Lop Nur

Lop Nur

Lop Nor, a lake in the southeast of Xinjiang Uygur Autonomous Region of China, is known as "the ear of the earth" and "the sea of death" because it is shaped like a human ear. It is also known as "n à o" in the book of mountains and seas. It is also known as "youze" in the book of mountains and seas. It is also known as cuanze, Yanze, puchanghai, Yanze, laolanhai, furihai, Linhai, luopuchi, luobuchi, etc.

Luobunuoer is a Mongolian phonetic translation, which means a lake with many waters. At an altitude of about 780 meters, it is located at the lowest point in the east of Tarim Basin, the easternmost edge of Taklimakan Desert, the north of Ruoqiang county and the southeast of Bayinguoleng Mongolian Autonomous Prefecture. Its center is located at 40.5 ° N and 90.3 ° E. Tarim River, Kongque River, Che'erchen River and Shule River are the second largest saline lake in China, covering an area of 2400-3000 square kilometers.

Before 330 ad, there was a lot of water in the lake, and Loulan city in the northwest was the throat of the famous "Silk Road". Later, due to climate change and the impact of human water conservancy projects, the water from the upper reaches decreased until it dried up, and now it is only a large salt shell.

Geography

Location context

Lop Nur is located in the east of Tarim Basin, Xinjiang, China, and the easternmost edge of Taklimakan Desert, the largest desert in China. It is a world-famous drought center with an altitude of about 780 meters. It is located in the lowest point in the east of Tarim Basin, the easternmost edge of Taklimakan Desert, the north of Ruoqiang County, and the southeast of Bayinguoleng Mongolian Autonomous Prefecture, with a geographical location of 39.5 ° to 41.5 ° n, 88 ° to 92 ° e, and the center of the world It is located at 40.5 ° N and 90.3 ° E.

geographical environment

Lop Nur, located in the northeast of Ruoqiang County, was once the second largest inland lake in China, with an altitude of 780 meters. Lop Nor has many names, some of which are named for its characteristics, such as AOZE, Yanze, ganhai, etc., and some of which are named for its location, such as puchanghai, laolanhai, kongquehai, lopchi, etc. After Yuan Dynasty, it was called luobunuoer. In the middle and late 20th century, due to the decrease of the flow of the Tarim River, the surrounding desertification was serious and degraded rapidly, until it completely dried up in the late 1970s (before the 1970s, it was the second largest saline lake in China, since the drying up of Lop Nur, Namco became the second largest saline lake in China, and the first largest is Qinghai Lake).

Rivers in the basin, such as Tarim River, Kongque River, Che'erchen River and Shule River, once formed huge lakes. After that, the lake water decreased and Loulan city became a ruin. In 1931, Chinese scholar Chen zongqi and German geologist hornier made a field investigation on the newly formed water area in Lop Nur since the diversion of Tarim River in 1921, and completed the measurement of the whole lake area in 1931. The measured water area in Lop Nur is 2375 square kilometers. The water source comes from Kongque River, which flows into the lake from the north end, into the center of the lake, and expands eastward, like a "boot" in the south The lake is 85 kilometers long in the north, 20 kilometers wide in the north and 45 kilometers wide in the south. The water is very shallow. In some areas, boats can't even travel, and sometimes it is stranded. In the southwest, there is a river connected with Kala Heshun lake.

After 1921, the Tarim River stopped flowing, and the lake water increased. In 1942, the lake water area reached 3000 square kilometers. In 1962, the lake water was reduced to 660 square kilometers. After 1970, the river dried up mainly because of the sudden increase of population on both sides of the Tarim River and the continuous demand for water from the Tarim River, which made the length of the river shrink sharply to less than 1000 km, dried up more than 300 km of the river and finally dried up Lop Nur. Dunhuang, Hami, Shanshan, Turpan, Korla, Ruoqiang, Qiemo, Hetian, Aksai, Subei, Guazhou, Yuli, Minfeng, Yutian, Moyu, Yumen and Tiemenguan are all located in the surrounding areas of Lop Nur.

The time when Lop Nur dried up is a controversial issue. Most literatures record it as 1972. Since 1972 when the United States released the dried up satellite photos of "big ear" in Lop Nur, "big ear" has been regarded as the dry basin of East Lake in Lop Nur

. During the scientific expedition of "re taking the road of Pengjiamu scientific exploration" which has been completed, the researchers found the continuous westward extension shoreline of Lop Nur East Lake, and calculated that the area of Lop Nur ancient lake is more than 10000 square kilometers.

The results of DGPS measurement in 2006 show that the topography of the da'er Lake Basin in Lop Nur is relatively gentle, with a depth of only 5.2 meters, an average slope of 0.19 ‰ in the southwest and 0.09 ‰ in the northeast. It is an eccentric shallow lake basin with a salt pan covering an area of nearly 5500 square kilometers and an altitude of about 800 meters.

climate

The climate in Lop Nor is extremely dry and hot. The annual average temperature is 11.6 ℃, the maximum temperature in summer is 40 ℃, the minimum temperature in winter is below - 20 ℃, the annual precipitation is 20 mm, the evaporation is 3000 mm, the annual sunshine hours is 3200 h, and the annual accumulated temperature is 4500 ℃. And the wind erosion is strong. The prevailing wind direction throughout the year is ne. The windy season is from March to may, and the windy season is from June to August. The strong wind days with magnitude 8 are 60 days, which often cause sandstorms. The annual floating dust weather in Ruoqiang and Qiemo areas located in the downwind direction of Lop Nur is 115-193 days.

Geomorphological features

West Bank of Lop Nor

The northwest Bank of Lop Nur rises westward along 40 ° 27 ′ n in a step like manner. The dry lake bottom is 780 meters above sea level, and the surface is covered with 20-30 cm thick salt crust, which is loose and is the new salt crust formed when it finally dried up in 1962. The new salt crust rises westward to 782 meters, which is the first lacustrine platform. The western boundary of the platform is 90 ° 15 ′ e, but the width is different from north to south, the narrow part is only about 2 kilometers, and the widest part is more than 10 meters The platform was formed in the 1930s when the lake surface expanded. In the west of the second lacustrine platform, there is a vast lacustrine plain with an altitude of 784-785 meters, which is composed of light gray lacustrine clay with silty sand layer. The surface is eroded by wind to form a ridge or low Yadan landform extending about 2 meters in N40 ° e direction.

 

 

Loulan ancient city area, i.e. 40 ° 30 ′～ 40 ° 39 ′ n, 89 ° 54 ′～ 90 ° 01 ′ e, is a lacustrine platform with a height of about 789 meters. The ground cutting depth is about 6 meters. It is composed of light gray and gray silty clay with a thin layer of silt. The edge of the platform is eroded by wind to form a ridge like Yadan landform extending N45 ° E.

 

Yadan landform in Longcheng

Yadan landform in Longcheng is located on the North Bank of Lop Nur, with a height of 815-820 meters and a distribution area of about 1800 square kilometers

 

It is cut into 20-25m wide and 30-50m long ridges with n20-30 ° e extension and steep surroundings, which is called Yadan landform.

 

The upper part of Yadan is composed of grayish yellow single crystal gypsum containing silty clay, the middle part of Yadan is composed of grayish green silty clay with thin layer of silty sand and a small amount of gypsum crystal, and the lower part is composed of grayish green and grayish yellow silty clay with thin layer of gypsum.

 

Lakeshore terraces in the north of Lop Nur East Lake

There are a series of islands distributed in the north of East Lake of Lop Nur, with different sizes. The top heights of the islands are 781-782m and 784-785m respectively. The composition of the islands is similar. The ground is about 30cm thick salt shell, and the lower part is gypsum bearing lacustrine silty clay. Therefore, most of these islands are formed by the later erosion of the early lacustrine platform. Besides the islands, there are two erosion terraces with the same height as the islands, and the top of the terrace is also covered by salt crust or sand.

 

Yadan landform in bailongdui

Yalan landform of bailongdui is located around the north depression. The top of Yalan is 800-810 meters above sea level, covering an area of about 1000 square kilometers

 

The cut depth of the ground is 10-220 meters. It is a ridge or mound landform extending in NNE direction. It is composed of grayish white and grayish yellow silty clay and grayish white Glauber's salt mixed with gypsum. Because of its grayish white color, it is called bailongdui.

 

Shayadan landform in Sanlong

Sanlong shayadan landform is distributed between Beishan and Yumenguan on the East Bank of East Lake and the east of Aqike Valley, with a total area of more than 600 square kilometers. Sanlong shayadan extends in NNE direction, and its top surface is about 805 meters above sea level, with a relative height of 15-20 meters. It is composed of brown yellow lacustrine silty clay with silty fine sand. The top surface of Yadan landform in the east of Aqike Valley is about 800 meters above sea level and 10 meters above sea level. It is slightly north-south trending, cut and broken, and distributed in isolated hillock shape. The upper part is composed of yellowish clay, silty sand with medium sand, the bottom is gray green mudstone, and the ground is loose gray gravel layer.

 

Historical changes

history

Ancient Lop Nur was born at the end of the tertiary and the beginning of the Quaternary. It is 18 million years ago and covers an area of about 20000 square kilometers. Under the influence of neotectonic movement, the lake basin tilted and uplifted from south to North and was divided into several depressions.

 

During the Han Dynasty, there was a time here

Chinese PinYin : Luo Bu Bo