth. Most of the time, rivers stay in their main channels and floodplains are dry. But in years like this one, so much rain falls that water spills over the banks and fills floodplains. This is a life-giving process which nourishes and replenishes. Without floods, rivers would not be rivers – they’d just be drains, unfit for all but the very hardiest of animals and plants. Herbivores like wallabies flock to the new growth after floods. Shutterstock Why does nature need floods? It’s not all good news for nature. Flooding is a disturbance for wildlife and plants, moving things around and shaking things up. Some animals may drown, high flows may rip out plants and even undermine and topple trees. Low-oxygen blackwater events and fish kills – heartbreaking for many – often follow floods, as they have recently on the Murray. But after the damage comes the boom. Once the initial pulse of water subsides, it often takes much longer for the water to evaporate or drain from the floodplains. Plants killed by the water will add to the organic matter load, which may later be used by other plants. The pulse of nutrients that goes with flooding is wonderful for freshwater phytoplankton (miniscule aquatic plants), as well as zooplankton which feed on them, such as tiny rotifers, known as wheel animals, and crustaceans. Some fish leave the main channel of the river and swim onto their new temporary habitat, feeding on the zooplankton. Waterbirds follow them. Read more: Beyond a state of sandbagging: what can we learn from all the floods, here and overseas? Should the timing be right, native fish like golden and silver perch may breed in floodplain wetlands. Their larvae are poor swimmers, and these still, food-rich water bodies are ideal nurseries. South Australia’s Kati Thanda-Lake Eyre has only filled a handful of times over the last century. But the unprecedented rains this year have partly filled the lake. When water covers the arid land, brine shrimp eggs hatch in their millions and start feeding and breeding. It’s a brief boom for fish, but as the water evaporates, the lake gets saltier and eventually kills the fish. Pelicans, cormorants, terns and gulls head inland to feast on shrimp and dying or dead fish. Birds like red-necked avocets flock to ephemeral lakes like Kati Thanda–Lake Eyre. Graham Winterflood/Flickr, CC BY In northern Australia, many rivers are not dammed, and widespread natural flooding occurs most years. Indigenous people here are accustomed to living alongside flooding and have been making use of the riches of floodplain productivity for more than 50,000 years. Tropical floodplains offer food and habitat to everything from aquatic plants and barramundi to saltwater crocodiles and magpie geese. Freshwater floodplain wetlands like this one on the Roper River floodplain in northern Australia are rich in species - but at risk from climate change. ` Keller Kopf, Author provided In Australia’s south-east, floodwaters generally don’t linger quite as long as they do in the tropical north. But they do rise rapidly – sometimes several metres over only a couple of days. Much of the water will never return to the main channel of the river but will evaporate slowly. Deeper remnants like billabongs, lagoons or oxbow lakes – actually old river channels – linger longest. The giant of Australia’s rivers, the Murray, takes longer to flood because Australia is mostly flat. Pulses of water move slowly down its tributaries to the main channel. It can take weeks to months for rain that falls on the Great Dividing Range to make it to the Murray’s mouth at Goolwa in South Australia. These lingering floodwaters are perfect for freshwater mussels, as well as frogs, lizards, platypus and snakes. Bottlebrushes, wattles, reeds, rushes and aquatic plants do well out of floods too. Of course, introduced species often thrive too. Common carp populations typically boom after floods. And willow trees and other invasive aquatic plants that spread through pieces breaking off, do well on the back of floods. Floodplain fertility can be seen with the naked eye, as in this image of the Murray River flowing through the Riverina in New South Wales. Shutterstock Our uneasy relationship with rivers Nature needs floods. But while you might not believe it, we need them too. Most of the world’s major cities were founded next to rivers, which gave their inhabitants water, fish, transport, and fertile farmland. But for all river cities, there are times when the river surges and can destroy houses and livelihoods. Many cities have tried to tame floods with levees and dams. But as we’re finding now, you can reduce the impact of smaller floods – but the big ones are all but unstoppable. Because we have farmed and settled so many floodplains, farmers are particularly vulnerable to floods. Floodwaters hitting bush will be slowed by trees and plants. But farms are often cleared, which can see more erosion take place. Whole farms can be devastated by flooding, leading to food prices spiking. With climate change, Australia is expected to experience bigger and more frequent floods. This may be a good thing for nature but means people will no longer be able to live safely in some places. It will also mean iconic ecosystems like Kakadu will be at risk, with sea level rise predicted to push saltwater into almost half of its famous wetlands by 2070. While floods bring pain in the short term, over the longer term both humans and nature need the benefits they bring. Read more: Floods play a vital role in ecosystems – it's time to get out of their way Paul Humphries has received funding from the Murray-Darling Basin Authority, the Australian Government’s Commonwealth Environmental Water Office and the Victorian Department of Environment, Land, Water and Planning. Keller Kopf receives funding from the Commonwealth Scientific and Industrial Research Organization, Australian Research Council and the Fisheries Research and Development Corporation.

Floods upend the plans of humans and wildlife – but after the water calms, it’s boom time for nature.

Shutterstock

Humans, as a rule, do not like floods. And three years of La Niña rains have meant Australians have had more than enough of floods.

But Australia’s plants and animals have evolved alongside periodic floods, as they have for fire. For them, floods are a boon. These pulses of water are vital to the health of most river floodplain ecosystems. For some native fish, floods create new habitat as the waters fill floodplains, wetlands and creeks. Many trees like river red gums need periodic flooding too.

Floods trigger a huge spike in growth. Nutrient-rich sediment is washed downstream and out on to floodplains. This is a boon to algae and aquatic plants at first, and, once the water evaporates, to grasses, shrubs and trees. Herbivores such as wallabies and wombats feast on the new growth.

Most of the time, rivers stay in their main channels and floodplains are dry. But in years like this one, so much rain falls that water spills over the banks and fills floodplains. This is a life-giving process which nourishes and replenishes. Without floods, rivers would not be rivers – they’d just be drains, unfit for all but the very hardiest of animals and plants.

wallaby eating
Herbivores like wallabies flock to the new growth after floods. Shutterstock

Why does nature need floods?

It’s not all good news for nature. Flooding is a disturbance for wildlife and plants, moving things around and shaking things up. Some animals may drown, high flows may rip out plants and even undermine and topple trees. Low-oxygen blackwater events and fish kills – heartbreaking for many – often follow floods, as they have recently on the Murray. But after the damage comes the boom.

Once the initial pulse of water subsides, it often takes much longer for the water to evaporate or drain from the floodplains. Plants killed by the water will add to the organic matter load, which may later be used by other plants.

The pulse of nutrients that goes with flooding is wonderful for freshwater phytoplankton (miniscule aquatic plants), as well as zooplankton which feed on them, such as tiny rotifers, known as wheel animals, and crustaceans. Some fish leave the main channel of the river and swim onto their new temporary habitat, feeding on the zooplankton. Waterbirds follow them.


Read more: Beyond a state of sandbagging: what can we learn from all the floods, here and overseas?


Should the timing be right, native fish like golden and silver perch may breed in floodplain wetlands. Their larvae are poor swimmers, and these still, food-rich water bodies are ideal nurseries.

South Australia’s Kati Thanda-Lake Eyre has only filled a handful of times over the last century. But the unprecedented rains this year have partly filled the lake. When water covers the arid land, brine shrimp eggs hatch in their millions and start feeding and breeding. It’s a brief boom for fish, but as the water evaporates, the lake gets saltier and eventually kills the fish. Pelicans, cormorants, terns and gulls head inland to feast on shrimp and dying or dead fish.

red necked avocet
Birds like red-necked avocets flock to ephemeral lakes like Kati Thanda–Lake Eyre. Graham Winterflood/Flickr, CC BY

In northern Australia, many rivers are not dammed, and widespread natural flooding occurs most years. Indigenous people here are accustomed to living alongside flooding and have been making use of the riches of floodplain productivity for more than 50,000 years. Tropical floodplains offer food and habitat to everything from aquatic plants and barramundi to saltwater crocodiles and magpie geese.

roper river wetland
Freshwater floodplain wetlands like this one on the Roper River floodplain in northern Australia are rich in species - but at risk from climate change. ` Keller Kopf, Author provided

In Australia’s south-east, floodwaters generally don’t linger quite as long as they do in the tropical north. But they do rise rapidly – sometimes several metres over only a couple of days. Much of the water will never return to the main channel of the river but will evaporate slowly. Deeper remnants like billabongs, lagoons or oxbow lakes – actually old river channels – linger longest.

The giant of Australia’s rivers, the Murray, takes longer to flood because Australia is mostly flat. Pulses of water move slowly down its tributaries to the main channel. It can take weeks to months for rain that falls on the Great Dividing Range to make it to the Murray’s mouth at Goolwa in South Australia.

These lingering floodwaters are perfect for freshwater mussels, as well as frogs, lizards, platypus and snakes. Bottlebrushes, wattles, reeds, rushes and aquatic plants do well out of floods too.

Of course, introduced species often thrive too. Common carp populations typically boom after floods. And willow trees and other invasive aquatic plants that spread through pieces breaking off, do well on the back of floods.

riverina murray floodplains
Floodplain fertility can be seen with the naked eye, as in this image of the Murray River flowing through the Riverina in New South Wales. Shutterstock

Our uneasy relationship with rivers

Nature needs floods. But while you might not believe it, we need them too. Most of the world’s major cities were founded next to rivers, which gave their inhabitants water, fish, transport, and fertile farmland. But for all river cities, there are times when the river surges and can destroy houses and livelihoods.

Many cities have tried to tame floods with levees and dams. But as we’re finding now, you can reduce the impact of smaller floods – but the big ones are all but unstoppable.

Because we have farmed and settled so many floodplains, farmers are particularly vulnerable to floods. Floodwaters hitting bush will be slowed by trees and plants. But farms are often cleared, which can see more erosion take place. Whole farms can be devastated by flooding, leading to food prices spiking.

With climate change, Australia is expected to experience bigger and more frequent floods. This may be a good thing for nature but means people will no longer be able to live safely in some places. It will also mean iconic ecosystems like Kakadu will be at risk, with sea level rise predicted to push saltwater into almost half of its famous wetlands by 2070.

While floods bring pain in the short term, over the longer term both humans and nature need the benefits they bring.


Read more: Floods play a vital role in ecosystems – it's time to get out of their way


The Conversation

Paul Humphries has received funding from the Murray-Darling Basin Authority, the Australian Government’s Commonwealth Environmental Water Office and the Victorian Department of Environment, Land, Water and Planning.

Keller Kopf receives funding from the Commonwealth Scientific and Industrial Research Organization, Australian Research Council and the Fisheries Research and Development Corporation.

Read the full story here.
Photos courtesy of

Toyota SUV adverts banned in UK on environmental grounds

Advertising Standards Authority says Hilux poster and video condone driving that disregards ‘impact on nature’The UK advertising watchdog has banned two Toyota adverts for condoning driving that disregards its environmental impact in a landmark ruling, stating that the SUV ads had been created without “a sense of responsibility to society”.It is the first time the Advertising Standards Authority (ASA) has blocked an SUV advert on the grounds of breaching social responsibility in an environmental context. Continue reading...

The UK advertising watchdog has banned two Toyota adverts for condoning driving that disregards its environmental impact in a landmark ruling, stating that the SUV ads had been created without “a sense of responsibility to society”.It is the first time the Advertising Standards Authority (ASA) has blocked an SUV advert on the grounds of breaching social responsibility in an environmental context.The regulator barred two ads, first released in a 2020 campaign: a poster and a video shown on social media, where dozens of Toyota Hilux cars drive across off-road terrain, including a river, while a voiceover describes the scene as “one of nature’s true spectacles”. The vehicles then join a road and drive through an urban area, before a lone car enters a driveway, with the voiceover continuing: “Toyota Hilux. Born to roam.” The poster shows two SUVs in the foreground, followed by a swarm of others traversing a rocky terrain over a cloud of dust.The complaint was lodged by Adfree Cities, a network of groups trying to get advertising out of public spaces. They argued, in partnership with the UK campaign group Badvertising, that the adverts condoned environmentally harmful behaviour, and are calling for an end to advertising of high-carbon products and services.The ASA ruled that the adverts “condoned the use of vehicles in a manner that disregarded their impact on nature and the environment … they had not been prepared with a sense of responsibility to society”.A poster showing two Toyota Hilux SUVs followed by a swarm of others. Photograph: Advertising Standards Authority/PAVeronica Wignall, a co-director at Adfree Cities, said: “These adverts epitomise Toyota’s total disregard for nature and the climate, by featuring enormous, highly polluting vehicles driving at speed through rivers and wild grasslands.”Wignall said there was a disconnect between the way SUVs were advertised – with campaigns often depicting them in rugged environments – and the reality of where they were largely driven. Research has shown that three-quarters of new SUVs in the UK are registered to people in urban areas. “It’s a cynical use of nature to promote something incredibly nature-damaging.”She said: “This ruling is a good moment to think about the limitations of what the regulator can do,” noting that the body relied on civil society to monitor ads for potential harm. “The ASA can only act on adverts that are environmentally damaging through breaches of advertising codes … But the harms caused by high-carbon advertising go much deeper than that.“Advertising for SUVs is pushing up demand for massive gas-guzzling, highly polluting cars in urban environments, just when we want streets that are safer and cleaner and an [accessible] low carbon transport system,” Wignall said, adding that the situation was similar for flights, meat and dairy.She called for the government to “stop high-carbon advertising at source” with a tobacco-style ban. “Similarly, climate breakdown is increasingly damaging health in the UK, as well as obviously across the world where impacts are felt more severely.”Toyota defended the Hilux campaign by arguing that the vehicle was designed for the toughest environments, with those working in industries including farming and forestry having a genuine need for off-road vehicles. It did not depict any such workers in the commercial, but it said it should not have to.In 2021 the regulator announced plans for a series of investigations into environmental advertising claims and practices. In a submission to the House of Lords that year, the ASA noted that it received few complaints related to social responsibility, describing it as “an area that we believe will require greater regulatory scrutiny in future”.skip past newsletter promotionSign up to Business TodayGet set for the working day – we'll point you to all the business news and analysis you need every morningPrivacy Notice: Newsletters may contain info about charities, online ads, and content funded by outside parties. For more information see our Privacy Policy. We use Google reCaptcha to protect our website and the Google Privacy Policy and Terms of Service apply.after newsletter promotionThe ASA has previously issued a draft ruling banning adverts for a Land Rover Defender off-roader in 2021 on social responsibility grounds, before overturning it.A Toyota spokesperson said: “Toyota does not condone behaviour that is harmful to the environment. In fact, over the course of the past three decades, not only has Toyota been one of the leaders in the automotive field in terms of carbon emissions reduction across its vehicle offering, it has shared hundreds of royalty-free licences, allowing others to use its electrification technology.“As part of its wide range of global vehicle offerings, Toyota caters for customers who require a mobility option for reliable use in the harshest of terrains – those people who operate in off-road and remote settings.”The spokesperson said footage in the advert had been shot on private land abroad, a non-UK location, with permission and “in a non-ecologically sensitive environment”, adding that the poster ad used computer-generated imagery and so had “no environmental impact”.While the definition of an SUV varies, the vehicles have surged in popularity in recent years in the UK to account for almost a third of vehicles sold. In Europe, the share of SUVs in new car registrations hit a record 51% this year.The effect of rising sales of SUVs, and the fact they tend to be heavier than the traditional models previously bought, means the average conventional-engined car bought in 2023 has higher carbon emissions than its 2013 equivalent, according to the climate campaign organisation Possible.

At the Portrait Gallery: ‘Forces of Nature,’ for good and ill

National Portrait Gallery show features subjects who have helped advance — and, in some instances, resisted — environmental stewardship.

The term for a likeness that captures a person in her or his defining home or workplace is “environmental portrait.” There are many of those in the National Portrait Gallery’s “Forces of Nature: Voices That Shaped Environmentalism.” But nearly as common are pictures such as the show’s oldest entry, an unknown artist’s small rendering of Henry David Thoreau, circa 1863, in which the “Walden” author looks as if he’s dressed for afternoon tea.Of course, he might have been. Thoreau’s celebrated haven in the woods was a short walk from the home of the property’s owner, Ralph Waldo Emerson, the author’s close friend. “Walden” remains influential for people who seek a return to nature, but Thoreau didn’t venture nearly so far into the wilderness as other 19th- and early-20th-century Americans pictured in this survey focusing on scientists, politicians, writers, artists and others who have helped advance — and, in some instances, resisted — environmental stewardship.Carl Everton Moon’s 1909 photograph of author and naturalist John Burroughs and Sierra Club co-founder John Muir shows them together at the Grand Canyon. Underwood & Underwood’s 1903 stereoscopic photo of presidential outdoorsman Teddy Roosevelt and a group of companions (including Muir) was made at the base of a giant sequoia. Gifford Pinchot, the first head of the U.S. Forest Service, also traveled far into the West, but Pirie MacDonald’s 1909 photo of him is no wilder than that of Thoreau.The museum owns more than 2,000 artworks originally made for the cover of Time magazine, so it’s hardly a surprise that some of them are included in this show. Mathias Klarwein’s 1970 illustration splits the face of ecologist and professor Barry Commoner between full color and reversed black and white, keyed to landscape backdrops that are, respectively, utopian and catastrophic. Also made for Time are Raul Vega’s 1980 photograph of cosmologist Carl Sagan standing in the surf fully clothed, and another split image that’s not technically a portrait: “Toxic Wastes,” James Marsh’s 1985 acrylic-on-board painting in which an anonymous man’s head turns skeletal below the surface of an apparently corrosive body of water.Two other pieces of Time cover art may come as thematic surprises. Mark Hess’s 1982 painting depicts James Watt, Ronald Reagan’s first secretary of the interior, depicted in front of a stylized rendering of the United States — whose public lands he appears ready to sell off. Dixy Lee Ray, the pro-development and pro-nuclear-power governor of Washington state from 1977 to 1981, is portrayed with her head grafted onto the body of an American goldfinch (the state bird) in David Palladini’s 1977 drawing in crayon, gouache and ink. Both former officials might be classified as forces against, rather than for, nature.The inclusion of Watt and Ray isn’t really explained, but the show is not divided equally between those who would preserve the planet and those who, for whatever reason, are not concerned about that. The only other subject who might be classified as an anti-environmentalist is Freeman Dyson, a physicist who in his final years became a critic of climate-change scientists, in a Francis Bello photograph.The show does feature portraits of people who are not known — or at least not known primarily — for their environmental campaigns. Among these are Prentice H. Polk’s photo of agricultural scientist George Washington Carver; Rudy Rodriguez’s photo of Dolores Huerta, the organizer of migrant farmworkers; and an unidentified picture of American Indian Movement activists Dennis Banks and Russell Means, depicted together by an unknown photographer during the 1973 armed occupation of Wounded Knee, S.D. But each of those subjects was concerned with the state of nature, even if indirectly.Coincidentally, all of the three-dimensional likenesses are of women. Two are bronze busts of authors: Rachel Carson (“Silent Spring”) by Una Hanbury, and Mary Austin (“The Land of Little Rain”) by Ida Rauh. The third is a small 3D print: a full-body color scan of Vietnam Veterans Memorial designer Maya Lin, who is now overseeing a different sort of memorial: a multimedia project about environmental and climate crises, “What Is Missing?”Among the most contemporary pieces are large paintings that exemplify a trend toward less formal and more playful portraits reflected in the museum’s recent acquisitions. Evolutionary biologist Edward O. Wilson communes with ants, a longtime interest, in Jennie Summerall’s 2006 painting, and tropical hues and cartoonishly outlined forms characterize Hope Gangloff’s 2019 painting of Julie Packard, the executive director of the Monterey Bay Aquarium. The contrast between these approachable images and the more solemn one of Thoreau demonstrates a notable development over the last 160 years. But that change is in art, which will probably prove less significant than the changes Mother Earth is undergoing.Forces of Nature: Voices That Shaped EnvironmentalismNational Portrait Gallery, Eighth and F streets NW. npg.si.edu.

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