Not only Jakarta – the capital and largest city of Indonesia, many parts of Vietnam’s Ho Chi Minh City are sinking by 0.2-0.4 inches per year. According to a research report by the Vietnamese Ministry of Natural Resources & Environment and the Ho Chi Minh City University of Technology, the city has sunk by around 1.3 feet (0.4 meters) already. The main reasons cited were “over-exploitation of underground water, rapid urbanization and effervescent transport activities.”
This week, Amid devastating flooding, Indonesia announced it’s planning to move its capital out of Jakarta, which really is nothing new—the country’s first president was talking about it way back in 1957. Part of the problem is extreme congestion, but today the city of more than 10 million is facing nothing short of obliteration by rising seas and sinking land, two opposing yet complementary forces of doom. Models predict that by 2050, 95 percent of North Jakarta could be submerged. And Jakarta is far from alone—cities the world over are drowning and sinking, and there’s very little we can do about it short of stopping climate change entirely. Wired.com reports.
Jakarta is a victim of climate change, the fault of humans the world over (though mostly the fault of corporations), but it’s also a victim of its own policies. The city is sinking—a process known as land subsidence—because residents and industries have been draining aquifers, often illegally, to the point that the land is now collapsing. Think of it like a giant underground water bottle: If you empty too much of it and give it a good squeeze, it’s going to buckle. Accordingly, parts of Jakarta are sinking by as much as 10 inches a year.
That’s destabilizing buildings in the short term—some structures have sunk straight down, enveloping their lower levels in mud—but in the long term it means that about half the city is now beneath sea level. All it takes is one storm surge to inundate a huge chunk of the metropolis: In 2007, for instance, a monsoon left half of Jakarta under as much as 13 feet of water, causing more than half a billion dollars in damage.
Jakarta’s situation may be particularly dire, but it isn’t the only coastal metropolis that’s sinking. “Almost every coastal city around the world builds on loose sediment, and all of them are subsiding, regardless of pumping groundwater,” says Arizona State University geophysicist Manoochehr Shirzaei, who studies land subsidence. “In fact, vertical land motion is as important as sea level rise, but unfortunately it gets very little attention, because the process is slow.”
Vietnam’s Ho Chi Minh city ranked among top 5 fastest-sinking cities in the world
Consider the Ho Chi Minh City of Vietnam, Gilles Erkens, an expert from Deltares Institute of Netherlands has warned that the city is among the five cities across the world that are at risk of sinking.
Gilles Erkens said, if no prompt and assertive measures are taken, the southern Vietnamese metropolis may end up under water in the near future, a problem that Jakarta is facing.
According Tuoi Tre Newspaper, a local media, Gilles Erkens pointed out that Ho Chi Minh City had sunk by half a meter over the past 25 years. Over 60 percent of the southern hub has an elevation of under 1.6 meters, while the highest tide was recorded at 1.72 meters in January 2018.
The situation is most evident around the flyover on Nguyen Huu Canh Street in Binh Thanh District, which usually becomes flooded whenever it rains.
The street was opened to traffic in 2002 and subsidence was first discovered along multiple sections in 2003.
As part of the road sank by five centimeters to up a meter, the municipal administration had to ask the Institute for Building Science and Technology to evaluate the problem.
Short-term solution makes the situation became worse?
Scientists, urban planners and disaster preparedness experts have been stressing for years that HCMC holistically address a myriad of problems contributing to increased frequency and severity of flooding. Areas of the city, many that are already half a meter below sea level, are sinking further due to groundwater depletion. Largely unmanaged property development has filled in runoff areas and canals. Existing drainage systems are neither being effectively maintained nor expanded, while plans for installing water retention mechanisms go unimplemented. Meanwhile, planners have not heeded the warnings of increased urban flooding resulting from more sever rainfall events and rising tidal surges brought on by climate change.
According to a report by Le Quynh on Mekong Eye. Rather than employ the technical sophistication and vision necessary to tackle the complexity of HCM City’s urban flooding situation, most discussions and resources are now being channeled toward a single sea dyke costing upwards of $US 20 billion, even though such a dyke will not address the city’s key flooding challenges. Indeed, the Vung Tau – Go Cong Sea dyke is designed for tidal control and keeping sea water out—not decreasing the accumulation of extensive rainfall upstream and accelerating its evacuation from urban areas into the sea.
Kim Minh Company surveyed hundreds of flooding sites within HCM City. Only 14 – 28 percent of these sites were identified as primarily being affected by tidal floods, whereas 50 – 68 percent were affected by rainfall.
The local authority has implemented different flood control projects under two major programs: HCM City 2020 Urban Drainage System Master Plan (Plan 752) and HCM City Tide Flood Control Master Plan (Plan 1547). Although these plans have been in place for more then a decade, lack of resources has limited their implementation.
According to the Ho Chi Minh City Steering Center of Flood Control Program (SCFC), within the 650 square kilometer management area, only 2,593 kilometers of the required 6,000 kilometers of drainage channels have been completed or renovatedWorse still, of the 4,369 km of rivers, canals and creeks in the four main catchments that were targeted for flood management upgrades, only 60 km have been completed.The city has finished just two of its 12 planned wastewater treatment plants, 64 km out of 149 km of dykes along the Saigon River, and one-tenth of a major tidal control sluice. Moreover, not a single one of the 104 flood retention ponds authorized has been built.