Land subsidence has appeared in 16 Chinese provincial areas due to the excessive exploitation of underground water and over half of geological disasters are caused by human activities, an official with the Ministry of Land Resources said on Wednesday.

Jiang Jianjun, director of the geological environment department of the ministry, said that land subsidence appeared most severely in China's plain and delta regions such as the Yangtze River Delta region, Pearl River Delta region and North China Plain.

Provinces including Jiangsu, Zhejiang and Hebei, and municipalities of Shanghai, Beijing and Tianjin are suffering from land subsidence.

The foremost reason is the lowering of underground water level due to excessive exploitation of underground water. Geological movement of the earth and too many skyscrapers also contributed to land subsidence, Jiang noted.

Human activities such as railway, road, building construction activities, are having greater influence on land conditions and increasing the chances of geological disasters, he said.

Jiang said road or railway tunnels in hills or mountains weaken the stability of the hills and mountains, irrational mining and random stack of mining wastes and tailings in mountainous areas may lead to bigger possibility of mud-rock flow in cases of cloudbursts and torrential floods.

He urged that professional evaluation on the geological impact of large and key projects be conducted so as to prevent human-resulted geological disasters.

Statistics showed that in first half of this year, there were 2690 geological disasters in China, with 199 people dead or missing. Direct economic losses topped 600 million yuan (US$79.365 million).

(Xinhua News Agency July 26, 2007)