Bosten Lake

Bosten Lake

Bosten Lake, which means "oasis" in Uighur, is located in Bohu County, Southeast of Yanqi Basin, Xinjiang Uygur Autonomous Region, China. It is the largest inland fresh water huff and puff Lake in China. In the biography of the western regions of the Han Dynasty, "Yanqi king to Yuanqu City, South to Yuli hundred Li, near the sea, many fish" in the "offshore" and "dunhongpu" in the "shuijingzhu" all refer to this lake.

Bosten Lake is located between 86 ° 40 ′ - 87 ° 25 ′ E and 41 ° 56 ′ - 42 ° 14 ′ n, 55 km long from east to west and 25 km wide from north to south, with a total water area of more than 800 square kilometers (2014). The lake is 1048 meters above sea level, with an average depth of 9 meters and the deepest of 17 meters. The lake area is located in the hinterland of Eurasia, with abundant light, abundant heat and scarce rainfall, which is a typical temperate continental climate.

Bosten Lake is an inter mountain subsided lake, which is mainly supplied by Kaidu River and Kongque River. Bosten Lake can be divided into two parts: large lake area and small lake area. The large lake area is nearly 1000 square kilometers, while the small lake area is only more than 100 square kilometers. According to the book of Sui, the lake has the advantages of fish, salt, cattail and reed. The lake area is an important reed production base in China. In addition, Bosten Lake is rich in all kinds of freshwater fish, which is the largest fishery production base in Xinjiang.

In 2002, Bosten Lake area was rated as a national key scenic area, which is a natural lake water scenery type natural scenic area, involving three counties and one city of Bohu, Yanqi, Heshuo and Korla. In May 2014, Bosten Lake scenic spot was rated as a national 5A scenic spot, becoming the Eighth National 5A scenic spot in Xinjiang.

physical geography

Location context

Bosten Lake is located in Bohu County, south foot of Tianshan Mountain and southeast of Yanqi Basin, Bayinguoleng Mongolian Autonomous Prefecture, Xinjiang Uygur Autonomous Region, between 86 ° 40 ′～ 87 ° 25 ′ E and 41 ° 56 ′～ 42 ° 14 ′ n. the water surface is 55 km long from east to west and 25 km wide from north to south, with a maximum area of 1646 square kilometers. In 2014, the lake covers an area of more than 800 square kilometers.

Formation and evolution

Yanqi Basin, where Bosten Lake is located, is an Intermountain faulted basin in the South Tianshan orogenic belt. It was once a part of the ancient Tarim block in geological history. Its formation and evolution history can be traced back to the pre Sinian about 800 million years ago. The neotectonic movement started at the end of Neogene about 2.5 million years ago, which caused a large-scale differential rise and fall in this area. The old fault in the south margin of Bosten and the new fault in the north margin were active strongly. The Bosten Lake area between the faults began to sink strongly. The Kaidu River in the upper reaches of Bosten Lake was also affected by the subsidence of dayuludus basin and Yanqi Basin, and the uplift of the peneplain between the two basins In addition, most of the mountains in the source area of the Kaidu River have been raised above the snow line, so that the precipitation is stored in the form of grains of snow and ice, and the Bosten Lake is continuously supplied with water for many years.

topographic features

Bosten Lake Basin is located in Yanqi Basin, a closed Intermountain basin. The general trend of topography is higher in the north and lower in the south. From the front of the mountain to Bosten Lake, it is the piedmont alluvial plain, Kaidu River Delta and Bosten Lake Basin. In other words, the West and east sides of Bosten Lake are flat and more easily affected by the change of lake water level, while the South and north sides are less affected by the change of lake water level because of the higher terrain.

Climatic characteristics

Overall situation

Bosten Lake is located in Xinjiang, which is the farthest province from the ocean in China. Due to the regulation of Bosten Lake, the lakeside wetland has formed a typical continental desert climate with changeable climate in spring, hot and dry in summer, rapid cooling in autumn and severe cold in winter, which is also the transition zone of climate in northern and southern Xinjiang. Due to the blocking of the Altay Mountains, Tianshan Mountains, Kunlun Mountains, Pamirs and Qinghai Tibet Plateau, the ocean airflow can not reach the lake area smoothly. Therefore, the climate with large annual temperature difference, large evaporation, dry and less rain is formed.

Data statistics

The average annual temperature of Bosten lakeside zone is 8.2-11.5 ℃, the average temperature in January is - 7.8-12.3 ℃, the average temperature in July is 22.9-26.0 ℃, the extreme value of maximum temperature is 37.1-40.0 ℃, the extreme value of minimum temperature is - 25.3-31.6 ℃, the average frost free period is 175.8-211.3 days, the days of daily maximum temperature ≥ 35 ℃ is only 0.1-4.3 days, and the days of daily minimum temperature ≤ - 20 ℃ is only 0.1-1.9 days God. The annual average relative temperature is 45-56%, the annual precipitation is 47.7-68.1 mm, and more than 80% of the precipitation is concentrated in May to September. The maximum number of days without precipitation is 158-190 days, and the annual evaporation is 1880.0-2785.8 mm. The annual average wind speed is 1.1-2.7 M / s, the gale days are 26.3-40.9 days, and the sunshine hours are 3008.4-3130.6 hours.

hydrographic features

The monthly variation of runoff, water level, precipitation, evaporation and other factors in Bosten Lake Basin is significant; the Mountain Runoff and Bosten Lake precipitation are mainly concentrated in summer, accounting for 44.82% and 56.07% of the total, respectively, with distinct changes in four seasons; the Bosten Lake evaporation is mainly concentrated in spring and summer, accounting for 33.85% and 44.04% of the total, respectively; the interannual variation of runoff and water level is relatively large, and the water level is relatively stable The precipitation is less, the interannual variation is small, and the evaporation is larger, showing a fluctuating upward trend. Precipitation has inhibitory effect on evaporation, and precipitation in the source area of Kaidu River is the main source of runoff; water level change of Bosten Lake is affected by climate and human activities, climate changes runoff by adjusting temperature and precipitation, and indirectly affects water level change; human activities mainly affect water level through land reclamation, inter basin water diversion and downstream water distribution.

Flow rate

From 1958 to 2009, the total inflow of Bosten Lake was 14.23 × 10 ⁸ m3 / A, of which the river inflow was 5.24-35.46 × 10 ⁸ m3 / a (average annual 13.49 × 10 ⁸ m3 / a), accounting for 94.80% of the total; the precipitation recharge was 0.19-1.59 × 10 ⁸ m3 / A (average annual 0.74 × 10 ⁸ m3 / a), accounting for 5.20%; the total outflow of Bosten Lake was 14.58 × 10 ⁸ m3 / A, of which The output water of the lake is 1.37-13.61 × 10 ⁸ m3 / a (average annual 5.88 × 10 ⁸ m3 / a), accounting for 39.58% of the total water; the evaporation of the lake is 5.94-11.66 × 10 ⁸ m3 / a (average annual 8.70 × 10 ⁸ m3 / a), accounting for 60.42%; the increment of water storage in the lake area is - 8.97-7.74 × 10 ⁸ m3 / a (average annual - 0.74 × 10 ⁸ m3 / a), and the residual water (agricultural drainage and groundwater) -62-16.96 × 10 ⁸ m3 / a (average annual 0.39 × 10 ⁸ m3 / a), accounting for only 2.89% of the inflow.

Water level

The water level change of Bosten Lake can be divided into four stages

(1) In the stage of wave type decline (1955-1987), the average water level of Bosten Lake decreased from 1048.42 cm in 1955 to 1044.95 cm in 1987, with a decrease of 3.47 cm and a rate of 10.8 cm / year.

(2) In this period, the average water level of Bosten Lake increased from 1044.95cm in 1987 to 1048.62cm in 2002. Within 15 years, the average water level of Bosten Lake increased by 3.77cm at a rate of 25.1cm, which is 2.32 times of that of (1) period. When the lowest highest water level of Bosten Lake is used to calculate the change range, it is in this period During this period, the water level rose by 4.68 cm, and the rate of water level rise was 31.2 cm. It can be seen that the water level of Bosten Lake changed rapidly during this period.

(3) During the period of rapid decline (2002-2010), the water level of Bosten Lake decreased rapidly after reaching the highest water level in history in 2002. During the eight years from 2002 to 2010, the average water level of Bosten Lake decreased by 2.87 cm, 35.9 cm per year on average. Compared with the period (1), the water level decreased at the same time, but the rate was 3.31 times faster than that in the period (1), which was the same as that in the period (2) ）The rate of water level rising is also less than 10.8 cm M / A in this period.

Therefore, the annual variation range of water level in Bosten Lake is quite different, ranging from 0.2 cm to 1.24 cm, and the annual average variation range is 0.59 cm. 2002 is the year with the highest average water level in Bosten Lake, while in the same year, the annual variation range is 0.5 cm

Chinese PinYin : Bo Si Teng Hu