LookAtVietnam – Unscientific and wasteful exploitation of groundwater sources in the Mekong Delta region has sharply reduced underground water levels and severely polluted it, scientists say.

Farmers in U Minh District of Ca Mau Province dig a well to supply groundwater to crops. Groundwater sources in the Mekong Delta region have reduced both in volume and in quality in recent years.

He said the Hau River, the main source of water for domestic and industrial purposes to Can Tho City and provinces in the region, had become polluted. Until recently, it was considered the cleanest source of water in the area.

According to Dr Duong Van Vien of the Water Resources University-2nd Base in HCM City, excessive exploitation of groundwater in the Mekong Delta had seen levels drop from 12 to 15m.

Vien said that if measures were not implemented immediately, the groundwater level in Can Tho City and other provinces in the region would be completely depleted by 2014.

Statistics from the Ministry of Natural Resources and Environment (MNRE) showed that about a million bore wells 10 to 300m deep were in use in the Mekong Delta region. The southernmost province of Ca Mau had as many as 178,000 wells followed by Bac Lieu Province with 98,000. Furthermore, hundreds of water supply stations were exploiting groundwater to the tune of hundreds of cubic metres per day.

Many towns in the region including Ca Mau, Bac Lieu, Soc Trang and Tra Vinh mainly used groundwater sources for domestic use. Residents were also using groundwater to irrigate rice fields, orchards, vegetable gardens and aquaculture.

The estimated volume of groundwater exploited and used in the entire region was about one million cubic metres per day, but most provinces in the region had no plans for groundwater exploitation, use and protection.

The ministry said that the distribution of groundwater was complicated both in surface and depth. In many places, fresh aquifers were interspersed with salt water aquifers. The exploitation and use of groundwater in the region was also unscientific and wasteful, and haphazard drilling had led to the high risk of saline intrusion of fresh groundwater resources. There were currently hundreds of abandoned, uncemented wells which could cause sinking of aquifers from 75 to 110m.

Ca Mau alone had thousands of abandoned wells that salt water had penetrated into, mainly wells of 50m.

According to surveys done by the Community Health Hygiene Institute under the Health Ministry, arsenic levels in Mekong Delta groundwater sources had risen alarmingly. In An Giang Province, for instance, toxic substances were found in 40 per cent of 2,966 test samples taken.

To improve the situation and ensure effective and sustainable use of groundwater, scientists were recommending that provinces in the region immediately undertake systematic surveys and assessments of groundwater resources and introduce appropriate management policies.

They said that it was necessary to calculate the volume of water that was percolating into the earth as well as the volume that was exploited in order to come up with a reasonable solution to using groundwater in the region.

Provinces should also end excessive exploitation that was reducing groundwater causing the ground to sink and polluting water sources, they added.

They have called for information to be shared because provinces were not told of groundwater statistics compiled by concerned ministries.

It was also important to enhance the ability of government agencies and local governments to manage groundwater resources as well as raise public awareness on the issue, the scientists said.

VietNamNet/Viet Nam News