At a three-day seminar that began on November 20, foreign and local researchers said that changing precipitation patterns and rising sea levels were increasing the salinity of surface water and groundwater.

Extracting groundwater for domestic, agricultural and industrial use might exacerbate natural land subsidence, especially in river deltas, they said.

To ensure the sustainability of future water supply in the region and especially in the southwest, the Ministry of Construction plans to build two inter-regional water supply plants using surface water sources from the Hau River, said Le Van Tuan, General Director of Vietnam Water Sanitation and Environment Joint Stock Company.

High investment costs will be needed for the two plants, so economic efficiency will not be high initially, according to Tuan.

"This is a challenge in building the plants," he said.

Le Anh Tuan, Vice Director of Research Institute for Climate Change under Can Tho University, said on the sidelines of the meeting that many methods for sustainable water supply should be carried out in case the plants break down a suspension of water supply occurs.

Moreover, if water sources for the inter-regional water-supply systems come only from the Hau River, long-term sustainable water supply would not be ensured.

If the Hau River's water sources are polluted or the water level falls in the future, the region would lack sufficient water, he added.

Because long water pipelines can easily cause water losses, the best method to use would be artificial aquifer recharge (AR), which is common in many countries.

With AR, natural groundwater supplies are enhanced by using man-made conveyances such as infiltration basins or injection wells, according to the US Environmental Protection Agency.

Tuan said that Vietnamese researchers should seriously consider using the AR method.

Tom Kompier, First Secretary for water and climate at the Embassy of the Netherlands, said his country was located at the end of a river system in a very fertile plain and has huge agricultural potential, just like Vietnam's Mekong Delta.

"Climate change is of great concern to us," he said.

Not all of its impacts are negative, but there is ample cause for worry, he said.

The sea-level is rising, weather patterns are shifting, and discharge from the rivers is changing.

"We need to prepare for floods on the one hand and water shortages on the other. I am sure this sounds familiar, because these are major concerns in Vietnam, too," he said.

The Netherlands focuses on the important relations between water management and the ability to adapt to climate change.

"We know that climate change is happening, we know its direction, but what we don't know is how fast change will be. We also know that dealing with climate change is going to cost a lot of money, but we realise our funds are limited," he added.

"In the Netherlands, we also have abundant fresh water, but not the entire year. Like Vietnam, we have problems with subsidence and with increased salinisation," Kompier said.

One innovation to deal with water scarcity is the introduction of service levels, he said.

The national and local government, utilities, and users would discuss what the maximum sustainable level of water supply should be, and practical water use during periods of scarcity, he added.

The seminar is part of a project on climate-change preparedness for public water utilities.

Begun last year, the four-year project is carried out by a partnership of water utilities, provincial governments and academic institutions in Vietnam and the Netherlands.

VitensEvides International (VEI), a joint venture of the two largest public water utilities of the Netherlands, is the lead partner.