Three-dimensional meteorological-hydrological drought propagation identification and matching method, storage medium and program product

Abstract

The invention discloses a three-dimensional meteorological-hydrological drought propagation identification and matching method, a storage medium and a program product, and the method comprises the steps: employing an elbow method to determine a proportion parameter of a minimum drought area in a whole watershed and a proportion parameter of a minimum overlapping area based on a meteorological drought index matrix and a hydrological drought index matrix, and combining with a moderate drought standard threshold value to determine the proportion of the minimum drought area in the whole watershed; identifying all meteorological drought events and hydrological drought events; pairing the identified meteorological drought event and hydrological drought event to generate a meteorological-hydrological drought event pair; grouping the meteorological-hydrological drought event pairs according to whether the drought events repeatedly appear in all the meteorological-hydrological drought event pairs or not, and generating drought event groups; and by taking the drought event group as a unit, extracting the characteristics of the transfer process from the meteorological drought event to the hydrological drought event. According to the method, the characteristic change in the meteorological-hydrological drought propagation process can be quantitatively identified, the propagation characteristics from meteorological drought to hydrological drought are visually revealed, and the propagation mechanism between meteorological drought and hydrological drought is clarified.

Description

Technical Field

[0001] The present invention belongs to the technical field of drought transmission identification, and in particular relates to a three-dimensional meteorological-hydrological drought transmission identification and matching method, a storage medium and a program product. Background Art

[0002] Currently, most research on drought, both domestically and internationally, is based on drought events at grid points, using run theory to identify drought events. Run theory identifies drought events from a temporal perspective. However, its singular focus on time loses significant spatial information and fails to comprehensively reflect the dynamics of drought events across time and space. Drought, as a meteorological phenomenon that develops simultaneously in time and space, is complex and requires a three-dimensional perspective for analysis.

[0003] Lettenmaier et al. first proposed the severity-area-duration (SAD) method to track the spatiotemporal variation of drought. This method has been widely used in drought research at the basin, continental, and even global scales. Subsequently, V. Diaz et al. employed a drought migration tracking method based on the distance from the drought centroid and applied it to both the basin and continental scales. Wu Chuanhao et al. improved the traditional SAD method and compared its effectiveness. They also compared the effectiveness of two-dimensional and three-dimensional methods.

[0004] Despite significant progress in three-dimensional drought identification methods, they still suffer from significant uncertainty. Whether a drought is continuous in time is conceptually or parameterized, which cannot accurately and truly reflect the drought transmission process and significantly limits the identification of drought transmission characteristics. For example, V. Diaz and Liu Yi et al. calculated the overlapping area between consecutive time slices of each drought patch to make judgments. This can lead to temporal discontinuities in rapidly evolving droughts. By leveraging the transmission links between meteorological and hydrological droughts, matching drought events and grouping them into one-to-one, one-to-many, and many-to-many scenarios, and studying these groups, the impact of three-dimensional drought identification errors can be reduced. Therefore, comprehensively matching drought events across time and space, calibrating the parameters of the identification method, and then quantitatively identifying drought transmission characteristics are key issues to address in clarifying the mechanisms of drought transmission. Summary of the Invention

[0005] To address the above issues, the present invention proposes a three-dimensional meteorological-hydrological drought propagation identification and matching method, storage medium, and program product. These methods can comprehensively match the characteristics of drought events in the temporal and spatial dimensions, quantitatively identify characteristic changes during the meteorological-hydrological drought propagation process, intuitively reveal the propagation characteristics of meteorological drought to hydrological drought, and clarify the propagation mechanism between meteorological drought and hydrological drought.

[0006] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, the present invention provides a three-dimensional meteorological-hydrological drought propagation identification and matching method, comprising:

[0008] Based on the grid precipitation, runoff and evapotranspiration data with longitude-latitude-time dimensions, the meteorological drought index matrix and hydrological drought index matrix with longitude-latitude-time dimensions are calculated;

[0009] Based on the meteorological drought index matrix and the hydrological drought index matrix, the elbow method was used to determine the minimum drought area ratio parameter of the entire basin and the minimum overlapping area ratio parameter. Combined with the moderate drought standard threshold, all meteorological drought events and hydrological drought events in the study period were identified.

[0010] Pair the identified meteorological drought events with the hydrological drought events to generate meteorological-hydrological drought event pairs;

[0011] Grouping the meteorological-hydrological drought event pairs according to whether the drought events occur repeatedly in all meteorological-hydrological drought event pairs to generate drought event groups;

[0012] Taking drought event groups as units, the characteristics of the transmission process from meteorological drought events to hydrological drought events are extracted, and the meteorological-hydrological drought propagation process in time and space is analyzed.

[0013] In combination with the first aspect, optionally, the calibration method of the minimum drought area ratio parameter to the entire basin and the minimum overlap area ratio parameter includes:

[0014] The minimum overlapping area ratio parameter is defined as b, and the minimum drought area ratio parameter is defined as p.

[0015] Let b = 0.01, take p as the variable, start from 0.01, 0.01 as the step size, and the upper bound is 1, and identify drought events one by one based on the meteorological drought index matrix and the hydrological drought index matrix;

[0016] The number of drought events is used as the vertical axis and p as the horizontal axis to generate a curve, and the horizontal axis value of the maximum inflection point of the curve is used as the calibrated p;

[0017] Let p remain at the calibrated value, b as a variable, starting from 0.01, 0.01 as the step size, and the upper bound is 1, and based on the meteorological drought index matrix and the hydrological drought index matrix, identify and record drought events one by one;

[0018] The number of drought events is used as the vertical axis and b as the horizontal axis to generate a curve, and the horizontal axis value of the maximum inflection point of the curve is used as the calibrated b.

[0019] In conjunction with the first aspect, optionally, the method for identifying meteorological drought events and hydrological drought events includes:

[0020] For the meteorological drought index matrix and the hydrological drought index matrix, the grid points whose drought index at the monthly scale is less than the moderate drought standard threshold are respectively screened out, and drought patches are formed based on the screened grid points using the Euclidean distance clustering algorithm;

[0021] Calculate the number of grid points of the drought patch, and calculate the area of ​​the drought patch by the resolution of a single grid point. If the area of ​​the drought patch is greater than the minimum patch area, it means that the drought patch is established; otherwise, the drought patch is discarded.

[0022] The drought patches were temporally connected and the overlapping area ratio between drought patches in adjacent months was calculated. If the calculated overlapping area ratio was less than the minimum overlapping area ratio parameter, the two drought patches were marked as two independent drought events; otherwise, the two drought patches were marked as the same drought event.

[0023] All meteorological drought events and hydrological drought events during the study period were numbered separately to complete the identification of meteorological drought events and hydrological drought events.

[0024] In combination with the first aspect, optionally, the overlapping area ratio is calculated using the following formula:

[0025]

[0026] Where, P overlap is the overlapping area ratio, A * is the area of ​​drought patch overlap, A t is the number of grid points of drought patches at the tth moment, A t+1 is the number of grid points of drought patches at the t+1th moment.

[0027] In combination with the first aspect, optionally, the minimum plaque area is calculated using the following formula:

[0028] S min =p×S;

[0029] Where S minis the minimum patch area, p is the ratio of the minimum drought area to the whole basin, and S is the basin area.

[0030] In combination with the first aspect, optionally, the moderate drought standard threshold is -1, the minimum drought area ratio parameter to the entire basin is 0.06, and the minimum overlapping area ratio parameter is 0.2.

[0031] In conjunction with the first aspect, optionally, the method for generating meteorological-hydrological drought event pairs includes:

[0032] Identify whether the meteorological three-dimensional drought event and the hydrological three-dimensional drought event intersect in time and space. If they do intersect, record the numbers of the intersecting meteorological drought event and hydrological drought event respectively.

[0033] The order of occurrence of all intersecting meteorological drought events and hydrological drought events is determined. If the meteorological drought event occurs earlier than the hydrological drought event, the intersecting meteorological drought event and hydrological drought event are considered a successfully matched drought event pair. If the meteorological drought event occurs later than the hydrological drought event, the ratio of the intersecting volume when the meteorological drought event occurs later than the hydrological drought event to the average value of the meteorological drought event and the hydrological drought event is calculated. If the ratio is greater than the set ratio threshold, the intersecting meteorological drought event and hydrological drought event are considered a successfully matched drought event pair. Other event situations are considered to be drought matching failures.

[0034] In combination with the first aspect, optionally, the drought event group consists of drought event pairs, including the following three situations:

[0035] Case 1: There is a one-to-one relationship between meteorological drought events and hydrological drought events:

[0036] In this case, a pair of drought events forms a drought event group;

[0037] Case 2: There is a one-to-many relationship between meteorological drought events and hydrological drought events:

[0038] In this case, all involved drought event pairs are combined into a drought event group;

[0039] Case 3: There is a many-to-many relationship between meteorological drought events and hydrological drought events:

[0040] In this case, all involved drought event pairs are grouped into a drought event group, in which the number of meteorological drought events and hydrological drought events is greater than 1.

[0041] In a second aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the three-dimensional meteorological-hydrological drought propagation identification and matching method described in any one of the first aspects.

[0042] In a third aspect, the present invention provides a computer program product comprising a computer program / instruction, which, when executed by a processor, implements the three-dimensional meteorological-hydrological drought propagation identification and matching method described in any one of the first aspects.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention calibrates drought identification parameters and searches for the optimal full-basin ratio parameter and minimum overlapping area ratio parameter within a selectable parameter range, thereby optimizing drought event identification, reducing the interference of small-scale drought events on drought characteristics, and rationally distinguishing consecutive drought events. By recombination of drought event pairs, interrelated drought event pairs are regrouped, allowing those incorrectly identified as multiple drought events to be recombined into a single group of drought events. This achieves rational identification of drought events, reduces interference from incorrect identification, and facilitates accurate extraction of drought event characteristics. By calibrating drought identification parameters and recombinating drought event pairs, the present invention achieves both drought event identification and feature extraction, improving drought feature extraction to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0046] Figure 1 This is one of the flow charts of the three-dimensional meteorological-hydrological drought propagation identification and matching method in one embodiment of the present invention;

[0047] Figure 2 This is a second flow chart of a method for identifying meteorological drought events and hydrological drought events in one embodiment of the present invention;

[0048] Figure 3 is a schematic diagram of the intersection volume of drought events in drought event matching in one embodiment of the present invention;

[0049] Figure 4 This is a diagram of a typical "one-to-one" meteorological-hydrological drought event pair transmission process in one embodiment of the present invention;

[0050] Figure 5 This is a diagram of the transmission process of a typical "one-to-many" meteorological-hydrological drought event pair in one embodiment of the present invention;

[0051] Figure 6This is a diagram of the transmission process of a typical meteorological-hydrological drought event pair of "many-to-many" type in one embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0053] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0054] Example 1

[0055] The present invention provides a three-dimensional meteorological-hydrological drought propagation identification and matching method, such as Figure 1 As shown, the following steps are included:

[0056] (1) Based on the grid precipitation, runoff and evapotranspiration data with longitude-latitude-time dimensions, the meteorological drought index matrix and the hydrological drought index matrix with longitude-latitude-time dimensions are calculated;

[0057] (2) Based on the meteorological drought index matrix and the hydrological drought index matrix, the elbow method is used to determine the minimum drought area ratio parameter of the entire basin and the minimum overlapping area ratio parameter, and combined with the moderate drought standard threshold, all meteorological drought events and hydrological drought events in the study period are identified, as well as their duration, cumulative intensity, and maximum impact range;

[0058] (3) Pairing the identified meteorological drought events and hydrological drought events to generate meteorological-hydrological drought event pairs;

[0059] (4) grouping the meteorological-hydrological drought event pairs according to whether the drought event appears repeatedly in all meteorological-hydrological drought event pairs to generate drought event groups;

[0060] (5) Taking drought event groups as units, extract the characteristics of the transmission process from meteorological drought events to hydrological drought events, and analyze the meteorological-hydrological drought propagation process in time and space. In the specific implementation process, the analysis of the meteorological-hydrological drought propagation process in time and space specifically refers to analyzing the duration, cumulative intensity, maximum impact range, development and decline process of meteorological-hydrological drought, and the spatial transfer process of drought centroid, and using this to characterize the meteorological-hydrological drought propagation process in time and space.

[0061] In a specific implementation of the embodiment of the present invention, the calculation method of the meteorological drought index matrix and the hydrological drought index matrix includes:

[0062] According to actual needs, drought indicators and drought time scales are selected; in the specific implementation process, the drought indicators include the standardized precipitation evapotranspiration index (i.e., meteorological drought index) and the standardized runoff index (i.e., hydrological drought index); the drought time scale is generally selected as one month; the calculation process of the standardized precipitation evapotranspiration index and the standardized runoff index is prior art, so it will not be described in detail in the present invention;

[0063] Based on the grid potential evapotranspiration data and raster runoff data in the raster precipitation, runoff and evapotranspiration data with longitude-latitude-time dimensions, the meteorological drought index matrix and the hydrological drought index matrix with three-dimensional characteristics were calculated according to the drought index calculation method. The parameter in the meteorological drought index matrix is ​​the standardized precipitation evapotranspiration index; the parameter in the hydrological drought index matrix is ​​the standardized runoff index.

[0064] An appropriate minimum drought area to basin ratio parameter p can filter out droughts with a small impact range and high frequency when identifying drought events, while retaining large-scale droughts, reducing the interference of small droughts, and reasonably reflecting the drought characteristics of the region. An appropriate minimum overlapping area ratio parameter b can reasonably distinguish two drought events that overlap in time and space, without misclassifying one drought event into two. To this end, in a specific implementation of an embodiment of the present invention, the calibration method of the minimum drought area to basin ratio parameter and the minimum overlapping area ratio parameter includes:

[0065] The minimum overlapping area ratio parameter is defined as b, and the minimum drought area ratio parameter is defined as p.

[0066] Let b = 0.01, take p as the variable, start from 0.01, 0.01 as the step size, and the upper bound is 1, and identify drought events one by one based on the meteorological drought index matrix and the hydrological drought index matrix; the identification of drought events refers to the identification of meteorological drought events and hydrological drought events;

[0067] The number of drought events is used as the vertical axis and p as the horizontal axis to generate a curve, and the horizontal axis value of the maximum inflection point of the curve is used as the calibrated p;

[0068] Let p remain at the calibrated value, b as a variable, starting from 0.01, 0.01 as the step size, and the upper bound is 1, and based on the meteorological drought index matrix and the hydrological drought index matrix, identify and record drought events one by one;

[0069] The number of drought events is used as the vertical axis and b as the horizontal axis to generate a curve, and the horizontal axis value of the maximum inflection point of the curve is used as the calibrated b.

[0070] In a specific implementation of the embodiment of the present invention, Figure 2 As shown, the method for identifying meteorological drought events and hydrological drought events includes:

[0071] For the meteorological drought index matrix and the hydrological drought index matrix, the grid points whose drought index at the monthly scale is less than the moderate drought standard threshold are respectively screened out, and drought patches are formed based on the screened grid points using the Euclidean distance clustering algorithm;

[0072] Calculate the number of grid points of the drought patch, and calculate the area of ​​the drought patch by the resolution of a single grid point. If the area of ​​the drought patch is greater than the minimum patch area, it means that the drought patch is established; otherwise, the drought patch is discarded.

[0073] The drought patches were temporally connected and the overlapping area ratio between drought patches in adjacent months was calculated. If the calculated overlapping area ratio was less than the minimum overlapping area ratio parameter, the two drought patches were marked as two independent drought events; otherwise, the two drought patches were marked as the same drought event.

[0074] All meteorological drought events and hydrological drought events during the study period were numbered separately to complete the identification of meteorological drought events and hydrological drought events.

[0075] In a specific implementation of the embodiment of the present invention, the overlapping area ratio is calculated using the following formula:

[0076]

[0077] Where, P overlap is the overlapping area ratio, A * is the area of ​​drought patch overlap, A t is the number of grid points of drought patches at the tth moment, A t+1 is the number of grid points of drought patches at the t+1th moment.

[0078] In a specific implementation of the embodiment of the present invention, the minimum plaque area is calculated using the following formula:

[0079] S min =p×S;

[0080] Where S min is the minimum patch area, p is the basin-wide ratio parameter of the minimum drought area station, and S is the basin area.

[0081] In a specific implementation of the embodiment of the present invention, the moderate drought standard threshold is -1, the minimum drought area ratio parameter of the entire basin is 0.06, and the minimum overlapping area ratio parameter is 0.2.

[0082] In a specific implementation of the embodiment of the present invention, Figure 3 As shown, the method for generating meteorological-hydrological drought event pairs includes:

[0083] Identify whether the meteorological three-dimensional drought event and the hydrological three-dimensional drought event intersect in time and space. If they do intersect, record the numbers of the intersecting meteorological drought event and hydrological drought event respectively.

[0084] The order of occurrence of all intersecting meteorological drought events and hydrological drought events is determined. If the meteorological drought event occurs earlier than the hydrological drought event, the intersecting meteorological drought event and hydrological drought event are considered a successfully matched drought event pair. If the meteorological drought event occurs later than the hydrological drought event, the ratio of the intersecting volume when the meteorological drought event occurs later than the hydrological drought event to the average value of the meteorological drought event and the hydrological drought event is calculated. If the ratio is greater than the set ratio threshold, the intersecting meteorological drought event and hydrological drought event are considered a successfully matched drought event pair. Other event situations are considered to be drought matching failures.

[0085] In the process of identifying drought events, it is inevitable that drought event identification errors may occur, resulting in one drought event being divided into multiple drought events. However, by regrouping drought event pairs, interrelated meteorological and hydrological droughts can be re-merged into the same group, eliminating the interference of drought event misidentification on drought characteristics. To this end, in a specific implementation of the present invention, the drought event group is composed of drought event pairs, including the following three situations:

[0086] Case 1: There is a one-to-one relationship between meteorological drought events and hydrological drought events:

[0087] In this case, a pair of drought events forms a drought event group;

[0088] Case 2: There is a one-to-many relationship between meteorological drought events and hydrological drought events:

[0089] In this case, all involved drought event pairs are combined into a drought event group;

[0090] Case 3: There is a many-to-many relationship between meteorological drought events and hydrological drought events:

[0091] In this case, all involved drought event pairs are grouped into a drought event group, in which the number of meteorological drought events and hydrological drought events is greater than 1. The drought event group generated in Case 1 is defined as a simple drought event group, where both meteorological drought events and hydrological drought events are considered to be the same drought event. The drought event groups generated in Cases 2 and 3 are defined as complex drought event groups.

[0092] In a specific implementation of the present invention, the characteristics of the process of transferring a meteorological drought event to a hydrological drought event include: the maximum impact range of the drought event, the duration of the drought event, the cumulative drought severity of the drought event, the spatiotemporal centroid of the drought event, the duration of a drought event group, the cumulative drought severity of a drought event group, and the spatial centroid movement of the drought event group. The process of extracting the characteristics of the process of transferring a meteorological drought event to a hydrological drought event is implemented using existing technology and is not further described in detail in the present invention.

[0093] In this embodiment, the meteorological drought and hydrological drought in the Yellow River Basin from 1961 to 2022 are taken as an example to specifically illustrate the execution process of the three-dimensional meteorological-hydrological drought propagation identification and matching method based on the recombination of drought event pairs.

[0094] The Yellow River Basin spans arid, semi-arid, and semi-humid regions. Due to its vast area and significant elevation differences from east to west, the hydrological and meteorological conditions are complex and changeable, and drought conditions vary from region to region. Precipitation in the Yellow River Basin is mostly between 200-650 mm, concentrated from June to September. The average annual evaporation is 1,100 mm, and the average annual natural runoff is 53.48 billion m3. The per capita water volume in the basin is less than 600 m3. 3 , accounting for only a quarter of the national average. The drought situation is more prominent. Between 1966 and 2010, there were 16 years of severe drought or above, which caused a reduction in grain production and huge economic losses.

[0095] In this example, the CN05.1 gridded dataset with a resolution of 0.25°×0.25° from the Climate Change Research Center is used, and the VIC model is used to simulate the daily hydrological process to provide a 0.25°×0.25° gridded runoff.

[0096] In this embodiment, a three-dimensional meteorological-hydrological drought propagation identification and matching method based on the recombination of drought event pairs is used to match meteorological-hydrological drought event pairs in the Yellow River Basin and quantitatively identify the transmission characteristics of meteorological-hydrological drought event pairs.

[0097] 1. Identification results of meteorological drought events and hydrological drought events

[0098] Using drought identification methods, a total of 262 meteorological drought events and 181 hydrological drought events were identified in the Yellow River Basin from 1961 to 2022. Based on the grouping of drought events, drought characteristics were extracted based on drought event groups. The average duration of meteorological drought was 1.62 months, the average area affected by meteorological drought accounted for 43.4% of the entire basin, and the average meteorological drought intensity was 10.72*105months*km. 2 The average duration of hydrological drought was 1.38 months, the average area affected by hydrological drought accounted for 21.5% of the entire basin, and the average hydrological drought intensity was 4.49*105months*km 2 .

[0099] 2. Transmission characteristics of meteorological-hydrological drought event groups

[0100] After drought event matching and regrouping, 81 drought event groups were formed, including 62 "one-to-one" groups, 18 "one-to-many" groups, and 1 "many-to-many" group.

[0101] Figure 4 This is a case study of a "one-to-one" drought event cluster. The meteorological drought occurred one month before the hydrological drought. As the meteorological drought progressed, it advanced from the southeast to the northwest, with the center of mass shifting 15.9 degrees (approximately 1,700 kilometers) northwestward, reaching its maximum area in September. Subsequently, the meteorological drought began to decline, with the center of mass shifting back southeastward. Simultaneously, the meteorological drought began to fragment and dissipate.

[0102] Figure 5 This is an example of a "one-to-many" drought event cluster. This situation primarily occurs when meteorological droughts persist for a long time. In the autumn of 1998, a widespread drought occurred in North China, which rapidly subsided after November. However, due to surface conditions, hydrological drought was not identified in October. However, as the meteorological drought moved northeastward, hydrological drought began to occur in some areas in January and February 1999.

[0103] Figure 6It is a group of complex drought events. This meteorological drought event developed very rapidly and had the characteristics of a short-term continuous drought. Under the identified identification parameters, the event was divided into two different meteorological droughts. Similarly, due to the influence of underlying surface factors, the hydrological drought was also split into two events. In traditional drought matching methods, meteorological drought events (such as event number 147) may not be connected with subsequent monthly drought events due to low overlap, resulting in an incomplete and inaccurate understanding of the characteristics of drought events. However, by adopting this method, the two January drought events can be reorganized into a single drought event group. This method reduces the impact of sporadic events on the overall drought characteristic analysis by recombining the characteristics of drought events.

[0104] In the embodiment of the present invention Figure 4-Figure 6 Meteorological drought and Hydrological drought refer to meteorological drought and hydrological drought respectively; LAT and LON refer to longitude and latitude respectively.

[0105] Example 2

[0106] Based on the same inventive concept as Example 1, a computer-readable storage medium is provided in an embodiment of the present invention, on which a computer program is stored, characterized in that when the program is executed by a processor, the three-dimensional meteorological-hydrological drought propagation identification and matching method described in Example 1 is implemented.

[0107] Example 3

[0108] Based on the same inventive concept as Example 1, a computer program product is provided in an embodiment of the present invention, including a computer program / instruction, characterized in that when the computer program / instruction is executed by a processor, the three-dimensional meteorological-hydrological drought propagation identification and matching method described in Example 1 is implemented.

[0109] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0110] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0111] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0112] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0113] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all protected by the present invention.

[0114] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A three-dimensional meteorological-hydrological drought propagation identification and matching method, characterized in that: include: Based on the grid precipitation, runoff and evapotranspiration data with longitude-latitude-time dimensions, the meteorological drought index matrix and hydrological drought index matrix with longitude-latitude-time dimensions are calculated; Based on the meteorological drought index matrix and the hydrological drought index matrix, the elbow method was used to determine the minimum drought area ratio parameter of the entire basin and the minimum overlapping area ratio parameter. Combined with the moderate drought standard threshold, all meteorological drought events and hydrological drought events in the study period were identified. Pair the identified meteorological drought events with the hydrological drought events to generate meteorological-hydrological drought event pairs; Grouping the meteorological-hydrological drought event pairs according to whether the drought events occur repeatedly in all meteorological-hydrological drought event pairs to generate drought event groups; Taking drought event groups as units, the characteristics of the transmission process from meteorological drought events to hydrological drought events are extracted, and the meteorological-hydrological drought propagation process in time and space is analyzed.

2. The three-dimensional meteorological-hydrological drought propagation identification and matching method according to claim 1, characterized in that: The calibration method of the minimum drought area to whole basin ratio parameter and the minimum overlapping area ratio parameter includes: The minimum overlapping area ratio parameter is defined as b, and the minimum drought area ratio parameter is defined as p. Let b = 0.01, take p as the variable, start from 0.01, 0.01 as the step size, and the upper bound is 1, and identify and record drought events one by one based on the meteorological drought index matrix and the hydrological drought index matrix; The number of drought events is used as the vertical axis and p as the horizontal axis to generate a curve, and the horizontal axis value of the maximum inflection point of the curve is used as the calibrated p; Let p remain at the calibrated value, b as a variable, starting from 0.01, 0.01 as the step size, and the upper bound is 1, and based on the meteorological drought index matrix and the hydrological drought index matrix, identify and record drought events one by one; The number of drought events is used as the vertical axis and b as the horizontal axis to generate a curve, and the horizontal axis value of the maximum inflection point of the curve is used as the calibrated b.

3. The three-dimensional meteorological-hydrological drought propagation identification and matching method according to claim 2, characterized in that: The method for identifying meteorological drought events and hydrological drought events includes: For the meteorological drought index matrix and the hydrological drought index matrix, grid points whose drought index is less than the moderate drought standard threshold at the monthly scale are respectively screened out, and drought patches are formed based on the screened grid points using the Euclidean distance clustering algorithm; the number of grid points in the drought patch is calculated, and the area of ​​the drought patch is calculated using the resolution of a single grid point. If the area of ​​the drought patch is greater than the minimum patch area, it means that the drought patch is established; otherwise, the drought patch is discarded; the drought patches are temporally connected, and the overlapping area ratio between drought patches in adjacent months is calculated. If the calculated overlapping area ratio is less than the minimum overlapping area ratio parameter, the two drought patches are marked as two independent drought events; otherwise, the two drought patches are marked as the same drought event; All meteorological drought events and hydrological drought events during the study period were numbered separately to complete the identification of meteorological drought events and hydrological drought events.

4. The three-dimensional meteorological-hydrological drought propagation identification and matching method according to claim 3, characterized in that: The overlapping area ratio is calculated by the following formula: Where, P overlap is the overlapping area ratio, A * is the area of ​​drought patch overlap, A t is the number of grid points of drought patches at the tth moment, A t+1 is the number of grid points of drought patches at the t+1th moment.

5. The three-dimensional meteorological-hydrological drought propagation identification and matching method according to claim 3, characterized in that: The minimum plaque area is calculated by the following formula: S min =p×S; Where S min is the minimum patch area, p is the ratio of the minimum drought area to the whole basin, and S is the basin area.

6. The three-dimensional meteorological-hydrological drought propagation identification and matching method according to claim 1, characterized in that: The threshold value of the moderate drought standard is -1, the minimum drought area ratio to the entire basin parameter is 0.06, and the minimum overlapping area ratio parameter is 0.

2.

7. The three-dimensional meteorological-hydrological drought propagation identification and matching method according to claim 3, characterized in that: The method for generating the meteorological-hydrological drought event pair comprises: Identify whether the meteorological three-dimensional drought event and the hydrological three-dimensional drought event intersect in time and space. If they do intersect, record the numbers of the intersecting meteorological drought event and hydrological drought event respectively. The order of occurrence of all intersecting meteorological drought events and hydrological drought events is determined. If the meteorological drought event occurs earlier than the hydrological drought event, the intersecting meteorological drought event and hydrological drought event are considered a successfully matched drought event pair. If the meteorological drought event occurs later than the hydrological drought event, the ratio of the intersecting volume when the meteorological drought event occurs later than the hydrological drought event to the average value of the meteorological drought event and the hydrological drought event is calculated. If the ratio is greater than the set ratio threshold, the intersecting meteorological drought event and hydrological drought event are considered a successfully matched drought event pair. Other event situations are considered to be drought matching failures.

8. The three-dimensional meteorological-hydrological drought propagation identification and matching method according to claim 1, characterized in that: The drought event group consists of drought event pairs, including the following three situations: Case 1: There is a one-to-one relationship between meteorological drought events and hydrological drought events: In this case, a pair of drought events forms a drought event group; Case 2: There is a one-to-many relationship between meteorological drought events and hydrological drought events: In this case, all involved drought event pairs are combined into a drought event group; Case 3: There is a many-to-many relationship between meteorological drought events and hydrological drought events: In this case, all involved drought event pairs are grouped into a drought event group, in which the number of meteorological drought events and hydrological drought events is greater than 1.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the three-dimensional meteorological-hydrological drought propagation identification and matching method according to any one of claims 1 to 8 is implemented.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the three-dimensional meteorological-hydrological drought propagation identification and matching method according to any one of claims 1 to 8 is implemented.

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