One in three people in informal settlements in the global south live in floodplains and are at risk of a “disastrous flood”.
That is according to a new study published in Nature Cities, which measures the flood risk of global-south populations living in “slums” – as defined by UN-Habitat.
Using a combination of machine learning, satellite images, household surveys and socioeconomic data, the study finds that these slum populations are often concentrated in regions that have recently or frequently experienced severe floods.
Though large slum communities are vulnerable to floods, limited locational choices often mean that inhabitants have nowhere else to go, according to the study.
The research reveals the consequences of socioeconomic challenges when compounded with environmental pressures driven by urbanisation.
Dr Gode Bola, a water risk and climate scientist at the Congo Basin Water Resources Research Centre, who was not involved in the study, tells Carbon Brief:
“Slums in the Congo Basin used to face flooding to an extent that communities could deal with. Rainfall, which is where climate change is coming in, has meant people are facing larger floods and it’s difficult for people to adapt.”
Hotspots and vulnerability
According to the UN definition used by the study, slum households are those in urban areas that lack at least one of the following: “durable housing, sufficient living space, easy access to safe water, adequate sanitation and security of tenure.”
Using this, the study estimates that at least 17% of the global-south population, equivalent to more than 880 million people, live in slums. For some countries, such as Sierra Leone and Liberia, a majority of the population live in slums, the authors note.
Many of these slum communities are situated in areas that face substantial flood exposure. The study identifies northern India, Bangladesh, Nepal, Rwanda and the coastal regions of Rio de Janeiro as notable hotspots – as the map below illustrates:

Beyond physical exposure, these communities face social vulnerabilities that are exacerbated by flooding. Poor infrastructure, limited access to social services and a lack of institutional support impede effective responses to floods in these areas, the study finds.
At 80%, sub-Saharan Africa has the highest proportion of slum populations living in floodplains, the study finds.
Despite these challenges, relocation opportunities for people living in slums are slim. Financial constraints and reduced access to employment make it difficult to move to safer areas. Flood zones often offer cheaper land or housing, which pushes poorer households into vulnerable areas, the study finds.
For example, flood-prone areas in Mumbai in India, Dar es Salaam in Tanzania and Jakarta in Indonesia are considered “low value”, the authors say, making it more accessible to those in urban areas with lower incomes.
Nevertheless, the need for housing and an income continue to draw people to these flood-risk zones, separate research suggests.
Bola tells Carbon Brief:
“These slums are less expensive and poor people can afford the land. They buy this plot of land for life and asking them to relocate is asking them to have savings to buy another plot when there are no loans or government assistance.”
Disastrous floods
The authors mapped where slum populations are concentrated and where disastrous floods have historically occurred across 129 countries in the global south.
Disastrous floods were categorised in the study as events that resulted in “severe societal disruption, often leading to fatalities and severe humanitarian consequences”.
Their findings showed that, across the global south, those living in slums make up 35% of the total population, but account for 41% of those who live in flood-prone areas. This suggests that slum residents are more likely to settle in flood-risk areas in comparison to non-slum residents.
In fact, the study finds that in countries which often face disastrous floods, such as Bangladesh, slum residents are overrepresented in nearly all areas where disastrous floods have occurred.
Rourkela and Kinshasa’s slums
Floods in Rourkela, India, and Kinshasa, Democratic Republic of Congo, in recent months illustrate the issue of slums being situated in floodplains.
Heavy monsoon downpours caused floods in slum settlements in Rourkela, while floods and landslides devastated 13 communes in Kinshasa’s urban slums, resulting in 165 deaths.
In Kinshasa, rapid urban growth is pushing development into floodplains without proper infrastructure, making floods worse and recovery harder, according to a recent article by researchers. As a result, healthcare systems and transportation are routinely damaged.
In India, separate research suggests that slum settlements are prone to flooding because many are in low-lying areas on the periphery of water bodies, without proper storm-water drainage.
According to the new study, rapid urbanisation and land pressures will likely drive even more slum populations into flood zones in the global south, indicating that the cases of Rourkela and Kinshasa could become an even more frequent reality.
Flood protection
The “intensifying” effects of climate change amplifies the need to address the location of slums in the global south, the authors state.
However, other research has shown that minimal policies to support slum communities in flood zones exist. Yet, as rapid urbanisation occurs, slums continue to spread into high-risk areas.
Poor governance has failed to recognise the rights and needs of the urban poor in city planning, according to research from Cities Alliance.
The study in Nature Cities mentions that governments are often politically reluctant to formally recognise slums because doing so could increase pressure to deliver services, complicate future development plans or damage the international image of the city or country.
Dr Nausheen Anwar, director of Karachi Urban Lab and principal researcher and urban climate resilience lead at the International Institute for Environment and Development, tells Carbon Brief about the government response to flooding of informal settlements in Karachi in 2022.
Anwar, who was not involved in the new study, says:
“People were living alongside the banks of those specific channels and were quickly labelled as encroachers, even though many of them had tenure in these informal settlements and the supreme court essentially backed the entire plan for eviction. This is where the role of the law became very effective in displacing people and razing their homes.”
The authors of the study say their findings can be used to inform data-driven policies that address flood risk, as well as to help shape local regulations.
In the study, they call for governments to recognise the inequalities that slum populations face and to acknowledge slum communities as key stakeholders. This would mean considering their needs and interests when designing policies to respond to climate change.
The authors also suggest that communities be empowered through capacity building, including training in sanitation and waste management.
Anwar adds:
“Data speaks for itself whether it comes in the form of numbers or is quantitative or qualitative…We need that to buttress the sort of changes we want to make on ground in terms of influencing policy agendas and planning interventions, whether it is at the local scale or going up even at the global scale.”
The post Third of ‘slum residents’ in global south are exposed to ‘disastrous’ flood risks appeared first on Carbon Brief.
Third of ‘slum residents’ in global south are exposed to ‘disastrous’ flood risks
Climate Change
Efforts to green lithium extraction face scrutiny over water use
Mining companies are showcasing new technologies which they say could extract more lithium – a key ingredient for electric vehicle (EV) batteries – from South America’s vast, dry salt flats with lower environmental impacts.
But environmentalists question whether the expensive technology is ready to be rolled out at scale, while scientists warn it could worsen the depletion of scarce freshwater resources in the region and say more research is needed.
The “lithium triangle” – an area spanning Argentina, Bolivia and Chile – holds more than half of the world’s known lithium reserves. Here, lithium is found in salty brine beneath the region’s salt flats, which are among some of the driest places on Earth.
Lithium mining in the region has soared, driven by booming demand to manufacture batteries for EVs and large-scale energy storage.
Mining companies drill into the flats and pump the mineral-rich brine to the surface, where it is left under the sun in giant evaporation pools for 18 months until the lithium is concentrated enough to be extracted.
The technique is relatively cheap but requires vast amounts of land and water. More than 90% of the brine’s original water content is lost to evaporation and freshwater is needed at different stages of the process.
One study suggested that the Atacama Salt Flat in Chile is sinking by up to 2 centimetres a year because lithium-rich brine is being pumped at a faster rate than aquifers are being recharged.
Lithium extraction in the region has led to repeated conflicts with local communities, who fear the impact of the industry on local water supplies and the region’s fragile ecosystem.
The lithium industry’s answer is direct lithium extraction (DLE), a group of technologies that selectively extracts the silvery metal from brine without the need for vast open-air evaporation ponds. DLE, it argues, can reduce both land and water use.
Direct lithium extraction investment is growing
The technology is gaining considerable attention from mining companies, investors and governments as a way to reduce the industry’s environmental impacts while recovering more lithium from brine.
DLE investment is expected to grow at twice the pace of the lithium market at large, according to research firm IDTechX.
There are around a dozen DLE projects at different stages of development across South America. The Chilean government has made it a central pillar of its latest National Lithium Strategy, mandating its use in new mining projects.
Last year, French company Eramet opened Centenario Ratones in northern Argentina, the first plant in the world to attempt to extract lithium solely using DLE.
Eramet’s lithium extraction plant is widely seen as a major test of the technology. “Everyone is on the edge of their seats to see how this progresses,” said Federico Gay, a lithium analyst at Benchmark Mineral Intelligence. “If they prove to be successful, I’m sure more capital will venture into the DLE space,” he said.
More than 70 different technologies are classified as DLE. Brine is still extracted from the salt flats but is separated from the lithium using chemical compounds or sieve-like membranes before being reinjected underground.
DLE techniques have been used commercially since 1996, but only as part of a hybrid model still involving evaporation pools. Of the four plants in production making partial use of DLE, one is in Argentina and three are in China.
Reduced environmental footprint
New-generation DLE technologies have been hailed as “potentially game-changing” for addressing some of the issues of traditional brine extraction.
“DLE could potentially have a transformative impact on lithium production,” the International Lithium Association found in a recent report on the technology.
Firstly, there is no need for evaporation pools – some of which cover an area equivalent to the size of 3,000 football pitches.
“The land impact is minimal, compared to evaporation where it’s huge,” said Gay.


The process is also significantly quicker and increases lithium recovery. Roughly half of the lithium is lost during evaporation, whereas DLE can recover more than 90% of the metal in the brine.
In addition, the brine can be reinjected into the salt flats, although this is a complicated process that needs to be carefully handled to avoid damaging their hydrological balance.
However, Gay said the commissioning of a DLE plant is currently several times more expensive than a traditional lithium brine extraction plant.
“In theory it works, but in practice we only have a few examples,” Gay said. “Most of these companies are promising to break the cost curve and ramp up indefinitely. I think in the next two years it’s time to actually fulfill some of those promises.”
Freshwater concerns
However, concerns over the use of freshwater persist.
Although DLE doesn’t require the evaporation of brine water, it often needs more freshwater to clean or cool equipment.
A 2023 study published in the journal Nature reviewed 57 articles on DLE that analysed freshwater consumption. A quarter of the articles reported significantly higher use of freshwater than conventional lithium brine mining – more than 10 times higher in some cases.
“These volumes of freshwater are not available in the vicinity of [salt flats] and would even pose problems around less-arid geothermal resources,” the study found.
The company tracking energy transition minerals back to the mines
Dan Corkran, a hydrologist at the University of Massachusetts, recently published research showing that the pumping of freshwater from the salt flats had a much higher impact on local wetland ecosystems than the pumping of salty brine. “The two cannot be considered equivalent in a water footprint calculation,” he said, explaining that doing so would “obscure the true impact” of lithium extraction.
Newer DLE processes are “claiming to require little-to-no freshwater”, he added, but the impact of these technologies is yet to be thoroughly analysed.
Dried-up rivers
Last week, Indigenous communities from across South America held a summit to discuss their concerns over ongoing lithium extraction.
The meeting, organised by the Andean Wetlands Alliance, coincided with the 14th International Lithium Seminar, which brought together industry players and politicians from Argentina and beyond.
Indigenous representatives visited the nearby Hombre Muerto Salt Flat, which has borne the brunt of nearly three decades of lithium extraction. Today, a lithium plant there uses a hybrid approach including DLE and evaporation pools.
Local people say the river “dried up” in the years after the mine opened. Corkran’s study linked a 90% reduction in wetland vegetation to the lithium’s plant freshwater extraction.
Pia Marchegiani, of Argentine environmental NGO FARN, said that while DLE is being promoted by companies as a “better” technique for extraction, freshwater use remained unclear. “There are many open questions,” she said.
AI and satellite data help researchers map world’s transition minerals rush
Stronger regulations
Analysts speaking to Climate Home News have also questioned the commercial readiness of the technology.
Eramet was forced to downgrade its production projections at its DLE plant earlier this year, blaming the late commissioning of a crucial component.
Climate Home News asked Eramet for the water footprint of its DLE plant and whether its calculations excluded brine, but it did not respond.
For Eduardo Gigante, an Argentina-based lithium consultant, DLE is a “very promising technology”. But beyond the hype, it is not yet ready for large-scale deployment, he said.
Strong regulations are needed to ensure that the environmental impact of the lithium rush is taken seriously, Gigante added.
In Argentina alone, there are currently 38 proposals for new lithium mines. At least two-thirds are expected to use DLE. “If you extract a lot of water without control, this is a problem,” said Gigante. “You need strong regulations, a strong government in order to control this.”
The post Efforts to green lithium extraction face scrutiny over water use appeared first on Climate Home News.
Efforts to green lithium extraction face scrutiny over water use
Climate Change
Maryland’s Conowingo Dam Settlement Reasserts State’s Clean Water Act Authority but Revives Dredging Debate
The new agreement commits $340 million in environmental investments tied to the Conowingo Dam’s long-term operation, setting an example of successful citizen advocacy.
Maryland this month finalized a $340 million deal with Constellation Energy to relicense the Conowingo Dam in Cecil County, ending years of litigation and regulatory uncertainty. The agreement restores the state’s authority to enforce water quality standards under the Clean Water Act and sets a possible precedent for dozens of hydroelectric relicensing cases nationwide expected in coming years.
Climate Change
A Michigan Town Hopes to Stop a Data Center With a 2026 Ballot Initiative
Local officials see millions of dollars in tax revenue, but more than 950 residents who signed ballot petitions fear endless noise, pollution and higher electric rates.
This is the second of three articles about Michigan communities organizing to stop the construction of energy-intensive computing facilities.
A Michigan Town Hopes to Stop a Data Center With a 2026 Ballot Initiative
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