Basin safety evaluation method and system, equipment and storage medium

Abstract

The invention discloses a drainage basin safety evaluation method and system, equipment and a storage medium, and belongs to the technical field of ecological hydrology. The drainage basin safety evaluation method comprises the following steps: constructing a comprehensive index system of drainage basin safety, wherein the comprehensive index system comprises a target layer, a criterion layer, a classification layer and an index layer; determining corresponding representation data in the index layer; performing normalization processing on the representation data, and determining the weight of a subitem corresponding to each level layer by layer; and obtaining a drainage basin safety comprehensive evaluation result of the target layer according to the weight of the subitem corresponding to each layer. Starting from the three-element angle of'water resource-ecological environment-extreme event ', the method highlights the evaluation of the drainage basin toughness, emphasizes the potential threats of composite drought and vegetation loss events to the drainage basin safety, and comprehensively considers the contribution degrees of different dimensions and sub-fields by determining the weight layer by layer, thereby improving the drainage basin toughness. And a scientific reference basis is provided for implementing the priority of water resource and ecological environment protection and restoration measures in a watershed or a region.

Description

Technical Field

[0001] This invention belongs to the field of eco-hydrology technology, and in particular relates to a watershed safety assessment method, system, equipment, and storage medium. Background Technology

[0002] In watershed-scale studies, hydrological systems and ecosystems are interdependent and mutually restrictive, and their connection is constantly being strengthened by the impact of human activities. It focuses on the impact of hydrological processes on the distribution patterns, structure, and function of ecosystems, as well as the impact of biological processes on water cycle elements. Therefore, watershed security involves multiple perspectives, including water resource health, ecological environment security, and the risk of extreme events.

[0003] However, existing research often focuses on the assessment of single-level indicator systems, such as from the perspective of water resources or the ecological environment; and it lacks consideration of the increasingly prominent watershed stability and resilience. For example, at the eco-hydrological system level, there is a significant positive feedback loop mechanism between drought and vegetation loss, with both reinforcing each other and accumulating risks, which are often overlooked. In other words, current research generally ignores the characteristics of multi-element and multi-process coupling and interaction in watershed ecosystems, making it difficult to comprehensively and accurately reflect the overall safety status and risk level of the watershed.

[0004] Therefore, there is an urgent need for a watershed safety assessment method that integrates multiple dimensions and fields to help build a regional eco-hydrological risk identification system. Summary of the Invention

[0005] To fill the gaps in the existing technologies, this invention provides a watershed safety assessment method. This method takes a three-dimensional approach of "water resources-ecological environment-extreme events" and comprehensively considers the cumulative effect of watershed risk caused by the positive feedback loop mechanism between drought and vegetation loss. It more comprehensively and accurately reflects the overall safety status and risk level of the watershed, and provides a scientific reference for prioritizing water resources and ecological environment protection and restoration measures in watersheds or regions.

[0006] This invention is achieved through the following technical solution: The first aspect provides a watershed safety assessment method, including the following steps: A comprehensive indicator system for watershed safety is constructed, comprising a target layer, a criterion layer, a classification layer, and an indicator layer. The target layer represents the watershed safety status; the criterion layer comprises detailed evaluation dimensions of the target layer, including water resource health, ecological environment safety, and extreme event risk; the classification layer comprises sub-domains of evaluation under the corresponding evaluation dimensions of the criterion layer, where the evaluation sub-domain of extreme event risk includes the frequency of compound extreme events; and the indicator layer comprises characterizing indicators for each evaluation sub-domain in the classification layer, where the characterizing indicators for the frequency of compound extreme events include the number of compound drought and vegetation loss events. Obtain the raw data of the watershed, and determine the corresponding representation data in the indicator layer based on the raw data; The representation data is normalized, and the weights of the corresponding sub-items at each level are determined layer by layer from the classification layer, criterion layer to the target layer. The comprehensive evaluation result of watershed safety for the target layer is obtained by using the weights of the corresponding sub-items at each level. The step of acquiring the original data of the watershed and determining the characterization data corresponding to the characterization index based on the original data includes: constructing a composite drought and vegetation loss event identification model based on the Copula method, and obtaining the number of composite drought and vegetation loss events in the watershed through the composite drought and vegetation loss event identification model.

[0007] Optionally, in some embodiments, the step of constructing a combined drought and vegetation loss event identification model based on the Copula method, and obtaining the number of combined drought and vegetation loss events in the watershed through the combined drought and vegetation loss event identification model, includes: A drought severity index based on land water storage As a quantifiable indicator of drought, the total primary productivity of the ecosystem is... As a quantitative indicator of vegetation loss, the Copula method is used to construct a joint distribution of drought and vegetation loss indicators, with the following formula: ; in: ; ; In the formula, For joint distribution, and These are the thresholds for drought and vegetation loss indicators, respectively. The joint probability distribution is fitted using the Copula method. and The marginal cumulative distribution functions of TWS-DSI and GPP are respectively. and To combine two random variables ( and The thresholds obtained after converting each component into its respective marginal distribution; Based on the aforementioned joint distribution, a standardized index for combined drought and vegetation loss is obtained, expressed by the following formula: ; In the formula, As an indicator of combined drought and vegetation loss, It follows a standard normal distribution. This indicates the joint probability distribution. Remapped to a cumulative distribution function with uniform marginal distribution; Based on run theory, when the standardized composite drought and vegetation loss indicators are less than a preset threshold for at least two consecutive months, it is identified as a composite drought and vegetation loss event, and the number of composite drought and vegetation loss events is obtained.

[0008] Optionally, in some embodiments, the normalization process for the representation data includes: normalizing the data using the following formula: ; ; In the formula, For the first The first indicator One sample data, for The normalized value, and The first The maximum and minimum values ​​of the indicator data series.

[0009] Optionally, in some embodiments, obtaining the comprehensive watershed safety evaluation result of the target layer from the weights of the corresponding sub-items at each level includes: determining the evaluation result of each layer layer by layer using the following formula until the comprehensive watershed safety evaluation result of the target layer is obtained: ; In the formula, =1 represents the target layer. =2 represents the criterion layer. =3 represents the classification layer; For the first The first in the layer The comprehensive evaluation value of each element For the first The first in the layer The element is the first The overall evaluation value of each sub-item For the first The first in the layer The element is the first The weight of each sub-item, the first The sub-item is located in the first +1 floor.

[0010] Optionally, in some embodiments, the water resource health assessment subfield includes water area conditions, surface water resource status, groundwater resource status, soil water status, and human water use status; the characterization indicators of water area conditions include wetland area and lake area, the characterization indicators of surface water resource status include surface water runoff, the characterization indicators of groundwater resource status include groundwater runoff, the characterization indicators of soil water status include soil moisture content, and the characterization indicators of human water use status include water consumption. The evaluation subfield of ecological environment security includes vegetation conditions and hydrothermal conditions. The characterization indicators of vegetation conditions include total primary productivity, leaf area index and ecological water use efficiency. The characterization indicators of hydrothermal conditions include the 10th percentile of temperature, the 90th percentile of temperature, the 10th percentile of precipitation and the 90th percentile of precipitation. The subfield of extreme event risk assessment also includes drought frequency and flood frequency. The indicator for drought frequency includes the number of drought events, and the indicator for flood frequency includes the number of flood events.

[0011] Optionally, in some embodiments, acquiring the raw data of the watershed and determining the corresponding representation data in the indicator layer based on the raw data includes: Ecological water use efficiency is calculated using the following formula: ; In the formula, For ecological water use efficiency. For the total primary productivity of the ecosystem, Evapotranspiration for the ecosystem; The drought index is determined using the following formula. Based on runs theory, a drought event is identified when the drought index is below a preset drought threshold for at least two consecutive months, and the number of drought events is then recorded: ; In the formula, As a drought indicator, For the first The year's first The land water storage in the month is abnormal. and These are the first [number] years in the study period. The mean and standard deviation of monthly land water storage anomalies; The surface water runoff time series is sorted from largest to smallest. Based on the runs theory, when the surface water runoff exceeds the preset flood threshold for at least two consecutive months, it is identified as a flood event, and the number of flood events is obtained.

[0012] Optionally, in some embodiments, the watershed is divided into multiple segments; The step of determining the corresponding characterization data in the indicator layer based on the original data includes: determining the corresponding characterization data in the indicator layer for each segment of the watershed in each year of the research period based on the original data; The step of normalizing the representation data and determining the weight of each corresponding sub-item at each level from the classification layer, criterion layer to the target layer includes: normalizing the representation data and determining the weight of each corresponding sub-item at each level in each section of the basin in each year from the classification layer, criterion layer to the target layer. The step of obtaining the comprehensive evaluation result of watershed safety of the target layer by the weights of the corresponding sub-items of each level includes: obtaining the comprehensive evaluation result of watershed safety of the target layer of each segment of the watershed in each year by the weights of the corresponding sub-items of each level of each segment of the watershed in each year. The year with the worst comprehensive safety evaluation result for the watershed is selected as a typical year. Based on the comprehensive safety evaluation results of each section of the watershed in the typical year, the priority of watershed protection in different areas of the watershed is determined.

[0013] The second aspect provides a watershed safety assessment system, including: A comprehensive indicator system construction module is used to construct a comprehensive indicator system for watershed safety. This comprehensive indicator system includes a target layer, a criterion layer, a classification layer, and an indicator layer. The target layer represents the watershed safety status; the criterion layer comprises subdivided evaluation dimensions of the target layer, including water resource health, ecological environment safety, and extreme event risk; the classification layer consists of sub-domains refined under the corresponding evaluation dimensions of the criterion layer, where the evaluation sub-domain of extreme event risk includes the frequency of compound extreme events; and the indicator layer consists of characterizing indicators for each evaluation sub-domain in the classification layer, where the characterizing indicators for the frequency of compound extreme events include the number of compound drought and vegetation loss events. The data acquisition and processing module is used to acquire the raw data of the watershed and determine the corresponding characterization data in the indicator layer based on the raw data; specifically, it is used to construct a compound drought and vegetation loss event identification model based on the Copula method, and to obtain the number of compound drought and vegetation loss events in the watershed through the compound drought and vegetation loss event identification model; it is also used to normalize the characterization data and determine the weight of each corresponding sub-item at each level from the classification layer, criterion layer to the target layer; and it is used to obtain the comprehensive watershed safety evaluation result of the target layer from the weight of each corresponding sub-item at each level.

[0014] A third aspect provides an electronic device, wherein the electronic device includes a memory and a processor coupled to each other, the processor being used to execute program instructions stored in the memory to implement the above-described watershed safety assessment method.

[0015] This fourth aspect provides a computer-readable storage medium having program instructions stored thereon, which, when executed by a processor, implement the above-described watershed safety assessment method.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention starts from the three-element perspective of "water resources-ecological environment-extreme events" and constructs a comprehensive evaluation index system including target layer, criterion layer, classification layer and indicator layer. It provides a comprehensive and efficient tool for assessing the safety status of watersheds or regions and can provide a scientific reference for prioritizing water resources and ecological environment protection and restoration measures in watersheds or regions. (2) The comprehensive index system constructed in this invention highlights the assessment of watershed resilience, especially emphasizing the cumulative effect of watershed risk caused by the positive feedback loop mechanism between drought and vegetation loss, revealing its potential threat to watershed security.

[0017] (3) The present invention assigns branch weights to the comprehensive index system layer by layer, which facilitates the analysis of the contribution of different evaluation dimensions and sub-fields in the comprehensive evaluation results of watershed safety; (4) The comprehensive index system constructed in this invention is not targeted at a specific watershed, but has universality and applicability. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating an embodiment of a watershed safety assessment method provided by the present invention; Figure 2 This is a flowchart illustrating a specific embodiment of a watershed safety assessment method provided by the present invention; Figure 3 This is a safety status classification diagram of a specific embodiment of a watershed safety assessment method provided by the present invention; Figure 4 This is a schematic diagram of an embodiment of the watershed safety assessment system provided by the present invention; Figure 5 This is a schematic diagram of the structure of an embodiment of the electronic device provided by the present invention; Figure 6 This is a schematic diagram of an embodiment of the computer-readable storage medium provided by the present invention. Detailed Implementation

[0019] The following example, "Assessing the safety status of a typical river basin under the current climate change background," further illustrates a river basin safety assessment method based on a comprehensive indicator system of "water resources-ecological environment-extreme events." To make the objectives, technical solutions, and advantages of the embodiments of this invention clearer, the technical solutions in the embodiments of this invention will be described completely and clearly below with reference to the accompanying drawings. The following embodiments are intended to further illustrate the content of this invention in detail, but are not intended to limit the scope of protection of the claims of this invention.

[0020] This invention provides a method for watershed safety assessment, see reference. Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of a watershed safety assessment method provided by the present invention, including the following steps: Step S1: Construct a comprehensive indicator system for watershed safety; Step S2: Obtain the raw data of the watershed, and determine the corresponding characterization data in the index layer based on the raw data; Step S3: Normalize the representation data and determine the weight of each sub-item at each level from the classification layer, criterion layer to the target layer. Step S4: Obtain the comprehensive evaluation result of watershed safety of the target layer based on the weights of the corresponding sub-items at each level.

[0021] The target layer represents the watershed's safety status; the criterion layer comprises subdivided evaluation dimensions of the target layer, including water resource health, ecological environment safety, and extreme event risk; the classification layer consists of sub-domains refined under the corresponding evaluation dimensions of the criterion layer, where the evaluation sub-domain of extreme event risk includes the frequency of compound extreme events; and the indicator layer comprises characterization indicators for each evaluation sub-domain in the classification layer, where the characterization indicators for the frequency of compound extreme events include the number of compound drought and vegetation loss events. The step of acquiring the original data of the watershed and determining the characterization data corresponding to the characterization index based on the original data includes: constructing a composite drought and vegetation loss event identification model based on the Copula method, and obtaining the number of composite drought and vegetation loss events in the watershed through the composite drought and vegetation loss event identification model.

[0022] In this embodiment, a comprehensive evaluation index system is constructed from the ternary perspective of "water resources-ecological environment-extreme events," comprising a target layer, a criterion layer, a classification layer, and an indicator layer. This system emphasizes the assessment of watershed resilience, particularly highlighting the cumulative risk effect caused by the positive feedback loop mechanism between drought and vegetation loss, revealing its potential threat to watershed security. The system assigns weights to branches within the comprehensive index system layer by layer, comprehensively considering the contribution of different evaluation dimensions and sub-domains. This provides a comprehensive and efficient tool for assessing the security status of watersheds or regions, and offers a scientific reference for prioritizing water resources and ecological environment protection and restoration measures in watersheds or regions. Furthermore, the comprehensive index system and watershed security assessment method constructed in this invention are universal and applicable, not limited to a specific watershed, and can be widely applied to security assessments of various watersheds and different areas within watersheds.

[0023] The watershed safety assessment method provided in this embodiment, which integrates multiple dimensions and multiple fields based on a comprehensive indicator system of "water resources-ecological environment-extreme events", helps to build a regional eco-hydrological risk identification system, provides a solid theoretical foundation for future regional economic sustainable development and water security research, and provides scientific and technical support for watershed water ecological protection.

[0024] In step S1: In some embodiments, refer to Figure 1 and Figure 2 , Figure 2 This is a flowchart illustrating a specific embodiment of a watershed safety assessment method provided by the present invention. A comprehensive indicator system for watershed safety is constructed, specifically a comprehensive indicator system of "water resources-ecological environment-extreme events". Watershed safety status serves as the target layer; the criterion layer includes at least three dimensions: (a) water resource health, (b) ecological environment safety, and (c) extreme event risk; for the classification layer, (a) water resource health is further subdivided into five evaluation sub-domains: (a1) water area conditions, (a2) surface water resource status, (a3) ​​groundwater resource status, (a4) soil water status, and (a5) human water use status; (b) ecological environment safety is further subdivided into two evaluation sub-domains: (b1) vegetation conditions and (b2) hydrothermal conditions; and (c) extreme event risk is further subdivided into three evaluation sub-domains: (c1) drought frequency, (c2) flood frequency, and (c3) frequency of combined extreme events; the indicator layer consists of representation indicators for each item in the classification layer, including: (a1) Water conditions are characterized by both wetland area and lake area; (a2) Surface water resources are characterized by surface water runoff; (a3) Groundwater resources are characterized by groundwater runoff; (a4) Soil water condition is characterized by soil moisture content; (a5) Human water use is characterized by water consumption; (b1) Vegetation conditions were characterized by total primary productivity, leaf area index and ecological water use efficiency. (b2) Hydrothermal conditions are characterized by the 10th percentile of temperature, the 90th percentile of temperature, the 10th percentile of precipitation, and the 90th percentile of precipitation. (c1) Drought frequency is characterized by the number of drought events; (c2) Flood frequency is characterized by the number of flood events; (c3) The frequency of compound extreme events is characterized by compound drought and vegetation loss events.

[0025] In other embodiments, in addition to the three dimensions of water resource health, ecological environment safety and extreme event risk, the criteria layer of the comprehensive indicator system may also include other dimensions based on the watershed or research period.

[0026] In other embodiments, extreme events may include not only the frequency of combined extreme events (characterized by the number of combined drought and vegetation loss events), drought frequency, and flood frequency, but also other unconventional extreme risk events.

[0027] It is understandable that the classification layers and indicator layers corresponding to water resource health and ecological environment security can be adjusted accordingly based on different research scopes and specific data availability.

[0028] In some specific embodiments, the details of the comprehensive indicator system for watershed safety are shown in Table 1.

[0029] Table 1. Comprehensive Indicator System for "Water Resources - Ecological Environment - Extreme Events"

[0030] Note: (+) represents a positive indicator, with higher values ​​indicating a better security situation; (-) represents a negative indicator, with lower values ​​indicating a better security situation.

[0031] In step S2: The raw data of the watershed is acquired, and the corresponding representational data in the indicator layer is determined based on the raw data. Some of the representational data corresponding to the indicators in the indicator layer can be directly determined from the raw data, while the representational data corresponding to other indicators requires corresponding calculations and data processing to extract and determine from the raw data. In one specific embodiment, the source of the raw data can be referred to in the "Source of Raw Data" column of Table 1. In other embodiments, the raw data can also be obtained from other data sources.

[0032] In some embodiments, the ecological water use efficiency, number of drought events, number of flood events, and number of combined drought and vegetation loss events in the indicator layer need to be further calculated and extracted from the raw data.

[0033] Among them, ecological water use efficiency ( The result is obtained by calculating using the following formula: ; In the formula, For the total primary productivity of the ecosystem, Evapotranspiration for the ecosystem.

[0034] The number of drought events was obtained through the following steps: Calculate the land water storage-drought severity index (i.e., drought index): ; In the formula, As a drought indicator, For the first The year's first The land water storage in the month is abnormal. and These are the first [number] years in the study period. The mean and standard deviation of monthly land water storage anomalies; Based on run theory, when drought index If the number of drought events is below the detection threshold for at least two consecutive months, it is identified as a drought event, and the number of drought events is recorded.

[0035] Specifically, referring to Table 2, -0.5 is used as the threshold for identifying drought events.

[0036] In this invention, the identification threshold for drought events, the preset thresholds for compound drought and vegetation loss events, etc., correspond to the specified frequency quantile values ​​of each indicator, as shown in Table 2. The levels in the table are widely used in related research fields. Based on the critical percentile value (30th) of each indicator entering an abnormal state (level 0), the normally distributed TWS-DSI and SCDVI are -0.5.

[0037] Table 2. Classification of vegetation loss index GPP and standardized composite drought and vegetation loss index SCDVI based on drought index TWS-DSI (each level corresponds to its occurrence probability).

[0038] In some embodiments, the number of flood events is obtained by the following steps: sorting the surface water runoff time series from largest to smallest, selecting the 40th percentile as a threshold, and based on the runs theory, identifying a flood event as having occurred when the surface water runoff is greater than the threshold for at least two consecutive months, thereby obtaining the number of flood events.

[0039] In some embodiments, step S2 includes: constructing a combined drought and vegetation loss event identification model based on the Copula method, and obtaining the number of combined drought and vegetation loss events in the watershed through the combined drought and vegetation loss event identification model.

[0040] In some specific embodiments, the construction of the complex drought and vegetation loss event identification model based on the Copula method includes: Drought index was constructed using the Copula method. ) and vegetation loss index ( joint distribution of ) Combined drought and vegetation loss events can be characterized by both drought indicators and vegetation loss indicators being less than or equal to a threshold. and :

[0041] in:

[0042]

[0043] In the formula, The joint probability distribution is fitted using the Copula method. and The marginal cumulative distribution functions of TWS-DSI and GPP are respectively. and To combine two random variables ( and The thresholds are obtained by converting each of them into their respective marginal distributions.

[0044] Among them, the joint probability distribution This represents the probability distribution when a certain degree of drought and vegetation loss occur simultaneously. The smaller the probability value, the more extreme the combined event.

[0045] Based on the joint distribution of drought index and vegetation loss index Standardized composite drought and vegetation loss indices were obtained. ): ; In the formula, It follows a standard normal distribution. This indicates the joint probability distribution. The cumulative distribution function is remapped to a uniform marginal distribution.

[0046] Based on runs theory, when standardized composite drought and vegetation loss indicators... If the value is below a preset threshold for at least two consecutive months, it is identified as a combined drought and vegetation loss event. Specifically, referring to Table 2, -0.5 is used as the preset threshold for combined drought and vegetation loss events.

[0047] The above-mentioned compound drought and vegetation loss event identification model is used to identify compound drought and vegetation loss events and obtain the number of compound drought and vegetation loss events.

[0048] In this step, the advantage of using the Copula method lies in its ability to link two random variables, capturing both their distribution characteristics, particularly their tail dependence (i.e., the correlation between the two random variables at extreme values). This makes Copula more accurate in constructing the extreme correlation between the two random variables and characterizing extreme risks (because extreme drought and extreme vegetation loss both occur when the corresponding characterization indicators are at their minimum values). Furthermore, after obtaining the joint distribution of the two random variables using the Copula method, we can subsequently remap and standardize the joint distribution to obtain a standardized index, SCDVI. This single standardized index can conveniently quantify the combined effects of drought and vegetation loss.

[0049] In step S3: The representation data of the indicator layer are normalized to eliminate the differences in forward and reverse directions, dimensions, and magnitudes between different indicator data.

[0050] In some specific embodiments, the calculation formula for normalization is as follows: ; ; In the formula, For the first The first indicator One sample data, for The normalized value, and The first The maximum and minimum values ​​of the indicator data series.

[0051] The weights of the corresponding sub-items at each level are determined progressively from the classification layer, criterion layer, to the target layer. The weights can be calculated using weight calculation methods known in the art. In some embodiments, the objective entropy weight method is used to calculate the weights, thus determining the weights entirely based on the distribution characteristics of the data itself. This avoids interference from subjective factors in weight assignment, making the evaluation results more objective and fair, and also offering high computational operability.

[0052] Specifically, the weight calculation process is as follows: ① Calculate the first The first indicator The contribution (weight) of each sample data: ; ② Calculate the first Entropy value of the item indicator: ; ③ Calculate the first Information entropy redundancy of the indicator: ; ④ Calculate the first Weight of each indicator: .

[0053] In step S4, In some embodiments, the comprehensive evaluation result of watershed safety at the target layer is obtained from the weights of the corresponding sub-items at each level, i.e., watershed safety is evaluated layer by layer based on the weights of each branch in the comprehensive indicator system, including: (1) From the indicator layer to the classification layer, calculate the evaluation result of the classification based on the weight of each indicator under each classification; (2) From the classification layer to the criterion layer, calculate the evaluation result of the criterion based on the weight of each category under each criterion; (3) From the criterion layer to the target layer, based on the weights of each criterion under the target, calculate the evaluation result of the target. That is, the watershed safety status (comprehensive index). ).

[0054] In some specific embodiments, the evaluation result of each layer is determined layer by layer using the following formula. Until the comprehensive evaluation result of watershed security at the target layer is obtained. : ; In the formula, , For the first The first in the layer The comprehensive evaluation value of each element ( =1 represents the target layer. =2 represents the criterion layer. =3 is the classification layer). For the first The first in the layer The element is the first The nth sub-item (i.e., the one located at the nth) The comprehensive evaluation value of the layer ( =3 represents the values ​​of each indicator). For the first The first in the layer The element is the first The weight value of each sub-item.

[0055] In some embodiments, after obtaining the comprehensive watershed safety evaluation result of the target layer, the method further includes: classifying the comprehensive safety level based on the comprehensive watershed safety evaluation result. In this embodiment, the comprehensive safety level is more conducive to visualization, enabling a more intuitive comparison of the safety between multiple different watershed flows or the comprehensive safety of multiple different regions within a watershed, and facilitating the creation of a safety level distribution map.

[0056] In some specific embodiments, based on the comprehensive safety evaluation results of a typical watershed, a comprehensive evaluation standard for the safety status of the typical watershed is determined, and the watershed safety status is divided into five levels: unsafe, relatively unsafe, critically safe, relatively safe, and safe, as shown in Table 3. Based on the comprehensive watershed safety evaluation results at the target layer... Based on the evaluation criteria in Table 3, the comprehensive safety level is classified.

[0057] Table 3. Evaluation Criteria for Watershed Safety Status

[0058] in, This is the result of a comprehensive evaluation of watershed safety.

[0059] In other specific embodiments, the results of the comprehensive watershed safety evaluation can be used as a basis. The safety status of the watershed can be divided into three comprehensive safety levels: unsafe, relatively safe, and safe; or it can be divided into two comprehensive safety levels: trending towards unsafe and trending towards safe.

[0060] In specific application scenarios, the watershed safety assessment method provided by this invention can be applied to the safety status assessment of different watersheds. Specifically, through steps S1-S4, comprehensive watershed safety assessment results at the target layer of multiple watersheds are obtained, and based on these results, the priority of watershed protection in different watersheds is determined. In this application scenario, the watershed safety assessment method provided by this invention can be used to assess the safety status of different watersheds and identify watersheds where priority for water resource and ecological environment protection and restoration can be given, for example, based on the comprehensive safety assessment results. Watersheds with relatively small safety values ​​(i.e., lower safety) should be prioritized for processing. Furthermore, watersheds with relatively low safety assessment levels (i.e., lower safety) can also be prioritized for processing to optimize resource allocation.

[0061] In other specific application scenarios, the watershed safety assessment method provided by this invention can be applied to the safety status assessment of multiple different areas within a watershed. Specifically, the watershed is divided into multiple segments, such as by hydrological units (i.e., sub-watersheds), or by administrative divisions such as provinces, cities, and counties. Then, through steps S1-S4, the comprehensive safety assessment results of each segment of the watershed are obtained, and based on these results, the priority for watershed protection in each segment is determined. In this embodiment, the watershed safety assessment method provided by this invention can be used to assess the safety status of different areas within a watershed, determine the watershed areas where priority for water resources and ecological environment protection and restoration can be implemented, for example, by analyzing the comprehensive safety assessment results. Watershed areas with relatively small values ​​(i.e., lower safety) or relatively low safety assessment levels (i.e., lower safety) will be prioritized for processing in order to optimize resource allocation.

[0062] Specifically, in the above application scenario, in step S2, the original data of the watershed is obtained, and the corresponding characterization data in the indicator layer of each segment of the watershed in each year is determined based on the original data; then steps S3 and S4 are performed to obtain the comprehensive evaluation results of watershed safety for each segment of the watershed in each year, and the priority of watershed protection in each segment is determined based on the comprehensive evaluation results of watershed safety. Specifically, the year with the worst comprehensive evaluation results of watershed safety (e.g., the year with the most areas with poor safety in the watershed) can be selected as a typical year, and the priority of watershed protection in different areas can be determined based on the comprehensive evaluation results of safety in each segment of the typical year, or one or more areas with poor safety in the watershed can be selected, and watershed protection can be prioritized for the selected areas.

[0063] In some embodiments, taking the index processing, weight calculation, safety status evaluation and classification of Region VIII (the study basin is divided into eight regions from upstream to downstream) in the study period of "Assessing the Safety Status of a Typical Watershed during the Study Period of 2001-2015" as an example, the results are shown in Tables 4-10.

[0064] Table 4. Normalized calculation results of index layer indicators for watershed region VIII.

[0065] Note: The normalization and calculation of the indicator layer only include evaluation subdomains consisting of two or more evaluation indicators.

[0066] Table 5. Calculation results of indicator weights for the indicator layer in the study area VIII of the watershed.

[0067] Note: The normalization and calculation of the indicator layer only include evaluation sub-domains consisting of two or more evaluation indicators. The superscripts a, b, and c represent the three evaluation sub-domains consisting of multiple evaluation indicators: water conditions, vegetation conditions, and hydrothermal conditions, respectively.

[0068] Table 6. Normalized calculation results of classification stratum indices for watershed region VIII.

[0069] Table 7. Calculation results of the classification stratum index weights for watershed region VIII.

[0070] Table 8. Normalized calculation results of criterion-level indicators for watershed region VIII.

[0071] Table 9. Calculation results of the criterion layer index weights for the VIII-level study area.

[0072] Table 10. Safety Status Assessment Results of Area VIII in the Study Basin

[0073] Following the same steps above, the safety status of eight regions in the typical watershed during the current study period was assessed, and the final results were compiled and summarized as shown in Table 11.

[0074] Table 11. Safety Status Assessment Results of Eight Regions in the Study Basin During the Current Study Period

[0075] Based on the watershed safety status evaluation criteria in Table 1, the specific classification of safety status levels for the eight regions of this typical watershed during the current study period is as follows: Figure 3 As shown, Figure 3 This is a safety status classification diagram of a specific embodiment of a watershed safety assessment method provided by the present invention.

[0076] according to Figure 3As shown, the safety status of the eight regions in this typical watershed varied considerably from year to year during the current status study period. Overall, the safety status of the eight regions in the study watershed was relatively good in 2004, 2009, 2012, and 2015, with the upstream region showing a significantly better safety status than the downstream region. Specifically, Region I had a safety status rating of ≥0.8 in 2009 and 2010, Region II in 2012, Region III in 2004, and Region IV in 2015. The region with the best safety status throughout the entire current status study period was the watershed source region (Region I) in 2009, with a safety status rating of 0.967 (safe).

[0077] Table 12 Water resource health, ecological environment safety, and ecological environment security in a typical year (2006) of the study basin. Extreme event risk and overall assessment level

[0078] Depend on Figure 3 It can be seen that the largest number of areas in the basin were assessed as unsafe (<0.2) in 2006. Therefore, 2006 was a year with a relatively poor overall safety situation. Using 2006 as a typical year for the current status study, further analysis of the spatial distribution of the basin's safety situation is needed to optimize resource allocation and identify key areas for priority water resource and ecological environment protection and restoration. Specifically, as shown in Table 11, the upper and middle reaches of the basin (regions III, IV, and V) were unsafe in 2006, and priority should be given to water resource and ecological environment protection and restoration. Region V was mainly unsafe due to its water resource health status assessment, while Region IV was mainly unsafe due to both its ecological environment safety status and extreme event risk assessment. This indicates that the comprehensive evaluation results for different regions are affected by different dimensions.

[0079] This invention also provides a watershed safety assessment system, see reference. Figure 4 , Figure 4 This is a schematic diagram of an embodiment of the watershed safety assessment system provided by the present invention. The watershed safety assessment system 100 includes a comprehensive indicator system construction module 10 and a data acquisition and processing module 20.

[0080] The comprehensive indicator system construction module 10 is used to construct a comprehensive indicator system for watershed safety. This comprehensive indicator system includes a target layer, a criterion layer, a classification layer, and an indicator layer. The target layer represents the watershed safety status; the criterion layer comprises subdivided evaluation dimensions of the target layer, including water resource health, ecological environment safety, and extreme event risk; the classification layer consists of subdivided evaluation sub-domains under the corresponding evaluation dimensions of the criterion layer, where the evaluation sub-domain of extreme event risk includes the frequency of compound extreme events; and the indicator layer consists of characterizing indicators for each evaluation sub-domain in the classification layer, where the characterizing indicators for the frequency of compound extreme events include the number of compound drought and vegetation loss events.

[0081] The data acquisition and processing module 20 is used to acquire the raw data of the watershed and determine the corresponding characterization data in the indicator layer based on the raw data. Specifically, the data acquisition and processing module 20 is used to construct a compound drought and vegetation loss event identification model based on the Copula method, and to obtain the number of compound drought and vegetation loss events in the watershed through the compound drought and vegetation loss event identification model. The data acquisition and processing module 20 is used to normalize the characterization data and determine the weight of the corresponding sub-items at each level from the classification layer, criterion layer to the target layer; it is used to obtain the comprehensive watershed safety evaluation result of the target layer based on the weights of the corresponding sub-items at each level.

[0082] See Figure 5 , Figure 5 This is a schematic diagram of an embodiment of the electronic device provided by the present invention. The electronic device 110 includes a memory 111 and a processor 112 coupled to each other. The processor 112 is used to execute program instructions stored in the memory 111 to implement the watershed safety assessment method provided by the present invention. In a specific implementation scenario, the electronic device 110 may include, but is not limited to, a display device, a microcomputer, or a server.

[0083] See Figure 6 , Figure 6 This is a schematic diagram of an embodiment of a computer-readable storage medium provided by the present invention. The computer-readable storage medium 120 stores program instructions 121, which, when executed by a processor, implement the watershed safety evaluation method of the present invention.

[0084] In the several embodiments provided by this invention, it should be understood that the disclosed methods and apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms. Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, i.e., they may be located in one place or distributed across network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0085] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0086] The above provides a detailed description of a watershed safety assessment method, system, device, and storage medium provided by embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for assessing watershed safety, characterized in that, Includes the following steps: A comprehensive indicator system for watershed safety is constructed, comprising a target layer, a criterion layer, a classification layer, and an indicator layer. The target layer represents the watershed safety status; the criterion layer comprises detailed evaluation dimensions of the target layer, including water resource health, ecological environment safety, and extreme event risk; the classification layer comprises sub-domains of evaluation under the corresponding evaluation dimensions of the criterion layer, where the evaluation sub-domain of extreme event risk includes the frequency of compound extreme events; and the indicator layer comprises characterizing indicators for each evaluation sub-domain in the classification layer, where the characterizing indicators for the frequency of compound extreme events include the number of compound drought and vegetation loss events. Obtain the raw data of the watershed, and determine the corresponding representation data in the indicator layer based on the raw data; The representation data is normalized, and the weights of the corresponding sub-items at each level are determined layer by layer from the classification layer, criterion layer to the target layer. The comprehensive evaluation result of watershed safety for the target layer is obtained by using the weights of the corresponding sub-items at each level. The step of acquiring the original data of the watershed and determining the characterization data corresponding to the characterization index based on the original data includes: constructing a composite drought and vegetation loss event identification model based on the Copula method, and obtaining the number of composite drought and vegetation loss events in the watershed through the composite drought and vegetation loss event identification model.

2. The watershed safety assessment method according to claim 1, characterized in that, The construction of a combined drought and vegetation loss event identification model based on the Copula method, and the acquisition of the number of combined drought and vegetation loss events in the watershed through the combined drought and vegetation loss event identification model, include: Using drought severity based on terrestrial water storage as a quantified drought indicator and total primary productivity of the ecosystem as a quantified vegetation loss indicator, the Copula method is employed to construct a joint distribution of the drought and vegetation loss indicators. The formula is as follows: ； in: ； ； In the formula, For joint distribution, As a drought indicator, As an indicator of vegetation loss, and These are the thresholds for drought and vegetation loss indicators, respectively. The joint probability distribution is fitted using the Copula method. and The marginal cumulative distribution functions of TWS-DSI and GPP are respectively. and To make random variables and The corresponding thresholds are obtained after converting them to their respective marginal distributions; Based on the aforementioned joint distribution, a standardized index for combined drought and vegetation loss is obtained, expressed by the following formula: ； In the formula, As an indicator of combined drought and vegetation loss, It follows a standard normal distribution. This indicates the joint probability distribution. Remapped to a cumulative distribution function with uniform marginal distribution; Based on run theory, when the standardized composite drought and vegetation loss indicators are less than a preset threshold for at least two consecutive months, it is identified as a composite drought and vegetation loss event, and the number of composite drought and vegetation loss events is obtained.

3. The watershed safety assessment method according to claim 1, characterized in that, The normalization process for the representation data includes: normalizing the data using the following formula: ； ； In the formula, For the first The first indicator One sample data, for The normalized value, and The first The maximum and minimum values ​​of the indicator data series.

4. The watershed safety assessment method according to claim 1, characterized in that, The step of obtaining the comprehensive watershed safety evaluation result of the target layer from the weights of the corresponding sub-items at each level includes: determining the evaluation result of each layer level by level using the following formula until the comprehensive watershed safety evaluation result of the target layer is obtained: ； In the formula, =1 represents the target layer. =2 represents the criterion layer. =3 represents the classification layer; For the first The first in the layer The comprehensive evaluation value of each element For the first The first in the layer The element is the first The overall evaluation value of each sub-item For the first The first in the layer The element is the first The weight of each sub-item, the first The sub-item is located in the first +1 floor.

5. The watershed safety assessment method according to any one of claims 1-4, characterized in that, The evaluation subfield of water resource health includes water area conditions, surface water resource status, groundwater resource status, soil water status, and human water use status; the characterization indicators of water area conditions include wetland area and lake area, the characterization indicators of surface water resource status include surface water runoff, the characterization indicators of groundwater resource status include groundwater runoff, the characterization indicators of soil water status include soil moisture content, and the characterization indicators of human water use status include water consumption. The evaluation subfield of ecological environment security includes vegetation conditions and hydrothermal conditions. The characterization indicators of vegetation conditions include total primary productivity, leaf area index and ecological water use efficiency. The characterization indicators of hydrothermal conditions include the 10th percentile of temperature, the 90th percentile of temperature, the 10th percentile of precipitation and the 90th percentile of precipitation. The subfield of extreme event risk assessment also includes drought frequency and flood frequency. The indicator for drought frequency includes the number of drought events, and the indicator for flood frequency includes the number of flood events.

6. The watershed safety assessment method according to claim 5, characterized in that, The process of acquiring the raw data of the watershed and determining the corresponding representation data in the indicator layer based on the raw data includes: Ecological water use efficiency is calculated using the following formula: ； In the formula, For ecological water use efficiency. For the total primary productivity of the ecosystem, Evapotranspiration for the ecosystem; The drought index is determined using the following formula. Based on runs theory, a drought event is identified when the drought index is below a preset drought threshold for at least two consecutive months, and the number of drought events is then recorded: ； In the formula, As a drought indicator, For the first The year's first The land water storage in the month is abnormal. and These are the first [number] years in the study period. The mean and standard deviation of monthly land water storage anomalies; The surface water runoff time series is sorted from largest to smallest. Based on the runs theory, when the surface water runoff exceeds the preset flood threshold for at least two consecutive months, it is identified as a flood event, and the number of flood events is obtained.

7. The watershed safety assessment method according to any one of claims 1-4, characterized in that, The watershed is divided into multiple regions; The step of determining the corresponding characterization data in the indicator layer based on the original data includes: determining the corresponding characterization data in the indicator layer for each segment of the watershed in each year of the research period based on the original data; The step of normalizing the representation data and determining the weight of each corresponding sub-item at each level from the classification layer, criterion layer to the target layer includes: normalizing the representation data and determining the weight of each corresponding sub-item at each level in each section of the basin in each year from the classification layer, criterion layer to the target layer. The step of obtaining the comprehensive evaluation result of watershed safety of the target layer by the weights of the corresponding sub-items of each level includes: obtaining the comprehensive evaluation result of watershed safety of the target layer of each segment of the watershed in each year by the weights of the corresponding sub-items of each level of each segment of the watershed in each year. The year with the worst comprehensive safety evaluation result for the watershed is selected as a typical year. Based on the comprehensive safety evaluation results of each section of the watershed in the typical year, the priority of watershed protection in different areas of the watershed is determined.

8. A watershed safety assessment system, characterized in that, include: A comprehensive indicator system construction module is used to construct a comprehensive indicator system for watershed safety. This comprehensive indicator system includes a target layer, a criterion layer, a classification layer, and an indicator layer. The target layer represents the watershed safety status; the criterion layer comprises subdivided evaluation dimensions of the target layer, including water resource health, ecological environment safety, and extreme event risk; the classification layer consists of sub-domains refined under the corresponding evaluation dimensions of the criterion layer, where the evaluation sub-domain of extreme event risk includes the frequency of compound extreme events; and the indicator layer consists of characterizing indicators for each evaluation sub-domain in the classification layer, where the characterizing indicators for the frequency of compound extreme events include the number of compound drought and vegetation loss events. The data acquisition and processing module is used to acquire the raw data of the watershed and determine the corresponding characterization data in the indicator layer based on the raw data; specifically, it is used to construct a compound drought and vegetation loss event identification model based on the Copula method, and to obtain the number of compound drought and vegetation loss events in the watershed through the compound drought and vegetation loss event identification model; it is also used to normalize the characterization data and determine the weight of each corresponding sub-item at each level from the classification layer, criterion layer to the target layer; and it is used to obtain the comprehensive watershed safety evaluation result of the target layer from the weight of each corresponding sub-item at each level.

9. An electronic device, characterized in that, The electronic device includes a memory and a processor coupled to each other, the processor being used to execute program instructions stored in the memory to implement the watershed safety assessment method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores program instructions, which, when executed by a processor, implement the watershed safety assessment method according to any one of claims 1 to 7.

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