Urban agglomeration ecological safety index scene modeling method, device and equipment based on system dynamics model

Abstract

The invention discloses an urban agglomeration ecological safety index scene modeling method, device and equipment based on a system dynamics model, and relates to the cross technical field of system dynamics and urban sustainable development evaluation. According to the embodiment of the invention, the ecological safety index integrating the ecological resource guarantee degree, the ecological system service value and the ecological risk pathology degree is constructed, the ecological safety system is divided into a plurality of subsystems, the future ecological safety scene is simulated and predicted by constructing the system dynamics model, and the method has the advantages of convenience in operation and high adaptability, and is suitable for popularization and application. According to the method, the complex relation between indexes on a large time scale is disclosed, the development trend and trend of future ecological safety indexes can be adaptively predicted according to urban agglomeration development policies of different scenes, and a basis is provided for subsequent urban space planning and sustainable development decision making.

Description

Technical Field

[0001] The present invention relates to the cross-technical field of system dynamics and urban sustainable development assessment, and in particular to a scenario modeling method, device and equipment for an urban agglomeration ecological security index based on a system dynamics model. Background Art

[0002] Urban agglomerations have become the main form of new urbanization. Due to high population and economic density, rapid land use changes and overexploitation of water resources pose a serious threat to the ecosystem. Disastrous consequences such as vegetation degradation, drying up of rivers and lakes, and loss of ecosystem service value have become key factors restricting the healthy development of urban agglomerations, and ecological security has attracted much attention.

[0003] Previous studies have provided various ecological security indicators and evaluation methods. Most indicator systems are based on the Driver-Pressure-State-Impact-Response (DPSIR) framework. Therefore, a weighted aggregation method is usually used. As for the selection of specific indicators, land and water security are usually given priority because land and water are the basic components of irreplaceable ecological resources. In recent years, some scholars have emphasized the importance of ecosystem service value and used it as the main indicator for evaluating ecological security. However, it should be noted that the ecological security of a region depends not only on its rich ecological resources and high ecosystem service value, but also on its ability to cope with risks.

[0004] Although different ecological security indicators have been proposed and applied in current and historical assessments, only a few models have conducted ecological security early warning, such as gray early warning models, cellular automata, ant colony algorithms, etc. However, most of them are time series trend predictions based on the historical changes of the ecological security index itself, and often ignore the inherent change mechanism of the ecological security pattern and its influencing factors. Since ecological security is a complex dynamic system involving natural, economic and social factors, there are interactions and constraints between them and even the external environment, so it is difficult to accurately predict future changes by simulating the connections between key driving factors of ecological security. Summary of the invention

[0005] To solve the above problems, the present invention provides a scenario modeling method for the ecological security index of an urban agglomeration based on a system dynamics model, the method comprising: comprehensively determining a plurality of ecological security indexes based on the ecological resource security degree, the ecosystem service value and the ecological risk pathology degree; the ecological security indexes comprising: vegetation coverage, wetland coverage, ecological water security degree, ecosystem service value, degree of ecological space destruction and pathological degree of ecological risk; dividing the ecological security system into a plurality of subsystems, and constructing a system dynamics model of ecological security based on the plurality of subsystems; the subsystems comprising an ecological resource security degree subsystem, an ecosystem service value subsystem, an ecological risk pathology degree subsystem, a population subsystem and an economic subsystem; inputting each of the ecological security indexes to train the system dynamics model; and performing ecological security prediction and analysis on different scenario modes according to the trained system dynamics model.

[0006] The scenario modeling method of the urban agglomeration ecological security index based on the system dynamics model provided in the embodiment of the present invention constructs an ecological security index that integrates the ecological resource security degree, ecosystem service value and ecological risk pathology. The ecological security system is divided into multiple subsystems. By constructing a system dynamics model to simulate and predict future ecological security scenarios, it has the advantages of easy operation and strong adaptability, reveals the complex relationship between indicators on a large time scale, and can adaptively predict the development trend and direction of future ecological security indicators according to the urban agglomeration development policies in different scenarios, providing a basis for subsequent urban spatial planning and sustainable development decision-making.

[0007] Optionally, constructing a system dynamics model of ecological safety based on the multiple subsystems includes: constructing a stock-flow diagram for each of the subsystems, and constructing a system dynamics model based on the stock-flow diagram.

[0008] In the embodiment of the present invention, a system dynamics model is constructed to establish equations between stocks and flows, so that each subsystem is interconnected and feedback is provided. This model has the advantages of convenient operation and strong adaptability, and can reveal the complex relationship between indicators on a large time scale.

[0009] Optionally, the calculation formula of the ecological resource security subsystem is as follows:

[0010]

[0011] In the formula, D is the degree of damage to the ecological space, D i is the degree of damage to the i-th land; i is farmland, grassland, forest land and water area, S i is the reduction of the i-th land area; S i0 is the i-th land area in the base year;

[0012] C v=(S f +S g +S cv +S cg ) / S

[0013] Among them, C v is the vegetation coverage, S f is the forest area; S g is the grassland area, S cv is the vegetation coverage area of ​​cultivated land; S cg is the green coverage area of ​​the built-up area; S is the total land area;

[0014] C w =S w / S

[0015] Among them, C w is the wetland coverage rate; S w is the water area;

[0016]

[0017] In the formula, R w is the water resource utilization rate; W dem is the total water demand, W sup is the total water supply; W i For industrial water; W a For agricultural water use, W d For domestic water, W e For ecological water use; u Available water resources; W r It is a reusable water resource; W t is a transferable water resource, R w The normalized value of is the degree of ecological water use guarantee W;

[0018] The calculation formula of the ecosystem service value subsystem is as follows:

[0019]

[0020] In the formula, ESV is the total value of regional ecosystem services, k The value of ecosystem services for the kth place, A k is the area of ​​the kth land; VC k is the ecosystem service value coefficient of the kth site;

[0021] The calculation formula of the ecological risk pathology subsystem is as follows:

[0022]

[0023] In the formula, R is the pathological degree of ecological risk; i is the land use type, Si is the i-th land use area; n is the number of land use types; W i is the ecological risk intensity parameter of the i-th land use type;

[0024] The calculation formula of the population subsystem is as follows:

[0025] P=p b +p d +p i +p m =UP+RP

[0026] Where P is the total population; p b is the birth population; p d is the death population; p i is the net immigrant population; p m is the policy immigrant population; UP is the urban population, and RP is the rural population;

[0027] The calculation formula of the ecosystem service value subsystem is as follows:

[0028]

[0029] In the formula, GDP is gross domestic product; V i is the ith industry at the current time t; is the added value of the ith industry at the initial time t0; R i is the industry with the ith value added growing in time t.

[0030] The embodiment of the present invention specifically provides equations between the stocks and flows of the five subsystems, so that the five subsystems are interconnected and feedback is provided.

[0031] Optionally, the scenario model includes: an existing development model, an economic development model or an ecological development model.

[0032] The embodiment of the present invention specifically provides three scenario modes, which respectively focus on continuing the current mode, focus on economic growth, and focus on ecological protection, and prediction and analysis are performed under different scenario modes.

[0033] Optionally, the method further comprises: determining an error between a simulated value and an actual value output by the system dynamics model to evaluate the system dynamics model.

[0034] In order to maintain the reliability and availability of the model in the embodiment of the present invention, the accuracy of the model is evaluated based on the error between the model simulation value and the actual value, thereby ensuring the robustness of the constructed system dynamics model.

[0035] Optionally, the method further includes: normalizing the ecological security indexes using a multi-objective fuzzy membership function, and calculating the comprehensive ecological security index using a weighted aggregation method.

[0036] In the embodiment of the present invention, each ecological security index is normalized to facilitate evaluation, and ecological security is evaluated based on the future trend of the comprehensive ecological security index.

[0037] Optionally, the method further includes: determining the grade of the ecological safety level according to the normalized value of each of the ecological safety indexes.

[0038] In the embodiment of the present invention, the normalized result based on the ecological security index can evaluate the ecological security level.

[0039] The embodiment of the present invention provides an urban agglomeration ecological security index scenario modeling device based on a system dynamics model, comprising: an indicator construction module, which is used to comprehensively determine multiple ecological security indexes based on ecological resource security, ecosystem service value and ecological risk pathology; the ecological security indexes include: vegetation coverage, wetland coverage, ecological water security, ecosystem service value, degree of ecological space destruction and pathological degree of ecological risk; a model simulation module, which is used to divide the ecological security system into multiple subsystems, and construct a system dynamics model of ecological security based on the multiple subsystems; the subsystems include an ecological resource security subsystem, an ecosystem service value subsystem, an ecological risk pathology subsystem, a population subsystem and an economic subsystem; a model training module, which is used to input each of the ecological security indexes to train the system dynamics model; and a model prediction module, which is used to perform ecological security prediction analysis on different scenario modes according to the trained system dynamics model.

[0040] An embodiment of the present invention provides an electronic device, comprising: a processor, a memory and a bus; the processor and the memory communicate with each other via the bus; the memory stores program instructions, and the processor calls the program instructions to execute the above-mentioned urban agglomeration ecological security index scenario modeling method based on the system dynamics model.

[0041] An embodiment of the present invention provides a non-transitory computer-readable storage medium, characterized in that the non-transitory computer-readable storage medium stores computer instructions, and when the computer instructions are executed by a computer, the computer executes the above-mentioned urban agglomeration ecological security index scenario modeling method based on the system dynamics model.

[0042] The above-mentioned urban agglomeration ecological security index scenario modeling device based on the system dynamics model, electronic device and non-transitory computer-readable storage medium in the embodiments of the present invention can achieve the same technical effect as the above-mentioned urban agglomeration ecological security index scenario modeling method based on the system dynamics model. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0044] Figure 1 A schematic diagram of the execution of the system dynamics model algorithm provided by an embodiment of the present invention;

[0045] Figure 2 A schematic diagram of a flow chart of a scenario modeling method for an urban agglomeration ecological security index based on a system dynamics model provided in an embodiment of the present invention;

[0046] Figure 3 A schematic structural diagram of a scenario modeling device for an urban agglomeration ecological security index based on a system dynamics model provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] Ecological security plays a vital role in the sustainable development of urban agglomerations. High population density and high economic density have brought tremendous pressure to the ecosystem. Urban agglomerations have become the main form of new urbanization. Due to the high population and economic density, the rapid transformation of land use and the overexploitation of water resources have posed a serious threat to the ecosystem. Disastrous consequences such as vegetation degradation, drying up of rivers and lakes, and loss of ecosystem service value have become key factors restricting the healthy development of urban agglomerations.

[0049] Since ecological security is a complex dynamic system involving natural, economic and social factors, with interactions and constraints among them and even among the external environment, it is difficult to accurately predict future changes by modeling the connections between key drivers of ecological security.

[0050] The embodiment of the present invention proposes a scenario modeling method for the ecological security index of an urban agglomeration based on a system dynamics model, which simulates and predicts future ecological security scenarios by constructing a system dynamics (SD) model. Because it has the advantages of easy operation and strong adaptability, it can reveal the complex relationship between indicators on a large time scale. The main purpose of the present invention is to provide a framework for evaluating the historical and future conditions of the ecological security of urban agglomerations based on a clear understanding of the coupling mechanism between its driving factors.

[0051] Among them, the ecological security index system is constructed using the collected indicator data and empirical data. The research ideas of the embodiment of this application include: constructing an ecological security index that integrates the ecological resource security, ecosystem service value and ecological risk pathology; using multi-objective fuzzy membership function and weight aggregation method to calculate the comprehensive index; constructing a system dynamics model to simulate and predict future ecological security scenarios.

[0052] Figure 1 Schematic diagram of the execution of the system dynamics model algorithm provided in the embodiment of this application. System dynamics has three general steps: expression of ecological security issues or concepts, construction and simulation of system dynamics models, and verification and predictive analysis of system dynamics models. Specifically:

[0053] The first step is to determine the key variables of the system dynamics model based on a review of the existing urban agglomeration ecological security indicators. The availability of data should also be considered when identifying key variables. The present invention constructs an ecological security index from three aspects: the degree of ecological resource security, the value of ecosystem services, and the degree of ecological risk pathology. Among them, ecological resources are mainly divided into land resources and water resources. Vegetation coverage and wetland coverage are used to measure the degree of security of ecological space. Since water is a key element of the ecological environment, the utilization rate of water resources is used to reflect the degree of security of ecological water use.

[0054] Based on this, the embodiment of the present invention determines multiple basic indicators under three dimensions and uses them as key variables of the SD model. At the same time, each indicator is normalized according to the normalization equation, and the region is divided into five levels: low, lower, medium, higher, and high, as a reference for subsequent ecological security assessment.

[0055] Specifically, all indicators are normalized to 0-1, and the ecological security level is divided into five types: low, lower, medium, higher, and high. For example, h1 represents the low security type and h1∈[k1, k2); h2 represents the lower security type and h2∈[k2, k3); h3 represents the medium security type and h1∈[k3, k4); h4 represents the higher security type and h4∈[k4, k5); h5 represents the high security type and h2∈[k5, k6). k1=0, k2=0.2, k3=0.4, k4=0.6, k5=0.8, k6=1. For any indicator, its threshold u1, u2, u3, u4, u5, u6, determined by national and international standards or average levels, corresponds to the threshold k1, k2, k3, k4, k5, k6 of the ecological security level, respectively.

[0056] The second step is to construct a stock-flow diagram between the variables of the system dynamics model. The stock flow diagram describes the relationship between the variables in the system through the above two flows. The existing SD model related to sustainable urbanization is used as a reference for analyzing the relationship between the variables in this study. Here, the ecological security system is divided into five subsystems: ecological resource security subsystem, ecological service value subsystem, ecological risk pathology subsystem, population subsystem and economic subsystem. Exemplarily, Vensim software can be used to draw stock and flow diagrams, establish equations between stocks (level variables) and flows (rate variables), and connect and feedback the five subsystems.

[0057] The third step is scenario prediction analysis of the system dynamics model. In order to ensure the ecological security of urban agglomerations, it is important to grasp the future trend of the ecological security index. The SD model can provide decision support to determine how the ecological security index changes and how the related ecological and socio-economic systems work. Since the links between the key drivers of ecological security are complex, three scenario models can be assumed.

[0058] (1) Scenario A is set as the current development model. This scenario is used as a baseline that the previous development model will continue, that is, the growth rates of population, urbanization rate and economy, and the land use change and water use change of all cities in the future period are obtained by trend prediction of historical data.

[0059] (2) Scenario B is set as an economic development model. Compared with Scenario A, this scenario aims at rapid economic growth rather than ecological protection. It has a higher urbanization rate, a higher GDP growth rate, and higher water and land consumption. In this scenario, key parameters such as urbanization rate and water quota are 5% higher than the baseline.

[0060] (3) Scenario C is set as an ecological development model. Compared with Scenario B, the goal of this scenario is ecological protection rather than economic growth. It has a lower urbanization rate, lower GDP growth rate, and lower water and land consumption. In this scenario, key parameters such as urbanization rate and water quota are 5% lower than the baseline.

[0061] Finally, based on the constructed system dynamics model, predictions, simulations and analyses were carried out according to three different scenario modes.

[0062] Figure 2 A schematic flow chart of a scenario modeling method for an urban agglomeration ecological security index based on a system dynamics model provided by an embodiment of the present invention is shown. The method is used to simulate the relationship between key driving factors of ecological security and accurately predict future scenarios, and includes the following steps:

[0063] S202, based on the ecological resource security, ecosystem service value and ecological risk pathology, comprehensively determine multiple ecological security indexes.

[0064] Ecological security refers to ensuring the safety, health and sustainable development of the ecosystem. Abundant ecological resources, huge ecological service value and low ecological risk are the most important aspects of ecological security. To this end, the ecological security index is constructed from three aspects: ecological resource security, ecosystem service value and ecological risk pathology.

[0065] Among them, ecological resources are mainly divided into land resources and water resources. Land resources, as a spatial carrier, provide ecological space. Therefore, the degree of destruction of ecological space, vegetation coverage and wetland coverage are used to measure the degree of guarantee of ecological space. Since water is a key element of the ecological environment, the utilization rate of water resources is used to reflect the degree of guarantee of ecological water use. The ecological security index can include: vegetation coverage, wetland coverage, ecological water security, ecosystem service value, degree of destruction of ecological space and pathological degree of ecological risk.

[0066] In summary, the ecological security index is constructed as follows:

[0067] ESI=(D'+C' v +C' w +W'+ESV'+R') / 6

[0068] Among them, ESI is the ecological security index; D' is the normalized degree of damage to the ecological space (D); C' v is the vegetation coverage (C v )’ w is the wetland coverage (C w) is the normalized value of the ecological water security degree; W' is the normalized value of the ecological water security degree, is the positive value of the water resource utilization rate; ESV' is the positive value of the ecosystem service value (ESV); R' is the ecological risk (R) of the pathological degree of the positive normalized value. D, C v , C w , R w The actual values ​​of , ESI and R were calculated by the SD model. The normalized values ​​were calculated by the multi-objective fuzzy membership function (Bao Chao, Zou Jianjun. Evaluation of water resources security pattern in the Beijing-Tianjin-Hebei urban agglomeration based on human-water relationship. Acta Ecologica Sinica. 2018).

[0069] Based on this, the above method may also include: according to the above ecological security indexes, using a multi-objective fuzzy membership function for normalization, and using a weighted aggregation method to calculate the ecological security comprehensive index. The ecological security comprehensive index is the above ESI.

[0070] For each ecological security index, the level of ecological security can be determined according to the normalized value of each ecological security index. For example, all indicators are normalized to 0-1, and the ecological security level is divided into five types: low, relatively low, medium, relatively high, and high, corresponding to different levels of ecological security.

[0071] For vegetation coverage (C v ), wetland coverage (C w ), ecological water security, ecosystem service value (ESV) and other positive indicators, the normalized formula is:

[0072]

[0073] For negative indicators, such as the degree of ecological space destruction (D), water resource utilization rate (R w ), the pathological degree of ecological risk (R), and its normalized formula is:

[0074]

[0075] Among them, s λij and x λij are the positive normalized value and actual value of indicator i in spatial unit j and year λ, respectively; n is the number of classification intervals.

[0076] S204, dividing the ecological security system into multiple subsystems, and constructing a system dynamics model of ecological security based on the multiple subsystems.

[0077] The Ecological Security Index and its six indicators do not change over time. In addition, complex physical, social and economic factors may affect their dynamics. Since the system dynamics model can simulate nonlinear dynamics, time delays, system feedback behavior responses and alternative future scenarios well, it is used to simulate and predict its future scenarios. For example, based on the historical data of the first 15 years, the system behavior of 13 cities in the urban agglomeration is simulated, after which the future of the next 15 years can be predicted.

[0078] For example, the ecological security system is divided into five subsystems: ecological resource security subsystem, ecosystem service value subsystem, ecological risk pathology subsystem, population subsystem and economic subsystem. In this embodiment, an equation between stock (level variable) and flow (rate variable) is established to make the five subsystems interconnected and feedback.

[0079] Specifically, the ecological security system is divided into five subsystems, and the equation between stocks and flows is established by constructing a system dynamics model, so that the five subsystems are interconnected and feedback.

[0080] S206, inputting various ecological security indexes to train the system dynamics model.

[0081] The values ​​of various ecological security indexes are obtained, which can be extracted from the recorded real historical data.

[0082] In order to maintain the reliability and availability of the model, the model accuracy is evaluated based on the error between the model simulation value and the actual value, thereby ensuring the robustness of the constructed system dynamics model. The model parameters are updated through continuous training and iteration of the model.

[0083] S208, conducting ecological security prediction analysis on different scenario modes based on the trained system dynamics model.

[0084] In this embodiment, three different scenario modes are set to respectively perform scenario prediction and analysis of the ecological security index. Specifically, the scenario modes include: existing development mode, economic development mode or ecological development mode.

[0085] The existing development model is used as the previous development model will continue, the economic development model aims at rapid economic growth rather than ecological protection, and the ecological development model aims at ecological protection rather than economic growth.

[0086] The scenario modeling method of the urban agglomeration ecological security index based on the system dynamics model provided in the embodiment of the present invention constructs an ecological security index that integrates the ecological resource security degree, ecosystem service value and ecological risk pathology. The ecological security system is divided into multiple subsystems. By constructing a system dynamics model to simulate and predict future ecological security scenarios, it has the advantages of easy operation and strong adaptability, reveals the complex relationship between indicators on a large time scale, and can adaptively predict the development trend and direction of future ecological security indicators according to the urban agglomeration development policies in different scenarios, providing a basis for subsequent urban spatial planning and sustainable development decision-making.

[0087] Specifically, each subsystem is introduced as follows:

[0088] a) Ecological resource protection subsystem

[0089] The core variables of the ecological resource protection degree subsystem include ecological space destruction degree (D), vegetation coverage (C), wetland coverage (G w ), ecological water security (W), where land resources include cultivated land area, grassland area, construction land area, forest area and water area, which are calculated based on land use conversion, which is closely related to the speed of population and economic urbanization. Water resources are expressed by the degree of ecological water security or the utilization rate of water resources, which links water supply and demand, and then links population and economic subsystems. The main calculation formula is as follows:

[0090]

[0091] In the formula, D is the degree of damage to the ecological space, D i is the degree of damage to the i-th land; i is farmland, grassland, forest land and water area, S i is the reduction of the i-th land area; S i0 is the i-th land area in the base year;

[0092] C v =(S f +S g +S cv +S cg ) / S

[0093] Among them, C v is the vegetation coverage, S f is the forest area; S g is the grassland area, S cv is the vegetation coverage area of ​​cultivated land; S cg is the green coverage area of ​​the built-up area; S is the total land area;

[0094] C w =S w / S

[0095] Among them, C w is the wetland coverage rate; S w is the water area;

[0096]

[0097] In the formula, R w is the water resource utilization rate; W dem is the total water demand, W sup is the total water supply; W i For industrial water; W a For agricultural water use, W d For domestic water, W e For ecological water use; u Available water resources; W r It is a reusable water resource; W t is a transferable water resource, R w The normalized value of is the degree of guarantee W for ecological water use.

[0098] b) Ecosystem service value subsystem

[0099] The ecosystem service value includes the service value of cultivated land, grassland, forest, water and construction land, which are determined by the area of ​​each land and the ecosystem service value coefficient. The embodiment of the present invention adopts the previous estimation of the ecosystem service value coefficient of each land area in the urban agglomeration, that is, the ecosystem service value coefficients of cultivated land, forest, grassland, water and unused land are 7064.41, 32690.52, 21299.16, 195842.8 and 1642.48 yuan / (hm2*a) respectively, and the main calculation formulas are as follows:

[0100]

[0101] In the formula, ESV is the total value of regional ecosystem services, k The value of ecosystem services for the kth place, A k is the area of ​​the kth land; VC k is the ecosystem service value coefficient of the kth place.

[0102] c) Ecological risk pathology subsystem

[0103] The pathological degree of ecological risk reflects the risk of ecosystem degradation due to pathological factors. Generally speaking, it is related to the land use structure due to the fragility of various land use types. The greater the vulnerability of the land use type, the smaller the elasticity, and the greater the intensity of the ecological risk that may occur. According to previous studies, the ecological risk intensity parameters of each land use type are set as follows: 0.32 for cultivated land, 0.12 for forest land, 0.16 for grassland, 0.53 for water area, and 0.85 for construction land. The main calculation equations are as follows:

[0104]

[0105] In the formula, R is the pathological degree of ecological risk; i is the land use type, S i is the i-th land use area; n is the number of land use types; W i is the ecological risk intensity parameter of the i-th land use type.

[0106] d) Population subsystem

[0107] Population is determined by natural growth and mechanical growth. Natural growth is controlled by birth rate and death rate, while mechanical growth is mainly controlled by net immigration and policy immigration. The total population includes urban and rural populations, which are the main indirect factors affecting economic development, land use types, water demand and supply. Therefore, the population subsystem is associated with other subsystems of ecological security, and the main calculation equation is as follows:

[0108] P=p b +p d +p i +p m =UP+RP

[0109] Where P is the total population; p b is the birth population; p d is the death population; p i is the net immigrant population; p m is the policy immigrant population; UP is the urban population, and RP is the rural population;

[0110] e) Economic subsystem

[0111] The core variable of the economic subsystem is the gross domestic product (GDP). It consists of the tertiary industry, which is calculated using the growth rate method. They are direct or indirect factors that affect land use types, water demand and supply. Therefore, the economic subsystem is interconnected with other subsystems of ecological security. The main calculation formula is as follows:

[0112]

[0113] In the formula, GDP is gross domestic product; V i is the ith industry at the current time t; is the added value of the ith industry at the initial time t0; R i is the industry with the ith value added growing in time t.

[0114] Simulation results and verification

[0115] In order to verify whether the simulation of the ecological security SD model is reliable and accurate, the parameters are input into the SD model, and the simulation results are compared with the actual values ​​in the process. The embodiment of the present invention selects five important variables, including ecological land area, population, GDP, water demand, and wetland coverage rate of 13 cities, to test the relative error between the simulated value and the actual value. The results show that the annual average error of the 13 cities from 2000 to 2015 is within 5%. The SD model does not produce abnormal behavior, indicating that this SD model is in line with reality. Therefore, the simulated values ​​of population, economy, water use and land use of B13 cities can be used to reflect the actual values. This shows that the SD model has good calibration and can be used to predict future ecological security scenarios.

[0116] Scenario forecast analysis

[0117] In order to ensure ecological security, it is important to grasp the future trend of ESI. The SD model can provide decision support to determine how ESI changes and how the related ecological and socio-economic systems work. Since the links between the key drivers of ecological security are complex, it can be assumed that the overall parameters will change with their respective historical development trends and the key parameters will change under different scenarios. Although many scenarios can be set, by designing comprehensive scenarios from the main aspects of ESI and related ecological and socio-economic systems, the focus can be grasped and the simulation can be simplified. Therefore, three comprehensive scenarios are designed from the perspective of urban agglomeration development mode:

[0118] a) Scenario A is set as the existing development pattern. This scenario is used as a baseline that the previous development pattern will continue, that is, the growth rates of population, urbanization rate and economy, as well as the future land use change and water use change of all cities are obtained through trend prediction.

[0119] b) Scenario B is set as an economic development model. Compared with Scenario A, this scenario aims at rapid economic growth rather than ecological protection. It has a higher urbanization rate, a higher GDP growth rate, and higher water and land consumption. In this scenario, key parameters such as urbanization rate and water quota are 5% higher than the baseline.

[0120] c) Scenario C is set as an ecological development model. Compared with Scenario B, this scenario aims at ecological protection rather than economic growth. It has a lower urbanization rate, lower GDP growth rate, and lower water and land consumption. In this case, key parameters such as urbanization rate and water use quota are 5% lower than the baseline.

[0121] Based on the above scenario settings, scenario forecasts are carried out and results are analyzed.

[0122] The embodiment of the present invention provides a scenario modeling device for the ecological security index of an urban agglomeration based on a system dynamics model. Figure 3 A schematic diagram of a scenario modeling device for an urban agglomeration ecological security index based on a system dynamics model is provided in an embodiment of the present invention. The device comprises:

[0123] The indicator construction module 301 is used to comprehensively determine multiple ecological security indexes based on the ecological resource security, the ecosystem service value and the ecological risk pathology; the ecological security indexes include: vegetation coverage, wetland coverage, ecological water security, ecosystem service value, ecological space destruction and ecological risk pathology;

[0124] The model simulation module 302 is used to divide the ecological security system into multiple subsystems, and to construct a system dynamics model of ecological security based on the multiple subsystems; the subsystems include an ecological resource security degree subsystem, an ecosystem service value subsystem, an ecological risk pathology degree subsystem, a population subsystem, and an economic subsystem;

[0125] A model training module 303, used for inputting each of the ecological security indexes to train the system dynamics model;

[0126] The model prediction module 304 is used to perform ecological security prediction analysis on different scenario modes according to the trained system dynamics model.

[0127] The urban agglomeration ecological security index scenario modeling device based on the system dynamics model provided in the embodiment of the present invention constructs an ecological security index that integrates the ecological resource security degree, ecosystem service value and ecological risk pathology. The ecological security system is divided into multiple subsystems. By constructing a system dynamics model to simulate and predict future ecological security scenarios, it has the advantages of easy operation and strong adaptability, reveals the complex relationship between indicators on a large time scale, and can adaptively predict the development trend and direction of future ecological security indicators according to the urban agglomeration development policies in different scenarios, providing a basis for subsequent urban spatial planning and sustainable development decision-making.

[0128] Furthermore, it also includes an acquisition module for acquiring data and its indicator values.

[0129] An embodiment of the present invention provides an electronic device, comprising: a processor, a memory and a bus; the processor and the memory communicate with each other via the bus; the memory stores program instructions, and the processor calls the program instructions to execute the above-mentioned urban agglomeration ecological security index scenario modeling method based on the system dynamics model.

[0130] An embodiment of the present invention provides a non-transitory computer-readable storage medium, which stores computer instructions. When the computer instructions are executed by a computer, the computer executes the above-mentioned urban agglomeration ecological security index scenario modeling method based on the system dynamics model.

[0131] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the control device through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it may include the processes of the above-mentioned method embodiments, wherein the storage medium may be a memory, a disk, an optical disk, etc.

[0132] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0133] The above contents described in this specification are merely examples of the present invention. The present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A scenario modeling method for the ecological security index of urban agglomerations based on a system dynamics model, characterized in that: The method comprises: Based on the ecological resource security, ecosystem service value and ecological risk pathology, a number of ecological security indexes are comprehensively determined; the ecological security indexes include: vegetation coverage, wetland coverage, ecological water security, ecosystem service value, ecological space destruction and ecological risk pathology; Dividing the ecological security system into multiple subsystems, and constructing a system dynamics model of ecological security based on the multiple subsystems; the subsystems include an ecological resource security degree subsystem, an ecosystem service value subsystem, an ecological risk pathology degree subsystem, a population subsystem, and an economic subsystem; Inputting each of the ecological safety indexes to train the system dynamics model; The ecological security prediction and analysis of different scenario modes are carried out according to the system dynamics model after training.

2. The method according to claim 1, characterized in that: The system dynamics model of ecological safety based on the multiple subsystems includes: A stock-flow diagram of each of the subsystems is constructed, and a system dynamics model is constructed based on the stock-flow diagram.

3. The method according to claim 1, characterized in that The calculation formula of the ecological resource security subsystem is as follows: In the formula, D is the degree of damage to the ecological space, D i is the degree of damage to the i-th land; i is farmland, grassland, forest land and water area, S i is the reduction of the i-th land area; S i0 is the i-th land area in the base year; C v =(S f +S g +S cv +S cg ) / S Among them, C v is the vegetation coverage, S f is the forest area; S g is the grassland area, S cv is the vegetation coverage area of ​​cultivated land; S cg is the green coverage area of ​​the built-up area; S is the total land area; C w =S w / S Among them, C w is the wetland coverage rate; S w is the water area; In the formula, R w is the water resource utilization rate; W dem is the total water demand, W sup is the total water supply; W i For industrial water; W a For agricultural water use, W d For domestic water, W e For ecological water use; u Available water resources; W r It is a reusable water resource; W t is the transferable water resource, R w The normalized value of is the degree of ecological water use guarantee W; The calculation formula of the ecosystem service value subsystem is as follows: In the formula, ESV is the total value of regional ecosystem services, k The value of ecosystem services for the kth place, A k is the area of ​​the kth land; VC k is the ecosystem service value coefficient of the kth site; The calculation formula of the ecological risk pathology subsystem is as follows: Where R is the pathological degree of ecological risk; i is the land use type, S is the i-th land use area; n is the number of land use types; W i is the ecological risk intensity parameter of the i-th land use type; The calculation formula of the population subsystem is as follows: P=p b +p d +p i +p m =UP+RP Where P is the total population; p b is the birth population; p d is the death population; p i is the net immigrant population; p m is the policy immigrant population; UP is the urban population, and RP is the rural population; The calculation formula of the ecosystem service value subsystem is as follows: In the formula, GDP is gross domestic product; V i is the ith industry at the current time t; is the added value of the ith industry at the initial time t0; R i is the industry with the ith value added growing in time t.

4. The method according to claim 1, characterized in that The scenario models include: existing development model, economic development model or ecological development model.

5. The method according to claim 1, characterized in that The method further comprises: The error between the simulated value and the actual value of the system dynamics model output is determined to evaluate the system dynamics model.

6. The method according to claim 1, characterized in that The method further comprises: According to each of the ecological security indexes, a multi-objective fuzzy membership function is used for normalization, and a weighted aggregation method is used to calculate the comprehensive ecological security index.

7. The method according to claim 6, characterized in that The method further comprises: The grade of the ecological safety level is determined according to the normalized value of each of the ecological safety indexes.

8. A scenario modeling device for the ecological security index of urban agglomerations based on a system dynamics model, characterized in that: include: An indicator construction module is used to comprehensively determine multiple ecological security indices based on ecological resource security, ecosystem service value, and ecological risk pathology; The ecological security index includes: vegetation coverage, wetland coverage, ecological water security, ecosystem service value, ecological space destruction degree and ecological risk pathological degree; A model simulation module is used to divide the ecological security system into multiple subsystems, and to construct a system dynamics model of ecological security based on the multiple subsystems; the subsystems include an ecological resource security degree subsystem, an ecosystem service value subsystem, an ecological risk pathology degree subsystem, a population subsystem, and an economic subsystem; A model training module, used for inputting each of the ecological safety indexes to train the system dynamics model; The model prediction module is used to perform ecological security prediction analysis on different scenario modes according to the trained system dynamics model.

9. An electronic device, characterized in that: include: processor, memory, and bus; The processor and the memory communicate with each other via the bus; The memory stores program instructions, and the processor calls the program instructions to execute the scenario modeling method of the urban agglomeration ecological security index based on the system dynamics model as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium stores computer instructions, and when the computer instructions are executed by a computer, the computer is caused to execute the scenario modeling method of the urban agglomeration ecological security index based on the system dynamics model as described in any one of claims 1 to 7.

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