Three-dimensional drought event transmission analysis method, device, equipment, storage medium and program product

Abstract

The application discloses a three-dimensional drought event transmission analysis method and device, equipment, a storage medium and a program product, and relates to the technical field of drought monitoring and risk assessment. The method comprises the following steps: acquiring a drought event set of multiple drought types in a target region; for each preset drought transmission direction, determining the synchronization strength of the preset drought transmission direction according to the space-time information of the drought events in each event combination conforming to the preset drought transmission direction, a time delay threshold and a preset spatial overlap threshold; constructing a drought transmission network taking the drought events as nodes and the drought transmission directions between the drought events as edges according to the synchronization strengths of the preset drought transmission directions; and determining a drought transmission analysis result of the target region according to the drought transmission network, so as to solve the defects of the prior art, i.e., the lack of unified depiction of the synchronization strengths and spatial distances between the drought events, and to realize accurate quantification of the drought transmission relationship and effective identification of high-risk areas.

Description

Technical Field

[0001] This invention relates to the field of drought monitoring and risk assessment technology, and in particular to a three-dimensional drought event transmission analysis method, apparatus, equipment, storage medium, and program product. Background Technology

[0002] Drought is one of the key natural disasters affecting water resource security, food production and ecosystem stability. Compared with events such as floods, drought often has the characteristics of wide range of impact, long duration and obvious cumulative effect. Its formation and evolution are controlled by the coupling of multiple spheres such as atmosphere, hydrology, soil and vegetation.

[0003] Existing drought transmission analysis methods are mostly based on basic statistical methods such as time series threshold discrimination and correlation coefficients. They rely solely on empirical thresholds to judge drought transmission relationships, without quantifying the degree of correlation between events (synchronization strength) or systematically considering the correlation of spatial locations (spatial distance). This results in insufficient physical meaning of drought event matching results and makes it difficult to identify high-risk areas of multi-sphere drought transmission from the overall network structure. Summary of the Invention

[0004] The purpose of this invention is to provide a three-dimensional drought event transmission analysis method, apparatus, equipment, storage medium, and program product to address the shortcomings of existing technologies in uniformly characterizing the synchronization intensity and spatial distance between drought events, thereby achieving accurate quantification of drought transmission relationships and effective identification of high-risk areas.

[0005] To achieve the above objectives, firstly, this application provides a three-dimensional drought event transmission analysis method, comprising: Obtain sets of drought events of various drought types within the target region; each drought event set includes multiple drought events. For each preset drought propagation direction, the synchronization intensity of the preset drought propagation direction is determined based on the spatiotemporal information, time delay threshold, and preset spatial overlap threshold of each event combination that conforms to the preset drought propagation direction; wherein, each event combination includes two drought events belonging to different drought event sets, and the spatiotemporal information includes start and end time and spatial impact range. Based on the synchronization intensity of each preset drought transmission direction, a drought transmission network is constructed with drought events as nodes and drought transmission directions between drought events as edges; Based on the drought transmission network, determine the drought transmission analysis results for the target area.

[0006] Secondly, this application also provides a three-dimensional drought event transmission analysis method, including: The acquisition module is used to acquire a set of drought events of various drought types within the target area; each drought event set includes multiple drought events. The determination module is used to determine the synchronization intensity of the preset drought transmission direction for each preset drought transmission direction based on the spatiotemporal information, time delay threshold, and preset spatial overlap threshold of each event combination that conforms to the preset drought transmission direction; wherein, each event combination includes two drought events belonging to different drought event sets, and the spatiotemporal information includes start and end time and spatial impact range. The network construction module is used to construct a drought transmission network with drought events as nodes and drought transmission directions between drought events as edges, based on the synchronization intensity of each preset drought transmission direction. The analysis module is used to determine the drought transmission analysis results for the target area based on the drought transmission network.

[0007] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the various method embodiments provided in the first aspect above.

[0008] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the various method embodiments provided in the first aspect above.

[0009] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the various method embodiments provided in the first aspect above.

[0010] The aforementioned three-dimensional drought event transmission analysis methods, devices, equipment, storage media, and program products provide a standardized basis for unified characterization by acquiring a set of drought events of multiple drought types within the target area. This ensures that drought events of different drought types have clear start and end times and spatial impact ranges, avoiding characterization biases caused by inconsistent event attributes. Secondly, by determining the synchronization intensity based on a preset drought transmission direction, combined with event spatiotemporal information, time delay thresholds, and preset spatial overlap thresholds, the spatial overlap threshold directly achieves a unified quantification of the spatial distance correlation between events, while the synchronization intensity achieves a unified quantification of the degree of correlation between events. This approach replaces traditional empirical judgments and fills the core deficiencies of existing technologies. Secondly, by constructing a drought transmission network based on synchronization intensity, with drought events as nodes and transmission directions as edges, the quantified synchronization intensity and spatial correlation are transformed into a structured network, making the quantitative results of drought transmission relationships more systematic and readable. Finally, based on the transmission network, the drought transmission analysis results for the target area are determined. By integrating standardized node attributes and quantified edge relationships in the network, a precise quantitative presentation of drought transmission relationships is directly achieved. Simultaneously, by leveraging the transmission correlation characteristics reflected by the network structure, high-risk areas with tight transmission correlations and strong spatial correlations are effectively identified. Attached Figure Description

[0011] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 A flowchart illustrating a three-dimensional drought event transmission analysis method provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of a drought index identification result in Embodiment 1 of this application; Figure 3 This refers to the drought transfer network in Embodiment 1 of this application; Figure 4 This is a spatial distribution map of drought-transmitted NSTI in Embodiment 1 of this application; Figure 5 This is a schematic diagram of the functional modules of a three-dimensional drought event transmission analysis method provided in Embodiment 2 of this application; Figure 6 This is a schematic diagram of the structure of a computer device provided in Embodiment 3 of this application. Detailed Implementation

[0012] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.

[0013] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0014] In this invention, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between the associated objects, indicating that three relationships can exist.

[0015] Example 1 Research has revealed that traditional drought event analysis methods attempt to describe the spatiotemporal correlation structure of extreme hydrological and climatic events such as drought by incorporating complex network theory and event synchronization methods. However, these studies primarily focus on single drought indices or types, with limited quantitative diagnosis of the hierarchical transmission relationships between meteorological, soil, and ecological droughts. Furthermore, their network nodes are mostly grids or climate zones, failing to model specific drought events as three-dimensional spatiotemporal objects and lacking a unified index system for quantifying drought intensity and transmission efficiency at the event level. Moreover, current methods for analyzing the transmission of meteorological, soil, and ecological droughts typically rely on basic statistical methods such as time-series threshold discrimination, correlation coefficients, or time lags, using the order and temporal overlap of different droughts as the basis for judging drought transmission. While these methods are technically feasible, they generally rely heavily on empirical thresholds for drought transmission judgment, lack a unified characterization of synchronization intensity and spatial distance between events, easily leading to poorly physically meaningful matching results. Additionally, they have not yet incorporated new methods such as complex network event synchronization into the analysis of the three types of drought linkages, making it difficult to identify high-risk areas for multi-sphere drought transmission from the overall network structure. Therefore, existing technologies still need to introduce a method for analyzing the synchronicity of complex network events within a unified three-dimensional spatiotemporal drought event framework. This would allow for a systematic characterization of the hierarchical transmission process and intensity among meteorological drought, soil drought, and ecological drought, providing more reliable technical support for the precise monitoring and risk diagnosis of multi-sphere drought.

[0016] In order to overcome these technical shortcomings, such as Figure 1 As shown, this embodiment provides a three-dimensional drought event transmission analysis method, including: S1, obtains a set of drought events of various drought types within the target area.

[0017] Each drought event set includes multiple drought events.

[0018] The target area refers to the specific geographical area from which drought event transmission analysis is to be conducted. It can be defined according to monitoring needs (such as administrative regions or hydrological basins) and serves as the spatial carrier for drought transmission analysis. The drought event set refers to a collection of multiple drought events that meet preset conditions (area, duration, intensity) for a specific type of drought. Each drought event is an independent drought phenomenon with a clear spatiotemporal scope.

[0019] Optionally, raw observation data corresponding to different drought types within the target area over a given time period can be collected and analyzed to obtain a set of drought events for different drought types. In this embodiment, drought types may include meteorological drought, soil drought, and ecological drought. Meteorological drought is caused by precipitation shortage, soil drought by insufficient soil moisture, and ecological drought by vegetation water stress. These drought types are the core types of drought transmission.

[0020] As an optional implementation, the specific process of S1 includes: S11: Obtain the raw observation data corresponding to different drought types within the target area.

[0021] The so-called raw observation data refers to the basic monitoring data corresponding to different drought types. The raw observation data for meteorological drought can include precipitation data used to monitor meteorological drought, the raw observation data for soil drought can include soil moisture data used to monitor soil drought, and the raw observation data for ecological drought can include NDVI (Normalized Difference Vegetation Index) data used to monitor ecological drought.

[0022] Optionally, the geographical scope of the target area (such as a specific administrative region, hydrological basin, or latitude and longitude definition) and the analysis time span can be determined according to the needs. Precipitation data, soil moisture data, and NDVI data of the target area under the corresponding analysis time span can be collected, and the data spatial resolution can be uniform and there can be no obvious missing or abnormal data.

[0023] S12, for each drought type, perform steps S13-S16.

[0024] S13 identifies multiple initial drought blocks based on the original monitoring data of drought type and preset drought intensity threshold.

[0025] The so-called initial drought block refers to the drought area initially identified based on the drought intensity threshold, which is the prototype of a drought event; the so-called preset drought intensity threshold refers to the critical value for judging the occurrence of drought, which is used to distinguish between drought and non-drought areas.

[0026] Optionally, the NDVI data can be preprocessed first. For example, the seasonal trend decomposition method based on locally weighted regression can be used to preprocess the NDVI data to remove seasonal fluctuations and long-term trend interference. Then, according to the precipitation data, soil moisture data, and preprocessed NDVI data, the corresponding drought indices are calculated respectively. Taking the precipitation data as the precipitation data with a 90-day cumulative time scale, the soil moisture data as the soil moisture data with a 30-day cumulative time scale, and the NDVI data as the NDVI data with a 30-day cumulative time scale as an example, the standardized precipitation index SPI-90 on a 90-day scale, the standardized soil moisture index SSMI-30 on a 30-day scale, and the standardized normalized vegetation index SNDVI-30 are calculated respectively based on the precipitation data, soil moisture data, and preprocessed NDVI data; when calculating the daily-scale SPI, the cumulative precipitation should be calculated for daily values using a suitable length sliding window; referring to the construction method of SPI, based on the assumption that the soil moisture and NDVI in the same period of previous years conform to a normal distribution, the soil moisture and NDVI are subjected to normal standardization processing to construct the daily standardized soil moisture index SSMI-30 and the standardized normalized vegetation index SNDVI-30. Preset drought intensity thresholds include precipitation intensity thresholds, soil moisture intensity thresholds, and vegetation intensity thresholds, and the SPI-90, SSMI-30, and SNDVI-30 are respectively restricted by the intensity thresholds a, b, and c. All three-dimensional drought blocks of meteorological drought (i.e., initial drought blocks) are identified by the condition SPI-90 < a, all three-dimensional drought blocks of soil drought are identified by the condition SSMI-30 < b, and all three-dimensional drought blocks of ecological drought are identified by the condition SNDVI-30 < c.

[0027] S14. Eliminate the initial drought blocks with a spatial projection area smaller than the preset area threshold, and merge at least two remaining initial drought blocks after elimination whose spatial projection overlapping area exceeds the preset block merging spatial overlapping threshold and the time interval between occurrences is less than the preset time interval threshold, to obtain the drought blocks after merging processing.

[0028] Among them, the so-called preset area threshold refers to the critical area for eliminating sporadic droughts, ensuring the spatial significance of drought events.

[0029] The so-called preset block merging spatial overlapping threshold refers to the critical overlapping ratio for merging adjacent drought blocks, uniformly depicting the spatial continuity of drought events.

[0030] The so-called preset time interval threshold refers to the critical time difference for merging adjacent drought blocks, ensuring the time continuity of drought events.

[0031] The so-called drought blocks after merging processing refer to the drought areas after elimination and merging, which are more in line with the characteristics of actual drought events.

[0032] Optionally, a minimum drought area threshold (i.e., a preset area threshold) can be set to... All three-dimensional drought blocks, including meteorological drought, soil drought, and ecological drought, were screened, and those with a spatial projection area smaller than [amount missing] were excluded. The three-dimensional drought blocks are defined. An overlap area threshold (i.e., a preset block merging spatial overlap threshold) is set as the smaller area α (%) of the spatial projected areas of the two three-dimensional drought blocks, and a time interval threshold (i.e., a preset time interval threshold) is set as t0 (days). The remaining three-dimensional drought blocks (i.e., the remaining initial drought blocks) after the removal of meteorological drought, soil drought, and ecological drought are judged. Taking the remaining three-dimensional drought blocks of meteorological drought as an example, if the overlap of the spatial projected areas of the two three-dimensional drought blocks (i.e., the remaining three-dimensional drought blocks) is greater than the overlap area threshold and the time interval between the two three-dimensional drought blocks is less than the time interval threshold, then the two three-dimensional drought blocks are merged to obtain a merged drought block, and the two three-dimensional drought blocks are considered as the same drought event; otherwise, the two three-dimensional drought blocks are not merged, and the two three-dimensional drought blocks are considered as two independent drought events.

[0033] S15, remove drought blocks whose duration is less than the preset duration from the drought blocks after merging, and obtain the target drought block.

[0034] The duration refers to the difference between the end time and the start time of the drought block after merging.

[0035] The so-called preset duration refers to the critical duration that excludes short-term droughts, ensuring the temporal salience of drought events.

[0036] Optionally, a duration threshold (i.e., a preset duration) is set to T (days). Drought blocks whose duration is less than the preset duration are removed from the combined drought blocks corresponding to the three types of drought: meteorological drought, soil drought, and ecological drought, to obtain the target drought block.

[0037] S16 defines the target drought block as a drought event, thereby forming a set of drought events of drought type.

[0038] Optionally, each target drought block is considered a drought event. Drought events are sorted and numbered according to a priority order of start time → end time → spatially projected area. Specifically, drought events are sorted by start time; if start times are the same, they are sorted by end time; if both start and end times are the same, they are sorted by the size of the spatially projected area of ​​the drought block, with smaller drought-affected areas ranked first. Following this method, a set of meteorological drought events, a set of soil drought events, and a set of ecological drought events, each containing multiple standardized drought events, are ultimately formed.

[0039] This embodiment, through steps S11-S16, provides a standardized drought event unit for the unified characterization of synchronization intensity and spatial distance. First, by presetting parameters such as area thresholds and spatial overlap thresholds, the spatial saliency and continuity of drought events are ensured, providing a reliable spatial carrier for spatial distance characterization (spatial overlap calculation). Second, the standardized event set makes the spatiotemporal information of different drought types comparable, avoiding deviations in synchronization intensity calculation caused by inconsistent event definitions. Finally, the drought events constructed by this method have clear spatiotemporal ranges and intensity characteristics, laying the foundation for the subsequent quantification of synchronization intensity and spatial distance of event combinations, indirectly supporting the overcoming of core shortcomings.

[0040] S2, for each preset drought transmission direction, determine the synchronization intensity of the preset drought transmission direction based on the spatiotemporal information, time delay threshold and preset spatial overlap threshold of each event combination that conforms to the preset drought transmission direction.

[0041] Each event combination includes two drought events belonging to different drought event sets, and the spatiotemporal information includes start and end times and spatial impact range.

[0042] The so-called pre-defined drought transmission direction refers to the drought transmission path set based on physical logic, including meteorological drought → soil drought, meteorological drought → ecological drought, and soil drought → ecological drought.

[0043] The so-called event combination refers to a pair of drought events belonging to two different drought types and conforming to the preset transmission direction time logic (the baseline drought precedes the target drought). It is the basic unit for quantifying the synchronization intensity and spatial distance.

[0044] Spatiotemporal information refers to the start and end times (temporal attribute) and spatial impact range (spatial attribute) of drought events, which is the core basis for calculating synchronization intensity and spatial distance.

[0045] The so-called time delay threshold refers to the critical value (including minimum and maximum delay) for judging the time correlation of event combinations, and is used to filter event combinations with reasonable time lag.

[0046] The so-called preset spatial overlap threshold refers to the critical proportion for judging the spatial correlation of event combinations. It is used to quantify the tightness of spatial distance and is the core parameter for uniformly characterizing spatial distance.

[0047] Synchronization intensity refers to the ratio of the number of matching event combinations to the total number of baseline drought events in the preset transmission direction. It is used to uniformly characterize the degree of correlation between events and has a value range of [0,1].

[0048] Optionally, for each preset drought transmission direction (based on the physical logic of drought formation and evolution, such as meteorological drought → soil drought, meteorological drought → ecological drought, soil drought → ecological drought), first associate the two sets of drought events corresponding to the transmission direction (i.e., the set of drought events at the transmission starting point and the set of drought events at the transmission ending point), and construct all event combinations that satisfy the basic temporal logic that the occurrence time of the starting drought event is earlier than that of the ending drought event; for each event combination, extract the spatiotemporal information of the two types of drought events (including start and end times and spatial influence range), calculate the time delay of the event combination based on the start and end times, and calculate the spatial overlap of the event combination based on the spatial influence range; then, according to the preset time delay threshold (including the minimum delay threshold and the maximum delay threshold) and the preset spatial overlap threshold, perform double screening on all event combinations, and retain matching event combinations that meet the threshold requirements for both time delay and spatial overlap; finally, by statistically calculating the total number of matching event combinations and the ratio with the total number of drought events contained in the drought event set at the transmission starting point, the synchronization intensity of the preset drought transmission direction is obtained, thereby completing the determination of the synchronization intensity of all preset transmission directions one by one.

[0049] As an optional implementation, the specific process of S2 includes: S21, Based on the set of drought events of two different drought types associated with the preset drought transmission direction, determine multiple event combinations.

[0050] Optionally, based on the one-way transmission rule (i.e., the preset drought transmission direction), it is limited to matching only when meteorological drought occurs before soil and ecological drought, and soil drought occurs before ecological drought. The two types of drought event sets corresponding to each preset drought transmission direction are associated (i.e., the drought event set at the transmission starting point and the drought event set at the transmission ending point). All event combinations that satisfy the basic time logic that the starting point drought event occurs earlier than the ending point drought event are constructed. This results in event combinations of multiple meteorological drought events → soil drought events, multiple meteorological drought events → ecological drought events, and multiple soil drought events → ecological drought events, thereby ensuring that the transmission relationship conforms to physical logic.

[0051] S22, for each event combination, determine the time delay and spatial overlap of the event combination based on the spatiotemporal information of each drought event in the event combination.

[0052] The so-called time delay refers to the time difference between the start of the target drought and the baseline drought in the event combination, and is used to characterize the correlation in the time dimension.

[0053] Spatial overlap refers to the proportion of overlap in the spatial influence range of two drought events in a combination of events, and is a core indicator for uniformly describing spatial distance.

[0054] Optionally, for combinations of meteorological drought events (i=1, 2, ...) and soil drought events (j=1, 2, ...), the dynamic delay (i.e., time delay) between meteorological drought event M(i) and soil drought event S(j) is calculated:

[0055] in, The dynamic delay between a meteorological drought event with sequence number i occurring in region m and a soil drought event with sequence number j occurring in region n. Let i be the start time of the meteorological drought event with sequence number i that occurred in region m. Let j be the start time of the soil drought event that occurred in region n. and Let m be the time difference between the start of two consecutive meteorological drought events in region m. and Let be the start time difference between two consecutive soil drought events in region n. Similarly, for the event combinations corresponding to meteorological drought events (i=1, 2, ...), soil drought events (j=1, 2, ...), and ecological drought events (k=1, 2, ...), calculate the dynamic delay between meteorological drought event M(i) and ecological drought event E(k), and the dynamic delay between soil drought event S(j) and ecological drought event E(k):

[0056]

[0057] in, The dynamic delay between a meteorological drought event with sequence number i occurring in region m and an ecological drought event with sequence number k occurring in region p. This represents the dynamic delay between a soil drought event with sequence number j occurring in region n and an ecological drought event with sequence number k occurring in region p. Let i be the start time of the meteorological drought event with sequence number i that occurred in region m. This represents the start time of the ecological drought event with sequence number k that occurred in region p. Let j be the start time of the soil drought event that occurred in region n. and Let m be the time difference between the start of two consecutive meteorological drought events in region m. and Let p be the time difference between the start of two consecutive ecological drought events. and Let be the time difference between the start of two consecutive soil drought events in region n. Since drought propagation is regional, spatial constraints (i.e., spatial overlap) are introduced for the region m of meteorological drought events, the region n of soil drought events, and the region p of ecological drought events. :

[0058]

[0059]

[0060] in, Let m be the spatial overlap between region m and region n. Let m be the spatial overlap between region m and region p. Let n be the spatial overlap between region n and region p. The spatial projected area of ​​the meteorological drought event in region m. Let n be the spatial projected area of ​​the soil drought event in region n. The spatial projection area of ​​the regional ecological drought event p.

[0061] S23, based on the preset time delay threshold, the preset spatial overlap threshold, and the time delay and spatial overlap of each event combination, filter matching event combinations from all event combinations.

[0062] Among them, the so-called matching event combination refers to the event combination that simultaneously satisfies the time delay threshold, the spatial overlap threshold, and the time logic, and is an effective sample for calculating the synchronization strength.

[0063] The so-called preset time delay threshold refers to a pre-set reasonable range of time delay (minimum, maximum) used to filter combinations with effective time correlation.

[0064] Optionally, a minimum spatial overlap threshold (i.e., a preset spatial overlap threshold) can be set to... To eliminate unreasonable dynamic delays, a maximum delay threshold is set between meteorological drought events and soil and ecological drought events occurring in the two regions. and minimum delay threshold Take the final delay (i.e., the preset time delay threshold). for ,in The delay is dynamic. Based on the final delay and the minimum spatial overlap threshold, all event combinations are double-filtered, retaining matching event combinations that meet both the time delay and spatial overlap requirements.

[0065] S24, determine the synchronization intensity of the preset drought transmission direction based on the number of matching event combinations.

[0066] Optionally, based on the matching event combinations, the number of times meteorological drought events precede soil drought events can be calculated. The number of meteorological drought events preceding ecological drought events The number of soil drought events preceding ecological drought events :

[0067]

[0068]

[0069] Where the matrix for:

[0070]

[0071]

[0072] Therefore, the synchronization strength can be calculated:

[0073]

[0074]

[0075] in, The synchronization intensity of meteorological drought event m in region and soil drought event n in region. The synchronization intensity of regional meteorological drought event m and regional ecological drought event p. The synchronization intensity of regional n soil drought events and regional p ecological drought events. Let m be the total number of meteorological drought events occurring in region m. Let Q be the total number of soil drought events occurring in region n. When Q equals 1, it means that for every meteorological drought event in region m, at least one soil drought event can be found in region n within a specified lag time (or for every meteorological drought event in region m, at least one ecological drought event can be found in region p within a specified lag time, and for every soil drought event in region n, at least one ecological drought event can be found in region p within a specified lag time).

[0076] Through steps S21-S24 above, the step-by-step quantification and unified characterization of synchronization intensity and spatial distance between events are achieved. First, spatial distance is transformed into a calculable proportional parameter using a spatial overlap index, addressing the lack of spatial dimension characterization in existing technologies. Second, effective event combinations are screened by combining time delay, ensuring the spatiotemporal rationality of transmission relationships. Finally, the degree of correlation is quantified through synchronization intensity, replacing traditional qualitative judgment. This method makes the spatiotemporal correlation analysis of drought event transmission more quantitatively based, effectively improving the accuracy of transmission relationship judgment and overcoming the core deficiency of existing technologies lacking unified characterization.

[0077] S3. Based on the synchronization intensity of each preset drought transmission direction, construct a drought transmission network with drought events as nodes and drought transmission directions between drought events as edges.

[0078] The so-called drought transmission network refers to a network structure with drought events as nodes and directed edges with effective transmission relationships (meeting the requirements of synchronization intensity and spatial distance) to intuitively present the transmission relationship between events.

[0079] Optionally, based on the actual needs of drought monitoring and analysis, a unified preset synchronization intensity threshold is first set. The synchronization intensity of each preset drought transmission direction is then screened, retaining valid transmission relationships with synchronization intensity reaching or exceeding the threshold, and eliminating associations with insufficient synchronization intensity or no practical transmission significance. All drought events participating in valid transmission relationships (covering the starting and ending drought events of each preset transmission direction) are uniformly treated as network nodes, with each node associated with its corresponding drought type, spatiotemporal range, and other core attributes. Based on the preset drought transmission direction, the correspondence between the starting and ending drought events in the valid transmission relationships is defined as directed edges of the network. The direction of the edges is completely consistent with the drought transmission direction, and the corresponding synchronization intensity can be associated as the weight attribute of the edges as needed. Finally, all nodes and directed edges are integrated in a structured manner to form a drought transmission network with drought events as core nodes and effective transmission directions as directed edges, which can intuitively reflect the transmission associations and intensity characteristics between drought events.

[0080] As an optional implementation, the specific process of S3 includes: S31, for each preset drought transmission direction, compare the synchronization intensity of the preset drought transmission direction with the preset synchronization intensity threshold to obtain the comparison result, and determine the synchronization relationship between drought events in each matching event combination in the preset drought transmission direction based on the comparison result.

[0081] Among them, when the comparison result is that the synchronization strength is not less than the preset synchronization strength threshold, it is determined that there is a valid synchronization relationship.

[0082] The so-called preset synchronization strength threshold refers to the critical value for judging whether the transmission direction is valid, and is used to filter transmission relationships that have practical significance.

[0083] Optionally, a certain screening process can be applied to the synchronization intensity between drought events before matching can be performed. Therefore, the synchronization intensity thresholds for meteorological drought events and soil drought events, meteorological drought events and ecological drought events, and soil drought events and ecological drought events are set as follows: , , Therefore, the synchronization matrix is:

[0084]

[0085]

[0086] in, Let be the synchronization matrix of meteorological drought events in region m and soil drought events in region n. This is the synchronization matrix of regional meteorological drought events (m) and regional ecological drought events (p). Let be the synchronization matrix for soil drought events in region n and ecological drought events in region p, where 1 indicates synchronization (i.e., effective synchronization) and 0 indicates asynchrony. This allows us to determine the synchronization relationships between meteorological drought events and soil drought events, meteorological drought events and ecological drought events, and soil drought events and ecological drought events.

[0087] S32 constructs a drought propagation network with all drought events as nodes and the drought propagation direction between drought events as edges.

[0088] The direction of drought propagation is determined based on the synchronization relationship between drought events and the corresponding preset drought propagation direction.

[0089] Optionally, all drought events are treated as nodes (this could be all drought events with valid synchronization relationships, or all drought events regardless of whether they have valid synchronization relationships), and edges between preset nodes are determined based on the drought transmission direction and synchronization relationships. A drought transmission network is constructed from meteorological drought events to soil drought events, from meteorological drought events to ecological drought events, and from soil drought events to ecological drought events. Based on the constructed drought transmission network, matching meteorological drought events with soil drought events, from meteorological drought events with ecological drought events, and from soil drought events with ecological drought events can be obtained.

[0090] As an alternative implementation, the identified meteorological, soil, and ecological drought events can be used as nodes, and the event synchronization analysis method of complex networks can be used to construct drought transmission networks from meteorological drought to soil drought, from meteorological drought to ecological drought, and from soil drought to ecological drought in sequence. The construction process is similar to the above steps S31-S32, and will not be repeated here.

[0091] Through the steps S31-S32 described above, the uniformly characterized synchronization intensity and spatial distance can be transformed into a visualized drought transmission network. First, effective synchronization relationships ensure that the drought transmission network contains transmission relationships with quantitative evidence, avoiding interference from invalid associations. Second, the design of nodes and edges intuitively presents the distribution characteristics of synchronization intensity (edge ​​thickness) and spatial association (spatial correspondence of nodes) between events. Finally, the drought transmission network provides a structured carrier for subsequent high-risk area identification, solving the problem that existing technologies are difficult to analyze transmission patterns from the overall structure, and further enhancing the application value of the uniform characterization of synchronization intensity and spatial distance.

[0092] S4. Based on the drought transmission network, determine the drought transmission analysis results for the target area.

[0093] The results of drought transmission analysis refer to the conclusions drawn from the transmission network, characterized by the synchronicity of drought transmission in the target area, spatial correlation, and high-risk areas, as well as the use of the National Natural Science Indicator (NSTI).

[0094] Optionally, a unified comprehensive intensity index can be constructed based on the core attributes (including drought intensity, duration, and spatial impact range) of each node (drought event) in the drought transmission network to quantify the overall impact of each drought event. Then, for each edge (drought transmission relationship) in the network, a transmission characteristic index characterizing transmission stability and efficiency is calculated by combining its corresponding synchronization intensity and the comprehensive intensity index of the nodes at both ends of the edge, achieving quantitative fusion of transmission relationships. Next, based on the union of the spatial impact ranges of two drought events associated with a directed edge, the transmission characteristic index is assigned to the corresponding spatial units. For spatial units overlapping multiple event pairs, time weighting or intensity weighting is used for normalization fusion. Uncovered spatial units are filled in through interpolation to ensure spatial continuity of the results. Finally, through structured integration and visualization, drought transmission analysis results that comprehensively reflect the spatial differences in drought transmission stability and efficiency within the target area, as well as the distribution of high-risk areas, are generated, providing a quantitative basis for drought monitoring and risk prevention.

[0095] As an optional implementation, the specific process of S4 includes: S41, for each drought event in the drought transmission network, determine the comprehensive intensity index of the drought event based on the intensity, duration and spatial impact range of the drought event.

[0096] The Comprehensive Intensity Index (SDRI) is a quantitative index obtained by summing the products of drought intensity, duration, and grid area, which characterizes the comprehensive impact of drought events.

[0097] The intensity of a drought event refers to the absolute difference between the drought index and the intensity threshold, which characterizes the extreme nature of drought.

[0098] The duration of a drought event refers to the number of days the drought event lasts within a grid cell, characterizing the persistence of the drought.

[0099] The spatial impact range of a drought event refers to the grid set covered by the drought event, which characterizes the regional nature of drought.

[0100] Optionally, the extreme-persistence-regional drought index (i.e., the comprehensive intensity index, SDRI) of meteorological, soil and ecological drought events in the drought transmission network can be calculated separately.

[0101] For meteorological drought event sequences (i=1, 2, ...), soil drought event sequences (j=1, 2, ...), and ecological drought event sequences (k=1, 2, ...), the SDRI calculation method for each drought event is as follows:

[0102]

[0103]

[0104] in For grid point indexing, The drought intensity is the absolute amount by which the SPI-90, SSMI-30, and SNDVI-30 of this grid are reduced compared to the intensity thresholds a, b, and c of each index. This represents the duration (in days) of drought at this grid location. This represents the area of ​​the grid.

[0105] S42, for each drought event pair at both ends of an edge in the drought transmission network, determine the network synchronization transformation index based on the comprehensive intensity index of each drought event in the drought event pair and the synchronization intensity of the edge corresponding to the drought event pair.

[0106] The Network Synchronization Conversion Index (NSTI) is an index that represents the ratio of converged synchronization strength to overall strength, and uniformly characterizes transmission synchronization and transmission efficiency.

[0107] Optionally, a three-dimensional drought transmission characteristic index—the network synchronization transformation index—is used to calculate the transmission characteristics from meteorological drought to soil drought, from meteorological drought to ecological drought, and from soil drought to ecological drought. This index specifically includes: For meteorological drought event sequences (i=1, 2, ...), soil drought event sequences (j=1, 2, ...), and ecological drought event sequences (k=1, 2, ...), the network synchronization transformation index (NSTI) for the transmission of meteorological drought events to soil drought events, meteorological drought events to ecological drought events, and soil drought events to ecological drought events is calculated as follows:

[0108]

[0109]

[0110] in, Let i be the synchronization intensity of a meteorological drought event with sequence number i in region m and a soil drought event with sequence number j in region n. Let i be the synchronization intensity of a meteorological drought event with sequence number i in region m and an ecological drought event with sequence number k in region p. Let represent the synchronization intensity of soil drought event with sequence number j in region n and ecological drought event with sequence number k in region p. This is an indicator of the extreme-persistent-regional drought characteristics of the meteorological drought event with sequence number i. This is an indicator of the extreme-persistent-regional drought characteristics of the soil drought event with sequence number j. This is an indicator of the extreme-persistent-regional drought of the ecological drought event with sequence number k.

[0111] S43. Based on the spatial influence range of the two drought events in each drought event pair, the network synchronization transformation index of the drought event pair is spatially allocated and fused to form drought transmission analysis results that characterize the stability and efficiency of drought transmission within the target area.

[0112] Spatial allocation and fusion refers to the process of allocating NSTI values ​​to the spatial union of event pairs and weighting and fusion of overlapping regions to achieve spatialization of the analysis results.

[0113] Optionally, for synchronous drought event pairs, the spatial projected area (i.e., spatial influence range) of the three-dimensional drought blocks corresponding to the two drought events is calculated separately, and the union of the two is used as the assignment domain for the synchronous event pair. All grid points within this union are assigned the NSTI value corresponding to the synchronous event pair, while no value is assigned outside the union. When the same grid point is covered by multiple synchronous event pairs simultaneously, the NSTI value is summarized by a normalized weighted average of drought duration weights, thus obtaining the final NSTI value of the grid point. For grid points not covered by any synchronous event pairs, normalized inverse distance weighted interpolation is used to generate a continuous NSTI spatial distribution map. Based on the NSTI spatial distribution map, the drought transmission stability and efficiency analysis results within the target area can be determined. A high NSTI indicates stable drought transmission at this location, and a stronger correlation between the severity of meteorological drought events and the severity of soil drought events (or a stronger correlation between the severity of meteorological drought events and the severity of ecological drought events, and a stronger correlation between the severity of soil drought events and the severity of ecological drought events).

[0114] Steps S41-S43 above achieve deep integration and application of the results of synchronous intensity and spatial distance characterization. The SDRI index quantifies the comprehensive impact of drought events, provides an intensity benchmark for the NSTI index, and makes the characterization of synchronous intensity more practically meaningful; the spatialized analysis results intuitively present the spatial distribution of high-risk areas for drought transmission, solve the problem that existing technologies cannot accurately locate high-risk areas, and fully demonstrate the technical value of uniformly characterizing synchronous intensity and spatial distance.

[0115] This embodiment overcomes the shortcomings of existing technologies in uniformly characterizing the synchronization intensity and spatial distance between events through the above steps. Using spatial overlap as the core parameter, it uniformly quantifies the correlation of spatial distance, avoiding matching biases caused by ignoring spatial dimensions. Furthermore, it quantifies the tightness of the correlation between events through synchronization intensity, replacing traditional empirical threshold judgments and making the characterization of transmission relationships more scientific. By fusing synchronization intensity and comprehensive intensity indicators through the NSTI index, the generated spatial distribution map can accurately identify high-risk areas. This method realizes the transformation of drought transmission relationships from empirical judgment to quantitative characterization, significantly improving the accuracy and reliability of transmission analysis.

[0116] The execution process of the above method is described below with specific examples.

[0117] We have daily precipitation, daily soil moisture (0-28 cm), and daily NDVI data for a certain region from 2002 to 2022, with a spatial resolution of 0.1°. Based on the method of this invention, the process for analyzing the three-dimensional spatiotemporal transmission of drought in this region over the years is as follows: (1) First, the seasonal trend decomposition (STL) method based on local weighted regression is used to deseasonalize and detrend the NDVI. Then, the cumulative precipitation of the previous 90 days is calculated using a 90-day sliding window. Assuming that the cumulative precipitation of the previous 90 days is a random variable, the Gamma distribution F(t) is fitted with the historical value t(y,i) of the same period of the yth year on the i-th day (y=1, 2,…21; i=1, 2,…366). In actual cases, the probability of the event when the cumulative precipitation is 0 is estimated by q=m / n, where m is the number of samples with 0 precipitation and n is the total number of samples. The final distribution is: G(t)=q+(1-q)F(t). The obtained probability value is normalized to obtain the daily SPI-90. Following the SPI construction method, using a 30-day sliding window, and based on the assumption that daily soil moisture and daily NDVI follow a normal distribution for the same period in previous years, daily soil moisture and daily NDVI are normalized to obtain daily SSMI-30 and SNDVI-30. An intensity threshold of -0.5 is applied to SPI-90, SSMI-30, and SNDVI-30 respectively. The condition SPI-90 < -0.5 is used to identify all three-dimensional drought blocks related to meteorological drought, SSMI-30 < -0.5 is used to identify all three-dimensional drought blocks related to soil drought, and SNDVI-30 < -0.5 is used to identify all three-dimensional drought blocks related to ecological drought. Figure 2 The identification results of each drought index are shown, among which, Figure 2 In the image, (a) shows the recognition result of SPI-90. Figure 2 (b) in the image shows the recognition result of SSMI-30. Figure 2 (c) in the figure represents the recognition result of SNDVI-30.

[0118] (2) A minimum drought area threshold of 500 km² was set. All meteorological, soil, and ecological drought three-dimensional drought blocks were screened, and a few small drought events with a spatial projection area of ​​less than 500 km² were removed. An overlap area threshold of 30% of the smaller area of ​​the spatial projection area of ​​two three-dimensional drought blocks was set, and a time interval threshold of 10 days was set. Each meteorological, soil, and ecological drought three-dimensional drought block was judged separately. If the overlap of the spatial projection areas of two three-dimensional drought blocks was greater than the overlap area threshold and the time interval between the two three-dimensional drought blocks was less than the time interval threshold, then the two drought blocks were regarded as the same drought event; otherwise, they were regarded as two independent drought events. A duration threshold of 20 days was set. Drought events with a total duration of less than the duration threshold were deleted, and the remaining drought events were sorted by drought start time. If the drought start time was the same, the drought events with the same start time were sorted by end time. If both the start time and end time were the same, the drought events were sorted by the size of the spatial projection area of ​​the three-dimensional drought block, with the smaller drought area first.

[0119] (3) Using the identified meteorological, soil and ecological drought events as nodes, the event synchronization analysis method of complex networks is used to construct the transmission network from meteorological drought to soil drought, the transmission network from meteorological drought to ecological drought and the transmission network from soil drought to ecological drought in sequence.

[0120] First, based on the unidirectional transmission rule, matching is only possible if meteorological drought occurs before soil and ecological drought, and soil drought occurs before ecological drought, thus ensuring that the transmission relationship conforms to physical logic. On this basis, for meteorological drought event sequences (i=1, 2, ...) and soil drought event sequences (j=1, 2, ...), the dynamic delay between meteorological drought event M(i) and soil drought event S(j) is calculated. Similarly, for meteorological drought event sequences (i=1, 2, ...), soil drought event sequences (j=1, 2, ...), and ecological drought event sequences (k=1, 2, ...), the dynamic delay between meteorological drought event M(i) and ecological drought event E(k), and the dynamic delay between soil drought event S(j) and ecological drought event E(k), are calculated.

[0121] Because drought transmission is regional, spatial constraints are introduced for the region m of meteorological drought events, the region n of soil drought events, and the region p of ecological drought events. The minimum spatial overlap threshold is set at 5%.

[0122] To eliminate unreasonable dynamic delays, a maximum delay threshold of 90 days and a minimum delay threshold of 45 days were set between meteorological drought events and soil and ecological drought events occurring in the two regions. The final delay was taken. for ,in This is a dynamic delay. Based on this, the number of times meteorological drought events precede soil drought events can be calculated. The number of meteorological drought events preceding ecological drought events The number of soil drought events preceding ecological drought events And based on this, further calculate the synchronization strength. , and When Q equals 1, it means that for every meteorological drought event in region m, at least one soil drought event can be found in region n within a specified lag time (or for every meteorological drought event in region m, at least one ecological drought event can be found in region n within a specified lag time, and for every soil drought event in region n, at least one ecological drought event can be found in region p within a specified lag time).

[0123] (4) The synchronization intensity between drought events needs to be screened before matching can be performed. Therefore, the synchronization intensity thresholds for meteorological drought events and soil drought events, meteorological drought events and ecological drought events, and soil drought events and ecological drought events are set to 0.1, and the synchronization matrix is ​​calculated. , and Construct a transmission network from meteorological drought events to soil drought events, from meteorological drought events to ecological drought events, and from soil drought events to ecological drought events. Each node in the network represents a drought event, and the edges between nodes represent synchronization relationships, such as... Figure 3 The drought propagation network shown in the diagram has nodes whose size is determined by the number of edges connected to them; a larger node indicates more propagation relationships between the event and other events. The thickness of the edges is controlled by the synchronicity Q of two drought events; the larger Q is, the thicker the edge. The color of the edges is determined by the drought propagation time, which is calculated as the difference in start times between two drought events. Based on the constructed propagation network, we can obtain matching pairs of meteorological drought events with soil drought events, meteorological drought events with ecological drought events, and soil drought events with ecological drought events.

[0124] (5) Calculate the extreme-persistent-regional drought index (SDRI) for meteorological, soil and ecological drought events respectively.

[0125] (6) Calculate the three-dimensional drought transmission characteristic index—Network Synchronization Transformation Index (NSTI)—for meteorological drought to soil drought, meteorological drought to ecological drought, and soil drought to ecological drought, and draw a continuous spatial distribution map of NSTI, such as... Figure 4 The diagram shows the spatial distribution of drought transfer NSTI, where, Figure 4 (a) in the text represents the transfer of meteorological drought to soil drought. Figure 4 (b) in the text represents the transfer of soil drought to ecological drought. Figure 4 (c) represents the transmission of meteorological drought to ecological drought. The drought transmission analysis results for the target area were determined based on the NSTI spatial distribution map.

[0126] This embodiment provides a three-dimensional spatiotemporal transmission analysis method for meteorological-soil-ecological drought based on the synchronization analysis of complex network events. Building upon the existing three basic frameworks for drought identification and transmission analysis, it treats three-dimensional drought events as nodes in a complex network, introduces unidirectional transmission rules and dynamic time delay windows, and constructs a multi-sphere drought transmission network by combining multiple constraints such as spatial overlap. Furthermore, it incorporates the intensity, duration, impact range, and transmission efficiency of drought events into a unified quantitative system through extreme-persistent-regional drought indicators and network synchronization conversion indices. This method more realistically reflects the step-by-step transmission process from meteorological drought to soil and ecological drought than the three existing patented drought transmission methods that rely solely on simple time overlap and correlation analysis. It identifies high-risk areas that play a crucial role in the multi-sphere drought linkage, thus demonstrating greater applicability and promotional value in three-dimensional spatiotemporal drought transmission diagnosis, drought risk zoning, and disaster prevention and mitigation decision support.

[0127] Example 2 like Figure 5 As shown, this embodiment provides a three-dimensional drought event transmission analysis method, including: The acquisition module M1 is used to acquire a set of drought events of various drought types within the target area; each drought event set includes multiple drought events. The determination module M2 is used to determine the synchronization intensity of the preset drought transmission direction for each preset drought transmission direction based on the spatiotemporal information, time delay threshold, and preset spatial overlap threshold of each event combination that conforms to the preset drought transmission direction; wherein, each event combination includes two drought events belonging to different drought event sets, and the spatiotemporal information includes start and end time and spatial influence range. The network construction module M3 is used to construct a drought transmission network with drought events as nodes and drought transmission directions between drought events as edges, based on the synchronization intensity of each preset drought transmission direction. Analysis module M4 is used to determine the drought transmission analysis results for the target area based on the drought transmission network.

[0128] Example 3 This embodiment provides a computer device, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 6As shown, the computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage medium. The database stores data such as drought event sets. The I / O interfaces are used for information exchange between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements the three-dimensional drought event propagation analysis method provided in Embodiment 1.

[0129] Those skilled in the art will understand that Figure 6 The structures shown are merely block diagrams of some structures related to the present application and do not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than shown in the figures, or combine certain components, or have different component arrangements. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0130] Example 4 This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements a three-dimensional drought event transmission analysis method provided in Embodiment 1.

[0131] Example 5 This embodiment provides a computer program product, including a computer program that, when executed by a processor, implements a three-dimensional drought event transmission analysis method provided in Embodiment 1.

[0132] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0133] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A three-dimensional drought event transmission analysis method, characterized in that, The method includes: Obtain a set of drought events of various drought types within a target area; wherein each set of drought events includes multiple drought events; For each preset drought propagation direction, the synchronization intensity of the preset drought propagation direction is determined based on the spatiotemporal information, time delay threshold, and preset spatial overlap threshold of each drought event in each event combination that conforms to the preset drought propagation direction; wherein, each event combination includes two drought events belonging to different drought event sets, and the spatiotemporal information includes start and end times and spatial influence range; Based on the synchronization intensity of each preset drought transmission direction, a drought transmission network is constructed with drought events as nodes and drought transmission directions between drought events as edges; Based on the drought transmission network, the drought transmission analysis results for the target area are determined.

2. The method according to claim 1, characterized in that, The acquisition of a set of drought events of multiple drought types within the target area includes: Obtain the original observation data corresponding to different drought types within the target area; For each of the aforementioned drought types, perform the following steps: Multiple initial drought blocks were identified based on the original monitoring data of the drought type and the preset drought intensity threshold; Remove the initial drought blocks whose spatial projection area is less than a preset area threshold, and merge at least two remaining initial drought blocks after removal whose spatial projection overlap area exceeds a preset block merging spatial overlap threshold and whose occurrence time interval is less than a preset time interval threshold to obtain the merged drought blocks. After merging the drought blocks, remove those with a duration shorter than a preset duration to obtain the target drought block; wherein, the duration refers to the difference between the start time and the end time of the drought block after merging. The target drought block is defined as a drought event, thereby forming a set of drought events of the drought type.

3. The method according to claim 1, characterized in that, The step of determining the synchronization strength of the preset drought propagation direction based on the spatiotemporal information, time delay threshold, and preset spatial overlap threshold of each event combination conforming to the preset drought propagation direction includes: Based on the set of drought events of two different drought types associated with the preset drought transmission direction, multiple event combinations are determined; For each event combination, the time delay and spatial overlap of the event combination are determined based on the spatiotemporal information of each drought event in the event combination. Based on a preset time delay threshold, a preset spatial overlap threshold, and the time delay and spatial overlap of each event combination, a matching event combination is selected from all the event combinations; The synchronization intensity of the preset drought transmission direction is determined based on the number of matching event combinations.

4. The method according to claim 3, characterized in that, The process of constructing a drought transmission network based on the synchronization intensity of each preset drought transmission direction, with drought events as nodes and drought transmission directions between drought events as edges, includes: For each preset drought propagation direction, the synchronization intensity of the preset drought propagation direction is compared with a preset synchronization intensity threshold to obtain a comparison result, and based on the comparison result, the synchronization relationship between drought events in each matching event combination in the preset drought propagation direction is determined; A drought transmission network is constructed using all drought events as nodes and the drought transmission direction between drought events as edges; wherein the drought transmission direction is determined based on the synchronization relationship between drought events and the corresponding preset drought transmission direction.

5. The method according to claim 1 or 4, characterized in that, The step of determining the drought transmission analysis results for the target area based on the drought transmission network includes: For each drought event in the drought transmission network, a comprehensive intensity index of the drought event is determined based on the intensity, duration, and spatial impact range of the drought event; For each drought event pair corresponding to both ends of an edge in the drought transmission network, the network synchronization conversion index is determined based on the comprehensive intensity index of each drought event in the drought event pair and the synchronization intensity of the edge corresponding to the drought event pair. Based on the spatial influence range of the two drought events in each drought event pair, the network synchronization transformation index of the drought event pair is spatially allocated and fused to form drought transmission analysis results that characterize the stability and efficiency of drought transmission within the target area.

6. The method according to claim 5, characterized in that, The process involves spatially allocating and merging the network synchronization transformation index of drought event pairs based on the spatial influence range of the two drought events within each drought event pair, resulting in drought transmission analysis results characterizing the stability and efficiency of drought transmission within the target region. These results include: For each drought event pair, the union of the spatial influence ranges of the two drought events in the drought event pair is determined as the assignment region for the drought event pair; The network synchronization transformation index of the drought event pair is assigned to all spatial units within the assigned region; If the same spatial unit is covered by the assigned regions of multiple drought event pairs, then the multiple network synchronization transformation indices assigned to the spatial unit are weighted and fused to obtain the drought transmission characteristic value of the spatial unit. Based on the drought transmission characteristic values ​​of all spatial units, drought transmission analysis results are generated to characterize the stability and efficiency of drought transmission within the target region.

7. A three-dimensional drought event transmission analysis method, characterized in that, The device includes: The acquisition module is used to acquire a set of drought events of multiple drought types within a target area; each drought event set includes multiple drought events. The determination module is used to determine the synchronization intensity of the preset drought transmission direction for each preset drought transmission direction based on the spatiotemporal information, time delay threshold, and preset spatial overlap threshold of each drought event in each event combination that conforms to the preset drought transmission direction; wherein, each event combination includes two drought events belonging to different drought event sets, and the spatiotemporal information includes start and end times and spatial influence range; The network construction module is used to construct a drought transmission network with drought events as nodes and drought transmission directions between drought events as edges, based on the synchronization intensity of each preset drought transmission direction. The analysis module is used to determine the drought transmission analysis results of the target area based on the drought transmission network.

8. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the three-dimensional drought event transmission analysis method according to any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the three-dimensional drought event propagation analysis method as described in any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the three-dimensional drought event propagation analysis method as described in any one of claims 1-6.

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