Shijiu Lake

Shijiu Lake

Shijiu lake is located at the junction of Lishui district and Gaochun District of Nanjing City, Jiangsu Province and Dangtu County and Bowang District of Maanshan City, Anhui Province. The west part of the lake is connected with Qingyi River, Shuiyang River and Guxi River, and Hubei is connected with Qinhuai River through Tianshengqiao river. Among them, Shuiyang river is the main water source, and Guxi river is the main discharge channel.

Shijiu lake is adjacent to Gucheng Lake, both of which are part of the ancient Danyang Lake. The largest area is more than 200 square kilometers. It belongs to the type II water of calcium group of bicarbonate. The lake has many functions such as irrigation, flood storage, shipping and breeding. The lake area is rich in natural resources, among which silver carp, crab, wild duck and other "three treasures" are the most famous. Shijiu lake is praised as "a bucket of gold at sunrise and a bucket of silver at night". However, due to uncontrolled fishing, precious species such as silverfish have disappeared at the latest in the early 21st century. "Shijiu Fishing Song" is one of the 40 sceneries in new Jinling.

Shijiu lake is the main route connecting southeast Anhui with southwest Jiangsu Province, which can be used for navigation of 30 ton ships.

The origin of the name

The origin of the name of Shijiu lake, according to the records of Dangtu County, is because the shape of the lake is similar to Shijiu, so it is called Shijiu lake. Nanjing city is also known as the North Lake (relative to Gucheng Lake, South Lake). It and Danyang, Gucheng two lakes, known as three lakes.

The name of "Shijiu Lake" appeared earlier in the geographical work "Taiping Huanyu Ji", which was completed in the fourth year of Yongxi reign in the music history of the Northern Song Dynasty. At this time, Danyang Lake was no longer the general name of all lakes. Taiping Huanyu Ji, volume 89, the second edition of Jiangnan East Road: "Danyang is in the southwest half of the county, and it merges with Danyang Lake in Dangtu County. Shijiu lake is 30 Li southwest of the county, on Jianyang bank in the west, more than 160 Li wide, with Hengshan in the North, three QiuHuang mountains in the west, and four mountains in the lake.

Location context

Shijiu lake is located between 31 ° 23 ′ - 31 ° 33 ′ N and 118 ° 46 ′ - 118 ° 58 ′ E. In the southwest of Jiangsu Province and the east of Anhui Province, before 2012, the lake area crossed Lishui, Gaochun and Dangtu counties in Nanjing, Jiangsu Province. On September 12, 2012, Bowang town of Dangtu County on the northwest Bank of the lake was incorporated into the newly established Bowang District of Ma'anshan City, which straddles Lishui and Gaochun in Nanjing, Jiangsu Province, and Dangtu and Bowang districts and counties in Ma'anshan, Anhui Province.

Under the normal water level, the area of Shijiu lake was more than 250 square kilometers in the 1950s and more than 200 square kilometers after the 1990s. After 1990, there was little difference in area records, but it was different in 1950s. And the area is different in different water level and different period

Before 1949, Shijiu lake covered an area of 264 square kilometers (263 square kilometers). In the 1990s, the lake was 22 km long and 14 km wide, with an elevation of 5.5 meters and an area of 207.65 square kilometers, 78.6% of the area before 1949.

In 1990's, the area of Jiangsu Province geography is 201 square kilometers (the corresponding water level is 6.93 meters).

According to the natural environment records of Anhui Province in the 1990s, the lake area is 22 km long from east to west and 14 km wide at most. 235 square kilometers (of which Anhui is 99 square kilometers, and the lake surface mainly belongs to Jiangsu Province); in the late 1950s, when the water level was 6.93 meters, the lake covered an area of 208 square kilometers, with an average water depth of 1.7 meters and a volume of 350 million cubic meters; when the water level was 12.0 meters, the lake covered an area of 262 square kilometers and a volume of 1.7 billion cubic meters.

In the 1990s, the records of Dangtu County annals are quite different: in the 1950s, when the water level was 7 meters, the lake was 250 square kilometers, with a volume of 380 million cubic meters; when the water level was 9 meters, the lake was 260 square kilometers, with a volume of 900 million cubic meters; when the water level was 12 meters, the lake was 263 square kilometers, with a volume of 1.7 billion cubic meters. In the 1990s, there was about 200.71 square kilometers of lake surface. When the water level was 12 meters, the water storage was 1.3 billion cubic meters, which was 400 million cubic meters less than that in the 1950s.

hydrographic features

The average depth of Shijiu lake is 1.67m and the maximum depth is 2.42M. The volume of the lake is only 40 million cubic meters at the lowest water level. At high water level, the volume can reach 1.64 billion cubic meters. The high water level of Shijiu Lake generally appears in summer and autumn, while the low water level appears in winter. The range of water level is generally between 2.5-6.8 meters, and the maximum range is more than 7 meters. After 1949, the highest water level in August 1954 was 12.41 meters. In March 1979, the lowest water level was 5.08m and the warning water level was 10m. On July 14, 1983, the highest water level of Huajin station was 12.27 meters. The water is yellowish green with a transparency of 0.2-0.5m. The pH value is 7.8, and the salinity is 88.49 mg / L. it belongs to the type II water of bicarbonate calcium group.

The shrinking area of Shijiu lake is mainly caused by unreasonable human reclamation. Due to the shallow water, flat bottom and small capacity in the lake area, the regulation and storage capacity is more limited after occupying the beach and polder. Because of the connection of rivers and lakes, the river water in flood season flows backward, the passenger water presses the border, and the discharge is not smooth, which becomes the flood detention hinterland and flood corridor, so that the flood disasters are frequent in the polder area around the lake, and the man-made water conservancy disputes occur constantly, which also hinders the development of economy and agricultural production in the area.

The deposition of mud and sand into the lake mainly comes from the flood season, accounting for 55-84% of the annual deposition. The deposition amount in the wet year is 4.2 million tons (1954), and that in the normal year is 1.18 million tons (1960).

Formation and evolution

Shijiu lake was formed by disintegration and differentiation of ancient Danyang Lake. Gucheng Lake and Shijiu lake are located at the edge of Nanjing sag. Due to the faulting in the late Mesozoic Yanshanian movement, the northwest limb of the Ligao anticline subsided, resulting in a large number of depressions including Gucheng Lake, Shijiu lake, Danyang Lake, Nanyi Lake and its western polder area, thus laying the basic prototype of the lake basin. In the early Holocene, the Tongjiang gap in the western part of the depression was blocked, and the drainage was not smooth. * then the lake was built into the ancient Danyang lake. The ancient Danyang Lake covers a large area, including not only Gucheng Lake, Shijiu lake and Danyang Lake, but also the Western polder area. Since then, the Western Delta of the depression has gradually developed, and the lake has become shallower and narrower, which can be divided into Gucheng Lake, Shijiu lake, Danyang Lake and Nanyi Lake. Due to the continuous deposition of sediment and large-scale reclamation of the lake, the lake has changed even more. Danyang Lake has disappeared, Gucheng Lake has only two tenths of its original surface, and Shijiu Lake's surface has shrunk greatly.

Main tributaries

Shijiu Lake comes from Qingyi River and Shuiyang River in the mountainous area of Southern Anhui, Bowang River, Tianshengqiao River in the north, Xinqiao River in the East, and most of the reclaimed Danyang Lake in the West. After storage, the lake water is discharged into the Yangtze River through Guxi River and Qingshui River (connected with Qingyi River and Shuiyang River); Gucheng Lake is connected with Guanxi River and Longgang River in the south, and the river water can also be poured into the lake during the flood season. The drainage area is 958 square kilometers.

Upstream water system

Tianshengqiao River, a tributary of Qinhuai River. In the west of Lishui district. It is the only river connecting the two water systems in the county, and its main function is to regulate the flood control and water supply of Qinhuai River. It was called yanzhihe in ancient times. Gaoyang River (Jurong South River) was built in the early Ming Dynasty, starting from the Longde river of Tangjiazhuang Town, Guozhuang Town, Jurong City. It flows from east to west through jiashanba of Guozhuang town and Longdu street of Jiangning District, and joins Lishui River at 200m upstream of northwest village where Lishui River joins Jurong River. It is 7.40 km in Jurong and 2.5 km in Jiangning. In 1393, Li Xin, the Marquis of Chongshan, opened the river by chopping stones. He left huge stones in the ridge to drill holes. According to the situation, he built a bridge. The river was named after the bridge. After Yongle, it was gradually abandoned. Ming Wanli 15 years (1587) Junzhi restoration. Later, it was lost in disrepair. In 1966, Shituo river was dug, starting from Shijiu Lake in the south, connecting Yigan river with Shahe Bridge in the north and Lishui river through honglanbu, Tianshengqiao and Shahekou; Shijiu Lake in chenjiacun in the south, connecting Shijiu lake with Qinhuai River. It is 15.3km long and 20-85m wide, with a drainage area of 95.9km2.

Xinqiao River starts from laoyaba reservoir (Baima Lake) in the East and ends at the East Bank of Shijiu Lake in the west, with a length of 29 km and a bottom elevation of 3-26 M. Its tributary is yunhezhi River, with a total length of 11.99 kilometers and a catchment area of 103.17 square kilometers.

Bowang River, from the southern foot of Hengshan mountain to another Geng Village, 3km south of Bowang Town, flows into Shijiu lake. The highest water level in the estuary is 12.41m (1954.8.22).

Shuiyang River, originated in the south of Ningguo City, flows through Xuancheng, Dangtu and Wuhu counties, and then flows into Qingyi River in Qingshui town of Wuhu County. Shuiyang river is also called Huangchi River in Dangtu. It starts from Yunliang River (connecting Shijiu Lake) in the East and ends at sanligeng in Huangchi in the west, with a length of 18 km and a width of 60-250 m. It is navigable seasonally.

Yunliang River, on the Bank of Danyang Lake, used to be a water transport channel, so it is named. It flows from south to north, connects Shuiyangjiang River in the south, passes through the northwest of Gaochun County in Jiangsu Province, and reaches xiaohuajin in the north, with a total length of 22.5 km. The river bed is about 50m wide and the highest water level is 12.41m (July 14, 1983) at Dalong station. Yunliang river is connected with Shuiyang River and Shijiu lake, and flows into Guxi River from xiaohuajin. Ships of less than 10 tons can be navigable all year round.

Chinese PinYin : Shi Jiu Hu