Qinghai Lake
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2023-02-17 15:06:55
Qinghai Lake
Qinghai Lake
The Tibetan name of Qinghai Lake is "Tsowen Bu" (meaning "blue sea"). Located in the northeast of Qinghai-Tibet Plateau and Qinghai Province, it is the largest inland lake in China. It is formed by the collapse of the fault between Datong Mountain, Riyue Mountain and Nanshan Mountain in Qinghai， sports fitness .
Qinghai Lake is the largest saltwater lake in inland China and an important water body for maintaining ecological security in the northeast of the Qinghai-Tibet Plateau.
On July 30, 2012, the latest remote sensing monitoring results of the Qinghai Provincial Institute of Meteorological Sciences showed that the area of Qinghai Lake continued to increase for 8 years. At 9:50 on October 20, 2014, the spectacular scene of "dragon absorbing water" appeared on the north side of Haixin Mountain in Qinghai Lake.
Formation and evolution
Cause
The tectonic fault lake of Qinghai Lake is connected with the surrounding mountains by faults at the edge of the lake basin. At the early stage of lake formation, which was 20 to 2 million years ago, it was originally a large freshwater lake, connected with the Yellow River system. At that time, the climate was mild and rainy. The lake water discharged into the Yellow River through the inverted river in the southeast, which was an outflow lake. Up to 130000 years ago, due to the neotectonic movement, the surrounding mountains were strongly uplifted. From the end of the Pliocene, the Sun Moon Mountain and the Yeniu Mountain in the east of the lake rose rapidly, blocking the inverted river that originally flowed into the Yellow River, forcing it to flow into the Qinghai Lake from east to west, resulting in the emergence of Gahai and Erhai, and then separated out of sub-lakes such as Haiyan Lake and Shadao Lake.
Circumstances change
Due to the blockage of the outflow channel, Qinghai Lake has evolved into a closed lake. In addition to the dry climate, Qinghai Lake has gradually changed from a freshwater lake to a saltwater lake. During the Northern Wei Dynasty, the perimeter of Qinghai Lake was known as thousands of kilometers, 400 kilometers in the Tang Dynasty, and 350 kilometers in the Qianlong Period of the Qing Dynasty. There are ancient lake dyke ruins about 20 kilometers away from the front edge of the Buha River Delta; Chahan City (built in the Han Dynasty), 25 kilometers away from the east bank of the lake, was originally located at the lakeside. The eastern and western sides have retreated 25 kilometers and 20 kilometers respectively, and the water level has dropped by about 100 meters. Qinghai Lake is oval with a circumference of more than 300 kilometers.
In 1908, Kozlov, a Russian, speculated that the lake level was 3205 meters and the lake area was 4800 square kilometers; Surveying and mapping data in the 1950s showed that the water area of Qinghai Lake was more than 4568 square kilometers; The topographic map published in the 1970s measured the water level of the lake at about 3195 meters. The lake area is 4473 square kilometers; In 1988, the water level was 3193.59 meters, and the lake area was 4282 square kilometers. In 2000, through remote sensing satellite data analysis, the area of Qinghai Lake was more than 4256.04 square kilometers. In August 2013, the area of Qinghai Lake was 4337.48 square kilometers. [5] The lake water volume is 73.9 billion cubic meters, with a maximum length of about 104 kilometers, a maximum width of about 62 kilometers, and a maximum depth of 31.4 meters. The average salinity of the lake water is 12.32 g/L, and the salt content is 1.25%.
In August 2017, the area of Qinghai Lake was 4435.69 square kilometers, an increase of 60.19 square kilometers compared with the same period in 2016, and an average increase of 101.54 square kilometers compared with the same period in previous years (2005-2016).
In late April 2020, the water area of Qinghai Lake, the largest inland lake in China, was 4543 square kilometers, an increase of 28 square kilometers over the same period of the previous year, and an average increase of 164 square kilometers over the same period of the last 10 years (2010-2019).
By the end of September 2021, the water area of Qinghai Lake was 4625.6 square kilometers, an increase of 36.8 square kilometers over the same period in 2020, reaching the maximum since 2004.
Basin characteristics
Qinghai Lake is 105 kilometers long, 63 kilometers wide and 3196 meters above sea level. It is the largest inland lake in China. It is located in the northeast of the Qinghai-Tibet Plateau and the northwest of Xining City, between 99 ° 36 '- 100 ° 16' E and 36 ° 32 '- 37 ° 15' N. The lake is surrounded by four towering mountains: Datong Mountain in the north, Sun and Moon Mountain in the east, Qinghai Nanshan in the south, and Rubber Mountain in the west. The four mountains are between 3600 and 5000 meters above sea level. Qinghai Lake covers an area of 4456 square kilometers, with a circumference of more than 360 kilometers around the lake, more than twice the size of the famous Taihu Lake. The lake is long from east to west, narrow from north to south, and slightly elliptical. The average depth of Qinghai Lake is about 21 meters, the maximum water depth is 32.8 meters, the water storage capacity is 105 billion cubic meters, and the lake elevation is 3260 meters. It is about 200 kilometers away from Xining. There are nearly 30 rivers in the lake area. There are two sub-lakes on the east bank of the lake, one is Gahai, with an area of 48 square kilometers, which is saline water; One ear sea, with an area of 8 square kilometers, is fresh water. [6] [8]
In March 2022, it was learned from the 2022 working meeting of the Qinghai Lake Scenic Area Protection and Utilization Administration that the water area of Qinghai Lake increased by 2.9% from 2017 to 4625.6 square kilometers; The reserve of naked carp resources in Qinghai Lake increased by 33.6% from 2017 to 108500 tons; The number of resident water birds increased by 69.9% from 2017 to 571000; The number of Proctor's gazelle increased by 120.5% from 2017 to more than 2800; The comprehensive vegetation coverage of grassland reaches 60%, the protection rate of wetland reaches 69%, the protection rate of rare and endangered species reaches more than 90%, and the proportion of water quality is excellent reaches 100%.
Climatic characteristics
Qinghai Lake has a plateau continental climate with sufficient sunshine and strong sunshine; It is cold in winter and cool in summer, the warm season is short, the cold season is long, and there are many strong winds and sandstorms in spring; The rainfall is less, the rainy and hot seasons are the same, and the dry and wet seasons are distinct.
illumination
Most of the annual sunshine hours in the lake area are more than 3000 hours, about 700 hours higher than that in the same latitude area in the east of Qinghai; The annual sunshine percentage is 68~69%. The total annual radiation is 171.461~106.693 kcal/cm2 · year, which is 10~40 kcal/cm2 · year higher than that of the North China Plain and the Loess Plateau at the same latitude.
air temperature
The temperature in the east and south of the lake area is slightly higher, and the annual average temperature is between 1.1 and 0.3 ℃; It is slightly lower in the west and north, with an annual average temperature of - 0.8~0.6 ℃, an average maximum temperature of 6.7~8.7 ℃, an average minimum temperature of - 6.7~4.9 ℃, an extreme maximum temperature of 25 ℃ and 24.4 ℃, and an extreme minimum temperature of - 31~-33.4 ℃.
water content
The annual precipitation in the lake area is relatively low. However, the eastern and southern regions are slightly higher than the northern and western regions. The annual precipitation in the eastern region is 412.8 mm, the southern region is 359.4 mm, the northwestern region is 370.3 mm, and the western region is 360.4 mm and 324.5 mm. The annual evaporation is 1502 mm, which is far more than the precipitation. The precipitation in the lake area has a large seasonal variation. The precipitation is mainly concentrated in May to September, and the rain is hot in the same season.
Strong winds and sandstorms
The number of days of gale and sandstorm in the lake area is one of the most regions in the province. From February to April every year, there are strong winds from the afternoon to the evening, and the northwest wind prevails. Take Gangcha as an example. Strong wind (≥ 17 m/s) has an average annual average of 47.3 days, with the maximum from February to April, an average of 5.9 to 9.3 days, and a maximum of 19 days in March. The average duration of sandstorm over the years is 14 days. The Buha River Estuary - Bird Island, a key protected area, is windy in the northwest, with the maximum wind force of 9-10. Due to the high altitude of the lake area, the west wind of the lake is frequent, and the high air has a great impact, which is mostly controlled by the west wind throughout the year. The wind speed is the largest in winter and spring, and smaller in summer and autumn. Under the action of wind, the general wave is 2~3, and the maximum wave is 7~8. The number of days with wave above 6 in the whole year is about 40 days.
water temperature
Qinghai Lake
The temperature of Qinghai Lake varies with the seasons. In summer, the lake water temperature has obvious positive temperature layer phenomenon, with the maximum of 22.3 ℃ and the average of 16 ℃ in August; The temperature of the lower layer of water is relatively low, with an average temperature of 9.5 ℃ and a minimum of 6 ℃. In autumn, the lake water is agitated due to the wind in the lake area, which makes the phenomenon of stratified temperature of water temperature basically disappear. In winter, the lake surface freezes, and the temperature of the lake water appears inversion layer. In January, the temperature of the upper layer of the lake water under the ice is - 0.9 ℃, and the temperature of the bottom layer is 3.3 ℃. After thawing in spring, the surface water temperature of the lake began to rise again, and gradually returned to the temperature in summer and season.
Ice condition
Qinghai Lake contains a small amount of inorganic salts, and the freezing temperature of the lake water is slightly lower than 0 ℃. Every year from the middle of November, the temperature in the lake area drops to below 0 ℃, and the temperature is the lowest in January of the next year. The whole lake forms a stable ice sheet. The annual average ice cover period is 108~116 days, the shortest is 76 days, and the longest is 138 days. The ice thickness is generally 40 cm, and the maximum ice thickness is 90 cm. After ice sealing, the ice surface is flat, and cracks and crevices often appear due to violent winds. Come to watch the lake and mountains in winter, and your eyes are white and silvery. In the middle of March, the ice sheet broke and the lake surface appeared floating ice. Under the action of the wind, a huge iceberg was formed and floated to the shore. The maximum volume of the iceberg was about 10 cubic meters. After the middle of April, the ice in the lake completely melted.
