The largest saltwater lake in China.
Qinghai Lake, named "Cuowumbu" in Tibetan, which means "Blue Sea", is located in the northeast of Qinghai-Tibet Plateau in Qinghai Province, China. It is the largest lake in China, the largest saltwater lake and inland lake in China, with a total area of 4,625.6 square kilometers.
Formation reason: The structural faults in Qinghai Lake make the lake depressed, and the edge of the lake basin is mostly connected with the surrounding mountains by faults. In the early days of the lake's formation, it was originally a large freshwater lake, which was connected with the Yellow River system 200-200 million years ago. At that time, the climate was mild and rainy, and the lake was discharged into the Yellow River through the Daotang River in the southeast, which was an outflow lake.
Up to 6,543,800+300,000 years ago, due to neotectonic movement, the surrounding mountains rose strongly. Since the end of Pliocene, Sun Moon Mountain and Bison Mountain in the east of the lake have risen rapidly, blocking the Daotang River that has been injected into the Yellow River, forcing it to flow into Qinghai Lake from east to west, resulting in Gahai Lake and Erhai Lake, which are further divided into sub-lakes such as Haiyan Lake and Shadao Lake.
Hydrological characteristics:
The recharge source of Qinghai Lake is river water, followed by spring water and precipitation at the bottom of the lake. There are more than 70 rivers around the lake, which are obviously asymmetrical. There are many rivers in Hubei, northwest and southwest, with large basin area and many tributaries; There are few rivers and small watersheds in the southeast and south bank of the lake.
Buha River is the largest river that flows into the lake. It originates from Niniku Mountain in A Mu, a branch of Qilian Mountain, with a total length of about 300 kilometers, a main stream of 92 kilometers, dozens of tributaries and more than 0 tributaries/kloc-0. The width of the downstream channel is about 50 ~ 100 m, the depth is about 1 ~ 3 m, and the pH value is 8 ~ 8.2. The basin area is 16570 km2, accounting for 1/2 of the basin area in the lake area. Annual runoff11.200 million cubic meters, accounting for 60% of the runoff into the lake.
The annual runoff recharge of Qinghai Lake is mainly Buha River, Liusha River, Uhaalan River and Hargeer River. The annual runoff of these four rivers reaches16120,000 cubic meters, accounting for 86% of the runoff entering the lake. This is the place where fish migrate and lay eggs and birds are concentrated.
Qinghai Lake supplies 65.438+0.335 billion cubic meters of rivers, 65.438+0.557 billion cubic meters of precipitation and 40.65438+0 billion cubic meters of groundwater every year, with a total supply of 3.493 billion cubic meters. The wind in the lake area evaporates quickly, with an annual evaporation of 3.93 billion cubic meters and an average annual loss of 437 million cubic meters.