A method for constructing a flood characteristic evaluation index system

Abstract

The application discloses a flood characteristic evaluation index system construction method, and systematically constructs a set of comprehensive evaluation index system from four core dimensions of magnitude, time, dynamics and morphology. In the magnitude dimension, indexes such as total flood volume are selected to measure the flood scale and destructive power; in the time dimension, indexes such as flood event duration are used to describe the time process; in the dynamics dimension, indexes such as average rising speed are adopted to reflect the dynamics characteristics and energy size; and in the morphology dimension, indexes such as process line sharpness coefficient are used to depict the geometric morphology of the flood process line. The index system constructed by the method can comprehensively and multi-angelly extract the internal characteristics of the flood event through the organic combination of the four dimension indexes, and provides a systematic analysis tool and quantitative basis for the mechanism research and risk control of the basin flood, and can be widely applied to the fields of hydrological analysis, flood control and disaster mitigation, water conservancy engineering design and emergency management.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrology and water conservancy and disaster prevention and mitigation, and particularly relates to a method for constructing a flood characteristic evaluation index system. BACKGROUND

[0002] Flood is a common natural disaster, and its process is complex and changeable, which poses a serious threat to human society and ecological environment. Scientific and accurate identification and characterization of flood characteristics are the basis for flood type division, cause analysis, risk assessment, engineering design and emergency management.

[0003] At present, in the analysis of flood characteristics, a single or a few indicators are often used for description, such as mainly using flood peak flow and flood volume. Although this method is simple and intuitive, it has obvious defects, only focusing on the "size" of the flood, and ignoring the distribution of flood process in time, the strength of dynamics and the difference in morphology. For example, a "thin and tall" flood with a very high flood peak but a short duration, and a "short and fat" flood with a medium flood peak but a long duration, may have similar total volumes, but their formation mechanisms, disaster characteristics and coping strategies are completely different. Flood peak and volume cannot distinguish them.

[0004] Therefore, the prior art has the problems of single dimension of flood characteristic characterization and incomplete index system, which leads to insufficient and in-depth understanding of flood events, and restricts the level of flood science research and fine management. SUMMARY

[0005] The purpose of the present application is to provide a method for constructing a flood characteristic evaluation index system, which extracts the internal characteristics of flood events from multiple core angles, and provides a complete quantitative analysis tool for flood characteristic analysis, mechanism research and comprehensive risk management.

[0006] In order to solve the above technical problems, the present application provides the following technical solutions:

[0007] A method for constructing a flood characteristic evaluation index system, comprising the following steps:

[0008] Obtaining flood data in a study area;

[0009] Determining flood characteristic quantitative indicators corresponding to four dimensions of magnitude dimension, time dimension, dynamics dimension and morphological dimension;

[0010] Systematically integrating the flood characteristic quantitative indicators corresponding to each dimension to construct a flood characteristic evaluation index system;

[0011] Based on the flood characteristic evaluation index system, analyzing and calculating target flood hydrograph data to output index quantitative results under each dimension, and realizing comprehensive and systematic characterization of flood event characteristics.

[0012] wherein, for each flood event window a corresponding indicator vector :

[0013] ,

[0014] wherein, denotes a flood characteristic quantification indicator corresponding to the magnitude dimension, denotes a flood characteristic quantification indicator corresponding to the time dimension, denotes a flood characteristic quantification indicator corresponding to the dynamics dimension, denotes a flood characteristic quantification indicator corresponding to the morphological dimension.

[0015] According to the above technical solution, the flood characteristic quantification indicator of the magnitude dimension at least includes: flood peak magnitude, flood total volume, over-threshold flood volume, short-duration maximum flood volume, and unit-area flood peak;

[0016] wherein, the flood peak magnitude : wherein, is the maximum value of the flow process of the current flood event.

[0017] the flood total volume : wherein, is the starting time of the flood event, is the ending time of the flood event; is the base flow observed by the hydrological station, which can be taken as a low quantile or a smoothed minimum value segment statistical value in a long window.

[0018] the over-threshold flood volume : wherein, is a business threshold value, such as a warning flow / design flow, which can be given in combination with the needs of forecasting and scheduling.

[0019] the short-duration maximum flood volume : ; ~ corresponds to a window with a time step of j.

[0020] the unit-area flood peak : ; is the control area of the hydrological station.

[0021] The flood characteristic quantification indicator of the time dimension at least includes: flood event duration, rising water duration, falling water duration, over-threshold duration, and peak occurrence relative position; ​

[0022] Duration of the flood event : .

[0023] Duration of the flood : , for The corresponding moment.

[0024] Duration of floodwater receding : .

[0025] Overthreshold duration : In the formula, This indicates that the condition is met. The duration, here the condition is .

[0026] Peak relative position : .

[0027] The quantitative indicators of flood characteristics in the dynamic dimension include at least: average rise rate, maximum instantaneous rise rate, maximum acceleration during the rise phase, receding attenuation coefficient, and rise-fall asymmetry rate ratio;

[0028] Among them, the average rate of rise in water level : .

[0029] Maximum instantaneous rate of increase : .

[0030] Maximum acceleration during the flood stage Defined as the second derivative of a flood time series, it can be approximated using differences: .

[0031] Drainage attenuation coefficient It was determined by linear regression estimation of the logarithm of the discharge section flow and the time series.

[0032] ;

[0033] ;

[0034] In the formula, In the receding section The coefficient of the fitted exponential decay can be obtained by adjusting the coefficient of the fitted exponential decay. and Linear regression estimation and run only in Fitting is performed when the value is above a certain lower limit to improve stability.

[0035] Rate of asymmetry of fluctuation : .

[0036] The morphological dimension flood characteristic quantitative index at least includes a hydrograph sharpness coefficient, a hydrograph asymmetry coefficient and a waveform complexity entropy.

[0037] The hydrograph sharpness coefficient is defined as the ratio of the peak flow to the mean of the flood event flow, and is used to represent the steepness of the flood process: . .

[0038] The hydrograph asymmetry coefficient is defined as the ratio of the rising duration to the falling duration, and is used to represent the skewness of the hydrograph in the time axis: . .

[0039] The waveform complexity entropy is defined as the information entropy of the flood fluctuation energy , which quantitatively represents the uniformity and disorder degree of energy distribution in the time dimension in the flood process:

[0040] ;

[0041] ;

[0042] In the formula, is the normalization of the sequence to the probability distribution, , is the information entropy value calculated on this basis, and N is the number of observation points in the flood event.

[0043] According to the above technical scheme, the quantification results of the indexes in the four dimensions are used as the input feature vectors of the downstream tasks, and numerical simulation, physical simulation or numerical-physical coupling simulation technology is used to carry out systematic analysis on the downstream tasks. The downstream tasks include automatic classification of flood types, flood process similarity retrieval, flood disaster risk assessment of a river basin or generation of a flood control scheme for a water conservancy project. The quantification results of the indexes in the four dimensions can also be weighted and used as the input feature vectors of the downstream tasks.

[0044] The index system is applied to calculate and analyze the measured or simulated flood hydrograph data, and a set of multi-dimensional quantification characteristic values is output. The set of characteristic values can be used as a "flood characteristic fingerprint" for subsequent in-depth analysis and application.

[0045] The technical scheme includes a flood characteristic evaluation index system construction system, which comprises:

[0046] A data collection module is configured to obtain flood data in a study area.

[0047] The dimension index confirmation module determines the quantification index of flood characteristics corresponding to four dimensions of a magnitude dimension, a time dimension, a dynamics dimension and a morphological dimension based on flood data;

[0048] The evaluation index system construction module integrates the quantification index of flood characteristics corresponding to each dimension to construct a flood feature evaluation index system;

[0049] The index quantification module analyzes and calculates target flood hydrograph data based on the flood feature evaluation index system, outputs the index quantification results under each dimension, and realizes comprehensive and systematic characterization of flood event features;

[0050] The index application module uses the index quantification results under the four dimensions as input feature vectors of downstream tasks, and uses numerical simulation or physical simulation or numerical-physical coupling simulation technology to carry out systematic analysis on the downstream tasks.

[0051] The technical solution includes an electronic device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it realizes a flood feature evaluation index system construction method as described in the above technical solution.

[0052] The technical solution includes a computer-readable storage medium, which stores a computer program. When the processor executes the program, it realizes a flood feature evaluation index system construction method as described in the above technical solution.

[0053] Beneficial effects: compared with the prior art, the beneficial effects of the present application are that the present application systematically constructs a set of comprehensive evaluation index system from four core dimensions of magnitude, time, dynamics and morphology. In the magnitude dimension, indexes such as total flood volume are selected to measure the flood scale and destructive power; in the time dimension, indexes such as flood event duration are used to describe the time process; in the dynamics dimension, indexes such as average rising speed are used to reflect the dynamics characteristics and energy size; in the morphology dimension, indexes such as process line sharpness coefficient are used to describe the geometric morphology of the flood process line. Through the organic combination of the four dimensions of quantity, time, dynamics and shape, the one-sidedness of the traditional single index system is overcome, and the internal properties of the flood event can be revealed in all directions and stereoscopically, so that the description of any flood is more accurate and full. The index system proposed by the present application has clear definition and calculation method, is easy to standardize and program, and is convenient for popularization and application comparison in flood analysis in different basins, different countries and regions. The index system constructed by the method can extract the internal characteristics of the flood event in all directions and from multiple angles through the organic combination of the four dimension indexes, and provides a systematic analysis tool and quantitative basis for the mechanism research and risk control of the basin flood, which can be widely applied in the fields of hydrological analysis, flood control and disaster reduction, water conservancy engineering design and emergency management. BRIEF DESCRIPTION OF DRAWINGS

[0054] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application, and are used to explain the present application, and do not constitute a limitation on the present application. In the drawings:

[0055] Figure 1 is a step flow chart of a flood characteristic evaluation index system construction method of the present application;

[0056] Figure 2 is a flow process diagram of the flood event of the embodiment;

[0057] Figure 3 is a flood characteristic evaluation index system diagram of the embodiment. DETAILED DESCRIPTION

[0058] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0059] Taking the flood event with flood number 20200731 of hydrological station A as an example, the starting time of the flood event is 22:00 on September 17, 2021, and the ending time is 15:00 on September 22, 2021. The steps for calculating the quantitative results of the indicators in each dimension include: Figure 1

[0060] S1, obtain the flood data in the research area, and the flood event flow process is shown in FIG. 1. Figure 2 Four core dimensions of flood characteristics evaluation are determined, including magnitude dimension, time dimension, dynamics dimension and morphological dimension. The flood event window of the flood with the flood number 20200731 The integrated index vector may be:

[0061]

[0062] In the formula, represents the flood characteristic quantitative index corresponding to the magnitude dimension, represents the flood characteristic quantitative index corresponding to the time dimension, represents the flood characteristic quantitative index corresponding to the dynamics dimension, represents the flood characteristic quantitative index corresponding to the morphological dimension.

[0063] S2, for the four dimensions of magnitude dimension, time dimension, dynamics dimension and morphological dimension, a group of flood characteristic quantitative indexes capable of representing the corresponding dimensions are screened and defined respectively.

[0064] Among them, the magnitude dimension index at least includes: flood peak magnitude, total flood volume, threshold excess flood volume, short duration maximum flood volume and unit area flood peak, specifically:

[0065] Flood peak magnitude : , is the maximum value of the flow process of the flood event , which occurs at 7:00 on September 19, 2021.

[0066] Taking the base flow as the 5% quantile, the is 187.8 m 3 / s, and the total flood volume is calculated as: ;

[0067] In the formula, is the starting time of the flood event, is the ending time of the flood event; is the base flow of the hydrological station, which can be calculated by taking the low quantile in a long window or using the smoothed minimum value segment as the base flow value.​​

[0068] Take the alert flow 500 m3 / s, calculate the threshold flood volume : .

[0069] Take the time step 3h, calculate the short duration maximum flood volume : .

[0070] The control area of hydrological station A is 4623 km 2 , calculate the flood peak per unit area : .

[0071] The flood characteristic quantification index in time dimension includes at least flood event duration, rising duration, falling duration, threshold duration and peak relative position, specifically:

[0072] Flood event duration : .

[0073] Corresponding to September 19, 2021 7:00, rising duration : .

[0074] Falling duration : .

[0075] Threshold duration : ;

[0076] In the formula, Indicates the duration that meets the condition , here the condition is .

[0077] Peak relative position : .

[0078] The flood characteristic quantification index in dynamic dimension includes at least average rising rate, maximum instantaneous rising rate, maximum acceleration in rising stage, falling attenuation coefficient and rising-falling asymmetry rate ratio; Specifically:

[0079] Average rising rate : .

[0080] Maximum instantaneous rising rate : .

[0081] Maximum acceleration in rising stage : where the second derivative can be approximated by finite differences.

[0082] retreat attenuation coefficient ,

[0083] ;

[0084] ;

[0085] where, is the coefficient of exponential decay fitted to the retreat section , which can be estimated by linear regression of and , and run only above some lower limit for stability.

[0086] rate of asymmetry of fluctuation : .

[0087] The morphological dimension of flood characteristics quantitative indicators include at least: hydrograph sharpness coefficient, hydrograph asymmetry coefficient and waveform complexity entropy. Specifically:

[0088] hydrograph sharpness coefficient : ;

[0089] hydrograph asymmetry coefficient : ;

[0090] waveform complexity entropy :

[0091] ;

[0092] ;

[0093] where, is the normalization of the sequence to a probability distribution, , is the information entropy value calculated on this basis, and N is the number of observation points within the flood event.

[0094] S3, the four-dimensional indicators defined in S2 are systematically integrated to construct a multi-dimensional and multi-indicator flood characteristic evaluation index system. The flood characteristic evaluation index system constructed is shown in the accompanying Figure 3 .

[0095] ​​S4, based on the index system, target flood hydrograph data are analyzed and calculated, and index quantization results in each dimension are output, so as to comprehensively and systematically depict the characteristics of the flood event. The index quantization results in the four dimensions are taken as input feature vectors of a downstream task, and numerical simulation or physical simulation or numerical-physical coupling simulation technology is used to carry out systematic analysis on the downstream task. The downstream task includes automatic classification of flood types, flood process similarity retrieval, flood disaster risk assessment of a basin, or generation of a flood control scheduling scheme of a water conservancy project.

[0096] It should be noted that, in this document, the terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device.

[0097] Finally, it should be noted that: the above only describes the preferred embodiments of the present application, and does not limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or replace some technical features with equivalent ones. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for constructing a flood feature evaluation index system, characterized in that, The steps include: acquiring flood data in a study area; determining flood characteristic quantization indexes corresponding to four dimensions of magnitude dimension, time dimension, dynamics dimension, and morphological dimension; the flood characteristic quantization indexes of the magnitude dimension at least include flood peak magnitude, flood total amount, threshold-exceeding flood amount, short-duration maximum flood amount, and flood peak per unit area; the flood characteristic quantization indexes of the time dimension at least include flood event duration, rising duration, falling duration, threshold-exceeding duration, and relative position of peak occurrence; the flood characteristic quantization indexes of the dynamics dimension at least include average rising rate, maximum instantaneous rising rate, rising stage maximum acceleration, falling attenuation coefficient, and rising-falling asymmetry rate ratio; the flood characteristic quantization indexes of the morphological dimension at least include process line sharpness coefficient, process line asymmetry coefficient, and waveform complexity entropy; the process line sharpness coefficient is a ratio of flood peak flow to average flood event flow; the process line asymmetry coefficient is a ratio of rising duration to falling duration; and the waveform complexity entropy is information entropy of flood fluctuation energy; systematically integrating the flood characteristic quantization indexes corresponding to each dimension to construct a flood feature evaluation index system; based on the flood feature evaluation index system, analyzing and calculating target flood hydrograph data to output index quantization results in each dimension, taking the index quantization results in the four dimensions as input feature vectors of a downstream task, and using numerical simulation, physical simulation, or numerical-physical coupling simulation technology to systematically analyze the downstream task, so as to comprehensively and systematically characterize flood event features.

2. The method according to claim 1, characterized in that, The rising stage maximum acceleration is a second-order derivative of the flood time series; and the falling attenuation coefficient is determined by linear regression estimation of the logarithm of the falling section flow and the time series.

3. A system for implementing the flood feature evaluation index system construction method of claim 1, characterized in that, The steps include: a data collection module for acquiring flood data in a study area; a dimension index confirmation module for determining flood characteristic quantization indexes corresponding to four dimensions of magnitude dimension, time dimension, dynamics dimension, and morphological dimension based on the flood data; an evaluation index system construction module for systematically integrating the flood characteristic quantization indexes corresponding to each dimension to construct a flood feature evaluation index system; an index quantization module for, based on the flood feature evaluation index system, analyzing and calculating target flood hydrograph data to output index quantization results in each dimension, so as to comprehensively and systematically characterize flood event features; an index application module for taking the index quantization results in the four dimensions as input feature vectors of a downstream task, and using numerical simulation or physical simulation or numerical-physical coupling simulation technology to systematically analyze the downstream task.

4. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the method of any one of claims 1 to 2 when executing the program.

5. A computer-readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the method of any one of claims 1 to 2.

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