A method and system for constructing a short-term drought-flood rapid transition index

Abstract

The present invention discloses a method and system for constructing a short-period drought-flood sudden transition index, which belongs to the technical field of natural disaster risk assessment, and includes the following steps: obtaining meteorological data within i consecutive time periods, and performing standardization processing on the meteorological data; calculating drought-flood sudden transition intensity, absolute drought-flood intensity, calculation factors of drought-flood sudden transition event identification calculation parameters, and drought-flood sudden transition event identification calculation parameters; calculating drought-flood sudden transition event identification formula; and calculating drought-flood sudden transition index. The present invention fully considers the influence of drought and flood standards on drought-flood sudden transition events, solves the problems of missed judgment of short-period drought-flood sudden transition time and misjudgment of non-drought-flood sudden transition events in the prior art, corrects the bias and incompleteness of the short-period drought-flood sudden transition index in the prior art in judging the severity; unifies the threshold of short-period drought-flood sudden transition events, and can accurately identify short-period drought-flood sudden transition events when the drought-flood sudden transition threshold or drought threshold is changed.

Description

Technical Field

[0001] The present invention relates to the technical field of natural disaster risk assessment, and more specifically to a method and system for constructing a short-cycle drought-flood rapid transition index. Background Art

[0002] Sudden alternation from drought to flood refers to a natural phenomenon in which a long period of drought occurs in a certain area or a certain river basin, followed by sudden concentrated heavy rainfall, causing mountain torrents, sudden rise of river water, intrusion of foreign water, and difficulty in timely discharge of internal water.

[0003] Under the influence of global warming and human activities, extreme hydrological events such as droughts and floods coexist, and their frequency and intensity are increasing.

[0004] At present, the calculation of drought-flood transition index is usually based on a standardized precipitation or runoff sequence of a certain time scale (such as 1 to 2 months), and the product formula of the difference between adjacent values ​​and the sum of absolute values ​​is adopted to present the intensity term of drought-flood transition and the intensity term of drought-flood transition. By setting the weight term (negative exponential function of the sum absolute value), it is attempted to avoid two drought or flood events with large differences from being misjudged as drought-flood transition. The existing short-period drought-flood transition index fails to take drought and flood standards into consideration during the calculation process. Therefore, the existing technology has the following deficiencies: (1) When using the existing short-period drought-flood transition index to identify drought-flood transition events, there is a certain degree of omission of short-period drought-flood transition events and misjudgment of non-drought-flood transition events; (2) The existing research on short-period drought-flood transition has not obtained a unified critical threshold for drought-flood transition events; (3) The existing short-period drought-flood transition index shows deviation and incompleteness in reflecting the severity of drought-flood transition events. Summary of the invention

[0005] In view of this, the present invention provides a method and system for constructing a short-cycle drought-flood sudden transition index, unifies the threshold values ​​of short-cycle drought-flood sudden transition events, corrects the bias and incompleteness of the short-cycle drought-flood sudden transition index in the existing technology in judging the severity, and solves the problems of missed judgment of the short-cycle drought-flood sudden transition time and misjudgment of non-drought-flood sudden transition events in the existing technology.

[0006] In order to achieve the above object, the present invention provides a method for constructing a short-term drought-flood rapid transition index, comprising the following steps:

[0007] Acquire meteorological data within i consecutive time periods and perform standardization on the meteorological data;

[0008] Calculate drought-flood transition intensity, absolute drought-flood intensity, calculation factors of drought-flood transition event identification calculation parameters, and drought-flood transition event identification calculation parameters based on standardized meteorological data;

[0009] Using the drought-flood transition intensity, absolute drought-flood intensity, and drought-flood transition event identification calculation parameters, a drought-flood transition event identification formula is obtained;

[0010] Based on the drought-flood transition event identification formula, the drought-flood transition index is calculated.

[0011] Preferably, the meteorological data is precipitation data; the standardized meteorological data is a standardized precipitation index; and the unit of the time period is month.

[0012] Preferably, the calculation formula for the drought-flood rapid transition intensity is:

[0013] D=S i+1 -S i ;

[0014] Preferably, the absolute drought and flood intensity calculation formula is:

[0015] E=|S i+1 |+|S i |;

[0016] Preferably, the calculation factor calculation formula for the drought-flood rapid transition event identification calculation parameter is:

[0017]

[0018] Preferably, the calculation formula for the drought-flood rapid transition event identification calculation parameters is:

[0019] I1=F×min(|S i+1 |,|S i |);

[0020] Among them, D is the intensity of drought-flood transition, E is the absolute drought-flood intensity, F is the calculation factor of drought-flood transition event identification calculation parameters, I1 is the drought-flood transition event identification calculation parameter, S i is the standardized precipitation index of the ith month, S i+1 is the standardized precipitation index for month i+1.

[0021] Preferably, the drought-flood rapid transition event identification formula is:

[0022]

[0023] Among them, I′ is the drought-flood transition event identification formula, D is the drought-flood transition intensity, E is the absolute drought-flood intensity, I1 is the drought-flood transition event identification calculation parameter, S i is the standardized precipitation index of the ith month, S i+1 is the standardized precipitation index for month i+1.

[0024] Preferably, the drought-flood rapid transition index calculation formula is:

[0025]

[0026] Among them, SDWAI is the drought-flood transition index, sign is the intercept sign function, 0.5 is the drought threshold, I′ is the drought-flood transition event identification formula, D is the drought-flood transition intensity, E is the absolute drought-flood intensity, I1 is the drought-flood transition event identification calculation parameter, S i is the standardized precipitation index of the ith month, S i+1 is the standardized precipitation index for month i+1.

[0027] The present invention also provides a short-period drought-flood rapid transition index construction system, comprising a data acquisition module, a data processing module, and a calculation module; the data acquisition module is connected to the data processing module; the data processing module is connected to the calculation module;

[0028] The data acquisition module is used to obtain meteorological data;

[0029] The data processing module is used to perform standardized processing on the collected meteorological data;

[0030] The calculation module is used to calculate the drought-flood transition intensity, absolute drought-flood intensity, calculation factors of drought-flood transition event identification calculation parameters, drought-flood transition event identification calculation parameters, drought-flood transition event identification formula, and drought-flood transition index.

[0031] Preferably, the data collected by the data collection module is precipitation data; and the data processing module is used to convert the data collected by the data collection module into a standardized precipitation index.

[0032] Preferably, the calculation module includes a first calculation unit, a second calculation unit and a third calculation unit;

[0033] The first calculation unit is used to calculate the drought-flood sudden change intensity and the absolute drought-flood intensity;

[0034] The second calculation unit is used to calculate the calculation factor of the drought-flood sudden transition event identification calculation parameter according to the calculation result of the first calculation unit;

[0035] The third calculation unit is used to calculate the drought-flood sudden transition event identification calculation parameters according to the calculation results of the first calculation unit and the second calculation unit.

[0036] Preferably, the calculation module further includes a fourth calculation unit for calculating the drought-flood rapid transition event identification formula.

[0037] Preferably, the calculation module includes a fifth calculation unit for calculating the drought-flood transition index.

[0038] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method and system for constructing a short-cycle drought-flood sudden transition index. During the construction process, the influence of drought and flood standards on drought-flood sudden transition events is fully considered, and the problems of missed judgment of short-cycle drought-flood sudden transition time and misjudgment of non-drought-flood sudden transition events in the prior art are solved, and the bias and incompleteness of the severity judgment of the short-cycle drought-flood sudden transition index in the prior art are corrected; the threshold of short-cycle drought-flood sudden transition events is unified, and short-cycle drought-flood sudden transition events can be accurately identified when the drought-flood sudden transition threshold or the drought threshold is changed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0040] Figure 1 It is a schematic diagram of the method flow of the present invention.

[0041] Figure 2 (a) shows the missed and misjudgment of short-term drought-flood transition events based on the SDFAI changing the drought-flood transition threshold; (b) shows the missed and misjudgment of short-term drought-flood transition events based on the SDFAI changing the empirical coefficient; (c) shows the missed and misjudgment of short-term drought-flood transition events based on the SDWAI changing the drought threshold.

[0042] Figure 3 (a) shows the distribution of drought indices corresponding to short-term drought-flood transition events identified by SDWAI; (b) shows the distribution of drought indices corresponding to short-term drought-flood transition events identified by SDFAI under default conditions.

[0043] Figure 4 (a) shows the overall change of SDWAI index value; (b) shows the overall change of SDFAI index.

[0044] Figure 5 The SDWAI and SDFAI index values ​​reflect the comparison of the severity of periodic drought-flood sudden change events.

[0045] Figure 6 It is a system block diagram of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] like Figure 1 As shown, the embodiment of the present invention discloses a method for constructing a short-period drought-flood rapid transition index, comprising the following steps:

[0049] Acquire meteorological data within i consecutive time periods and perform standardization on the meteorological data;

[0050] Calculate drought-flood transition intensity, absolute drought-flood intensity, calculation factors of drought-flood transition event identification calculation parameters, and drought-flood transition event identification calculation parameters based on standardized meteorological data;

[0051] Using the drought-flood transition intensity, absolute drought-flood intensity, and drought-flood transition event identification calculation parameters, a drought-flood transition event identification formula is obtained;

[0052] Based on the drought-flood transition event identification formula, the drought-flood transition index is calculated.

[0053] Specifically, the meteorological data in the present invention is precipitation data; the meteorological data after standardization is the standardized precipitation index; and the unit of the time period is month.

[0054] Specifically, the calculation formula for the drought-flood rapid transition intensity in the present invention is:

[0055] D=S i+1 -S i ;

[0056] Specifically, the absolute drought and flood intensity calculation formula in the present invention is:

[0057] E=|S i+1 |+|S i |;

[0058] Specifically, the calculation factor calculation formula for the calculation parameters of drought-flood rapid transition event identification in the present invention is:

[0059]

[0060] Specifically, the calculation formula for the calculation parameters of drought-flood rapid transition event identification in the present invention is:

[0061] I1=F×min(|S i+1 |,|S i|);

[0062] Among them, D is the intensity of drought-flood transition, E is the absolute drought-flood intensity, F is the calculation factor of drought-flood transition event identification calculation parameters, I1 is the drought-flood transition event identification calculation parameter, S i is the standardized precipitation index of the ith month, S i+1 is the standardized precipitation index for month i+1.

[0063] Specifically, the drought-flood rapid transition event identification formula in the present invention is:

[0064]

[0065] The drought-flood transition event identification formula can identify the event where the standardized precipitation index of two consecutive months has different signs and the absolute value is greater than the given drought-flood standard as a drought-flood transition event (I'>1), but it cannot fully reflect the drought and flood situation of the two consecutive months of the drought-flood transition event. Therefore, the above formula only has an identification function and cannot determine the severity of the drought-flood transition event. Therefore, the present invention modifies the above formula and finally obtains the SDWAI expression.

[0066] Specifically, the calculation formula of the drought-flood rapid transition index in the present invention is:

[0067]

[0068] Among them, SDWAI is the drought-flood transition index, sign is the intercept sign function, 0.5 is the drought threshold, and the drought-flood transition threshold is always 1. For drought-flood transition events, |SDWA|≥1, and the larger |SDWAI| is, the more obvious the difference between drought and flood before and after the transition event is, and the more serious the drought-flood transition event is.

[0069] like Figure 2 (a) and Figure 2 As shown in (b), the existing short-term drought-flood transition index, under the condition of keeping the drought threshold unchanged, whether changing the drought-flood transition threshold or the empirical coefficient, cannot overcome the problem of missed and wrong judgment of short-term drought-flood transition events. In particular, Figure 2 As shown in (b), it is unscientific to use the default parameter values ​​of SDFAI (empirical coefficient of 3.2, drought-flood transition threshold of 1) to identify drought-flood transition events. Figure 2 (c) and Figure 2 As shown in (b), in comparison, the short-period drought-flood transition index constructed by the present invention can still accurately identify short-period drought-flood transition events after changing the drought threshold.

[0070] like Figure 3As shown in (a) and 3(b), compared with SDWAI, due to the structure of the SDFAI formula, the absolute value of SDFAI corresponding to the prominent short-term drought-flood transition event will be relatively much larger. Figure 4 It is not difficult to find that when the difference between the drought and flood levels in the i-th month and the i+1-th month is small, the absolute value of the SDFAI of the event will be particularly large; otherwise, it will be particularly small. In other words, for the short-term drought-flood transition event identified by the original index, the larger the absolute value of the SDFAI does not necessarily mean that the event is more serious, while the SDWAI can better reflect the severity of the drought-flood transition event.

[0071] Example 2

[0072] like Figure 6 As shown, the embodiment of the present invention discloses a short-period drought-flood rapid transition index construction system, including a data acquisition module, a data processing module, and a calculation module; the data acquisition module is connected to the data processing module; the data processing module is connected to the calculation module;

[0073] The data acquisition module is used to obtain meteorological data;

[0074] The data processing module is used to standardize the collected meteorological data;

[0075] The calculation module is used to calculate the intensity of drought-flood transition, absolute drought-flood intensity, calculation factors of drought-flood transition event identification calculation parameters, drought-flood transition event identification calculation parameters, drought-flood transition event identification formula, and drought-flood transition index.

[0076] The data collected by the data acquisition module is precipitation data; the data processing module is used to convert the data collected by the data acquisition module into a standardized precipitation index.

[0077] The calculation module includes a first calculation unit, a second calculation unit and a third calculation unit;

[0078] The first calculation unit is used to calculate the drought-flood sudden change intensity and the absolute drought-flood intensity;

[0079] The second calculation unit is used to calculate the calculation factor of the drought-flood sudden change event identification calculation parameter according to the calculation result of the first calculation unit;

[0080] The third calculation unit is used to calculate drought-flood sudden change event identification calculation parameters according to the calculation results of the first calculation unit and the second calculation unit.

[0081] The calculation module also includes a fourth calculation unit, which is used to calculate a drought-flood rapid transition event identification formula.

[0082] The calculation module includes a fifth calculation unit, which is used to calculate the drought-flood rapid transition index.

[0083] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0084] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for constructing a short-term drought-flood rapid transition index, characterized in that: The following steps are involved: Acquire meteorological data within i consecutive time periods and perform standardization on the meteorological data; Calculate drought-flood transition intensity, absolute drought-flood intensity, calculation factors of drought-flood transition event identification calculation parameters, and drought-flood transition event identification calculation parameters based on standardized meteorological data; The calculation formula for the intensity of drought-flood transition is: D=S i+1 -S i ; The calculation formula for the absolute drought and flood intensity is: E=|S i+1 |+|S i |; The calculation factor calculation formula for the drought-flood rapid transition event identification calculation parameter is: The calculation formula for the calculation parameters of drought-flood rapid transition event identification is: I1=F×min(|S i+1 |,|S i |); Among them, D is the intensity of drought-flood transition, E is the absolute drought-flood intensity, F is the calculation factor of drought-flood transition event identification calculation parameters, I1 is the drought-flood transition event identification calculation parameter, S i is the standardized precipitation index of the ith month, S i+1 is the standardized precipitation index for month i+1; The drought-flood transition intensity, absolute drought-flood intensity, and drought-flood transition event identification calculation parameters are used to obtain a drought-flood transition event identification formula; the drought-flood transition event identification formula is: Among them, I′ is the drought-flood transition event identification formula, D is the drought-flood transition intensity, E is the absolute drought-flood intensity, I1 is the drought-flood transition event identification calculation parameter, S i is the standardized precipitation index of the ith month, S i+1 is the standardized precipitation index for month i+1; Based on the drought-flood transition event identification formula, the drought-flood transition index is calculated.

2. A method for constructing a short-term drought-flood rapid transition index according to claim 1, characterized in that: The meteorological data is precipitation data; the standardized meteorological data is the standardized precipitation index; the unit of the time period is month.

3. The method for constructing a short-term drought-flood rapid transition index according to claim 1, characterized in that: The calculation formula of the drought-flood rapid transition index is: Among them, SDWAI is the drought-flood transition index, sign is the intercept sign function, 0.5 is the drought threshold, I′ is the drought-flood transition event identification formula, D is the drought-flood transition intensity, E is the absolute drought-flood intensity, I1 is the drought-flood transition event identification calculation parameter, S i is the standardized precipitation index of the ith month, S i+1 is the standardized precipitation index for month i+1.

4. A system for constructing a short-term drought-flood transition index, using a method for constructing a short-term drought-flood transition index according to any one of claims 1 to 3, characterized in that: It includes a data acquisition module, a data processing module and a calculation module; the data acquisition module is connected to the data processing module; the data processing module is connected to the calculation module; The data acquisition module is used to obtain meteorological data; The data processing module is used to perform standardized processing on the collected meteorological data; The calculation module is used to calculate the drought-flood transition intensity, absolute drought-flood intensity, calculation factors of drought-flood transition event identification calculation parameters, drought-flood transition event identification calculation parameters, drought-flood transition event identification formula, and drought-flood transition index.

5. A system for constructing a short-term drought-flood rapid transition index according to claim 4, characterized in that: The data collected by the data collection module is precipitation data; the data processing module is used to convert the data collected by the data collection module into a standardized precipitation index.

6. A system for constructing a short-term drought-flood rapid transition index according to claim 4, characterized in that: The calculation module includes a first calculation unit, a second calculation unit and a third calculation unit; The first calculation unit is used to calculate the drought-flood sudden change intensity and the absolute drought-flood intensity; The second calculation unit is used to calculate the calculation factor of the drought-flood sudden transition event identification calculation parameter according to the calculation result of the first calculation unit; The third calculation unit is used to calculate the drought-flood sudden transition event identification calculation parameters according to the calculation results of the first calculation unit and the second calculation unit.

7. A system for constructing a short-term drought-flood rapid transition index according to claim 4, characterized in that: The calculation module also includes a fourth calculation unit, which is used to calculate the drought-flood rapid transition event identification formula.

8. A system for constructing a short-term drought-flood rapid transition index according to claim 4, characterized in that: The calculation module includes a fifth calculation unit, which is used to calculate the drought-flood rapid transition index.

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