A group of Chinese and Japanese experts have completed a field investigation of the ecological environment in the Heihe River valley, China's second longest inland river that originates from the northwestern province of Qinghai.

The investigation and relevant research will play a guiding role in harnessing the environment of the Heihe River and developing local economy, said sources with an institute which studies environment and engineering in cold and dry areas under the Chinese Academy of Sciences (CAS).

Starting from September 1, a dozen experts from the two countries carried out surveys on climate and glacier, regional water circulation, studies on ecological environment and hydrology, and water-related issues in social and economic development in the Heihe River valley.

Jointly initiated by relevant institutes of CAS and Japan's Ministry of Education, the program is aimed at achieving new progress in the research on global environmental changes.

The 821-kilometer Heihe River originates from the glacier in the Qilian Mountains, in Qinghai Province, flows across the Zhangye Basin in Gansu Province and ends in the Ejina Banner of the Inner Mongolia Autonomous Region in north China.

The Zhangye Basin, located in the middle reaches of the river, is a commodity grain production base with developed irrigation farming. The Ejina oasis irrigated by the river is a natural screen blocking the invasion of wind and sand from Mongolia.

Due to climatic changes and excessive use of water over the past 20 years, the surface runoff of the river's lower reaches has reduced sharply, resulting in the disappearance of large areas of rose willow, poplar trees and other wetland plants and worsening desertification and intensifying sand storms in the area.