How AI can turn “smart” sewers into our first line of flood defences

Somerset, 2014. Image: Getty.

The UK will need to spend £1bn a year on flood management to avoid the worst consequences of climate change, according to the national Environment Agency. The organisation’s chair, Emma Boyd, said “we can’t win a war against water by building away climate change with infinitely high flood defences”, and warned that entire communities may need to change location due to flood risk.

More frequent extreme weather events – particularly flooding – are a hallmark of climate change. By their very nature, such events are unpredictable and can do substantial damage to communities. Significant floods occur in the UK every few years, so the way flooding is managed can have a major impact on how much damage is done, while poor strategic decisions such as building on historic flood plains can leave new communities vulnerable.

Coastal defences – including sea walls, buffer areas and evacuation plans – can help to protect towns and cities against flooding from storm surges. But inland flooding caused by excess rainwater requires more nuanced solutions. Humans have altered water courses such as rivers, streams and canals for centuries, and every change affects the way the ground responds to flooding. Today, artificial intelligence (AI) can use data to help make decisions about how water should flow in and around human settlements, to avoid the worst effects of flooding.

Introducing AI to the sewers

In cities, every drain is an opportunity to adjust the movement of water. At the University of Sheffield we worked with partners to create the CENTAUR system (Cost Effective Neural Technique to Alleviate Urban flood Risk), which uses AI to manage the flow of water in cities. The system works by installing “gates” in the sewer network that can control the flow of water from one part of the sewer network to another. Sensors are also added, to monitor water levels on either side of the gates.

The gates can be controlled remotely during extreme weather events, to prevent flooding in important areas. For example, if a part of the network starts flooding downstream, the system can detect rising water levels and close a gate upstream, to slow the flow of water or divert it into other parts of the sewer with spare capacity, and thereby prevent water from overflowing onto the street.


The “smart” bit, implemented by researchers at the university, was to create computer software that is capable of managing these systems independently of humans, and learning from its mistakes. The control system makes use of fuzzy logic – a way of interpreting uncertain conditions, such as the actual water level – and making decisions in those situations.

The CENTAUR system has proven successful in pilot installations in Coimbra, Portugal (2017) and Toulouse, France (2018). It has a relatively low cost, in the tens of thousands of euros, which means it can be easily incorporated into existing flood defence programmes. There are limitations though: if there is no spare capacity for water in a city’s sewers, then managing them with AI in this way would have very few benefits.

The limits of AI

The major issue when defending against floods is that water has to go somewhere. In small floods, water might be able to be diverted so that no area gets flooded. But during larger floods, the priority is not preventing flooding altogether, but managing which areas flood, and limiting the danger to people, property and key infrastructure.

Often, flood defence strategies divert flood water from urban areas into rural farmland and areas where fewer people live. To do this, water is either held upstream from urban areas by partially blocking rivers, or encouraged to move downstream more quickly by dredging or expanding rivers.

Some places may fare worse than others. Image: John D. Fielding/Flickr/creative commons.

While innovative flood management systems such as CENTAUR can help to protect people living in urban areas from flooding, the water has to be diverted. Decisions about which communities are offered greater protection from flooding, and which are left with limited defences, have the potential to set communities against one another. That’s why these higher level decisions cannot be left to AI.

Many different groups need to be involved in such decisions. Farmers might be in control of some drainage channels, water companies are generally responsible for the sewerage network, and environment agencies are responsible for river systems. Of course, the communities that are affected are also entitled to a say on it all. Local, regional and national governments must listen to and negotiate with all of these groups, to create a sound strategy for flood prevention.

These discussions have major implications, not just for the UK, but for the way nations deal with climate change around the world. The costs of stopping climate change will be very high for some countries – especially those which depend on coal for economic development, such as China. Yet for others – such as the Maldives, which is threatened by flooding from storms and rising sea levels – the cost of inaction will be far greater. Smart technology can help to mitigate the consequences of climate change, but it will take global action by world leaders to prevent it from reaching crisis point.

The Conversation

Jonathan Sykes, PhD Candidate, University of Sheffield

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 
 
 
 

In South Africa's cities, evictions are happening despite a national ban

An aerial view shows a destroyed house in Lawley, south of Johannesburg, on April 20, 2020. The city has been demolishing informal structures on vacant land despite a moratorium on evictions. (Marco Longari/AFP via Getty Images)

On the morning of 15 July, a South African High Court judge ruled that the city of Cape Town’s Anti-Land Invasion Unit had illegally evicted a man when it destroyed the shack where he was living.

That afternoon, the Anti-Land Invasion Unit was out again, removing shacks in another informal settlement.

Evictions were banned in South Africa for nine weeks, after the national government placed the country under a strict Covid-19 lockdown in late March. At present, eviction orders are automatically suspended until the country moves to a lower “alert level” and can only be carried out with a special order from a judge.

Yet major cities including Cape Town, Johannesburg and eThekwini (created through the merger of Durban with several surrounding communities), have continued to use municipal law enforcement agencies and private security companies to remove people from informal housing. In many cases those operations have been conducted without a court order – something required under regular South African law.

Around 900 people were evicted from three informal settlements in eThekwini during the eviction ban, according to the Church Land Programme, a local NGO. Its director, Graham Philpott, says it’s also aware of evictions in other informal settlements.

While evictions aren’t a “new experience” in these communities, the NGO released a report on lockdown evictions because they were “so explicitly illegal”. “There was a moratorium in place,” Philpott says, “and the local municipality acted quite flagrantly against it. There’s no confusion, there’s no doubt whatsoever, it is illegal. But it is part of a trend where the eThekwini municipality has acted illegally in evicting the poor from informal settlements.”

Evictions also took place in Cape Town and Johannesburg during so-called “hard lockdown” according to local activists. In eThekwini and other municipalities, the evictions have continued despite restrictions. In Cape Town, authorities pulled a naked man, Bulelani Qholani, from his shack. That incident, which was captured on video, drew condemnation from the national government and four members of the Anti-Land Invasion unit were suspended. 


The cities say they’re fighting “land invasions” – illegal occupations without permission from the land owner.

“Land invasions derail housing and service projects, lead to the pollution of waterways, severely prejudice deserving housing beneficiaries and cause property owners to lose their investments over night,” Cape Town’s executive mayor, Dan Plato said in a statement. (Plato has also claimed that Qholani did not live in the shack he was pulled from and that he disrobed when municipal authorities arrived.)

South African municipalities often claim that the shacks they destroy are unoccupied. 

If they were occupied, says Msawakhe Mayisela, a spokesman for the eThekwini municipality, the city would get a court order before conducting an eviction. “Everything we’re doing is within the ambit of the law,” Mayisela says. But “rogue elements” are taking advantage of Covid-19, he added.

“We fully understand that people are desperately in need of land, but the number of people that are flocking to the cities is too much, the city won’t be able to provide housing or accommodation for everyone overnight,” he says. 

While eThekwini claims to be a caring city, local activists say the evictions show otherwise.

In one case, 29 women were evicted from shacks during the hard lockdown. With nowhere to go, they slept in an open field and were arrested by the South African Police Service for violating the lockdown, Philpott says.

“These evictions are dehumanizing people whose dignity is already compromised in many ways,” says S’bu Zikode, the president of Abahlali baseMjondolo, a community organization whose Zulu name translates to “the people of the shacks”. 

“It has reminded us that we are the people that do not count in our society.”

Municipal law enforcement and private security contractors hired by cities regularly fire rubber bullets, or even live ammunition, at residents during evictions. Some 18 Abahlali baseMjondolo activists have been killed since the organization was founded in 2005, Zikode says, most by the eThekwini Land Invasion Unit and Metro Police.

(Mayisela says that if city employees have broken the law, Abahlali baseMjondolo can file a complaint with the police. “There is no conclusive evidence to the effect that our members have killed them,”  he says.)

Other Abahlali baseMjondolo activists have been killed by what Zikode calls “izinkabi,” hitmen hired by politicians. Two eThekwini city councillors were sentenced to life in prison 2016 after they organized the killing of Thuli Ndlovu, an Abahlali baseMjondolo organizer. A member of the Land Invasion Unit who is currently facing a charge of attempted murder after severely injuring a person during an eviction remains on the job, Zikode says.

South Africa’s 1996 constitution is intended to protect the public from arbitrary state violence and guarantees a right to housing, as well as due process in evictions. But for Zikode, the South African constitution is a “beautiful document on a shelf”.

“For the working class and the poor, it’s still difficult to have access to court. You’ve got to have money to get to court,” he says. 

The actions by municipal law enforcement are breaking down social trust, says Buhle Booi, a member of the Khayelitsha Community Action Network, a community group in the largest township in Cape Town.

“There’s a lack of police resources and those very few police resources that they have, they use to destroy people’s homes, to destroy people’s peace, rather than fighting crime, real criminal elements that we see in our society,” Booi says.

For him, it’s a continuation of the practices of the colonial and apartheid governments, pushing poor people, most of whom are Black, to the periphery of cities.

Around one-fifth of South Africa’s urban population live in shacks or informal dwellings, according to a 2018 report by SERI. Many more live in substandard housing. City governments maintain that the shacks destroyed during anti-land invasion operations are unfinished and unoccupied. But Edward Molopi, a research and advocacy officer at SERI, says that this claim is an attempt to escape their legal obligations to get a court order and to find alternative accommodation for affected people. 

The roots of the current eviction crisis go back to apartheid, which barred non-white people from living in cities. Between the 1940s and 1970s, tens of thousands of people were forcibly relocated from neighbourhoods like Johannesburg’s Sophiatown and Cape Town’s District Six to remote townships.

In the 26 years following the end of apartheid, deepening economic inequality and rampant unemployment have limited access to formal housing for millions of South Africans. Government housing programs have mostly focused on building small stand-alone homes, often on the peripheries of cities far from jobs and amenities.

While these well-intentioned projects have built millions of homes, they’ve failed to keep up with demand, says Marie Huchzermeyer, a professor at the Centre for Urbanism & Built Environment Studies at the University of the Witwatersrand in Johannesburg. Government-funded housing projects “will never on it’s own be enough,” she says. “It has to be accompanied by land release.”

Government policies call for the “upgrading” of informal settlements and the formalization of residents’ occupation. But “there are still very, very, very few projects” of that nature in South Africa, Huchzermeyer says. “Even if it’s an informal settlement that’s been around for 20 years, there still seems to be a political wish to punish people for having done that.” The government wants people to go through the formal process of being given a house, she says – and for them to be thankful to the government for providing it.

At the municipal level, change will require “real leadership around informal settlement upgrading and around ensuring that land is available for people to occupy,” she says. 

Despite the end of enforced racial segregation, spacial apartheid remains a factor in South Africa. There are few mixed-income neighbourhoods. Those who can afford to often live behind walls in sprawling low-density suburbs, while the poor live in overcrowded slums and apartment buildings.

The creation of the apartheid city “didn't happen by chance,” says Amira Osman, a professor of architecture at the Tshwane University of Technology. “It was a deliberate, structured approach to the design of the city. We need a deliberate, structured approach that will undo that.”

Since last fall, Johannesburg’s Inclusionary Housing Policy has required developments of 20 or more units to set aside 30% of those units for low-income housing.

The policy, which faced significant opposition from private developers, won’t lead to dramatic change, says Sarah Charlton, a professor at the Centre for Urbanism and Built Environment Studies, but it is “an important and significant step.”

Zikode isn’t optimistic that change will come for shack dwellers, however.

“People in the high positions of authority pretend that everything is normal,” he says. “They pretend that everyone is treated justly, they pretend that everyone has homes with running water, that everyone has a piece of land – and hide the truth and the lies of our democracy.”

Jacob Serebrin is a freelance journalist currently based in Johannesburg. Follow him on Twitter.