Residents and water experts are concerned that the 735-kilometre Min River in south-central China’s Sichuan province could become permanently altered by dams built on its upper reaches, and that the situation threatens one of the world’s oldest irrigation systems downstream.

One villager quoted blames the river’s disappearance on dam projects that drain the river into reservoirs for power generation. The river was channelled to tunnels in the mountains to generate electricity and make money, the villager said. “Of course, little water was left for us!”

Water experts in Sichuan say hydro development on the upper Min is responsible for the shrinking river, and that operators regulate their dams independently of one another without paying attention to water levels in the river.

Below the nearly completed Zipingpu dam, the largest water-control project in Sichuan, the Min dwindles to a thin stream that leaves most of its waterbed exposed. It is hard to imagine boats ever plied this part of the river, or that it once flowed freely, 100 metres across.

Further upstream, in the town of Nanxin in Mou county, Sichuan Online describes an even more shocking scene: The Min has completely disappeared, its riverbed resembling a desert strewn with huge rocks and pebbles. Even traces of the former river have vanished in places.

As many as 15 dams have either been built or are under construction in a 200-kilometre valley stretching from the ancient city of Songpan to the famous Dujiangyan irrigation system [a water conservancy project in the middle reach of the Min that was constructed during the warring states period (475-221 BC)]. One Sichuan water expert said: “A river should be seen as a living system. Unchecked hydropower construction and overdevelopment in the valley would destroy the [Min] river itself.”

The situation could jeopardize the Dujiangyan project, which functions as a comprehensive water web, providing cities and villages along the river with water for domestic use and irrigation for millions of hectares of farmland, as well as power for electricity generation.

Liu Daoguo, director of the Dujiangyan Management Bureau, said the system faces a number of challenges to be able to continue supplying water for domestic and agricultural use. He warned that dam operators must comply with regulations, to ensure continued supplies to local residents, agriculture and industry in the region. A dry winter also meant even less water was available than in previous years.

Sichuan water experts are further worried that the Min could become vulnerable to seasonal extremes if the current situation is allowed to continue. The flow of the Zagunao River, a Min tributary, has become so depleted that it measures only seven or eight metres across at its narrowest point. Meanwhile, the Min’s largest tributary, the Jinma River in the provincial capital of Chengdu, floods in summer but runs dry in winter.

Environmentalists in the area fear hydro development will eventually alter the river’s ecosystem and wreak havoc on aquatic life. Fish are already under serious threat, and do not survive the passage through the dam turbines they encounter after swimming through tunnels built for hydro generation beneath a range of nearby mountains. In addition, the area of the Min drained by dams is estimated to stretch for five kilometres, and this, combined with increasing water pollution, could endanger 40 species of fish in the river.

Overshadowing all of these fears is the possibility of natural disasters triggered by development. A substantial landslide at Baishui dam in Mou county last summer flooded nearby villages and severely damaged dozens of houses.

“We really don’t know how to survive in the circumstances. We suffer terrible floods in summer and unbelievable drought in winter,” said a resident of Baishui village. Local people were compensated by dam operators when disaster struck, but they still live in a state of uncertainty and foreboding about possible future calamities.