The South–North Water Transfer Project, also translated as the South-to-North Water Diversion Project is a multidecade infrastructure mega-project in China that ultimately aims to channel 44.8 cubic kilometers (44.8 billion cubic meters) of fresh water each year from the Yangtze River in southern China to the more arid and industrialized north through three canal systems: The Eastern Route through the course of the Grand Canal; The Central Route from the upper reaches of Han River (a tributary of Yangtze River) via the Grand Aqueduct to Beijing and Tianjin; The Western Route which goes from three tributaries of Yangtze River near the Bayankala Mountain to provinces like Qinghai, Gansu, Shaanxi, Shanxi, Inner Mongolia and Ningxia.
Mao Zedong discussed the idea for a mass engineering project as an answer to China's water problems as early as 1952. He reportedly said, "there's plenty of water in the south, not much water in the north. If at all possible; borrowing some water would be good." Construction began in 2003.
By 2014, more than $79 billion had been spent, making it one of the most ambitious and expensive engineering projects in human history.
East route
The Eastern Route Project (ERP) or Jiangdu Hydro Project consists of an upgrade to the Grand Canal, and will be used to divert a fraction of the total flow of the Yangtze River to Northern China. According to Chinese hydrologists, the entire flow of the Yangtze at the point of its discharge into the East China Sea is, on average, 956 km³ per year; the annual flow does not fall below around 600 km³ per year even in driest years. As the project progresses, the amount of water to be diverted to the north will increase from 8.9 km³/year to 10.6 km³/year to 14.8 km³/year.
Water from the Yangtze River will be drawn into the canal in Jiangdu, where a giant 400 m³/s (12.6 km³/year if operated continuously) pumping station was built in the 1980s. The water will then be pumped by stations along the Grand Canal and through a tunnel under the Yellow River and down an aqueduct to reservoirs near Tianjin. Construction on the Eastern route began officially on December 27, 2002, and water was expected to reach Tianjin by 2013. However, in addition to construction delays, water pollution has affected the viability of the route. Initially the route was expected to provide water for the provinces of Shandong, Jiangsu and Hebei, with trial operations to begin in mid-2013. Water started arriving in Shandong in 2014, and it is expected 1 cubic kilometer of water will have been transferred in 2018.
As of October 2017, water has reached Tianjin. Tianjin is expected to receive 1 km³/year. The Eastern route is not expected to supply Beijing which is to be supplied by the central route.
The completed line will be slightly over 1,152 km (716 miles) long, equipped with 23 pumping stations with a power capacity of 454 megawatts.
An important element of the Eastern Route will be a tunnel crossing under the Yellow River, on the border of Dongping and Dong'e Counties of Shandong Province. The crossing will consist of two 9.3 m diameter horizontal tunnels, positioned 70 m under the riverbed of the Yellow River.
Due to the topography of the Yangtze Plain and the North China Plain, pumping stations will be needed to raise water from the Yangtze to the Yellow River crossing; farther north, the water will be flowing downhill in an aqueduct.
Central route
The central route, known colloquially as the Grand Aquaduct, runs from Danjiangkou Reservoir on the Han river, a tributary of the Yangtze River, to Beijing. This project involved raising the height of the Danjiangkou Dam by increasing the dam's crest elevation from 162 m to 176.6 m above sea level. This addition to the dam's height allowed the water level in the reservoir to rise from 157 m to 170 m above sea level. This allows the flow into the water diversion canal to begin downhill, pulled by gravity into the lower elevation of the canals.
The central route crosses the North China Plain. The canal was constructed to create a continuous downhill flow all the way from the Danjiangkou Reservoir to Beijing without the need for pumping stations. The greatest engineering challenge of the route was building 2 tunnels under the Yellow River to carry the canal's flow. Construction on the central route began in 2004. In 2008, the 307 km-long northern stretch of the central route was completed at a cost of $2 billion. Water in that stretch of the canal does not come from the Han River but from reservoirs in Hebei Province south of Beijing. Farmers and industries in Hebei had to cut back on water consumption to allow for water to be transferred to Beijing.