Southernmost Ca Mau Province is in danger of sinking below sea level in the next few decades due to over-exploitation of underground water if something isn't done urgently.— File Photo

Experts released the warning at a conference held with the co-operation of the Ministry of Agriculture and Rural Development and the Norwegian Geotechnical Institute (NGI) in Mekong Delta Can Tho City on Monday.

Kjell Karlsrud, PhD, from the Norwegian institute said nearby provinces in the Mekong Delta also faced a risk of subsidence.

Seeking other clean water sources to replace the use of underground water was highly recommended, he stressed.

Filtering water from canals to serve daily lives of local residents was believed to be the best choice, however, it was costly, he said.

The local authority was advised to stop all use of underground water and to instead build water filter companies and sea dykes.

Nguyen Truong Tien, a member of the Viet Nam Society of Soil Mechanics and Geotechnical Engineering, said the province should apply advanced technologies to recycling water and storing rainwater to reduce the use of underground water.

The NGI said Ca Mau province's land surface is only 1m higher than the sea level.

The warning came after research on land subsidence in the province was conducted by the NGI from May 2012, at the request of the Vietnamese Agriculture Ministry and Norwegian Foreign Ministry.

It showed coastal erosion has been gauged at between 100m and 0.4km over the past 20 years in Ca Mau.

The province, covering an area of 4,350sq km, has a subsidence rate of 1.9-2.8cm per year, according to Viet Nam Institute of Geosciences and Mineral Resources head Tran Tan Van.

By initial calculations, the land surface of several local areas had subsided about 30-70cm over the last two decades.

Excessive exploitation of underground water from surrounding drill wells was blamed for the problem.

Van said about 370,000cu m of underground water was taken daily from 100,000 drilled wells in the province.

The drilled wells were only located in some urban areas, which had suffered a higher subsidence rate than others, Tan said.

(VNS)