Dams on tributaries of China’s Yellow River could collapse anytime!
At least five newly built dams on branches of the Yellow River in arid Gansu province, northeast China face imminent collapse, just a year or so after they were built, said China Daily.
“Improper construction procedures, disqualified workers, embezzlement of construction funds and mismanagement of local water resource departments are threatening the safety of the dams, according to China Youth Daily.”
“One dike more than 80-m long and 20-m high, built in 2006 in Yuanxian county on the middle and upper reaches of the Yellow River, has developed a breach about 10 meters wide in the middle.According to nearby villagers, at least five newly-built dams are in very fragile condition, the newspaper said.”
The dams, paid for by the central government, are managed by the Ministry of Water Resource, under their “soil and water conservation project of the Yellow River” program.
“With a length of 5,464 km, the Yellow River, dubbed the “mother river” of China, suffers the most serious soil erosion in the world, especially along its middle and upper reaches. The average amount of mud and sand washed into the river every year reaches 1.6 billion tons.” China Daily said.
“Since 2003, China has poured a total of 83 billion yuan ($12 billion) into tackling soil erosion along the river and constructed more than 160,000 dams, according to Xinhua News Agency.
“As flood season approaches in July, August and September, China’s dam safety is coming under heavy pressure and inspections show many of them are not in good condition, Minister of Water Resources Chen Lei said last month.”
The Chilling Statistics:
- Total number of dams, dikes and reservoirs in China: 91,500 units
- Units in potential danger: 37,000 (or just over 40 percent of the country’s total)
- Reinforced: Under 3,650 dams
- In need of immediate reinforcement: More than 7,600 Units
- Chen Lei said that between 1999 and 2008, some 59 dams were breached in China, 30 as a result of torrential rains and another 29 due to defects arising from poor construction.
Following quotes are from Ecology and Biodiversity, The University of Hong Kong: Conservation & Management of Freshwater Ecosystems ENVM8016 (2008)
- North-south water transfer from Yangtze to Yellow River (& northern cities); seen as essential for >100 million people depending on the river
- Yellow River did not reach the sea (no measurable flow) in 22 of the years between 1972 & 1997; duration of annual dryness in lower course was ~8 days in 1970s, 11 days in 1980s & 226 days in 1997
- 3,382 dams on Yellow River can store >90% of mean annual discharge; since 1997 flow has been optimized (by controlled release) to ensure that some water flows to the sea throughout the year; involves difficult trade-offs due to absolute water scarcity
- On large scales, dams reduce the downhill transfers of material from land to sea (e.g. amount & quality of water) & trap >30% of global sediment flux (retard SW silica inputs). Other effects could include blockage of uphill transfers of material.
- Dams (& overfishing) can reduce or prevent upstream breeding migrations of salmon, with significant effects on stream & riparian ecosystems – as seen in NW North America
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