Ho Chi Minh City is on the list of subsidence faster than sea level rise

In a recent study by Nanyang Technological University, Singapore, Cheryl Tay and colleagues and experts from NASA’s Jet Propulsion Laboratory and the Swiss Federal Institute of Technology (ETH Zürich) found There are evidences and signs that many large coastal cities are sinking faster than the rate of sea level rise.

It is known that this research group used radar from satellites to measure subsidence rates in the world’s 48 most populous coastal cities between 2014 and 2020. After a long period of research and monitoring, the results show that There are about 44 cities that have The subsidence area is sinking faster than sea level rise.

Ho Chi Minh City has an average subsidence rate of 16.2 mm a year

In particular, cities in the south and Southeast Asia are having the fastest sinking speed, including Tianjin (China) and Ahmedabad (India) with a subsidence rate of more than 20 mm a year, while The settlement of HCMC (Vietnam) is 16.2 mm per year.

Currently, sea level is average increase of about 3.7 mm per year, much of which is due to melting ice due to climate change. In many places, the land is also sinking due to groundwater pumping, oil and gas extraction, and the sediment is compressed by heavy buildings, causing the city’s sinking rate to increase faster.

In the study based on HCMC, the team found that if this rate of subsidence continues, about 20 square kilometers of the city could be submerged below sea level by 2030. About 880 square kilometers would be below sea level if the land did not subside. And tThe city of Rio de Janeiro (Brazil) may have an additional 2 square kilometers of water flooded, an increase of 16% of the flooded area compared to the case without subsidence.

The area of ​​wetlands of the city of Rio de Janeiro, Brazil may increase by 16%

However, Virginia Tech expert Manoochehr Shirzaei also said that elevation maps used in case studies to estimate inundation levels are unreliable for many areas of the world. Thus, focusing on the most rapidly sinking inland areas of cities rather than areas close to the coast could “exaggerate the impact” of land subsidence.

In addition, a recent report by the Intergovernmental Panel on Climate Change (IPCC) on changes in land levels along the world’s coastlines over the past century also found a narrower range – the fastest subsidence rate is about 5.2 mm a year

Still, expert Robert Kopp at Rutgers University in New Jersey, who worked on the IPCC report, warned that if the reported subsidence did indeed happen, it could very well be a hazard. related to sea level.

“Soil subsidence has always been considered an underappreciated issue. However, this study may make it more relevant,” he said. Shirzaei said.

Source: New Scientist

The article is in Vietnamese

Tags: Chi Minh City list subsidence faster sea level rise

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