Weishan Lake is located at east longitude 1 16. 34 degrees north latitude. 27'。 The largest area is about 1266 square kilometers, accounting for 45% of the province's fresh water area. It is the largest lake in Shandong Province and a famous large freshwater lake in China, and its fishing yield per unit area ranks first among large lakes (the area is greater than 1000 square kilometers). The whole Hunan is 126 km long in the north and 5-25 km wide in the east and west. The narrowest place in the middle is called the waist of the lake. 1960, a lake dam was built at the waist of the lake, and a sluice and a lock were built on the dam, which divided the lake into two parts. The upper lake area in the north of the dam is 602 square kilometers, and the lower lake area in the south is 664 square kilometers. The maximum allowable water level of Lake Superior is 36.50m, the water level of Li Xing is 34.20m, and the dead water level is 33.00m.. The maximum allowable water level in Xiahu Lake is 35.00 meters, the water level in Li Xing is 32.5 meters, and the dead water level is 1000 square kilometers). The whole Hunan is 126 km long in the north and 5-25 km wide in the east and west. The narrowest place in the middle is called the waist of the lake. 1960, a lake dam was built at the waist of the lake.

There are sluices and shiplocks on the dam, which divide the lake into two parts. The upper lake area in the north of the dam is 602 square kilometers, and the lower lake area in the south is 664 square kilometers. The maximum allowable water level of Lake Superior is 36.50m, the water level of Li Xing is 34.20m, and the dead water level is 33.00m.. The maximum allowable water level in Xiahu Lake is 35.00 meters, and the water level in Li Xing is 32.5 meters, so the water level is dead.

3 1.5 meters. The flood control capacity of the whole lake is 473 1 100 million cubic meters; Li Xing water level storage capacity is 65.438+70.2 million cubic meters; Li Xing adjusted storage capacity165438+28 million cubic meters; The average water depth is about1.5m. It is a large freshwater lake with shallow water. The lakeside is bordered by mountains in the east, plains in the west, fertile land in northern Jiangsu in the south and the hometown of Confucius and Mencius in the north, with a drainage area of 3 1.700 square kilometers. The Beijing-Hangzhou Canal runs through the northern part of Hunan, connecting the rivers and water systems in the north and south.

Weishan Lake belongs to Sihe River system in Huaihe River basin. Huxi is located in the Yellow River Plain between the Yellow River and the Old Yellow River, with gentle terrain, with a gradient of about 5000% to 20000%. The river is wide and shallow, with large flood peak and low flood volume. From west to east, it flows into Weishan Lake through Zhuzhaoxin River, Laowanfu River, Dongyu River and Fuxing River respectively. In the north, Ji Liang Canal receives water from northern Hebei and Yuncheng, Liangshan and Dongping Lake. In the east of the lake, the near lake area is the Quaternary alluvial hilly plain of Taiyi Mountain, and the far lake area is the Maiqi hilly area of Mengshan Mountain. The river channel is short, and the flood peak is high and urgent. From east to west, it flows into Weishan Lake through Sihe River, Quanhe River, Futao River, Baima River, Hecheng River, Guohe River, Shihe River and Dashahe River. Weishan Lake receives water from 32 counties, cities and districts in the east, west and north of Shandong, Jiangsu, Henan and Anhui provinces, with a drainage area of 310.7 million square kilometers. There are 47 major rivers entering the lake, including Sihe River, Ji Liang Canal, Baima River, Zhuzhaoxin River and Laolao River with a basin area of 65,438+0,000 square kilometers.

There are different opinions on the causes of Weishan Lake. According to the existing geological data and geomorphological analysis, controlled by geotectonics since Cenozoic, Luxi area has been in the process of intense decline for a long time, forming a depression and becoming a vast plain. The eastern part is adjacent to the hilly area in central Shandong, and the junction has the geological conditions of accumulating water to form a lake. From the analysis of geological structure and sediment types in the lake area, Weishan Lake is located on the Quaternary accumulation of late Cenozoic from north to south, but the sediments in the lake are few and thin, indicating that a large number of sediments have gone through a long historical stage, and the lake was not formed on the Quaternary accumulation for a long time. Through the analysis of the evolution process of recorded rivers such as the Yellow River and Sihe River, it is found that the breach of the Yellow River is an important reason for the gradual formation of lakes, and the change and development of canals have accelerated the formation of southern lakes. From Xia Dynasty to Qin Dynasty, many cities were built in the present Nansi Lake. According to historical records, the "Guo Huan" in Xia Dynasty was once located in Zhongjia Shallow Village on the east bank of Nansi Lake. The "Luan State" sealed by the Zhou Dynasty was established 6 kilometers west of Luqiao Town. According to Water Mirror Notes, Taoshui in Surabaya is located in Gaoping West, with Maoxiang Town in the west, Langting, Langtai, which is 40 miles southeast of Mao Cheng Town, belongs to Lu State, and now Hu Ling County in the northwest of Liu Zhuang Township is in Zhaoyang Lake in Chengzimiao Village, Zhanglou Township. This shows that Nansi Lake evolved gradually later.

According to historical records, Surabaya was originally on the west bank of Weishan Lake, flowing from Yanzhou through Luqiao and Nanyang in Weishan County, to Gu Ting in Yutai County in the east, to Peixian County in the south, across Xuzhou, from Huaiyin to Huaihe River and eastward into the sea. The current is gentle and is the main tributary of the lower reaches of Huaihe River.

BC 132 (the third year of Han Yuanguang), the Yellow River first seized Si and entered the Huaihe River. The Yellow River burst in Zanzi (now southwest of Puyang, Henan), slipped southeast to Juye Ze, seized the old road of Surabaya, and turned to Huaihe River to enter the sea. The Yellow River flooded between Ji and Pu for twenty-three years, until 109 (the second year of Yuanfeng in Liang Wudi), Emperor Wu of the Han Dynasty sent tens of thousands of soldiers to block the breach. At this time, the Yellow River did not seize Sri Lanka from the whole river. Until the early Song Dynasty, although Wang Mang moved the Yellow River for the second time within three years after the founding of the People's Republic of China, his influence on Surabaya was still not serious. However, the movement of the Yellow River water made some depressed sedimentary facies areas appear in Luxi Plain. According to the Biography of Zhou Xue in the Sui Dynasty, "The hydration of Dongyi and Yanzhou flowed south and flooded osawa". It can be seen that a swamp lake was formed in the Sui Dynasty in the south of Jining, below Yanzhou on the east coast of ancient Sishui.

Since 1077 (the tenth year of Xining in northern Song Shenzong), the Yellow River has changed its course and its breaches have gradually increased, and the role of the Yellow River flow in accelerating the evolution of Weishan Lake has also increased accordingly. In A.D. 1 194 (the fifth year of Jin Zhangzong Mingchang), the Yellow River burst in Wu Yang, Henan Province, and entered Liangshanbo into the north and south. The Southern Han Dynasty entered the Huaihe River from the South Qinghe River, passed by Shangfen, Jiaxiang and Jining, and now joins Sishui in the southwest of Luqiao Town, Weishan County, and enters the Huaihe River in Qingjiang City, Jiangsu Province. In AD 1495 (the eighth year of Hongzhi in Ming Dynasty), Liu Daxia built Huanglinggang and was repairing the Taihang levee. All the Yellow River water flowing northward, from Kaifeng to Xuzhou, then to Huaiyin, and from Huaiyin to Haikou Nanlankao copper tile box burst northward, and from Shandong Lijin to the sea to capture the Daqing River, formed the present Yellow River, which has gone through more than 660 years. On the one hand, a large amount of sediment silted up, forming the current bed of the Yellow River, blocking the road from Surabaya to Huaihe River, causing long-term stagnation of floods; On the other hand, due to the interaction between the Yellow River and the eastern rivers, the prototype of Nansi Lake with different size, shape and bottom elevation appeared from north to south in this area. According to the geological data of drilling and sediment analysis, the lake was formed in the middle and short term of Quaternary accumulation.

With the northward movement of political centers in past dynasties, the Yuan, Ming and Qing Dynasties successively established Beijing as the capital. In order to "deliver water along the Yangtze River and Huaihe River to meet the needs of the capital", they abandoned the canal waterway centered on Luoyang built by Sui Dynasty and began to communicate with the north and south canals in Yuan Dynasty, in 1289 (in the 26th year of Yuan Dynasty) and 1293 (in the 30th year of Yuan Dynasty). At this time, the natural river course of Surabaya was used as a canal between Jining and Xuzhou. In order to maintain the shipping depth, a sluice was built on the Sishui River, and the landscape of Hedong stopped at the east bank, and Zhaoyang Lake and dushan lake began to take shape. In the Ming Dynasty, the Yellow River continued to flood, Huang Qiang weakened, and the way out of Surabaya was blocked, which led to the continuous expansion of Zhaoyang and Dushan, and a small lake connecting Chishan, Weishan, Lvmeng and Zhangzhuang appeared near Weishan. During the Jiajing period of the Ming Dynasty, a new Nanyang River was dug, which moved the traffic route from Zhaoyang Lake to Hudong, and Dongsha River introduced dushan lake and He Xue introduced Lumeng Lake. In A.D. 1640 (thirty-two years of Ming Wanli), Hui River (now Hanzhuang Canal) was opened, and the canal moved eastward again, laying the foundation for the Beijing-Hangzhou Grand Canal. So far, four lakes, Chishan, Weishan, Lvmeng and Zhangzhuang, have expanded rapidly and merged into Weishan Lake. With the development of the canal, in order to store and deliver water in Dongshan, lakes such as Zhaoyang have become canal tanks. Here, Nanyang, Dushan, Zhaoyang and Weishan are connected, and today's Nansi Lake is initially formed.

Therefore, the genesis of Weishan Lake is not only controlled by the geotectonics, that is, the depression geological conditions formed by the long-term decline of Luxi Plain, but also influenced by the natural landforms in the middle and middle mountains of Shandong Province and the eastern landscape of Sihe River. Moreover, due to the long-term flooding of Huang Ke, the Sihe River lost its outlet and the water flow stagnated. In addition, the 240-mile-long zone between Jining and Xuzhou gradually evolved into a shallow lake-Weishan Lake. With the further development and utilization of Weishan Lake, more experts and emperors will continue to explore and improve the origin and evolution of Weishan Lake.

Weishan Lake flow area belongs to the continental climate of warm temperate and semi-humid monsoon region, with an average annual temperature of 65,438 03.7℃, an average annual sunshine of about 2,530 hours and a frost-free period of 209 to 224 days. The average annual precipitation in the west of the lake is about 700 mm, and that in the east of the lake is 750-850 mm. 60% to 70% of the rainfall is concentrated in the flood season, mostly cyclone rain or typhoon rain, which is easy to cause floods. There is little rain and snow in autumn, winter and spring. It is characterized by spring drought, summer waterlogging and late autumn drought. The interannual variation of rainfall is also great. There is a great difference between wet year and dry year, and the average rainfall in the basin is twice as different, so droughts and floods often occur. Before the treatment, the water system in Huxi Plain was disordered and the drainage was not smooth. The Hudong River is short and fast, and the flood is fierce. In addition, the area along the lake is low-lying. During the flood season, the water level of the lake rose sharply, causing floods. During the drought, the lake dried up, the land cracked and locust disasters occurred frequently. Many county chronicles record that "floods drift, Lushe is the city" and "bare land is thousands of miles away, and the road is hungry".

After the founding of People's Republic of China (PRC), in order to eradicate all kinds of natural disasters, large-scale water conservancy construction began, and 250 small and medium-sized reservoirs were built in the east of the lake; Flood control and high and low drainage measures have been taken in the West Lake Plain, and the water system has been greatly adjusted. Three main flood control and drainage rivers, Dongyu River, Zhuzhaoxin River and Ji Liang Canal, have been excavated, and more than ten medium-sized rivers, such as Wanfu River and Huihe River, have been treated. Leibaima River, Zhushui River, Caihe River, Zhuzhaoxin River, Futao River, Laowanfu River and other key rivers entering the lake are flooded once every three to five years. On the lakeside, west of the lake and east of Nitrate, a 66-mile levee was built. More than 6,000 meters long water control project was built at the waist of the lake, and Han Zhuang sluice control project was built at the exit of the lake. The total length of the deep ditch in the lake is 52.87 kilometers, which is used to dredge the drainage channels and open up the navigation channel that runs through the north and south. The lake began to store water in a planned way, and measures such as enclosure, station building and drainage were taken in the lakeside area.

After years of management and construction, Weishan Lake has changed from a lake with serious natural disasters to a lake with certain flood control and waterlogging elimination ability, with multiple functions such as water storage, fish and poultry breeding, shipping and tourism, and its economic benefits have been significantly improved.