Ca Mau, the southernmost province of Vietnam, may disappear entirely in the next few decades due to land subsidence, according to an assessment of the Norwegian Geotechnical Institute (NGI).
It is the outcome of a yearlong project conducted by NGI researchers following a request of the Ministry of Agriculture and Rural Development of Vietnam and the Norwegian Ministry of Foreign Affairs.
The assessment of the first phase of the project, “Land subsidence in the Ca Mau Peninsula”, was released at a conference held in the Mekong Delta city of Can Tho on Monday.
The risk may be realized without any solutions on putting an end to overexploitation of underground water there, according to the conference.
The most practical way to prevent land subsidence is stopping or restricting underground water exploitation in the area, and using tap water from water plants instead, said NGI assessment.
The NGI researchers have drawn the conclusion through research and data obtained from the Ministry of Agriculture and Rural Development and the field trips.
Particularly, in Ca Mau, land subsidence should be considered as the main cause of ongoing land loss, deterioration of coastal forest, and the intrusion of sea water into river systems, because most of the province's land averages just 1 meter above the sea level.
According to NGI, data obtained from satellites show that in the last 20 years, Ca Mau has lost a lot of ground, causing the provincial shoreline cut into the mainland from 100 meters to 1.4 km. Preliminary assessment showed that in Ca Mau the land subsidence rate can go up to 30 to 70cm in many places.
According to statistics, Ca Mau province has over 100,000 wells used to exploit underground water, or around 20 wells per km2 on average, pumping up around 370.000m3 per day in total.
In addition, a large proportion of wells are located in urban areas. Therefore, those areas are facing the biggest risk of possible land subsidence with an annual rate of 1.56 to 2.3 cm.
According to the NGI, land subsidence and landslides caused by underground water oveexploitation is a common problem that has happened, and will occur at many places in Ca Mau province and neighboring provinces in the Mekong Delta region.
From the ongoing subsidence, Ca Mau province will face many consequences, such as loss of natural land, increased coastal erosion due to sinking coastline, coastal forest decline causing stronger erosion, increased salinity in rivers and canals, and saltwater intrusion into groundwater systems.
At the conference, NGI advised Vietnam to quickly be informed of the possibility of subsidence that Ca Mau and the Mekong Delta region are facing. Since then, there will be more plans set up for the mitigation of worst-case scenarios.
Besides, the NGI also proposed a number of measures to prevent land subsidence and saltwater intrusion, including stopping all the underground water exploitation activities, investing into new water treatment plants and water pipeline networks, and establishing new coastal dike systems.