Annual flow of tributaries of Yellow River
Currently, river with largest annual flow in Northwest China is Ili River with an annual flow of 13 billion cubic meters, while annual flow of Tarim River is only 2.8 billion cubic meters. That is, if 26 billion cubic meters are successfully transferred to Xinjiang, volume of water in 2 Ili rivers or 10 Tarim rivers will be increased, and significance for Xinjiang is obvious.
Pipelines for transferring water will also pass through Niu, Lancang and Jinsha rivers. If summer floods are diverted from three rivers to northwest, total volume of water pumped will be significant. Moreover, annual flow of Yarlung Zangbo River has rapidly increased to over 600 billion cubic meters since leaving country. Moreover, massive floods occur here every summer, and at that time both Bangladesh and India wanted China to pump more water. Therefore, total water transfer volume can also be increased.
Grand Canyon of Brahmaputra
Now question arises, where is best water pumping point? Judging by position of Yarlung Zangbo River, upper and middle courses are not best water transfer points due to insufficient net flow. As for lower course, elevation difference is very large and it should not be too far to south, otherwise height will be too low and difficulty of transferring water will increase. Therefore, best place for water diversion should be a transitional place between lower reaches and middle course, where there is probably a large bend.
This place is Yarlung Zangbo Grand Canyon located between Daduka Village, Pai City, Milin County and Medog Siran Village. The height of village of Daduka is 3,000 meters and village of Rang is 700 meters above sea level. . In Milin County, a hydrological station was built here very early. In 1954, Indian Prime Minister Jawaharlal Nehru visited China, saw China's achievements in flood control on Yangtze River, and suggested that China build a hydrological station on Yarlung Zangbo River to provide information for flood control in India. Premier Zhou readily agreed. In second year, Sichuan Hydrological Group began to build Nuxia Hydrological Station here.
For half a century from 1960 to 2009, average annual flow of Yajiang River, measured by Nuxia hydrological station, amounted to 59.7 billion cubic meters, of which 26 billion to 40 billion cubic meters are quite possible.
However, if you want to pump water, you must build a hydroelectric plant. The hydroelectric dam can store water and raise water level, and regulate seasonal distribution of water, thereby reducing difficulty of water transfer and increasing total amount of water transfer. Hydroelectric power can also provide enough power to move water along way and reduce costs.
Tibet is region with richest hydropower resources in China. According to statistics, Tibet's theoretical hydropower resources are 205.5 million kilowatts, which is about a third of country's total. Among them, there are 48 million kilowatts of hydroelectric power in great bend of Yajiang River, and if a hydroelectric power station is built here, then its capacity will definitely exceed capacity of Three Gorges HPP.
According to plan, in future, China can build 6 super hydroelectric power plants here with a total installed capacity of 60 million kilowatts and an annual electricity generation of 300 billion kWh. At present, installed capacity of Three Gorges HPP is 22 million kilowatts, and annual electricity generation is 111.8 billion kWh. In other words, if these HPPs are built, their capacity will be equivalent to three Three Gorges HPPs. After construction of hydroelectric power plant is completed, water level can be raised directly by 300 meters, which greatly reduces difficulty of transferring water.
In fact, China has built several small hydroelectric power plants on Yarlung Zangbo River. Among them are Zangmu HPP and Jiacha HPP in middle reaches, which have an installed capacity of only hundreds of thousands of kilowatts.
Currently, biggest difficulty in building hydroelectric power plants in Tibet is transportation problem, because traffic in these places is mainly dependent on road transport, and capacity is seriously insufficient. To solve this problem, Sichuan-Tibet railway should be launched. According to plan, construction of Chengdu-Yaan section of Sichuan-Tibet Railway began in 2014, and opening of this section took place at end of 2018. The section from Lhasa to Nyingchi will be completed in 2021, and section from Nyingchi to Yaan, which is also most difficult section, is currently under construction. Construction of this section has already begun in 2020 and is expected to be completed in 2026.
After completion of Sichuan-Tibet railway, supply of Tibet from mainland will improve significantly, especially in Southern Tibet. The meaning is self-evident. After opening of Sichuan-Tibet railway, Medog hydroelectric power station will be built. Once hydroelectric power plants on Yarlung River are built one after other, Yarlung Zangbo River is likely to become navigable, which will be of great importance for Tibet's economic development and border stability.
In short, diverting water from Yarlung Zangbo River is not impossible, but very difficult and must be overcome one at a time. The construction of these projects requires a lot of money and a lot of money, but it's all worth it. It is even more difficult to assess economic value created after the completion of these projects. The strategic value of engineering is even more difficult to calculate using economics.