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CN-122022482-A - Technical method for rapidly evaluating flood risk of broken dam of silted dam

CN122022482ACN 122022482 ACN122022482 ACN 122022482ACN-122022482-A

Abstract

The invention discloses a technical method for quickly evaluating the flood risk of a siltation dam, which comprises the following steps of extracting a dam flow control area, a dam top elevation, a siltation dam current water level-reservoir capacity curve, determining the position of a residential point at the downstream of the siltation dam according to a current situation topographic map, determining the water quantity contained in a reservoir area when the siltation dam breaks, the corresponding frequency of the siltation dam and the depth of water before the dam breaks, calculating the maximum flow at a dam site when the dam breaks according to the depth of water before the dam breaks, calculating the maximum flow at a residential point, calculating the flood water level h 1 of the residential point, calculating the flood water depth at the residential point according to the flood water level at the residential point, and calculating the flood risk of the residential point at the downstream caused by the dam break. The invention improves the judging efficiency of the burst risk of the silted dam under the extreme rainfall condition, has simple required data and simple calculation method, and is suitable for the risk assessment of engineering facilities with large quantity and lacking engineering data, such as silted dam.

Inventors

  • MA XU
  • WEI SHUO
  • MA MENGHUA
  • Zhai Minting
  • DONG FANGFANG
  • CHEN ZHILI
  • XUE JUNHUA
  • FENG JIAHAO
  • BAI YU
  • LIU YUAN
  • ZHANG WEINA
  • GAO ZHEN

Assignees

  • 中国电建集团西北勘测设计研究院有限公司

Dates

Publication Date
20260512
Application Date
20260203

Claims (8)

  1. 1. A technical method for rapidly evaluating the flood risk of a silted dam, which is characterized by comprising the following steps: S1, extracting a dam flow control area, a dam top elevation and a current water level-reservoir capacity curve of a siltation dam according to a current topography map, and determining the position of a resident point at the downstream of the siltation dam; s2, determining the water quantity contained in a reservoir area when the silt dam breaks and the corresponding frequency P Ulcer of ulcer of the silt dam break and the depth h 0 of the dam before break by combining the current water level-reservoir capacity curve of the dam top elevation and the silt dam; S3, calculating the maximum flow Q Dam (dam) at the dam site during dam break according to the pre-dam water depth h 0 before dam break determined in the S2; S4, measuring the distance from the dam site section to the residential points according to the residential point position at the downstream of the silt dam, and calculating the maximum flow Q M at the residential points according to the maximum flow at the dam site during dam break; S5, calculating the submerged water level h 1 of the residential point by adopting a Manning formula according to the maximum flow rate of the residential point, the section shape of the river bed, the roughness and the specific drop of the river bed of the residential point; s6, calculating submerged water depth h of the residential points according to the submerged water level of the residential points; and S7, calculating the flooding risk degree R f of the downstream residential points caused by dam break according to the submerged depth of the residential points and the corresponding frequency of dam break of the silted dam determined in the step S2.
  2. 2. The technical method for rapidly evaluating the flood risk of a silted dam according to claim 1, wherein the specific step of S2 is as follows: S2-1, calculating design rainfall H P ; s2-2, calculating flood W P according to the dam control area and the design rainfall; S2-3, checking a current water level-reservoir capacity curve of the silted dam by adopting the flood W P calculated in the S2-2 to obtain a corresponding flood elevation, comparing the elevation of the dam top, and determining the water quantity contained in the reservoir area when the silted dam breaks, the corresponding frequency P Ulcer of ulcer of the silted dam break and the pre-dam water depth h 0 before the break.
  3. 3. The technical method for rapidly evaluating the flood risk of a silted dam according to claim 2, wherein in the step 2-2, the flood amount W P is calculated according to the following calculation formula: wherein F is the area of a dam flow control area, km 2 ;H P is the design rainfall, and mm; Is the runoff coefficient, W P is the flood, m 3 and p is the design frequency.
  4. 4. The method for quickly evaluating a flood risk of a broken dam of a silty land dam according to claim 1, wherein in S3, a maximum flow rate Q Dam (dam) at a dam site at the time of breaking is calculated: Wherein Q Dam (dam) is the maximum flow at the dam site when the dam is broken, m 3 /s;h 0 is the depth of water before the dam is broken, m, h' is the average height of the rest part of the dam after the dam is broken, the unit m, B is the average width of the cross section of the dam site, and m is the width of the broken opening of the silt dam.
  5. 5. The method for quickly evaluating a flood risk of a culvert dam according to claim 1, wherein in S4, the maximum flow Q M at the residential site is calculated: Wherein Q Dam (dam) is the maximum flow rate at the dam site when the dam is broken, m 3 /S, V is the flood storage capacity when the reservoir is broken, m 3 is the water quantity contained in the storage area when the dam is broken in the siltation area in S2, L is the distance from the section of the dam site to the residential point, m, and V M is the maximum flow rate of the section of the river channel in the flood period of the residential point, m/S.
  6. 6. The technical method for rapidly evaluating the flood risk of a silted dam according to claim 1, wherein the specific step of S5 is as follows: s5-1, firstly, assuming h 1 , calculating omega and R through a water level-water cross section curve and a water level-hydraulic radius curve, and calculating the flow Q Residing in at the residential point: Wherein ω is the water passing area of the cross section of the residential point, m 2 , R is the hydraulic radius of the cross section of the residential point, m, i is the hydraulic gradient, n is the roughness; And S5-2, if the calculated residential point flow Q Residing in of S5-1 is not equal to the calculated residential point maximum flow Q M of S4, h 1 is re-assumed, S5-1 to S5-2 are repeated until the calculated residential point flow Q Residing in of S5-1 is equal to the calculated residential point maximum flow Q M of S4, and finally h 1 is determined as the residential point submerged water level.
  7. 7. The method for quickly evaluating a flood risk of a culvert dam according to claim 1, wherein in S6, a submerged depth h at a residential site is calculated: h=h 1 -h 2 Wherein h is the submerged depth of the residential point, m, h 1 is the submerged water level of the residential point, m, h 2 is the elevation of the residential point, m.
  8. 8. The method for quickly evaluating a flood risk of a broken dam of a silty land dam according to claim 1, wherein in S7, a degree of flood risk of a downstream residential site caused by the broken dam is calculated: R f =10×h×P Ulcer of ulcer Wherein P Ulcer of ulcer is the corresponding frequency when the silted dam breaks, R f is less than 0.15 and equal to or less than 0.15 is low risk, R f is less than or equal to 0.5 and equal to or less than 0.5 is medium risk, R f is more than or equal to 0.5 and equal to or less than 1 is high risk, and R f is more than or equal to 1 is high risk.

Description

Technical method for rapidly evaluating flood risk of broken dam of silted dam Technical Field The invention belongs to the technical field of water and soil conservation engineering and flood risk assessment, and particularly relates to a technical method for rapidly assessing the flood risk of a silted dam. Background Loess plateau is a very unique and important geographical area worldwide, and its loess is loose in soil quality, rich in calcium carbonate and vertical in joint development, which makes it easy to cultivate, but also very easy to erode by water washing. Loess plateau is taken as an important landform component part of China, the water and soil loss problem is very serious, the water and soil loss is greatly treated in China from the beginning of the last 50 th century, and a silted-land dam is taken as an important engineering measure in water and soil conservation measures, so that the problems of mud blocking and sand blocking and mud soil loss can be effectively solved by mud making. At present, about 5.8 thousands of silt dams have been built on loess plateau, and due to the limitations of construction and management, in recent years, the event of the silt dam bursting frequently occurs, so that the consideration of the silt dam bursting risk is particularly important. Based on the study of domestic and foreign scholars on reservoir dam risk analysis, the evaluation method of the risk and loss risk of the reservoir dam is studied by a comparison system, but the study in the field of flood risk of a siltation dam is less. Meanwhile, the reservoir is complete in construction and management, the data which can be queried and traced are perfect, but the characteristics of numerous silt dams and distributed dispersion make professional management and maintenance difficult extremely, and the problem of 'rebuilding light pipes' causes most silt dams to have almost no future data. Therefore, the dam break risk research method of the reservoir dam is difficult to be suitable for the dam break risk of the silted dam. Disclosure of Invention The invention aims to provide a technical method for rapidly evaluating the flood risk of a silted dam, which improves the discrimination efficiency of the silted dam burst risk under the condition of extreme rainfall, has simple required data and simple calculation method, and is suitable for the risk evaluation of engineering facilities with large quantity of silted dams and lacking engineering data. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: a technical method for rapidly evaluating the flood risk of a silted dam, which comprises the following steps: S1, extracting a dam flow control area, a dam top elevation and a current water level-reservoir capacity curve of a siltation dam according to a current topography map, and determining the position of a resident point at the downstream of the siltation dam; s2, determining the water quantity contained in a reservoir area when the silt dam breaks and the corresponding frequency P Ulcer of ulcer of the silt dam break and the depth h 0 of the dam before break by combining the current water level-reservoir capacity curve of the dam top elevation and the silt dam; S3, calculating the maximum flow Q Dam (dam) at the dam site during dam break according to the pre-dam water depth h 0 before dam break determined in the S2; S4, measuring the distance from the dam site section to the residential points according to the residential point position at the downstream of the silt dam, and calculating the maximum flow Q M at the residential points according to the maximum flow at the dam site during dam break; S5, calculating the submerged water level h 1 of the residential point by adopting a Manning formula according to the maximum flow rate of the residential point, the section shape of the river bed, the roughness and the specific drop of the river bed of the residential point; s6, calculating submerged water depth h of the residential points according to the submerged water level of the residential points; and S7, calculating the flooding risk degree R f of the downstream residential points caused by dam break according to the submerged depth of the residential points and the corresponding frequency of dam break of the silted dam determined in the step S2. Preferably, the specific step of S2 is as follows: S2-1, calculating design rainfall H P; s2-2, calculating flood W P according to the dam control area and the design rainfall; S2-3, checking a current water level-reservoir capacity curve of the silted dam by adopting the flood W P calculated in the S2-2 to obtain a corresponding flood elevation, comparing the elevation of the dam top, and determining the water quantity contained in the reservoir area when the silted dam breaks, the corresponding frequency P Ulcer of ulcer of the silted dam break and the pre-dam water depth h 0 before the break. Preferably, i