That sinking feeling

We are literally pulling the rug from under our cities by drawing water from ancient aquifers

Good morning! The area near Delhi’s Indira Gandhi International Airport is sinking. As is Indonesia's Jakarta. Land subsidence, owing to excess groundwater extraction, is slowly but surely coming for urban areas. Land subsidence could trigger flooding or create water scarcity. It can wreak havoc on cities and their infrastructure, as experienced recently by the Himalayan town of Joshimath. This article from 360info highlights the severity of the problem. We've curated some excellent long reads for your reading pleasure as well.

The Signal is now on Telegram! We've launched a group — The Signal Forum — where we share what we’re reading and listening through the day. Join us to be a part of the conversation!

If you enjoy reading us, why not give us a follow at @thesignaldotco on Twitter and Instagram.

When you come into land at Delhi’s Indira Gandhi International airport it may not be obvious from the sky that the land in the surrounding area has been sinking more than 17cm a year.

The main reason for this subsidence is excessive pumping of groundwater.

As the water is removed from underground aquifers, the soil above begins to compact and sink. This can happen gradually, over years, or suddenly, in just hours. In either case, the effects can be long-lasting and expensive to repair.

India is ranked number one for excessive groundwater usage. Groundwater is a vital resource for our planet's survival. It sustains agriculture, provides drinking water and supports ecosystems.

However, overuse of groundwater is leading to a new problem: land subsidence which not only causes damage to infrastructure and buildings but threatens the livelihoods of millions of people around the world.

In India, the northern Gangetic plains are exploited more than anywhere else. The impact of disappearing groundwater is accelerating changes on the shape of the land surface. But residents and authorities are fighting back, changing years of water usage habits to stop the land sinking beneath them.

A recent study in Nature reported alluvial aquifers in India in the Delhi NCR region have sunk and continue to sink at a substantial rate. Around Kapashera, near the international airport, land subsided 11cm per year during 2014-2016. That increased to more than 17cm per year in the two years that followed.

On the vulnerability of Delhi to subsidence, Ryan Smith, assistant professor at Missouri University of Science and Technology said: “Aquifers that are pressurised and have lots of clay are most prone to subsidence.”

The soil in Delhi is mainly thick alluvium, which is clay-rich and thus vulnerable. It can cause significant damage to buildings, bridges, pipelines, railways and canals. Even minor subsidence in densely populated areas can put lives at risk. In cases where the rate of sinking is differential, It might lead to the weakening of foundations or develop cracks in the buildings.

A fifth of the world's population lives in areas that are at risk of subsidence, according to recent reports. In some cities, the problem is so severe that buildings have sunk by several metres. The consequences can be devastating, as entire communities are left vulnerable to flooding, infrastructure damage, and water scarcity.

There’s been land subsidence in various parts of the world where exploitation of groundwater has been high.

One of the most prominent cases is in Mexico City, where buildings have been tilting due to land sinking.

In Indonesia, over the last decade, the capital Jakarta has sunk more than 2.5m. The problem is so grave the government is planning to shift the capital.

Countries like Iran and China too, have witnessed prominent land subsidence in the last few decades.

It is possible to reduce land subsidence if groundwater replacement is equivalent to what’s taken out, or by using water sustainably. Rainwater harvesting is an effective way to boost groundwater, especially in dry cities, which receive low rainfall and have a lot of alluvial soil, which is prone to subsidence due to its softness.

In Delhi’s Dwarka region, residents and the government had been working on a plan to supply piped water to the area by 2016. Heavy fines were imposed on buildings still using borewells and residents began harvesting rainwater to increase the water table in the area. Two large lakes were cleaned up and rejuvenated which helped increase groundwater levels.

The government also decided that only treated sewage and surface water should be used to water public parks and grounds.

Town planner Vikas Kanojia said steps like reviving old reservoirs and harvesting rainwater helped Dwarka reduce its reliance on groundwater and reverse the trend of land subsidence. “This can be a model for other areas in Delhi and India", he said.

Dwarka's example shows that it's possible to deal with the issue of subsidence, however in more arid regions this process is difficult.

Iran, for instance, is home to some of the fastest sinking valleys in the world, but uncontrolled mining continues. Per capita water supplies have plummeted more than 65 percent in recent decades and it could be worse in the future.

The government has invested heavily in technologies such as desalination. "Technology can help, but what we need is a long-term program to conserve water resources involving farmers, industries and local communities, and at the moment there isn't one," said Mahdi Motagh, a senior scientist from GFZ Potsdam.

The issue of subsidence is becoming more serious and widespread, affecting the lives of millions of people around the world. However, there are solutions, as demonstrated by the efforts of residents and the government in the Dwarka region of Delhi.

Rainwater harvesting, reviving old reservoirs and using treated sewage and surface water can help to reduce reliance on groundwater and reverse land subsidence. But what’s more important is to address this issue through proper tracking and monitoring, and long-term programs involving farmers, industries and local communities.

Shagun Garg is a PhD student at the University of Cambridge EPSRC Centre for Doctoral Training in Future Infrastructure and Built Environment2 (FIBE2 CDT).

The research is being undertaken with financial assistance from DAAD KOSPIE, MHRD India, EPSRC CDT FIBE2, and BP.

Originally published under Creative Commons by 360info™.

Addendum: Where are cities sinking?

Chennai and Kolkata are sinking 3 cm per year. Ahmedabad and Mumbai are sinking by 6 cm, while Lagos, Nigeria and Tianjin, China are sinking by a whopping 11 cm and 18 cm, respectively. This interactive map of 48 cities around the world drives home the gravity of rising sea levels.

James Goldie, 360info

Data: Tay et al 2022

A MESSAGE FROM OUR PARTNER

Hottest Stock Ideas Delivered Every Morning

Get the most out of the trading day with 360 Wall Street.

Before the market opens, our experts have already found the 3 stocks they think have the best potential to make the biggest moves – stocks that you’ll see everyone else talking about – tomorrow!

This email is like a little gift 🎁 in your morning inbox, you can get the full details on the top 3 juiciest stocks on our radar - in less than 3 minutes.

Cut through the meaningless news and get right to what is most important!

Over 100,000 people rely on 360 Wall Street to make better-informed decisions.

Best of all... there is absolutely no cost to join!

Subscribe to start getting the best ideas delivered FREE to your inbox!

ICYMI

The fizzless heist: It’s not often that you hear about intellectual property theft of the inner liner of a Coca-Cola can. But Dr Shannon You, a former chemist with the beverage giant, was caught in the act doing just that. Not by Coke but her next employer, the Eastman Kodak Company… for a similar data theft. Cornered with no way out, You looked to flee to her native China via an Italian company—with funding from a Chinese government programme. Spoiler alert: none of that happened. Dive into this detailed Bloomberg Businessweek story about You’s brazen corporate espionage, and learn about China’s ‘Thousand Talents’ grant while you’re at it.

Uncool tech: Why are the world’s richest people obsessed with preparing for the apocalypse? City University of New York professor Douglas Rushkoff poses and answers the question himself: “Because they’re edging us all toward it.” In this lengthy profile, the Wired magazine sketches out the arc of Rushkoff’s transformation from a tech optimist to a Marxian humanist shaking his head at technology as the handmaiden of greedy capitalists. For many years as a sort of techno beatnik, Rushkoff romanticised the transformative power of edgy tech but got disillusioned as he watched it become the purposeful weapon of individuals with dreams of world domination. Although his diagnosis of the problem is Marxian, the answers he finds most appropriate appear to be very Gandhian.

“AI fearmongering is AI marketing”: That’s the premise of tech activist, journalist, and science fiction author Cory Doctorow’s takedown of Google Search, chatbots, and the hoopla over AI disrupting jobs. Doctorow likens AI hype to the bubblenomics of self-driving cars and drone delivery, arguing that automating low-wage jobs will yield modest profits (at best) for Big Tech companies. Meaning there’s more value in replacing the C-suite—ironically the cohort that’s overseen mass layoffs. As for Google, incorporating AI in Search will do it more harm than good. How so? Head here to find out.

Intergenerational (financial) trauma: But only for some. The top 1% (mostly white) families in the US are already transferring vast amounts of their wealth to their Gen X heirs, now in their 40s and 50s, via property purchases and tax-free gifts. Meanwhile, the bottom 50% has barely, if any, money and assets to pass on to their children. It’s creating starker divides among the rich and the poor by generation, The New York Times reports. Baby Boomers, born in the 1940-60s, have disproportionately benefited from a cycle of rising house prices while younger ‘sandwich’ generations struggle with caring for ageing parents and their children. What will be the impact of this great wealth transfer? Some will inherit wealth, and some, greater inequality. Economists estimate that eventually, high-income workers will also be unable to afford families and housing, and demands for a bigger welfare state will intensify.

Heartbreakers: Deception on the internet isn't new, but the pandemic made an industry out of it. We are talking about professional catfishers, who emerged in droves during Covid. Freelancers, hired as customer service reps, preyed on the lonely and eventually lured them to sign up for niche dating and hookup sites few have heard of. All this, for €2 ($2.16) per hour. These “freelance remote translators” have access to enough data on their clients to make the profiles seem real. And as is the case with catfishing, it only ends one way. This insane story in Wired plumbs the depths of the digital romance scam industry.

Milk power: “Does India have room for a dairy behemoth?” That’s the headline of this Mint story. On the face of it, it’s a ridiculous question. India is the world’s largest milk producer, accounting for a fifth of the global output. Surely it has room for a dairy behemoth? However, the industry is divided into over 190,000 dairy cooperatives, comprising nearly 17 million farmers. The largest cooperative is the Gujarat Cooperative Milk Marketing Federation, which markets its products under the Amul brand. Others include Nandini in Karnataka, Aavin in Tamil Nadu, and Milma in Kerala. Can these cooperatives not be merged to create a national brand? Let’s just say that even multinational dairy giants have been unable to crack the Indian market because of the strength of the big cooperatives. This story (linked above) is a good explainer of how the industry functions.

(360info and 360 Wall Street are unrelated entities.)

Reply

or to participate.