Wulongkou Town, Jiyuan is the first fertile land after Qinhe left Taihang Mountain. Since the Qin Dynasty, people on both sides of the Qinhe River have taken water across the mountain and built the first canal-Fangkouyan. For thousands of years, local people have dug dozens of canals, large and small, on the Qinhe River according to the principle of square weir. Some of these canals were rebuilt on the basis of abandoned canals, and some were newly built. By the Ming Dynasty, there were more than a dozen small canals and five grand canals in the lower reaches of the Qinhe River. Five canals, like five Wolong rivers, span the northern part of Henan Province, from which the place name of wulongkou comes. After the establishment of People's Republic of China (PRC), dikes were rebuilt three times, with earthwork12.58 million cubic meters. For the first time, from 1949 to 1953, the maintenance standards of embankments on both sides of the strait are: crest 1 933 2500m3/s, flood level1m, crest width 5m and dangerous section 6m. There is a natural flood detention area above Danjiangkou on the north bank, and it is not cultivated. The top of the south bank dike is 4m wide, with a river slope of 1:2 and a river slope of 1:3. A total of 3.82 million cubic meters of earth and stone were completed. 1954 In the small east station of Qinhe River, an over-standard flood of 3050 cubic meters per second occurred, and the dike stood the test. Since then, it has been made clear that the levees on both sides of the strait take the flood of 4000 cubic meters per second in Xiaodong Station as the defense standard. The flood level at the top of the south bank dike 1 m, and the flood level at the top of the north bank dike 1.5 m. The top of the dike is 7 meters wide and 5 meters horizontal. The south bank is 6 meters dangerous and 5 meters flat. The slope of the north and south banks of the newly-built dike section is 1:2, and that of the back river is 1:3. The top of the newly-built dike is 2m wide, and the riverside is as high as the design water level, while the backwater should be lower than the design water level 1m, and the slope is still Linjiang 1:2 and backwater 1:3. 1963 The superelevation of the north bank of Qinhe River embankment is increased to 2m, the width of the flat dike top is increased to 6m, the dangerous dike is increased to 8m, the superelevation of the south bank is unchanged, and the superelevation of the section from Mapo to Dongwangzhao dike in Qinyang is changed to 1.5m.. 1967, and most of the Pei Di section of Qinhe River is up to standard. 1954 ~ 1972, and the total earthwork for dike restoration is 3.58 million cubic meters. 1974 to 1983, according to the siltation of Qinhe River over the years, the dike was rebuilt for the third time. The task of flood control is still to ensure that 4000 cubic meters per second of Xiaodong Station will not burst. For the flood exceeding the standard, the principle of protecting the south above the Danhekou and protecting the north below the Danhekou is still adopted. Embankment length 1082 km, height 0.3 ~ 1.5 m, and planned earthwork 5.77 million cubic meters. By the end of 1987, 5.67 million cubic meters of earthwork had been completed, accounting for 98.3% of the planned volume.
Qinhe River in Muluandian section of Wuzhi County is located 8 kilometers above the Yellow River Estuary, with a dike distance of only 330 meters wide. It's a bayonet, and the hanging difference between the left and the back is large, and the flood control standard is insufficient. The top of the river rushed into the bay, and the double-curved arch bridge seriously poured back into the dike, threatening safety. In order to solve this dangerous point, manual shunt was carried out at 198 1 ~ 1984. Starting from Yangzhuang, a new river with a length of 3.5 kilometers and a width of 800 meters was opened to the right at the back of the river, with Old Zuo Di as the second line of defense. The old riverbed is 7 meters high and 200 ~ 900 meters wide. As the backwater platform of the new Zuo Di, the suspension difference between the front and rear is reduced by about 7 meters, and the fortification standard water level is reduced by about 1.8 meters, thus eliminating backwater. The newly-built Zuo Di in this project is 3195m long, and the right dike is 2417m long. All projects are designed according to the defense capacity of Xiaodong Station of 4000m3/s. The Zuo Di is 3.6m high, with a top width of 15m, a right embankment height of 1.0m, a top width of 10m and a slope of 60. The earthwork volume is 31160000m3 (including earth dam foundation16). There is a bayonet 46 kilometers below Danjiangkou in the lower reaches of Qinhe River. This section is about 750 meters long and the dike distance is only 330 meters wide. On the left bank is Muluandian (now Wuzhi County), and on the right bank is Wuzhi Old Town. The embankments on both sides of the river are attacked and the river turns sharply, which is the most dangerous embankment section of Qinhe River. In the 15th year of Wanli in Ming Dynasty (1587), the Qinhe River burst. 1933, the Yellow River overflowed and flowed back to Muluandian. 1968, another double-curved arch bridge was built at the entrance of Muluandian, with a water blocking area of 1 1%. 1980 decided to conduct artificial diversion at Yangzhuang on the right bank of the upper head of Muluan Hall to ensure the safety of the Qin Dyke.
The water diversion project is carried out at a section of about 3.5 kilometers from Yangzhuang to Lianhuachi. A new right dike was built at Zhanzhuang. By extending the old right dike up and down, the old river channel was sealed as the new Zuo Di, which widened the river channel from 330 meters to 800 meters and cut it smoothly. In order to keep the connection between the main channel of the new river section and the main channel of the original river, and prevent the river from swinging again, a dike protection project was laid on the new Zuo Di to meet the dangerous workers in Zhuyuan Village and send them to the old river. A beach protection project shall be built at the left bank beach edge at the outlet of diversion area to prevent the unfavorable river regime that may be washed away. And build another new bridge on Xinhe Road.
The diversion area of Yangzhuang is 3 square kilometers (new river 15 square kilometers), with a population of 4,675 and 4,899 houses, occupying, digging and stepping on 3,800 mu of land (permanently occupying 6,787 mu). The diversion project started on 198 1, and the main flood control project was completed on 1982 and before the flood season of 1984. In the meantime, on August 2, 1982, an over-standard flood of 4 130 m3/s occurred in Qinhe Xiaodong Station, the largest flood since 1895. The local people went to the levee to repair the dam, which ensured the safety of the levee and played a due role in the local diversion. The measured maximum discharge of the Qinhe River flood is 4 130 m3/s, and the historical investigation estimated that the maximum discharge is 14000 m3/s.. 1950. After that, the dike project built by Qinhe River with the defense capacity of 4000m3/s, except Beijincun, Longquan and Huayang above the Danhekou on the north bank, which have restored the flood discharge of 8656. In order to prevent over-standard flood and ensure the safety of the south dike above Danjiangkou and the north dike below Danjiangkou, two flood storage and detention areas are set up.
The natural flood detention area in the north of Qin is located at the intersection of Qin and Dan rivers above the mouth of Dan River, with Dan and Qin rivers in the east and south, and Taihang foothills in the west and north. The terrain is high and the slope is steep from northwest to southeast. The downstream flood peak is mainly reduced by natural backflow of Longquan and Huayang gaps. The influence scope of natural backward flow includes Beiguan, Zhuang Jie, Xishang and parts of Zi Ling Township in Qinyang County, with a total of 80,000 mu of cultivated land and more than 60,000 residents.
Qinnan flood storage and detention area is located in Wuzhi County, north bank of the Yellow River, upstream of Beijing-Guangzhou Railway Bridge 14 km, which is the included angle between the Yellow River and Qinhe River. The Yellow River levee in the south and the Qinhe levee in the north and east are low-lying and turn into flood storage and detention areas at 195 1 hour. When the flow of Xiaodongzhan exceeds 4000m3/s, a flood diversion outlet will be reserved at Wuchekou for natural overflow, and the flood will be diverted to the flood detention area on the south bank of Qinhe River to ensure the safety of the dike on the north bank of Qinhe River. The flood storage and detention area is located below the water level of 102m (Yellow Sea), with the submerged area of 142.6km2 and the corresponding storage capacity of 518m3. During the flood diversion period, the residents will be relocated temporarily, and discharged into the Yellow River from the Fangling levee at the end of the flood detention area when the water is withdrawn.
Before 1958, the flood detention area in southern Qin had the task of delaying some floods in the Yellow River. When the Yellow River rose, Zhengzhou Yellow River Railway Bridge was seriously stagnant, and then the three rivers of Yi, Luo and Qin rose together, which seriously threatened the safety of the Yellow River embankment. Wuzhi unsealed the Yellow River embankment and discharged part of the Yellow River flood into the flood detention area in southern Qin for safety. After 1958, there has been no task of diverting the Yellow River flood in the flood storage and detention area in southern Qin.