Rising sea water, drought and pollution of water sources are forecast to leave this thriving commercial hub short of drinking water later this year.

     And the United Nations Development Programme's policy adviser on climate change, Koos Neefjes, has warned that the situation could get worse.

     Sai Gon and Dong Nai rivers, the two major water sources for HCM City, have been experiencing serious salt water intrusion since early this month, the Sai Gon Giai Phong (Liberated Sai Gon) newspaper reported.

     The Binh An Water Plant, which supplies the city with 100,000cu.m of potable water a day, has begun closing its sluice gates for at least 10 hours a day to prevent saline water inflow from Dong Nai River because of the high salinity levels.

     The Thu Duc Water Plant, which usually supplies 300.000cu.m of potable water a day to the city, has been increasing its capacity to pick up slack water from the Binh An plant.

     While both plants source water from the Dong Nai River, the Thu Duc plant is located further upstream and, up until now, has been less effected by salt water intrusion.

     However, saline intrusion is now said to be approaching critical levels at the Thu Duc plant as well, according to Ho Thi Khanh, head of its water testing and analysis division.

     "The level (of salinity) has been around 20-25mg per litre during the last few years, but has risen to 150mg per litre in the last couple of weeks," said Khanh.

     "The intrusion has never been as bad as this year," said plant manager Truong Khac Hoanh, adding that the maximum salinity level allowed in Viet Nam was 250mg per litre.

     "It is still safe, but the rapid increase in intrusion should be taken seriously," he said. According to experts, average rainfall in the city decreased 35 per cent last year and was responsible for this year's early salt-water intrusion, which normally starts in March. They predicted the worst effects would happen in March and April.

     UNDP expert Koos Neefjes said low river flows allowed more saline water to enter river mouths from the sea.

     "If there's little fresh water coming, salty water will penetrate," he said.

     Meteorologists said Sai Gon and Dong Nai rivers' drought was causing the shortage of water.

     The Dau Tieng Reservoir, located on the Sai Gon River about 70km from HCM City, had a shortfall of 450 million cubic metres last year.

     Neefjes said the situation would get worse with climate change.

     "Climate change is making things worse. Salty water intrusion for countries with river basins, like Viet Nam and China, will become worse with more droughts," he said.

     The UN expert said water suppliers would need to keep moving water intake pipes further upstream.

     He also said large lakes in the Cuu Long (Mekong) Delta would have to be created to prevent fresh water from running into the sea.

     "It's a huge investment to build a dam. Such projects cannot be financed immediately, but Viet Nam need to start designing them," he said.

     In the short term, Dau Tieng reservoir, which supplies 100 million cubic metres of water every year to homes as well as industries, and regulates water flow to downstream areas where HCM City is based, will be used to tackle the salinity problem.

     In preparation for increased salinity this year, the reservoir, which is the largest irrigation reservoir in the country with a capacity of 1.6 billion cubic metres, has collected more than 60 million cubic metres of water during the past two months.

     The HCM City Irrigation Services Management Company has been repairing and upgrading the city's irrigation network to minimise water losses, said Nguyen Van Dam, head of the company.

     Viet Nam has been listed among the five countries in the world likely to be most affected by climate change - Source - monre.gov.vn