Glacial lakes threaten millions with flooding as planet heats up

 More than 12,000 deaths have already been attributed to glacial lake outburst floods worldwide

An increasing number of people are being threatened by flooding caused by glacial lakes bursting, scientists have warned.

As the planet warms and glaciers recede, meltwater accumulates and forms lakes, often as a result of ice or moraine acting as a dam. Since 1990, the volume, area and number of these glacial lakes has increased by 50% globally. When these lakes become too full there is a risk that they may breach or overflow, releasing huge volumes of water and causing catastrophic flooding.

Some lakes are more dangerous than others, and more likely to result in what are known as glacial lake outburst floods (GLOFs). Stephan Harrison, a professor of climate and environmental change at Exeter University, said: “The ones we’re concerned about are the very steep mountain valleys in the Andes and in the Himalayas, where you have glaciers retreating up into their steep valleys with lots of opportunity for bits of mountainside to fall off into lakes.”

Lake Palcacocha in Peru. The many factors at play in an outburst flood make it impossible to estimate how many people might be at risk globally. Photograph: Dan Collyns/The Guardian

The correlation between rising temperatures and glacial lake outburst floods is complicated. While glacial lake formation and growth can be attributed to anthropogenic climate change, the triggers that can cause disastrous flooding are often down to non-climatic factors such as moraine dam geometry, earthquakes, ice or rock avalanches into the lake or extreme rainfall.

Adam Emmer, a geographer at the University of Graz in Austria, said: “You need two conditions to generate a disaster – high magnitude GLOF, and exposed population as well as assets in its path. Population expansion along the potential GLOF paths and lack of building development regulations may be even more important driver of GLOF risk, especially in developing countries.”

One of the parameters that makes a glacial lake potentially dangerous is the size of downstream population that could be exposed to flooding, and that number can range from few hundreds to hundreds of thousands, as in the case of Huaraz city located downstream of Lake Palcacocha in Peru. However, the many factors at play in an outburst flood make it impossible to estimate how many people might be at risk globally.

A 2016 study found there have been at least 1,348 recorded glacial lake outburst floods so far worldwide, of which 24% had some societal impact.

More than 12,000 deaths have been attributed to such floods. Central Asia was the most affected region, followed by South America, then the European Alps, Iceland, Scandinavia, north-west America and Greenland. The authors identify South America and central Asia as the regions most likely to experience large numbers of deaths, extreme damage to infrastructure, flooding of farmlands and the destruction of homes and roads.

Of the world’s tropical glaciers, 70% are situated in Peruvian Andes, and they are melting rapidly, which has led to several glacial disasters over recent decades. The worst so far was the 1941 glacial lake outburst flood from Lake Palcacocha, which claimed at least 1,800 lives.

The Pastoruri glacier in Peru. The melting of the glacier has put the city of Huaraz, located about 35 miles downslope, at risk from GLOF. Photograph: Martin Mejia/AP

Subsequently, Peru started working on lake monitoring and implementation of hazard mitigation measures such as draining lakes, strengthening unstable moraine dams with concrete structures and artificial spillways, and installing early warning systems as early as the 1950s.

“Peruvian Cordillera Blanca [part of the Andes mountain range] is, in fact, the world’s pioneer region of GLOF mitigation works,” said Emmer. Despite this, “the biggest challenge is yet to come – communicating the risk and risk reduction measures to local communities and making them trust and accept it”, he added.

Nepal, which is also highly vulnerable to glacial floods, started taking interest in GLOFs after two serious floods in the 1980s. In 1999, Nepal drained a rapidly expanding lake called Tsho Rolpa near Mount Everest to lower the lake levels, a first in the region.

“GLOF has been recognised as a big challenge for Nepal. In the past, there also have been efforts made to reduce the risk from individual lakes and two lakes have already been intervened in [around] the Everest region,” said Arun Shrestha, a climate change specialist at the International Centre for Integrated Mountain Development.

A glacial lake in the Himalayas. Photograph: Goncalo Diniz/Alamy

According to Shrestha, Nepal has documented records of up to 35 GLOF events, but the true number is probably higher. International communication and cooperation is also critical to preventing deadly floods; a study published last year identified 47 potentially dangerous glacial lakes that could affect Nepal if breached, but only 21 were in Nepal itself. Twenty-five were also identified in China and one in India.

“It’s very important that Nepal talks with China and tries to address those issues,” said Shrestha. “Those lakes cannot be ignored, but for that, a bilateral diplomatic effort is required. With climate change, and infrastructure and settlements changing quite rapidly, I think the risk is growing every day.”

Despite the rapid recession of glaciers worldwide, the frequency of GLOFs has actually declined globally. Scientists attribute this trend to a lag between climate change and the occurrence of GLOFs.

Scientists predict an increase in GLOFs starting in the coming decades and extending well into the early 22nd century. Vulnerable countries with populations and infrastructure at risk of floods are now in a race against time to invest in disaster preparedness to avoid catastrophic outcomes in the event of an outburst flood.

(Source: The Guardian)

Storm Ciara: Travel disruption as UK hit by severe gales

Severe gales and heavy rain are sweeping across the UK as travellers face disruption from Storm Ciara.

Airlines have cancelled dozens of domestic and international flights, while several rail firms have urged passengers not to travel.

Firefighters in Blackpool rescue a stranded driver

Ferry passengers also face delays and cancellations, while drivers have been warned to take extra care.

Amber weather warnings for wind and heavy rain are in place for most of the UK, with gusts of up to 90mph expected.

More than 150 flood warnings have been issued around the UK.

Heathrow Airport said it had taken the joint decision with its airline partners to operate a reduced timetable to minimise the number of flights cancelled at short notice.

British Airways has cancelled some flights from Heathrow, Gatwick and London City, while Virgin Atlantic has posted a number of cancelled flights on its website.

Network Rail has imposed a blanket speed restriction of 50mph across the network on Sunday, warning passengers to only travel by train that day "if absolutely necessary".

This is a road in Ambleside, Cumbria - flood warnings have been issued around the UK

The rail firms which issued "do not travel" warnings for Sunday were Gatwick Express, Grand Central, Great Northern, Hull Trains, LNER, Northern, Southeastern, Southern, Thameslink and TransPennine Express.

Flooding and debris on the tracks have caused delays and cancellations to many services.

Some of the train companies affected by the weather include:

• Avanti West Coast - no trains running north of Preston
• Grand Central - all services cancelled on Sunday
• East Midlands Railway - trains not running between Luton and St Pancras
• Cross Country - services unable to stop at Birmingham International and Coventry

Ferry services have also been affected, with all services suspended at the Port of Dover because of strong winds.

DFDS has also cancelled all its ferries between Newhaven and Dieppe.

Forecasters have predicted gusts of up to 90mph, and a 86mph gust was recorded in Capel Curig in Snowdonia, overnight.

An amber warning for wind is in place across much of England and Wales until 21:00 GMT on Sunday. The Met Office advises wind-blown debris and large waves could pose a danger to life.

Yellow weather warnings now cover the whole of the UK until midnight on Sunday.

Weather warnings guide

• Yellow: Severe weather possible, plan ahead, travel may be disrupted
• Amber: Increased likelihood of impact, eg travel delays, power cuts
• Red: Dangerous weather expected - take action to keep safe

Source: Met Office

An amber warning for rain is in place in parts of Scotland, meaning homes and businesses are likely to be flooded and some communities could be cut off by impassable roads.

The heaviest rain is expected over high ground where 50-70mm is expected, with as much as 100mm in a few locations.

The Environment Agency has issued more than 100 flood warnings - meaning flooding is expected - in England, while there are almost 60 in Scotland, and 10 in Wales.

Gusts of 50-60mph are expected quite widely across inland areas as the storm passes over the country, reaching 80mph in coastal areas - particularly in south-east England and northern Scotland.

Other effects of the storm include:

• Scotland's Women's Six Nations match against England has been postponed
• Arsenal's Women's Super League game against Tottenham has also been called off
• Horse racing at Exeter, Southwell and Punchestown has been cancelled
• The London Winter Run 10k - due to be attended by 25,000 runners - was cancelled
• London's eight Royal Parks, which include Hyde Park and Regent's Park, are closed on Sunday
• The Dartford Crossing in Kent is closed to traffic on Sunday

In January, Storm Brendan swept into the UK, leading to power cuts and travel disruption.

This year's storm names have already been chosen, with Dennis due to be the name for the next storm.

(Source: BBC)

2018 flood has left dams, reservoirs in Kerala prone to earthquakes

As Kerala struggles to recover from the monsoon floods that ravaged the state yet again this season, research has highlighted that floods triggered by heavy rain has left reservoirs and dams highly prone to earthquakes.

The state has 43 dams and reservoirs predominantly located in the highly deformed and fractured Western Ghats. Of these 21 are now highly prone to tremors, a phenomenon called reservoir-induced seismicity (RIS), according to the latest geographic information system (GIS) analysis.

RIS occurs in deep reservoirs that have water columns more than 100 metres depth. Such huge water columns increase the stress on the earth crust, the infiltration of water from the reservoir reduces the effective stress. These changes in stress in the underlying rocks lead to RIS.

Studies have found that most of the seismic episodes occur after torrential rain lashes the region, indicating hydro-seismicity. (Photo: PTI)

“The RIS would have occurred during August 2018 flood itself, but this did not happen because all the dams of the overflowing reservoirs during the flood were opened and the water was released, our observations revealed," said S.M. Ramasamy of the Tamil Nadu-based Bharathidasan University, who led the study, which also involved researchers from Alagappa University. The findings were published in the journal Natural Hazards.

Kerala was ravaged by the worst floods of the century last year in August taking a heavy toll on lives and causing massive damage of an estimated $200 billion to infrastructure and property. After the floods, the research team studied the geology of the Western Ghats and found them to be highly deformed with folds and faults caused due to tectonic movements.

“The cracks are very active. With flooding going to become a recurring phenomenon, we need to study the hydro-dynamics of these dams and optimize their storage and water release to avert major disasters," said Ramasamy.

RIS has been known to be disastrous globally. In 1967, 180 people were killed and 1,500 injured due to induced seismicity in Koyna reservoir in Maharashtra.

Researchers found that in the case of Kerala, there are several conditions that can trigger RIS in and around the dams and reservoirs, including faults which are wide open.

The ecologically fragile Western Ghats cover almost half of Kerala, which has been known to be seismically active. The state has been witnessing seismicity of the magnitude of 3–5.5 for centuries. Previous studies have found that most of these seismic episodes occur after torrential rain lashes the region, indicating hydro-seismicity.

The 21 reservoirs that are prone to dam induced tremors include the Parambikulam reservoir, Peringalkuthu dam, Idamalayar dam, Mattupetty dam, Mangalam dam, Siruvani dam, Pothundi dam, Idukki dam, Chulliyar dam, Sagar dam and the Mullaperiyar dam.

“There is urgent need for effective water management strategies, especially for these 21 reservoirs," said Ramasamy.

(Source: Live Mint)

Jakarta, the fastest-sinking city in the world

The Indonesian capital of Jakarta is home to 10 million people but it is also one of the fastest-sinking cities in the world. If this goes unchecked, parts of the megacity could be entirely submerged by 2050, say researchers. Is it too late?

It sits on swampy land, the Java Sea lapping against it, and 13 rivers running through it. So it shouldn't be a surprise that flooding is frequent in Jakarta and, according to experts, it is getting worse. But it's not just about freak floods, this massive city is literally disappearing into the ground.

North Jakarta is sinking by about 25cm every year

"The potential for Jakarta to be submerged isn't a laughing matter," says Heri Andreas, who has studied Jakarta's land subsidence for the past 20 years at the Bandung Institute of Technology.

"If we look at our models, by 2050 about 95% of North Jakarta will be submerged."

Heri Andreas points at a dyke built to prevent sea water from flooding houses when it rains

It's already happening - North Jakarta has sunk 2.5m in 10 years and is continuing to sink by as much as 25cm a year in some parts, which is more than double the global average for coastal megacities.

Jakarta is sinking by an average of 1-15cm a year and almost half the city now sits below sea level.

The impact is immediately apparent in North Jakarta.

In the district of Muara Baru, an entire office building lies abandoned. It once housed a fishing company but the first-floor veranda is the only functional part left.

The ground floor of this abandoned office building is now underground

The submerged ground floor is full of stagnant floodwater. The land around it is higher so the water has nowhere to go. Buildings that are so deeply sunk are rarely abandoned like this, because most of the time the owners will try to fix, rebuild and find short-term remedies for the issue. But what they can't do is stop the soil sucking this part of the city down.

Stagnant water on the ground floor

An open air fish market is just a five-minute drive away.

"The walkways are like waves, curving up and down, people can trip and fall," says Ridwan, a Muara Baru resident who often visits the fish market. As the water levels underground are being depleted, the very ground market-goers walk on is sinking and shifting, creating an uneven and unstable surface.

"Year after year, the ground has just kept sinking," he said, just one of many inhabitants of this quarter alarmed at what is happening to the neighbourhood.

A large crack in the foundation of a fish market that has seen severe land subsidence

North Jakarta has historically been a port city and even today it houses one of Indonesia's busiest sea ports, Tanjung Priok. Its strategic location where the Ciliwung river flows into the Java Sea was one of the reasons why Dutch colonists chose to make it their bustling hub in the 17th Century.

Today 1.8 million people live in the municipality, a curious mixture of fading port businesses, poor coastal communities and a substantial population of wealthy Chinese Indonesians.

Fortuna Sophia lives in a luxurious villa with a sea view. The sinking of her home is not immediately visible but she says cracks appear in the walls and pillars every six months.

Fortuna says that when it rains, flood waters can submerge the pool

"We just have to keep fixing it," she says, standing beside her swimming pool with her private dock just a few metres away. "The maintenance men say the cracks are caused by the shifting of the ground."

She's lived here for four years but it has already flooded several times: "The seawater flows in and covers the swimming pool entirely. We have to move all our furniture up to the first floor."

But the impact on the small homes right by the sea is magnified. Residents who once had a sea view now see only a dull grey dyke, built and rebuilt in a valiant attempt to keep seawater out.

"Every year the tide gets about 5cm higher," Mahardi, a fisherman, said.

None of this has deterred the property developers. More and more luxury apartments dot the North Jakarta skyline regardless of the risks. The head of the advisory council for Indonesia's Association of Housing Development, Eddy Ganefo, says he has urged the government to halt further development here. But, he says, "so long as we can sell apartments, development will continue".

The rest of Jakarta is also sinking, albeit at a slower rate. In West Jakarta, the ground is sinking by as much as 15cm annually, by 10cm annually in the east, 2cm in Central Jakarta and just 1cm in South Jakarta.

Coastal cities across the world are affected because of rising sea levels caused by climate change. Increased sea levels occur because of thermal expansion - the water expanding because of extra heat - and the melting of polar ice. The speed at which Jakarta is sinking is alarming experts.

It may seem surprising but there are few complaints from Jakartans because for residents here the subsidence is just one among a myriad of infrastructure challenges they have to deal with daily.

And that is part of the story of why this is happening.

The dramatic rate at which Jakarta is sinking is partly down to the excessive extraction of groundwater for use as drinking water, for bathing and other everyday purposes by city dwellers. Piped water isn't reliable or available in most areas so people have no choice but to resort to pumping water from the aquifers deep underground.

But when groundwater is pumped out, the land above it sinks as if it is sitting on a deflating balloon - and this leads to land subsidence.

The situation is exacerbated by lax regulation allowing just about anyone, from individual homeowners to massive shopping mall operators, to carry out their own groundwater extractions.

"Everyone has a right, from residents to industries, to use groundwater so long as this is regulated," says Heri Andreas. The problem is that they take more than what is allowed.

People say they have no choice when the authorities are unable to meet their water needs and experts confirm that water management authorities can only meet 40% of Jakarta's demand for water.

Most of Jakarta's residents rely on groundwater

A landlord in central Jakarta, known only as Hendri, runs a dormitory-like block called a kos-kosan and has been pumping his own groundwater for 10 years to supply tenants. He is one of many on his street who do this.

"It's better to use our own groundwater rather than relying on the authorities. A kos-kosan like this needs a lot of water."

The local government has only recently admitted it has a problem with illegal groundwater extraction.

In May, the Jakarta city authority inspected 80 buildings in Central Jakarta's Jalan Thamrin, a road lined with skyscrapers, shopping malls and hotels. It found that 56 buildings had their own groundwater pump and 33 were extracting water illegally.

Jakarta's Governor Anies Baswedan says everyone should have a licence, which will enable the authorities to measure how much groundwater is being extracted. Those without a licence will have their building-worthiness certificate revoked, as would other businesses in the same building.

An inspection of buildings in Jalan Thamrin, central Jakarta found many operators pumping groundwater without a permit

Authorities are also hoping that the Great Garuda, a 32km outer sea wall being built across Jakarta Bay along with 17 artificial islands, will help rescue the sinking city - at a cost of about $40bn.

It's being supported by the Dutch and South Korean governments and creates an artificial lagoon in which water levels can be lowered to allow the city's rivers to drain. It will help with the flooding which is an issue when the rains come.

The sea wall is meant to mitigate the city's severe flooding

But three Dutch non-profit groups released a report in 2017 which cast doubt on whether the sea wall and artificial islands could solve Jakarta's subsidence problem.

Jan Jaap Brinkman, a hydrologist with the Dutch water research institute Deltares, argues it can only ever be an interim measure. He says it will only buy Jakarta an extra 20-30 years to stop the long-term subsidence.

"There is only one solution and everybody knows the solution," he says.

The construction of the sea wall is underway

That would be to halt all groundwater extraction and solely rely on other sources of water, such as rain or river water or piped water from man-made reservoirs. He says Jakarta must do this by 2050 to avoid major subsidence.

Alternative water sources like the Citarum river are extremely polluted

It is not a message that is being taken to heart yet and Jakarta's Governor Anies Baswedan thinks a less drastic measure will do.

He says people should be able to extract groundwater legally as long as they replace it using something called the biopori method.

This involves digging a hole, 10cm in diameter and 100cm deep, into the ground to allow water to be reabsorbed into the soil.

Critics say this scheme would only replace water at a superficial level, whereas in Jakarta water is often pumped out from several hundred metres below ground level.

Houses once overlooking the ocean now face a dyke

There is technology to replace groundwater deep at its source but it's extremely expensive. Tokyo used this method, known as artificial recharge, when it faced severe land subsidence 50 years ago. The government also restricted groundwater extraction and businesses were required to use reclaimed water. Land subsidence subsequently halted.

But Jakarta needs alternative water sources for that to work. Heri Andreas, from Bandung Institute of Technology, says it could take up to 10 years to clean up the rivers, dams and lakes to allow water to be piped anywhere or used as a replacement for the aquifers deep underground.

Jakarta's residents adopt a somewhat fatalistic attitude to their future in this sinking city.

"Living here is a risk," says Sophia Fortuna in her home. "The people here have all accepted that risk."

(Source: BBC)