Reservoir dam flood safety risk assessment method, computer storage medium and equipment

Abstract

The invention relates to the technical field of reservoir dam safety evaluation, in particular to a reservoir dam flood safety risk evaluation method, a computer storage medium and equipment. The reservoir dam flood safety risk assessment method comprises the following steps: deducing estimated values of hydrological statistical parameters of a sample series; randomly simulating a longer series of flood peak flow long series samples, and obtaining a flood hydrograph corresponding to the simulated flood peak flow series; flood regulation calculation is carried out according to a set scheduling scheme by combining the reservoir capacity curve and discharge curve data of the reservoir, and a flood regulation highest water level value is obtained; and deducing the conditional probability that the reservoir level exceeds different characteristic water levels due to the flood based on the obtained flood regulation highest water level value, and evaluating the flood safety risk of the reservoir dam according to the conditional probability. According to the method, simulation and calculation results can be visually presented, the calculation process is direct and clear, and the method has important practical significance and good application prospects in reservoir operation dam safety risk assessment.

Description

Technical Field

[0001] The invention relates to the technical field of reservoir dam safety assessment, and in particular to a reservoir dam flood safety risk assessment method, computer storage medium and equipment. Background Art

[0002] Flood overtopping is the main cause of dam failure, especially earth-rock dam failure. According to statistics, more than half of the dam failures in my country are caused by flood overtopping. The problem of reservoir dam overtopping has become an important issue in my country's reservoir safety risk management work.

[0003] In recent years, flooding incidents at reservoir dams have occurred frequently, especially in extreme weather conditions. When heavy rain and flooding exceeding the standard occur, there is a relatively high risk that the reservoir water level will exceed the checked water level and the dam top. If the safe operation of the reservoir is threatened and the dam fails, the resulting harm and losses will be immeasurable.

[0004] At present, reservoir dam safety risk assessments are mostly qualitative assessments, or safety evaluations are carried out based on dam structure, stability and other aspects. However, these methods cannot quantitatively assess the safety risks of reservoir dams caused by natural factors such as floods, and it is difficult to accurately divide the safety risk levels.

[0005] In summary, a new reservoir dam flood safety risk assessment method is urgently needed to solve the problems existing in the existing technology. Summary of the invention

[0006] The present invention aims to provide a method for assessing flood safety risks of reservoir dams. The specific technical scheme is as follows:

[0007] A reservoir dam flood safety risk assessment method comprises the following steps:

[0008] Step 1: deduce the empirical frequency value of the sample series and the estimated value of the hydrological statistical parameters based on the measured data sample series of flood peak flow into the reservoir for many years;

[0009] Step 2: According to the estimated values ​​of the hydrological statistical parameters of the sample series obtained in step 1, a longer series of flood peak flow samples is randomly simulated, and after amplifying the typical flood process line, the flood process line corresponding to the simulated flood peak flow series is obtained;

[0010] Step 3: Take the flood process line obtained in step 2 as the flood condition for entering the reservoir, combine the reservoir capacity curve and discharge curve data to perform flood control calculation according to the set dispatching plan, and obtain the maximum water level value for flood control;

[0011] Step 4: Based on the maximum flood control water level value obtained in step 3, the conditional probability that the flood causes the reservoir water level to exceed different characteristic water levels is calculated, and the flood safety risk of the reservoir dam is evaluated based on the conditional probability.

[0012] Preferably, the step 1 specifically comprises:

[0013] The measured data sample series of flood peak flow of floods entering the reservoir for many years are sorted from large to small, and the empirical frequency value of the flood peak flow sample series is calculated, where: the empirical frequency distribution function adopts Pearson III type distribution;

[0014] All the empirical frequency values ​​obtained are plotted on the hydrological frequency distribution curve, and the mean x and coefficient of variation C of the sample series are obtained after adjustment by the fitting method. v and the skewness coefficient C s The estimated values ​​of the three hydrological statistical parameters determine the values ​​of the hydrological statistical parameters, that is, the probability distribution function of the peak flow into the reservoir, which facilitates the subsequent random simulation of the peak flow and directly affects the random simulation results of the peak flow.

[0015] Preferably, the calculation formula of the empirical frequency value P0 of the inflow peak flow sample series is:

[0016] P0 = n / (N+1);

[0017] Where: n is the number of times a certain rainstorm intensity value occurs or exceeds it, and N is the total number of measured data sample series.

[0018] Preferably, the step 2 specifically comprises:

[0019] According to the estimated values ​​of the hydrological statistical parameters of the sample series obtained in step 1, the value range and simulation times of the conditional probability P are set based on the VBA tool, and the conditional probability P is randomly sampled in combination with the random number extraction function to obtain a long series of peak flow samples corresponding to the conditional probability P value of the random simulation;

[0020] The typical inflow flood process line selected from the long series of peak flow samples is magnified according to the widely used same-ratio method to obtain the flood process line corresponding to the simulated peak flow series.

[0021] Preferably, the conditional probability P is 0≤P≤1; the simulation times range from 100 to 100,000 times. According to actual needs, a reasonable number of simulations is selected to ensure the accuracy of the simulation results while avoiding excessively complicated calculations;

[0022] When applying the Pearson III distribution curve to deduce the design peak flow, the Pearson III distribution function is converted into the following expression:

[0023]

[0024] Where: x pis the simulated random variable; GAMINV means returning the inverse of the cumulative function of the gamma distribution.

[0025] Preferably, in step three:

[0026] The reservoir operation plan is set according to the flood control requirements of the upstream and downstream of the reservoir and itself. The flood control plan includes at least one of the following plans:

[0027] Scheme 1: The reservoir discharges flood water through all discharge facilities according to the discharge flow rate formulated in the dispatching regulations or flood season dispatching operation plan, and the reservoir's starting water level takes into account the dispatching plan of different water levels above the flood limit water level;

[0028] Option 2: The total flow of the reservoir discharged through all the discharge facilities is the safe discharge of the downstream river, and the reservoir water level is adjusted to consider the dispatching schemes of different water levels above the flood limit water level;

[0029] Scheme 3: The total flow discharged from the reservoir through all the discharge facilities is the maximum discharge flow of the reservoir, and the reservoir water level is adjusted to consider the dispatching schemes of different water levels above the flood limit water level;

[0030] The specific flood control calculation is: using VBA program to code the basic equations of reservoir flood control calculation, and realizing the reservoir flood control calculation process based on the trial algorithm, to further ensure that the calculation accuracy requirements are met.

[0031] Preferably, the conditional probability of the reservoir water level exceeding different characteristic water levels due to floods in step 4 is derived specifically by: counting the number of times that the highest flood control water level exceeds different characteristic water level elevations of the reservoir, and taking the ratio of the number to the total number of simulations as the conditional probability that the reservoir dam will be subjected to different safety risks due to floods, thereby accurately evaluating and dividing the safety risk level of the reservoir dam in a quantitative manner;

[0032] The different characteristic water level elevations of the reservoir include at least one of the dam crest water level, the check water level and the design water level.

[0033] Preferably, in step 4, the flood safety risk of the reservoir dam is evaluated according to the conditional probability as follows: divided by magnitude, specifically:

[0034] If the conditional probability P satisfies: P≤10 -5 , then it is assessed as low risk;

[0035] If the conditional probability P satisfies: 10 -5 <P≤10 -4 , then it is assessed as medium risk;

[0036] If the conditional probability P satisfies: 10 -4 <P≤10 -3 , it is assessed as high risk;

[0037] If the conditional probability P satisfies: P>10 -3 , it is assessed as extremely high risk.

[0038] The present invention also discloses a computer storage medium on which computer program instructions are stored. When the computer program instructions are executed by a processor, the reservoir dam flood safety risk assessment method as described above is implemented.

[0039] The present invention also discloses a device, comprising: at least one processor, at least one memory and computer program instructions stored in the memory. When the computer program instructions are executed by the processor, the above-mentioned reservoir dam flood safety risk assessment method is performed.

[0040] Applying the technical scheme of the present invention, the reservoir dam flood safety risk assessment method of the present invention includes the following steps: step 1, according to the measured data sample series of flood peak flow of many years, deduce the empirical frequency value of the sample series and the estimated value of hydrological statistical parameters; step 2, according to the estimated value of hydrological statistical parameters of the sample series obtained in step 1, randomly simulate a longer series of flood peak flow long series samples, amplify the typical flood process line, and obtain the flood process line corresponding to the simulated flood peak flow series; step 3, take the flood process line obtained in step 2 as the flood condition of the reservoir, combine the reservoir capacity curve and the discharge curve data of the reservoir according to the set scheduling scheme to perform flood control calculation, and obtain the maximum flood control water level value; step 4, based on the maximum flood control water level value obtained in step 3, deduce the conditional probability that the flood causes the reservoir water level to exceed different characteristic water levels, and evaluate the flood safety risk of the reservoir dam according to the conditional probability. The method can visualize the simulation and calculation results, the calculation process is direct and clear, and it saves calculation time while meeting the high calculation accuracy, and is easy to operate. It has important practical significance and good application prospects in the safety risk assessment of reservoir operation dams. Moreover, this method introduces conditional probability, so as to accurately evaluate and divide the safety risk level of reservoir dams in a quantitative manner, which can serve as an important supplement to the safety risk assessment of reservoir dams.

[0041] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0043] Figure 1 It is a fitting line diagram for estimating statistical parameters of a series of flood samples entering the reservoir in an embodiment of the present invention;

[0044] Figure 2 Schematic diagram of random simulation results of flood peak flow into the reservoir in an embodiment of the present invention;

[0045] Figure 3 It is a schematic diagram of an enlarged typical flood process line of a simulated flood peak flow in an embodiment of the present invention;

[0046] Figure 4 It is a schematic diagram of the maximum water level result and probability deduction of the reservoir flood control calculation in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0048] Example:

[0049] A reservoir dam flood safety risk assessment method is specifically a method for first deriving the conditional probability of the reservoir dam flood safety risk based on VBA, and then assessing the reservoir dam flood safety risk according to the conditional probability, and specifically includes the following steps:

[0050] Step 1: Based on the measured data sample series of peak flow of floods entering the reservoir over many years, deduce the empirical frequency values ​​of the sample series and the estimated values ​​of hydrological statistical parameters.

[0051] In this embodiment, a sample series of measured data of the peak flow of flood inflow in a reservoir in Hunan Province for 53 years is selected and sorted from large to small, and the empirical frequency value of the sample series of the peak flow of flood inflow is calculated, wherein: the empirical frequency distribution function adopts the Pearson III type distribution; the calculation formula of the empirical frequency value P0 of the sample series of the peak flow of flood inflow is:

[0052] P0 = n / (N+1);

[0053] Wherein: n is the number of occurrences equal to or exceeding a certain rainstorm intensity value, N is the total number of measured data sample series, and in this embodiment, N=53 is preferred;

[0054] All the empirical frequency values ​​obtained are plotted on the hydrological frequency distribution curve, such as Figure 1 As shown, the mean of the sample series is obtained after adjustment by the fitting method Coefficient of variation C v , skewness coefficient C s Estimated values ​​of three hydrological statistical parameters, in this embodiment: C v =0.32; C s =0.29.

[0055] Step 2: Based on the estimated values ​​of the hydrological statistical parameters of the sample series obtained in step 1, a longer series of flood peak flow samples is randomly simulated, and after amplifying the typical flood process line, the flood process line corresponding to the simulated flood peak flow series is obtained.

[0056] The specific implementation of this embodiment is as follows: according to the estimated values ​​of the hydrological statistical parameters of the sample series obtained in step one, based on the VBA tool, the value range and simulation times of the conditional probability P are set, and the conditional probability P is randomly sampled in combination with the random number extraction function to obtain a long series of peak flow samples corresponding to the conditional probability P value of the random simulation; the long series of peak flow samples are amplified according to the widely used same-multiple ratio method for the selected typical inflow flood process lines to obtain the flood process lines corresponding to the simulated peak flow series.

[0057] When applying the Pearson III distribution curve to deduce the design peak flow, the Pearson III distribution function is converted into the following expression:

[0058]

[0059] Where: x p is a simulated random variable; GAMINV represents the inverse function of the cumulative function of the gamma distribution.

[0060] When the three statistical parameters of the sample series are determined, the value of the peak flow is only related to the value of the conditional probability P, that is, it is a function of P, and 0≤P≤1. Therefore, the value interval of the conditional probability P can be set within the range of 0 to 1 according to actual needs, and the number of random simulations can be set to 10,000 times (different simulation times can be set according to actual needs, such as 100 to 100,000 times. Generally, the larger the number of simulations, the higher the accuracy). Based on the VBA tool, the conditional probability P is randomly sampled according to the average distribution within the value interval to form a sample of 10,000 randomly simulated P values. All simulated P values ​​are substituted into the above formula for calculation to obtain 10,000 sample values ​​of the peak flow corresponding to the randomly simulated P value sample series. The results are as follows. Figure 2 shown.

[0061] The simulated 10,000 flood peak flow sample series are magnified according to the same multiple method for the typical flood process line of the selected reservoir, such as Figure 3 As shown in Figure 1, 10,000 sets of flood process lines corresponding to the peak flow are obtained ( Figure 3 Only the typical flood process line, simulated flood process line 1, simulated flood process line 2, simulated flood process line 3 and simulated flood process line 4 are shown, and the six hollow circles below and above represent other simulated flood process lines not shown).

[0062] Step 3: Use the flood process line obtained in step 2 as the flood condition for entering the reservoir, combine the reservoir capacity curve and discharge curve data to perform flood control calculation according to the set scheduling plan, and obtain the maximum water level value for flood control.

[0063] In this embodiment, the reservoir dispatching scheme is set according to the upstream and downstream of the reservoir and its own flood control requirements. The flood control scheme includes but is not limited to the following schemes:

[0064] Scheme 1: The reservoir discharges flood water through all discharge facilities according to the discharge flow rate formulated in the dispatching regulations or flood season dispatching operation plan, and the reservoir's starting water level takes into account the dispatching plan of different water levels above the flood limit water level;

[0065] Option 2: The total flow of the reservoir discharged through all the discharge facilities is the safe discharge of the downstream river, and the reservoir water level is adjusted to consider the dispatching schemes of different water levels above the flood limit water level;

[0066] Scheme 3: The total flow discharged from the reservoir through all the discharge facilities is the maximum discharge flow of the reservoir, and the reservoir water level is adjusted to consider the dispatching schemes of different water levels above the flood limit water level;

[0067] The specific flood control calculation is as follows: the basic equation of reservoir flood control calculation is coded by VBA program, and 10,000 groups of flood process lines obtained by simulation are used as the flood conditions for the reservoir. According to the set dispatching scheme, the reservoir flood control calculation process is realized based on the trial algorithm, and the maximum flood control water level results of 10,000 reservoirs corresponding to the simulated flood (i.e., the maximum flood control water level value) are obtained. See Figure 4 .

[0068] Step 4: Based on the maximum flood control water level value obtained in step 3, the conditional probability that the flood causes the reservoir water level to exceed different characteristic water levels is calculated, and the flood safety risk of the reservoir dam is evaluated based on the conditional probability.

[0069] Preferred in this embodiment:

[0070] The conditional probability of deducing the reservoir water level exceeding different characteristic water levels due to floods in step 4 is specifically as follows: the number of times that the highest flood control water level exceeds the different characteristic water level elevations of the reservoir is counted, and the ratio of this number to the total number of simulations is used as the conditional probability that the reservoir dam will be subject to different safety risks due to floods; the different characteristic water level elevations of the reservoir include at least one of the dam crest water level, the check water level and the design water level.

[0071] In this embodiment, the number of water levels exceeding the reservoir check water level and the dam top water level, which pose a great threat to the dam safety, is counted among 10,000 flood control maximum water level results. Figure 4As shown in the figure, statistical calculations show that: ① the number of times the water level exceeds the check level of the reservoir is 9; ② ​​the number of times the water level exceeds the dam crest is 5. The conditional probability that the upstream flood causes the reservoir water level to exceed the check level and the dam crest is 0.0009 and 0.0005, respectively.

[0072] In step 4, the specific evaluation of the flood safety risk of the reservoir dam based on the conditional probability is as follows (it can be obtained based on historical statistical experience and divided by magnitude): if the conditional probability P satisfies: P≤10 -5 , then the risk is assessed as low; if the conditional probability P satisfies: 10 -5 <P≤10 -4 , then the risk is assessed as medium; if the conditional probability P satisfies: 10 -4 <P≤10 -3 , then it is assessed as high risk; if the conditional probability P satisfies: P>10 -3 , it is assessed as extremely high risk.

[0073] In this embodiment, the calculation results show that the conditional probability magnitude of the flood causing the reservoir water level to exceed the check water level and the dam top is 10. -4 , that is, the safety risk level of the reservoir dam is medium risk, which is still within the allowable risk range.

[0074] This embodiment also discloses a computer storage medium on which computer program instructions are stored. When the computer program instructions are executed by a processor, the reservoir dam flood safety risk assessment method as described above is implemented.

[0075] This embodiment also discloses a device, including: at least one processor, at least one memory, and computer program instructions stored in the memory. When the computer program instructions are executed by the processor, the reservoir dam flood safety risk assessment method as described above is performed.

[0076] In summary, the VBA-based reservoir dam flood safety risk assessment method disclosed in this embodiment includes: deducing the empirical frequency value of the sample series and the estimated value of the hydrological statistical parameters based on the measured data sample series of the peak flow of floods entering the reservoir for many years; randomly simulating a longer series of peak flow long series samples to obtain the flood process line corresponding to the simulated peak flow series; combining the reservoir capacity curve and discharge curve data to perform flood control calculation according to the set scheduling plan to obtain the maximum flood control water level; based on the obtained maximum flood control water level, deducing the conditional probability that the flood causes the reservoir water level to exceed different characteristic water levels, and evaluating the flood safety risk of the reservoir dam according to the conditional probability. This method can visualize the simulation and calculation results, and the calculation process is direct and clear. It has important practical significance and good application prospects in the safety risk assessment of reservoir operation dams.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A reservoir dam flood safety risk assessment method, characterized in that: The following steps are involved: Step 1: deduce the empirical frequency value of the sample series and the estimated value of the hydrological statistical parameters based on the measured data sample series of flood peak flow into the reservoir for many years; Step 2: According to the estimated values ​​of the hydrological statistical parameters of the sample series obtained in step 1, a longer series of flood peak flow samples is randomly simulated, and after amplifying the typical flood process line, the flood process line corresponding to the simulated flood peak flow series is obtained; Step 3: Take the flood process line obtained in step 2 as the flood condition for entering the reservoir, combine the reservoir capacity curve and discharge curve data to perform flood control calculation according to the set dispatching plan, and obtain the maximum water level value for flood control; Step 4: Based on the maximum flood control water level value obtained in step 3, the conditional probability that the flood causes the reservoir water level to exceed different characteristic water levels is calculated, and the flood safety risk of the reservoir dam is evaluated based on the conditional probability.

2. The reservoir dam flood safety risk assessment method according to claim 1 is characterized in that: The step 1 specifically comprises: The measured data sample series of flood peak flow entering the reservoir for many years are sorted from large to small, and the empirical frequency value of the flood peak flow sample series is calculated, where: the empirical frequency distribution function adopts Pearson III type distribution; All the empirical frequency values ​​obtained are plotted on the hydrological frequency distribution curve, and the mean of the sample series is obtained after adjustment by the fitting method. Coefficient of variation C v and the skewness coefficient C s Estimated values ​​of three hydrological statistical parameters.

3. The reservoir dam flood safety risk assessment method according to claim 2 is characterized in that: The calculation formula for the empirical frequency value P0 of the flood peak flow sample series is: P0 = n / (N+1); Where: n is the number of times a certain rainstorm intensity value occurs or exceeds it, and N is the total number of measured data sample series.

4. The reservoir dam flood safety risk assessment method according to claim 2 is characterized in that: The step 2 specifically includes: According to the estimated values ​​of the hydrological statistical parameters of the sample series obtained in step 1, the value range and simulation times of the conditional probability P are set based on the VBA tool, and the conditional probability P is randomly sampled in combination with the random number extraction function to obtain a long series of peak flow samples corresponding to the conditional probability P value of the random simulation; The typical inflow flood process line selected by the long series of flood peak flow samples is magnified according to the same multiple method to obtain the flood process line corresponding to the simulated flood peak flow series.

5. The reservoir dam flood safety risk assessment method according to claim 4 is characterized in that: The conditional probability P is 0≤P≤1; the number of simulations is 100-100000 times; When applying the Pearson III distribution curve to deduce the design peak flow, the Pearson III distribution function is converted into the following expression: Where: x p is the simulated random variable; GAMINV means returning the inverse of the cumulative function of the gamma distribution.

6. The reservoir dam flood safety risk assessment method according to claim 4 is characterized in that: In the step three: The reservoir operation plan is set according to the flood control requirements of the upstream and downstream of the reservoir and itself. The flood control plan includes at least one of the following plans: Scheme 1: The reservoir discharges flood water through all discharge facilities according to the discharge flow rate formulated in the dispatching regulations or flood season dispatching operation plan, and the reservoir's starting water level takes into account the dispatching plan of different water levels above the flood limit water level; Option 2: The total flow of the reservoir discharged through all the discharge facilities is the safe discharge of the downstream river, and the reservoir water level is adjusted to consider the dispatching schemes of different water levels above the flood limit water level; Scheme 3: The total flow discharged from the reservoir through all the discharge facilities is the maximum discharge flow of the reservoir, and the reservoir water level is adjusted to consider the dispatching schemes of different water levels above the flood limit water level; The specific steps of flood control calculation are: using VBA program to code the basic equations of reservoir flood control calculation, and realizing the reservoir flood control calculation process based on trial algorithm.

7. The reservoir dam flood safety risk assessment method according to claim 6 is characterized in that: The conditional probability of the reservoir water level exceeding different characteristic water levels due to floods in step 4 is specifically derived by: counting the number of times that the highest flood control water level exceeds different characteristic water level elevations of the reservoir, and taking the ratio of the number to the total number of simulations as the conditional probability that the reservoir dam will be subjected to different safety risks due to floods; The different characteristic water level elevations of the reservoir include at least one of the dam crest water level, the check water level and the design water level.

8. The reservoir dam flood safety risk assessment method according to claim 7 is characterized in that: The specific steps of evaluating the flood safety risk of reservoir dams based on conditional probability in step 4 are as follows: If the conditional probability P satisfies: P≤10 -5 , then it is assessed as low risk; If the conditional probability P satisfies: 10 -5 <P≤10 -4 , then it is assessed as medium risk; If the conditional probability P satisfies: 10 -4 <P≤10 -3 , it is assessed as high risk; If the conditional probability P satisfies: P>10 -3 , it is assessed as extremely high risk.

9. A computer storage medium, characterized in that Computer program instructions are stored thereon, and when the computer program instructions are executed by a processor, a reservoir dam flood safety risk assessment method as described in any one of claims 1 to 8 is implemented.

10. A device, characterized in that: include: At least one processor, at least one memory and computer program instructions stored in the memory, when the computer program instructions are executed by the processor, the reservoir dam flood safety risk assessment method as described in any one of claims 1 to 8.

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