Going down: Ha Noi’s underground water sources are drying up, causing the city to sink in some parts. — VNS Photo

Ha Noi city’s underground water drying up, polluted

HA NOI — The overuse of subterranean water is threatening to pollute the underground water sources and is leading to subsidence in some parts of the city, environmentalists have warned.

People have recognised rifts in the earth in the mountains and the plains, and in more recent years rifts have appeared in dykes and beside construction sites.

Scientists are pointing the finger at the overuse of the subterranean water resource. They predict Ha Noi will consume about 1.1 million cu.m of water per day by 2010, when the resource will be exhausted.

According to a recent report in the Ha Noi Moi (New Ha Noi) newspaper, the overuse of this water is polluting the resource and causing subsidence in the city.

The report quoted local residents as saying they have observed rifts in the earth and subsidence at some building sites. The use of underground water is controlled by residents themselves.

The Northern Geographic and Hydrographic Engineering Association has also reported visible subsidence in the city’s Nga Tu So, Nga Tu Vong, Mai Dich, Thanh Cong and Phap Van areas.

The experts warned Ha Noi Moi that parts of Ngo Sy Lien Street and the Phap Van and Van Dien areas are subsiding by about 20cm per year, which is posing a threat to local buildings.

They said that they have found no official reason yet, but unco-ordinated well drilling is one of the prime suspects.

The city’s larger wells are controlled by the Ha Noi Water Works Company, but many smaller wells are operated by factories, schools, hospitals and other bodies.

More and more households are drilling wells for their own use, especially in parts of the Old Quarter. The total numbers of private wells is unknown.

Recent surveys by the municipal authorities have found that the ground water is seriously polluted in many parts of the city, especially in the south and southwest of the city.

Smaller wells in Bach Mai, Phap Van and Kim Lien have been affected by toxins, and cyanide and phenol have been found in Yen So, Vinh Tuy and Duc Giang.

The survey also found that 60 per cent of samples from 50 different wells have bacteria counts above the permitted level.

Water plants are now having to drill their wells deeper and deeper. The average depth of wells is now 25m, about 5-10m deeper than before.

Environmentalists are calling on the Ha Noi authorities to bring the exploitation of subterranean water supplies under control to minimise the negative consequences on the city’s living environment. — VNS