Houses destroyed by high tides in the southern province of Ben Tre (Photo: VNA) HCM City (VNA) – Ho Chi Minh City’s districts andMekong Delta provinces are facing risks of soil submersion, studies have shown.
A group of researchers from the Department of Natural Resources andEnvironment, led by Prof. Le Van Trung of HCM City Polytechnic, compared remotesensing images between 1992 and 2010, which were updated in 2016.
They said the ground in the city’s Binh Chanh district, southernareas of Binh Tan district and district 8, as well as the northwestern area ofNha Be, has been sinking at 5 mm to 10 mm annually.
Human impact on the natural environment such as urbanisation,exploitation of underground water, and ground vibration from road traffic werethe main causes of ground submersion, the studies said.
Trung said the soil for several years had been sinking and was nowbelow the national height limit.
In low-lying zones, soil depression plus rising sea levels (anaverage of 3mm a year due to climate change) has enlarged inundated areas andcreated new ones, Trung said.
In coastal areas, the over-exploitation of underground water hascaused saltwater intrusion, which negatively affects growth of plants and treesas well as sustainable agricultural development.
“Necessary measures should be taken to limit ground submersion,”Trung warned. “Without efforts to reduce it, the region could face strongersoil sinking, like that encountered by Shanghai, causing a number of areas inthe region to sink into the sea.”
Ecologist Nguyen Huu Thien said that soil depression plus risingsea levels would cause the Mekong Delta and HCM City areas to submerge faster.
However, authorities have focused more efforts on rising sealevels than on soil submersion, which is more urgent.
Sea levels are rising about 3mm per year, while the region hasfaced soil sinking 10 to 20 times higher. Therefore, the most urgent effortshould be focused on ground submersion, he added.
A study from the Norwegian Geo-technical Institute (NGI) releasedin 2012 – 2013 said that ground submersion extends from the Mekong Delta to CaMau Cape at the southern tip of the country.
In Ca Mau province, the soil is sinking at 2cm to 5cm per year, whilemost of the ground in the locality is less than 1.5m above sea level.
This means the entire province could submerge into the sea in thenext few decades if local residents continue to use underground water.
Substantial evidence shows that most Mekong provinces would facesimilar risks of soil submersion because of underground water exploitation,which has been affecting 24 million residents in the region, according to theNGI study.
Meanwhile, a report released by the Ca Mau Department of NaturalResources and Environment said there were 141,226 underground water wells (30wells on each sq metre of land) in Ca Mau, the largest number in the Mekongprovinces.
The wells allow Ca Mau residents to pump out nearly 400,000 cubicmetres of underground water per day.
Being over-exploited, many underground water wells in Ca Mau havebecome exhausted. More than 2,100 wells in the province have been leftunexploited due to exhaustion of underground water.
A source from the Ca Mau Department of Natural Resources andEnvironment said these abandoned wells posed risks of underground waterpollution.
He said 1,500 of these abandoned wells had been filled and theremaining wells would be filled with cement by the end of the year.
To Quoc Nam, deputy director of Ca Mau’s Department of Agricultureand Rural Development, said Ca Mau planned to reserve fresh water, includingirrigating water from Hau (Posterior Mekong) River to the province.
In the near future, the province will build a 100ha reservoir tosupply fresh water to three northern districts of U Minh, Thoi Binh and Tran VanThoi.
The reservoir project will require investment of 200 billion VND(nearly 9.7 million USD).-VNA
A group of researchers from the Department of Natural Resources andEnvironment, led by Prof. Le Van Trung of HCM City Polytechnic, compared remotesensing images between 1992 and 2010, which were updated in 2016.
They said the ground in the city’s Binh Chanh district, southernareas of Binh Tan district and district 8, as well as the northwestern area ofNha Be, has been sinking at 5 mm to 10 mm annually.
Human impact on the natural environment such as urbanisation,exploitation of underground water, and ground vibration from road traffic werethe main causes of ground submersion, the studies said.
Trung said the soil for several years had been sinking and was nowbelow the national height limit.
In low-lying zones, soil depression plus rising sea levels (anaverage of 3mm a year due to climate change) has enlarged inundated areas andcreated new ones, Trung said.
In coastal areas, the over-exploitation of underground water hascaused saltwater intrusion, which negatively affects growth of plants and treesas well as sustainable agricultural development.
“Necessary measures should be taken to limit ground submersion,”Trung warned. “Without efforts to reduce it, the region could face strongersoil sinking, like that encountered by Shanghai, causing a number of areas inthe region to sink into the sea.”
Ecologist Nguyen Huu Thien said that soil depression plus risingsea levels would cause the Mekong Delta and HCM City areas to submerge faster.
However, authorities have focused more efforts on rising sealevels than on soil submersion, which is more urgent.
Sea levels are rising about 3mm per year, while the region hasfaced soil sinking 10 to 20 times higher. Therefore, the most urgent effortshould be focused on ground submersion, he added.
A study from the Norwegian Geo-technical Institute (NGI) releasedin 2012 – 2013 said that ground submersion extends from the Mekong Delta to CaMau Cape at the southern tip of the country.
In Ca Mau province, the soil is sinking at 2cm to 5cm per year, whilemost of the ground in the locality is less than 1.5m above sea level.
This means the entire province could submerge into the sea in thenext few decades if local residents continue to use underground water.
Substantial evidence shows that most Mekong provinces would facesimilar risks of soil submersion because of underground water exploitation,which has been affecting 24 million residents in the region, according to theNGI study.
Meanwhile, a report released by the Ca Mau Department of NaturalResources and Environment said there were 141,226 underground water wells (30wells on each sq metre of land) in Ca Mau, the largest number in the Mekongprovinces.
The wells allow Ca Mau residents to pump out nearly 400,000 cubicmetres of underground water per day.
Being over-exploited, many underground water wells in Ca Mau havebecome exhausted. More than 2,100 wells in the province have been leftunexploited due to exhaustion of underground water.
A source from the Ca Mau Department of Natural Resources andEnvironment said these abandoned wells posed risks of underground waterpollution.
He said 1,500 of these abandoned wells had been filled and theremaining wells would be filled with cement by the end of the year.
To Quoc Nam, deputy director of Ca Mau’s Department of Agricultureand Rural Development, said Ca Mau planned to reserve fresh water, includingirrigating water from Hau (Posterior Mekong) River to the province.
In the near future, the province will build a 100ha reservoir tosupply fresh water to three northern districts of U Minh, Thoi Binh and Tran VanThoi.
The reservoir project will require investment of 200 billion VND(nearly 9.7 million USD).-VNA
VNA
