"The major floods in the middle and lower reaches of the Yellow River, except for 1933, 1958 and 1982 with measured data, have been sorted out and verified according to historical documents and flood trace surveys, especially in recent years. There is also 176 1 year (twenty-six years of Qingganlong). Cheng Gang said: "176 1, 17, 18 (July 18th and 19th, 26th year of Qianlong), a serious flood occurred in the middle reaches of the Yellow River.
After years of historical research, the floods mainly come from the Yihe River, Luohe River and Qinhe River in Sanmenxia to Huayuankou section of the Yellow River and the small tributaries that directly flow into the Yellow River, and there are many outlets in the lower reaches of the Yellow River.
176 1, the peak flow of Huayuankou section is 32,000m3/s. ..
Luo Yi and the cities in the lower reaches of the Qinhe River are being hit by floods.
The whole beach area of Luo Yi River from Luoyang to Yanshi is more than ten feet deep.
Yanshi, Gongyi, Qinyang, Wuzhi and Xiuwu are also flooded cities with water depths ranging from five or six feet to more than ten feet.
According to the memorial of the governor of Henan at that time, ten counties in Henan were flooded and another sixteen counties were flooded. "
Cheng Gang went on to say that in August of 1843 (July of the 23rd year of Qing Daoguang), there was a heavy rain in the middle reaches of the Yellow River.
The highest flood level appears in Tongguan to Xiaolangdi reach of the Yellow River.
The flood was caused by the shear linear rainstorm from southwest to northeast.
According to the investigation of ancient sites and flood silt along the river, the flood level of 1843 is at least once in a thousand years, and its return period can be regarded as once in a thousand years.
In the flood investigation, residents on both sides of the Yellow River from Tongguan to Xiaolangdi have a deep memory of this flood, and there are many ballads that have been passed down to this day.
For example, "Daoguang 23, the Yellow River rose to the sky and rushed to the sun, bringing the Wanjin Beach".
According to the memorial of Anrun, the then Governor of Henan Province, on July 8th, he said: "According to reports from Shaanxi, Xin 'an, Mianchi, Wuzhi, Zhengzhou, Yingze and other counties, the county is located in the upper reaches of Jiubao. On July 4th, the Yellow River surged more than two feet, and the overflow tank was full, so that Tian He, a residential house along the river, was washed away ... and it was reported.
The flood was discharged to Zhongmou, widening the mouth that had been breached in June of the lunar calendar to 360 feet (about 1 1,000 meters). A large number of floods flow from Zhongmukou to the southeast, enter the Wohe River and Dasha River, and return to Hongze Lake via Jia Luhe.
The flooded areas include Fugou and Xihua in western Henan, Tongxu, Taikang, Lu Yi and Bozhou in the east and Hongze Lake in the south. "
1in early August, 1933, the largest flood occurred between Hekou Town and Shanxian County in the middle reaches of the Yellow River since the establishment of Shanxian Hydrological Station 19 19.
During the flood of 1933, the peak flow of Shanxian Station was 22,000 cubic meters per second, which was the largest flood since the station had measured data.
Because of the high flood peak, it has caused serious disasters to the middle and lower reaches of the Yellow River.
In the rainstorm area in the middle reaches, floods cross the river, people and animals drift away, and there are many executions in the lower reaches.
From July 1958 to July 14 to June 18, heavy rains and floods occurred in Sanmenxia to Huayuankou section of the Yellow River.
On the evening of July 17, and since June 19 19, the maximum flood peak flow at Huayuankou Station of the Yellow River is 22,300 cubic meters per second.
Then, Cheng Gang introduced the situation of 1982 Yellow River flood in detail.
1982 Yellow River flood
From July 29th to August 2nd 1982 There was heavy rain from Sanmenxia to Huayuankou on the Yellow River, with heavy rain locally. Heavy rains occurred in Shaanxi-Gansu-Ningxia region and Jinghe, Luohe, Weihe and Fenhe rivers.
The main stream of Sanhuajian of the Yellow River and Luo Yi River have risen successively. Huayuankou Station had a flood peak on August 2nd 18, with a flow rate of 15300 m3/s, with a 7-day flood of 5.02 billion m3. The flow rate above 10000 m3/s lasted for 52 hours, the largest flood since 1958.
In this flood, the floodplain in the lower reaches of the Yellow River generally overflowed, and the floodplain in Luo Yi and the floodplain on both sides of the river suddenly flooded, delaying the flood peak.
In order to reduce the flood control burden below Ai Shan, Dongping Lake is used for flood diversion and water storage.
Seven days later, the flood peak entered the sea on August 9.
The weather process began on July 29th, when the low-level southeast jet outside Typhoon No.9 in Huanghuai area met the cold trough that night, and heavy rain began to appear between Sanhua and local heavy rain.
The rain area expanded on the 30th.
From March 1 to August1,the typhoon low pressure moved to the south of Sanhuajian, and combined with the Shaanxi vortex, and the area of heavy rain and torrential rain continued to expand.
On August 2nd, the rain area moved northward to Qinhe River and Fenhe River, and by the 3rd, the typhoon depression disappeared, and the rainstorm process basically ended.
"This rainstorm is characterized by long duration, strong center intensity and uneven distribution," Cheng Gang said. "The largest rainstorm center is located in Luhun, Songxian County in the middle reaches of yi river. On July 29, the rainfall reached 544 mm, of which 1 1 half hour rainfall was 535 mm, the maximum intensity was 87 mm for one hour, and the maximum rainfall for five consecutive days was 782 mm. "
The continuous rainstorm caused three flood peaks in the tributaries of Sanhua trunk.
On July 3 1 Rihuayuankou Station 1982, the peak flow was 6400 cubic meters per second for the first time.
The second flood peak discharge of Huayuankou Station on August 2nd was11200m3/s. ..
The third flood peak 1982, and the maximum flood peak flow15300m3 per second.
Due to the water coming from Tan Jia and the floodplain on both sides of the river, the flooded area is about 260 square kilometers, and the detention reservoir capacity is about 460 million cubic meters. The flood at Xiaolangdi, Heishiguan and Wuzhi Stations merged with the water from the main stream of Xiaohua Section (Xiaolangdi to Huayuankou), forming the peak of Huayuankou Station/kloc-0.53 million cubic meters per second, with a flood volume of 5.02 billion cubic meters in seven days.
At 4 o'clock on August 3rd, the flood peak arrived at Jiahetan Station, and the flood peak discharge 14600 m3/s increased by 7.2% compared with the reduced 1958.
In order to reduce the flood control burden below Ai Shan, the old lake in Dongping Lake was used to store flood detention. Lin Xin sluice and Shilibao sluice were opened at 22: 06 on 6th and 1 10 on 7th, respectively, at 20: 00+02 on 9th and 23: 00+08 on 9th, with a total flood volume of 400 million cubic meters.
The sediment concentration of this flood is relatively small. The average sediment concentration at Huayuankou Station is 32. 1 kg/m3, and the maximum sediment concentration is 63.4kg/m3.
The river below Huayuankou "silted up and washed away".
There are 80 million tons of sediment deposited from Huayuankou to Sunkou, of which 67.6 tons are deposited from Gaocun to Sunkou.
Sunkou washed away 38.2 million tons.
According to Cheng Gang's analysis, the rainfall, rainstorm range and total flood volume of Sanhua are all greater than 1954 and 1958.
The flood peak is slightly larger than 1954 and smaller than 1958.
Along the way, the flood peak drops greatly, and the propagation speed is slow. The flood level of most substations is higher than 1958.
The rainfall of this flood is relatively large, but the peak discharge ratio is smaller than 1958. The main reasons are as follows: 1. The rainfall intensity of Sanxiaojian (Sanmenxia to Xiaolangdi) rainfall center is less than 1958, so the flood peak discharge of Sanxiaojian is 1 108.
2. The distribution of rainfall time history is not as concentrated as that of 1958, which leads to continuous flood peaks in the Luo Yi River and the Three Small Rooms, and successively discharges, while 1958 only produces one flood peak.
3. The flood detention of the mixed reservoir is reduced by more than 1958, by 30% from 1958 to Heishiguan, and by 50% and 55% from 1982, that is, the combined flow of Baimasi and Longmen Town is 7 100 and 9070 m3/s, which is reduced to.
4. The flood peaks of the main stream and tributaries are different. 1982, the flood peak of Xiaolangdi in the main stream did not completely encounter the flood peaks of Yi, Luohe, Qinhe Heishiguan and Wuzhi, but in 1958, the flood peak was mainly formed by the intersection of Xiaolangdi flood peak and Heishiguan flood peak.
1982 flood generally overflowed the beach, causing erosion and siltation, and the water level at the same flow rate decreased obviously during flood fluctuation. However, due to years of river siltation, the flood level of 1982 is generally higher than that of 1958, generally around 1 m high, Liuyuan.
Due to the flood detention in Dongping Lake, the water level ratio of Ai Shan and Luokou is about 0.4m lower than that of 1958, and the Lijin ratio is higher than that of 1958.