Neighboring Guizhou Province is out of luck. Guizhou is just at end of Siberian cold current, and western belt will also enter province of Guizhou. As a result, cold and warm currents converge in Guizhou, resulting in Guizhou's winters being cloudy and rainy. Therefore, winter climate in Yunnan seems to be very warm, while in Guizhou it is very humid and cold. Winter in Yunnan is similar to spring, which makes winter tourism in Yunnan very popular, while winter tourism in Guizhou is very deserted.
But there are pros and cons to everything. The weather in Yunnan in winter is mostly sunny, and blue sky extends for thousands of kilometers, which is very conducive to development of cold tourism. However, due to lack of rainfall in Yunnan, droughts often occur in Yunnan during winter. According to statistics, 85% of Yunnan's precipitation falls from May to October, while precipitation from November to April of following year accounts for only 15% of entire year. Therefore, winter in Yunnan is very dry. From 1950 to 2014, Yunnan experienced a severe drought for more than 20 years. In addition, drought in Yunnan lasted a long time and caused serious damage.
Dry conditions in 2019
Among them, central Yunnan is worst drought in Yunnan. Central Yunnan refers to four major cities of Kunming, Qujing, Chuxiong and Yuxi, which are economic center of Yunnan. The area here is only 24% of province, but population is 37% of province, and economic scale is about 60% of province.
However, Central Yunnan is located just in watershed zone of four river basins of Yangtze, Pearl River, Lancang River and Red River, water resources here account for only 12% of total resources of province. At present, water utilization rate in central Yunnan has reached 47%, exceeding internationally recognized upper limit of 40%. The shortage of water resources has seriously affected water for agricultural, residential and industrial needs in central Yunnan, limiting economic development of central Yunnan.
How to solve this problem? As early as 1950s, Zhang Chong, vice chairman of National Committee of People's Political Consultative Council of China, put forward idea of "bringing gold to Yunnan and connecting five lakes with shipping" after seeing Nujiang River, Lancang River, and Jinsha River. According to his vision, a large dam will be built in Tiger Leaping Gorge on Jinsha River, and then water from Jinsha River will be diverted to Erhai Lake, and then a canal will be dug between Erhai Lake and Dianchi. A lake so that people of Kunming can drink water from Jinsha River.
However, due to difficult terrain along line and huge number of engineering structures, project to "deliver gold to Yunnan" was not approved for construction. In 2011, Yunnan experienced a severe drought for three consecutive years, so CPPCC members in Yunnan proposed plans to divert water from central Yunnan, causing a great sensation. By 2014, Yunnan's central water diversion project was finally included in national 13th Five-Year Plan. In 2017, “Feasibility Study for Central Yunnan Water Intake Project” was prepared, and in 2018, construction of Central Yunnan Water Intake Project began.
The project is divided into two phases. The first stage has a total length of 755 km. The starting point of water diversion is Datong Village, Shigu City, Yulong County, Lijiang, then it passes through Lijiang, Dali, Chuxiong, Kunming, Yuxi and other cities, and finally reaches Xinpobei. in Honghe Prefecture. The second phase of project is a subsidiary project of first phase of project, and can also be called an offshoot, construction has already begun in 2022.
The Central Yunnan Water Diversion Project is a water conservation project with largest investment scale and most complex construction in China at present. Although south-north water diversion project has a long distance, it mainly passes through flat areas, so construction difficulty is much less than that of central Yunnan water diversion project. The total length of project's main canal is 664 km, of which 612 km are tunnels (a total of 58 main tunnels), which is 92.13% of canal's total water supply. In addition, 25 return siphons, 17 aqueducts and 15 concealed culverts will be built. You can see how complex and difficult this project is.
So how much water can be supplied by Yunnan Central Water Diversion Project? According to plan, by 2030 average annual volume of water intake will be 2.6 billion cubic meters, and by 2040 average annual volume of water intake will be 3.4 billion cubic meters. What is a concept? The water demand of Dianchi Lake is 1.5 billion cubic meters, which means that project can pump water from two Dianchi lakes per year.
Will water diversion project in central Yunnan lead to water shortages in Jinsha River? This question is nothing to worry about. The average annual flow of Huaping County on Jinsha River has reached 44 billion cubic meters, which means that annual water withdrawal from central Yunnan is less than one tenth of flow in middle reaches of Jinsha River. The annual flow of Jinsha River in Yibin has reached 154.6 billion cubic meters. Thus, diversion of water from central part of Yunnan will not affect total volume of water in Jinsha River.
However, 3-4 billion cubic meters of pumped water are of great importance for Central Yunnan. First, these water sources will greatly alleviate Yunnan's winter drought, and improved irrigation area has reached 630,000 mu. At same time, 672 million cubic meters of water can be replenished in Dianchi Lake, Xingyun Lake, Qilu Lake and Yilong Lake to improve ecological environment in central Yunnan and benefit more than 11 million people.
However, in my opinion, water diversion project in central Yunnan has far-reaching implications. The water diversion project in central Yunnan mainly uses transportation pipelines that run between mountains and can be said to be pipelines for water transportation. In future, when China plans to launch Nujiang-Lancang-Jinsha River Diversion Project as well as Tibetan North Diversion Project, it will inevitably adopt such a water transfer model. The Central Yunnan Water Diversion Project provides experience and lessons for these projects.
Recently, Ministry of Water Resources issued 2023 Jinsha River Basin Water Volume Management Plan, which covers 36 reservoirs, including Wudongde, Baihetan, Siluodu, Xiangjiaba, Lianghekou and Ertan reservoirs. A single order and scale of water transfer was established in five provinces, including Qinghai, Tibet, Sichuan, Yunnan and Guizhou. According to plan, in future, all provinces of Southwest China will start building water intake facilities for Jinsha River, so water resources of Jinsha River should be distributed evenly.
In future, provinces along Yangtze River and even northern provinces will need to divert water from Yangtze River, which may lead to insufficient water in Yangtze River. Thus, in foreseeable future, water diversion plans for Nu, Lancang and Yarlung Zangbo rivers can be launched to form a nationwide water distribution network for uniform planning and distribution. The plan to divert water to central Yunnan is just one of smaller plans, and it will lay foundation for a later grand plan.