HO CHI MINH CITY: Nguyen Van Cu is a building engineer whose speciality is elevating houses. That means he has been busy of late.
He just lately put the ending touches to a home he had lifted by greater than two metres. A couple of years in the past, he raised a 6,000-tonne church.
“When the pastor said the church would be raised by two metres, nobody in the parish believed him. They just didn’t think it would’ve been possible,” Cu remembers.
“The pastor said to me … ‘I had faith in you, but hearing what others in the parish said (worried) me.’”
Today, many individuals in Ho Chi Minh City need their homes raised — as a result of not solely does it flood yearly through the May to November wet season, but additionally the flooding is getting worse.
The metropolis of practically 9 million residents is going through excessive climate situations extra continuously, however the infrastructure to mitigate flooding has not stored tempo.
While the authorities have raised the roads, one consequence is everyone seems to be racing to elevate their property greater than the street degree.
For fruit vendor Tuan Hoang, who has a fruit juice stall alongside the roadside, frequent flooding has made it tough to run his enterprise.
“The water would rise here. On the road, the water would be higher than half the tyre … Where the street is lower, the water would (cover) a whole tyre,” he says.
“It’s hard for people to stop by and buy stuff.”
Population progress and fast urbanisation have prompted the town to sink as a lot as 80 millimetres a yr through the previous 20 years. But worse is to include local weather change and rising sea ranges.
By 2050, components of Vietnam’s greatest metropolis may slip underwater, in accordance to a report by the United Nations’ Intergovernmental Panel on Climate Change.
And with a number of the options supplied by the authorities — like constructing a large dyke — sparking a debate in regards to the suitability and dangers, the programme Insight explores whether or not one in all Asia’s fastest-growing financial centres could be saved.
CHALLENGES ON MULTIPLE FRONTS
Sitting in a flat delta area, 40 to 45 per cent of Ho Chi Minh City is lower than a metre above sea degree. So that has made it more and more susceptible to heavy rainfall, storms and rising sea ranges.
Many components of the coastal metropolis are already topic to common tidal floods. But local weather change isn’t the one reason behind the town’s flood issues.
“The second cause is the disappearance of natural canals and green spaces that help with the city’s drainage,” says 24-year-old environmentalist Hai Long Vu Diep.
The metropolis has grown relentlessly, including 1.8 million residents between 2009 and 2019, not together with migrants. But the density of its inexperienced house for timber is simply about two sq. metres per particular person.
“It’s very low,” says Ngo Viet Nam Son, the president of NgoViet Architects and Planners. “In other (advanced) cities, that may be 10 times higher, even more.
“When the rain comes down … we need adequate green space to hold the water.”
The metropolis, which covers greater than 2,000 sq. kilometres, is growing so quickly that additionally it is sinking, particularly the chunks of built-up areas close to the banks of the Saigon River, the place the soil is gentle.
“Those are areas that are considered problematic right now,” says Nguyen Viet Ky, who heads the Geotechnics Division at Ho Chi Minh City University of Technology. “It’s clear that there’s too much development density concentrated in weak foundation areas.”
The land subsidence can happen fairly shortly when high-rises are constructed.
“They put a lot of pressure on the current infrastructure system,” observes Son. “When it rains heavily, you can see that the area that’s most flooded is the area that’s next to some new development.”
Another reason behind subsidence is the over-extraction of groundwater, which might create underground cavities that will collapse, thereby inflicting the soil on prime to sink.
The metropolis’s fast growth has left the water provide system to play catch-up. So, whereas ready for piped water, many residents and companies have resorted to extracting groundwater.
“Thousands of (wells) small ones, big ones, —household or industrial-scale — have been built,” notes Ho Long Phi, vice managing director (operations and analysis) of city consultancy enCity.
“At the highest level, we could observe more than a million cubic meters per day of total groundwater extraction during the past 20 years.”
WATCH: Why is Ho Chi Minh City sinking? (2:44)
The authorities have since put in place measures to decelerate the extraction of groundwater and assist stop additional subsidence.
Owing to the distribution of piped water “all over the city”, says Ky, the speed of groundwater extraction has been “significantly reduced” to round 300,000 cubic metres.
Piped water was made out there to Nguyen Kim Thanh’s household simply over a yr in the past, for instance, after years of them counting on groundwater as their solely supply of water.
The housewife now makes use of the handled water to cook dinner. But the household nonetheless pumps water from their nicely “to water plants and wash our scooters”.
The diminished groundwater extraction has been essential, however the authorities nonetheless have their work reduce out for them.
And it isn’t solely Ho Chi Minh City that’s sinking, but additionally the delta area of Southern Vietnam which it sits on, from the Saigon Delta to the Mekong Delta.
“The whole delta has been sinking faster than the sea-level rise,” says Nguyen Huu Thien, an impartial guide and ecological skilled on the Mekong Delta. “At the hotspots, we’re sinking 10 times faster than the sea-level rise.
So the water rises and inundates the cities along this stretch of land.
Like in Ho Chi Minh City, groundwater extraction has aggravated the subsidence. But there is also another reason.
“Because we extract sand. To build this building, to build roads, we need sand,” says Marc Goichot, the World Wildlife Fund’s freshwater lead within the Asia-Pacific. “So the sand isn’t replenishing the delta.
“Even if we stop the extraction of water … the subsidence will continue. It’ll be slower, but it’ll continue. So the only way to address the subsidence is by ensuring that more sediment … is able to be deposited in the floodplains.”
Dang Nha Cong, a fifth-generation farmer in Southern Vietnam whose household’s farming custom goes again greater than 150 years, is now apprehensive about the way forward for his agricultural land and its tropical fruits, even after constructing a barrier round it.
“Everyone here suffers from floods … Even the street gets flooded,” says the 75-year-old dwelling close to Can Tho metropolis. “If it rises another 50 to 70 centimetres or if it rises a whole metre, I wouldn’t know what to do.
“If the farm’s flooded, all the trees will die.”
Extreme flooding would additionally price Ho Chi Minh City dearly. Global consultancy McKinsey estimates the infrastructure harm a once-in-100-years flood may trigger in the present day at US$200 million (S$267 million) to US$300 million.
The estimated knock-on results could possibly be a further US$100 million to US$400 million. Real property harm alone could attain US$1.5 billion. In 2050, the financial affect could possibly be 5 to 10 instances greater.
HOW TO STOP THE SEA?
The risk of rising sea ranges is extra actual for Vietnam than most others, notes Tran Ba Hoang, the top of the Southern Institute of Water Resources Research.
It is among the many 5 international locations almost certainly to be affected by world warming in future, in accordance to the World Bank, as well as to the report by the UN intergovernmental panel.
“Since it’s an assessment by an international body, I think it’s a dire warning to the government of Vietnam and local authorities in areas that would be flooded owing to rising sea levels,” says Hoang.
As of now, he notes, the common sea degree enhance — as measured within the port metropolis of Vung Tau for the final 40 years — is 0.45 cm per yr, which he described as “relatively high”.
To shield Ho Chi Minh City and the encircling area, authorities have proposed constructing a sea wall — 23 km or longer — from Vung Tau to the coastal area of Go Cong, which may price up to US$6.8 billion.
It would assist to stop the rising sea waters from coming into the delta. Ky, an affiliate professor, calls it a “far-sighted proposal” and “meaningful” mission.
Some observers, nonetheless, imagine that dykes are a “short-term” measure that alleviates the issue of rising sea ranges however doesn’t deal with different key points.
“If you address the symptoms with the dyke, you don’t solve the problem — you move the problem,” says Goichot.
“Dykes stop the water from going to the floodplain. And the water going to the floodplain brings the sediment and deposits. That’s the solution.”
The excessive price concerned has led some analysts to query the mission’s monetary viability, provided that dykes are additionally costly to preserve as seen within the Netherlands.
“Our economic status is not like theirs … and, truthfully, the cost would be very high,” says Phạm Viet Thuan, the director of the Institute of Natural Resources and Environment Economics.
Neither the tidal angle nor the geographical options of the tidal currents in our nation are the identical with theirs. That’s why we will’t use a dyke to resolve the flooding.
The danger to the ecosystem is one more reason to not copy the Dutch strategy to constructing dykes, cites Goichot.
“You block the movement of nutrients, which is food for living organisms. And you create barriers to … the place where they feed or the place where they go to spawn, then you affect their life cycle,” he says.
“(The Dutch) have one of the safest deltas on the planet because they can protect themselves from floods. But now they realise that they’ve lost fisheries and lost biodiversity. And that’s a very high cost. So now they’re removing dykes.”
The Mekong Delta already has “high dykes everywhere” to shield its agricultural land, factors out Thien. But that doesn’t resolve the issue of flooding.
“When the high tide comes in from the sea, pushing the river water back … the river can’t find enough space because all the other lands are blocked by the high dykes,” he says.
“Water has to find room somewhere. So it has to find room in the urban area, in the cities, where they’re still pretty open.”
MULTI-PRONGED SOLUTION NEEDED
Despite objections to the super-dyke plan on account of its environmental and financial impacts, the mission seems set to go forward.
If it’s to enhance Ho Chi Minh City’s defences, nonetheless, the mission wouldn’t solely be expensive, but additionally take a very long time to full.
In South Korea, the 33-km Saemangeum sea dyke and land reclamation mission has taken 30 years since building started, cites Ky. The sea wall itself wanted virtually 20 years to assemble.
Ho Chi Minh City has barely 30 years till the outcomes of local weather change are seen in 2050. With rising sea ranges, land subsidence and infrastructural shortcomings, can anything be carried out to save the financial coronary heart of Vietnam?
Hoang the fruit vendor, who has usually watched in dismay as floodwaters rushed down the streets in his neighbourhood, has just one selection.
“I assess how high the water is, and I raise my stall. The higher the water, the higher the stall … When it overflows, well, we have to live with the floods,” he says.
“I try to do my business as usual. It’s not as if I can quit.”
WATCH: The full episode — Asia’s sinking cities: Ho Chi Minh City (48:15)
But that may solely be a small a part of a multi-pronged resolution general. “First, the authorities must swiftly and effectively deal with groundwater extraction,” says Diep, who’s beginning his grasp’s in useful resource and environmental engineering.
“Second, we must develop more green spaces and reservoirs around Ho Chi Minh City. Finally, and very importantly, the city must improve its current drainage system.”
It is about dwelling with nature and never “trying to control nature”, provides Goichot. “We need to understand those processes and build with them. It’s not only a good, catchy concept, it’s really what we need to do.
“It isn’t so easy to implement, but it’s probably the most cost-effective way to adapt to climate change.”
Watch this episode of Insight here. The programme airs on Thursdays at 9pm.