Erhai

Erhai Lake, also known as "yeyushui" in ancient times, also known as "Xi'er River" and "kunmichuan", is a plateau lake formed by the collapse of Xi'er river. It looks like an ear. Overlooking from the air, Erhai Lake is like a crescent moon, lying quietly between Cangshan and dalibazi. Erhai Lake has three islands, four continents, five lakes and nine curves. The lake water is clear to the bottom. It has been called "the flawless jade among the mountains" since ancient times. There is an Erhai Park in Tuanshan, the southernmost part of Erhai Lake, which is a good place to enjoy the scenery of Cangshan and Erhai Lake.

Erhai

Erhai Lake, known as Kunming Lake, Erhe River, yeyuze, etc. Erhai Lake is located in Dali City, Dali Bai Autonomous Prefecture, Yunnan Province. Generally, the lake covers an area of about 246 square kilometers (251 square kilometers), with a water storage capacity of about 2.95 billion cubic meters. It is in a long and narrow shape. It starts from the southern end of Eryuan County in the north and ends at Xiaguan of Dali City in the south, with a length of 40 kilometers in the north and south. It is the second largest lake in Yunnan after Dianchi Lake, and the seventh largest freshwater lake in China. Erhai Lake was formed at the end of the ice age. Its main cause is subsidence and erosion. It is a fault lake with an altitude of 1972 meters.

Erhai Lake has seven main functions of water supply, agricultural irrigation, power generation, climate regulation, fishery, shipping and tourism. In the west of Erhai Lake, Cangshan Mountain is lined up like a screen, and in the East, Yushan Mountain is surrounded and set off, so the space environment is beautiful.

In 1981, Cangshan Erhai Nature Reserve was established with the approval of Yunnan Provincial People's government. In 1994, it was promoted to the national level. The main protected objects are plateau freshwater lakes and aquatic animals and plants, natural landscape of North-South animals and plants transition zone, glacial relics, covering an area of 79700 hectares.

Name evolution

Erhai Lake was named "yeyushui", "yeyuhe", "yeyuze", "Xierhe", "Erhe", "kunmichuan" in ancient times. The reason why Erhai Lake is finally named "Er" is that it is either "shaped like a human ear" or "like a moon embracing an ear". The name "Hai" comes from Yunnan customs. One of the eighteen monsters in Yunnan is called "the lake is called the sea". That is to say, lakes are often called "sea" in Yunnan. With the development of society, the name of "yeyushui" is often used in ancient literature; "Xi'er River" mainly refers to a section of river that flows westward at the southwest exit of Erhai Lake and finally confluences with Yangbi River; "kunmichuan" is rarely used with the disappearance of kunmi tribe; "Erhai Lake" has become the most popular name of this lake.

Location context

Erhai Lake is mainly located in Dali City, and its north bank connects with the southeast corner of Eryuan County, the east foot of Cangshan Mountain and the West foot of Yushan Mountain. The northern part of Erhai lake belongs to Eryuan County. On January 1, 2004, after Shuanglang and Jiangwei towns were included in Dali City, all water areas belonged to Dali city. Eryuan County has become the northern border situation. Along the lake area, there are Shuanglang and Jiangwei towns in the north, Xizhou, Wanqiao, Chengyi and Qiliqiao towns in the East, Xiaguan and Fengyi towns in the south, and gouse and Haidong towns in the West. Eryuan river is located in Xiaguan of Dali City in southwest.

hydrographic features

Erhai Lake, with an area of 251 square kilometers (water level of 1974 meters), a total capacity of 2.53 billion cubic meters and a catchment area of 2565 square kilometers, has a length of 42.5 kilometers, an average width of 6.3 kilometers, a maximum depth of 22 meters, an average depth of 10.2 meters and a perimeter of 117 kilometers.

Erhai Lake is 42.0 km long from north to south, 8.8 km wide from east to west, 3.05 km wide from east to west, 21.5 m deep, 10.8 m deep on average, with a surface area of 252.91 square kilometers, a water storage capacity of 2.794 billion cubic meters, an island area of 0.748 square kilometers, and a shoreline of 129.14 km,

It is the second largest freshwater lake in Yunnan plateau after Dianchi Lake.

The annual water temperature of the lake is 12 ℃ - 21 ℃. The lowest operating water level is 1962.84 meters above sea level (1971 meters above sea level), the highest water level is 1965.84 meters above sea level (1974 meters above sea level), and the normal water level range is 1962.84-1965.84 meters above sea level (1971-1974 meters above sea level, all below are yellow sea level).

Because the marble interlayer is conducive to the storage and infiltration of groundwater, most of the eighteen streams are formed by transverse faults and physical geological processes, and become the concentrated confluence zone of surface water and groundwater in Cangshan. In the North-South marble intercalation of Cangshan mountainside, karst is developed. In the East-West transverse section, there are large streams of spring water gushing out, such as mangyongxi along the foot of the mountain; in the exposed part of the rock contact zone or fault zone, there are also springs in different degrees in the alluvium, such as butterfly spring.

The East Bank of Erhai Lake is limestone and sandstone with strong water permeability, which is not conducive to water storage, so it is short of water. In addition to surface water supply, Erhai Lake receives good groundwater conditions, and the groundwater discharged from the surrounding mountains belongs to Erhai Lake.

The water temperature of Erhai Lake is between 1 ℃ and 20 ℃ in the whole year. The vertical distribution of water temperature has the characteristics of positive temperature layer and does not freeze all the year round. Erhai lake belongs to subtropical lake (warm Lake). The transparency is 4 meters, the seasonal variation is significant, the rainy season is smaller, and the dry season is higher. According to the monitoring results in December 1985, the average transparency is 5.4 meters, the maximum transparency is 8 meters, the water color is light blue, and the chroma is 6.625. The water quality is colorless and odorless. It belongs to clean grade calcium magnesium bicarbonate type freshwater lake, and its nutritional status is mesotrophic.

The water level of Erhai Lake plays a decisive role in the biological community and natural ecology of Erhai Lake. The water level of Erhai Lake has been recorded since 1951. After more than 50 years of repeated practice and scientific argumentation, the water level control elevation of Erhai Lake was formulated five times in 1966, 1982, 1989, 1998 and 2004. On March 26, 2004, the water level control elevation of Erhai Lake was approved and promulgated by the eighth meeting of the tenth Standing Committee of Yunnan Provincial People's Congress "Regulations on the administration of Erhai Lake in Dali Bai Autonomous Prefecture of Yunnan Province" stipulates that the water level of Erhai Lake is 1964.30 meters at the lowest level and 1966.00 meters at the highest level.

Lake system

Erhai lake belongs to Lancang River system, with pengbi lake, East Lake and West Lake in the north, flowing into Erhai Lake through Miju River, Luoshi River and Yong'an River respectively, which is the main water source of Erhai Lake; eighteen streams of Cangshan Mountain gather in the east slope catchment area of Cangshan Mountain in the West; BOLUO River and Jinxing River in the South; dozens of large and small gullies such as fengweiqing River and Yulong River in the East, with a total runoff area of 2565 square kilometers and 117 gullies entering the lake With an average annual inflow of 817 million cubic meters, the Xi'er river is the only natural outlet channel of Erhai Lake, with a length of 22 kilometers. Erhai water flows out of the Xi'er River, converges with Yangbi River, flows into Lancang River and flows into the Pacific Ocean.

Upstream water system

In addition to receiving atmospheric precipitation, the lake is mainly supplied by rivers. The rivers entering the lake from the north are Miju River, Luoshi River and Yong'an river. The river entering the lake from the south is BOLUO river. In the East are fengweiqing River, Yulong River and other small rivers. In the West are Cangshan eighteen streams. The average depth of the lake is 15 meters, and the deepest is 21 meters. At Xiaguan, the lake water flows southwest into Yangbi river through Xi'er River, and then flows south into Lancang River.

Eighteen streams of Cangshan Mountain

Eighteen streams of Cangshan Mountain are named because they originate from Cangshan mountains and alternate gullies. Among the peaks of the 19th peak of Cangshan Mountain, the famous eighteen streams of Cangshan Mountain are naturally formed. In the Ming Dynasty, Li Yuanyang recorded 18 streams according to the records of Yuan Yi Tong Zhi, which were Yangnan stream, Tingming stream, mocan stream, Qingbi stream, Longxi stream, Lvyu stream, Zhongxi stream, Taoxi stream, Meixi stream, Yinxian stream, Shuangyuan stream, Baishi stream, Lingquan stream, Jinxi stream, mangyong stream, Yangxi stream, Wanhua stream and Xiayi stream from south to north. In ancient times, the water of the eighteen streams or flowing springs and waterfalls, like a horse galloping down, "the water excites the rocks to jump, and roars like thunder"; or the water gurgling, one stream three fold, flows quietly, and finally flows into the Erhai Lake in the East.

Xiayixi, located in Zhoucheng village, Xizhou Town, Dali City, originates between Canglang peak and Yunlong peak, with an altitude of 2200 meters to 1966 meters and a length of 3646 meters. Cangshan eighteen streams from north to south of the first stream, upstream to the source of perennial water, water quality is clear. All the water flows into Zhoucheng village Waterworks in Jixin mountain. Since the downstream has dried up, there is basically no water flow in the downstream, and only a small amount of mountain torrents flow down in the rainy season.

Wanhua River, Cangshan eighteen River, the second river from north to south. Located in Xizhou town of Dali City, wanhuaxi hydropower station is built. It originates from huadianba and is excavated from Wutai peak of Cangshan Mountain. It flows through Jiangdu village, Xindeng village, Fengyang village, Wenge village and other villages, with an altitude of 2200 m to 1966 m and a total length of 6168 M. There is water in the source of Wanhua river all the year round, but the water is diverted to the surrounding villages for drinking through the forebay of the power station, and there is no water in the downstream, so there is no water flowing directly into Erhai Lake.

Yangxi, Cangshan eighteen streams, the third stream from north to south. In the south of Xizhou town and WanQiao Town, it originated between Lianhua peak and Wutai peak. There are two sources of the stream, deep valley and far Qing, rich in water. Because the stream flows behind shangyangxi, it is called Yangxi. It is a perennial River, with a total length of 13 km, a width of about 5 m, a drainage area of 41 square km, and a discharge of 1.56 m3 / s in February. It flows through beiyangxi, Qingdong, Beizhuang, Zuoyi, GUSHENG village and Zhuoren Erhai Lake. Its tributaries flow from the foot of hengwutai peak in Xikou to qingdongzhuang, and then divide into several branches, commonly known as qingxigou. The irrigation area is more than 10000 mu. The flood peak is 150 m3 / s.

Chinese PinYin : Er Hai