Urban green infrastructure comprehensive benefit applicability evaluation method based on subjective and objective weights

Abstract

The invention provides an urban green infrastructure comprehensive benefit applicability evaluation method based on subjective and objective weights. The urban green infrastructure comprehensive benefit applicability evaluation method comprises the steps of establishing a basic evaluation system, screening indexes, calculating index weights, calculating quantitative indexes, calculating qualitative indexes, performing grading evaluation, performing standardized score assignment and performing comprehensive evaluation. The basic evaluation system is of a three-layer structure and covers four criteria of runoff regulation and storage benefits, environmental benefits, economic benefits and social benefits and 19 indexes; a subjective weight is determined through an analytic hierarchy process, an objective weight is determined through an entropy weight method, and a comprehensive weight is obtained in combination with a D-S evidence theory fusion method; quantitative indexes are calculated through methods such as hydrological simulation, and qualitative indexes are rated by public; the indexes are unified into dimensionless scores through standardized score assignment, and finally an evaluation result is obtained through weighted summation. According to the method, the applicability quantitative evaluation of matching of the typical green infrastructure and the site condition construction target is realized, and a scientific and quantitative decision support tool is provided for sponge city planning.

Description

A method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights Technical Field

[0001] This invention relates to the field of applicability evaluation technology for urban green infrastructure, and in particular to a method for evaluating the comprehensive benefits of urban green infrastructure based on subjective and objective weights. Background Technology

[0002] Green infrastructure is an innovative solution to problems such as ecological space compression and hydrological cycle imbalance caused by rapid urbanization. Its development originated from the rise of the sponge city concept in the early 21st century and has gradually formed an engineering system integrating landscape design and stormwater management under the promotion of relevant policies. Its core lies in simulating the hydrological regulation function of natural ecosystems through low-impact development technologies such as bioretention facilities and permeable paving, and constructing a surface runoff management system that integrates infiltration, retention, and purification functions, providing an ecological technical path for solving urban problems such as stormwater flooding and non-point source pollution.

[0003] The effectiveness of green infrastructure is closely related to its construction scenario, and site adaptability has become a key factor restricting the release of its comprehensive benefits. Therefore, constructing a scientific and quantitative suitability assessment system is not only a necessary means to ensure the effective functioning of facilities, but also an important prerequisite for maximizing construction benefits. With the deepening of the concept of sustainable development, the evaluation of modern green infrastructure has expanded from a single focus on stormwater regulation to multiple dimensions such as carbon sink gains, ecological service enhancement, and optimization of life-cycle cost-effectiveness. This places higher demands on assessment methods, requiring multi-objective collaborative analysis.

[0004] However, current suitability assessment studies mostly focus on case studies of specific facility types or single construction scenarios, lacking a universally applicable standardized assessment framework. Furthermore, issues such as how to integrate different indicators into the scoring system, how to coordinate quantitative and qualitative indicators, and how to scientifically determine indicator weights have not been effectively resolved during the comprehensive evaluation process. This makes it difficult for existing research to provide effective guidance for the suitability assessment of urban green infrastructure.

[0005] To this end, this invention constructs a systematic evaluation framework, which sorts and classifies multi-dimensional evaluation indicators, establishes a scientific quantitative scoring method, and combines subjective and objective weighting to achieve a scientific assessment of the applicability of urban green infrastructure, providing a scientific and quantitative decision support tool for sponge city planning. Summary of the Invention

[0006] This invention provides a method for evaluating the applicability of urban green infrastructure based on subjective and objective weights. It simulates the operation of facilities in different application scenarios, formulates an evaluation system and scoring standards that match the background characteristics of the scenarios and the construction goals of the facilities, and combines subjective and objective weight calculation methods to achieve a comprehensive evaluation of the applicability of facility effectiveness.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights, comprising the following steps: S1: Establishing a basic evaluation system, wherein the basic evaluation system is a three-tiered structure, the highest tier being the target tier, i.e., the applicability evaluation of green infrastructure construction schemes; the second tier being the criterion tier, including runoff regulation benefits, environmental benefits, economic benefits, and social benefits; and the third tier being the indicator tier, encompassing 19 indicators characterizing the effectiveness of infrastructure construction schemes; S2: Indicator selection, based on the characteristics of the target area of ​​the project construction and the type of green infrastructure, refining, adjusting, optimizing, and simplifying the content of the indicator tier; S3: The calculation of indicator weights involves: S4: Calculating subjective weights using the Analytic Hierarchy Process (AHP), determining objective weights using entropy weighting based on actual data from similar projects, and finally obtaining the comprehensive weights of each indicator through the DS evidence theory fusion method; S5: Calculating quantitative indicators by simulating the construction plan based on the basic environmental conditions of the region to obtain the specific values ​​of each quantitative indicator; S6: Grading evaluation of qualitative indicators by using a grading evaluation model for landscape aesthetic value and public space restability; S7: Standardized scoring by converting indicators of different dimensions into dimensionless scores under a unified scoring system; and S8: Comprehensive evaluation by weighting and summing the standardized scores corresponding to each level of indicators according to the comprehensive weights to obtain the facility suitability evaluation results.

[0008] Furthermore, the 19 indicators in step S1 include annual runoff control rate, runoff reduction rate, peak reduction rate, peak delay time, groundwater recharge ratio, rainwater reuse ratio, annual runoff pollution removal rate, TSS reduction rate, TN reduction rate, TP reduction rate, COD reduction rate, vegetation cover growth rate, carbon emissions from construction, carbon sequestration in green spaces, construction costs, maintenance costs, landscape aesthetic value, public space recreational capacity, and heat island effect mitigation rate.

[0009] Furthermore, in step S1, the indicators are divided into two categories: mandatory and optional. Mandatory indicators include annual runoff control rate, runoff reduction rate, peak reduction rate, peak delay time, annual runoff pollution removal rate, and maintenance cost. The remaining indicators are optional.

[0010] Furthermore, in step S2, the subjective weight calculation uses the 1-9 scale method to establish the indicator judgment matrix, calculates the largest eigenvector of the judgment matrix and passes the consistency test. When the consistency ratio CR < 0.10, the judgment matrix is ​​acceptable; otherwise, the judgment matrix is ​​adjusted, and then the subjective weight of each indicator is calculated based on the judgment matrix.

[0011] Furthermore, the objective weight calculation in step S2 includes the following steps: collecting similar construction projects in the study area, obtaining the corresponding indicator values ​​for each project based on the evaluation indicator system determined in step S2, performing positive or negative standardization on the indicator values, calculating the proportion of each project in each indicator and the indicator entropy value, and finally calculating the objective weight of each indicator based on the entropy value.

[0012] Furthermore, the specific calculation process for objective weights is as follows: m items were collected, corresponding to n indicators, forming an indicator value matrix X=(x ij ) m*n For each indicator value (x) ij Standardization processing is performed; the standardization formula for positive indicators is: The standardized formula for the negative index is: After standardization, calculate the weight P of the i-th item in the j-th indicator. ij : The entropy value e of each indicator can be calculated. j : The objective weights of each indicator are derived as follows: .

[0013] Furthermore, the specific process of the DS evidence theory fusion method in step S3 is as follows: Subjective weight and objective weight are defined as the two evidence sources, defining the basic allocation probability. The conflict degree K of the two weight calculation methods is calculated. When the conflict degree K < 0.7, the DS synthesis rule is used to calculate the fused weight; when K ≥ 0.7, a weight coefficient λ is introduced, and the fusion weight is calculated using the formula... Calculate the fusion weight value.

[0014] Furthermore, the carbon emissions from construction in step S4 are calculated using the formula... Calculate, where C 13 T represents the indirect carbon emissions during the construction process. i,j,k V represents the number of machine shifts used per unit of work for the i-th type of project, the j-th type of construction equipment, and the k-th type of energy; i R represents the quantity of work for the i-th type of project. j F represents the energy consumption per unit shift of the j-th type of construction equipment. k The carbon emission factor represents the k-th energy type; the carbon sequestration of green spaces is expressed by the formula. Calculate, where C 14 A represents the carbon sink generated through green space carbon sequestration, where i represents the i-th facility capable of carbon sequestration; i The area F representing facility i * i T represents the carbon sequestration rate of facility i. iThe representative facility i represents the number of years of operation; the heat island effect mitigation rate is calculated by measuring the average temperature of the green infrastructure area 6-8 months after the construction project, the average temperature of the unmodified area within the study area, and the average temperature of the suburbs surrounding the urban area.

[0015] Furthermore, in step S5, the qualitative indicator grading evaluation is conducted by the surrounding closely related social public through a questionnaire survey, and the evaluation level is divided into five levels: very good, good, fair, poor, and very poor.

[0016] Furthermore, in step S6, the standardized scoring divides the evaluation results into five levels: very high efficiency corresponds to 90-100 points, relatively high efficiency corresponds to 80-90 points, average efficiency corresponds to 70-80 points, relatively low efficiency corresponds to 60-70 points, and very low efficiency corresponds to below 60 points. The quantitative index scores are obtained by linear interpolation of the corresponding score range, and the qualitative index scores are taken as the median of the corresponding evaluation level.

[0017] Compared with existing technologies, this invention has the following beneficial effects: 1. The evaluation dimensions are comprehensive and meet development needs, effectively covering the core benefits of green infrastructure: By constructing a three-level evaluation system that includes runoff regulation benefits, environmental benefits, economic benefits, and social benefits, encompassing 19 sub-indicators, especially including carbon reduction-related indicators such as construction carbon emissions, green space carbon sequestration, and heat island effect mitigation rate, it not only responds to low-carbon development goals but also achieves full-dimensional coverage of the diverse benefits of facilities, solving the problem of traditional evaluation focusing on a single function and neglecting comprehensive value.

[0018] 2. The determination of indicator weights is scientific and precise, taking into account both subjective experience and objective reality: Combining the analytic hierarchy process, entropy weight method and DS evidence theory, subjective weights reflect expert experience and regional development guidelines, while objective weights rely on actual operational data of similar projects. The conflict-adaptive fusion rules further coordinate the differences between the two. Compared with a single weighting method, the weight results are more convincing and improve the reliability of the evaluation conclusions.

[0019] 3. Flexible and adaptable indicator selection enhances the universality and relevance of the methodology: The indicators are divided into mandatory and optional categories, which can be dynamically adjusted according to the project construction goals, regional characteristics (such as geological conditions and pollution focus) and facility types. This ensures that the core evaluation dimensions are not missing while avoiding interference from redundant indicators, making the evaluation system adaptable to different scenarios such as new / existing projects and public / non-public projects. This solves the problems of rigidity and limited applicability of traditional evaluation frameworks.

[0020] 4. Quantitative and qualitative indicators are used in a coordinated evaluation process to achieve standardization and operability: Quantitative indicators provide clear calculation formulas and simulation methods, while qualitative indicators adopt a public tiered evaluation model. Combined with differentiated standardized scoring rules, indicators of different dimensions and types are unified into dimensionless scores. This not only solves the problem that qualitative indicators are difficult to quantify and that indicators cannot be directly compared, but also lowers the threshold for practical application through clear step design.

[0021] 5. The evaluation results are quantitative and intuitive, providing precise support for decision-making: By weighted summation, a clear comprehensive evaluation score and corresponding benefit level are obtained, which can intuitively reflect the degree of matching between the green infrastructure construction plan and the site conditions and construction goals. This provides a scientific quantitative basis for the selection, optimization and adjustment of construction plans in sponge city planning, and helps to maximize the benefits of facility construction. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 is a flowchart of an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] This invention provides a method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights, including the following steps: Step S1: Establishing a basic evaluation system: This invention generally adopts the hierarchical analysis method, with basic evaluation indicators divided into three layers from top to bottom. The highest layer is the target layer, i.e., the applicability evaluation of green infrastructure construction schemes; the second layer is the criterion layer, including runoff regulation and storage benefits, environmental benefits, economic benefits, and social benefits; the third layer is the indicator layer. The initial framework includes 19 indicators used to characterize the construction effects of specific construction schemes, including calculable quantitative indicators and qualitative indicators that require manual scoring. The 19 indicators are: annual runoff control rate, runoff reduction rate, peak reduction rate, peak delay time, groundwater replenishment ratio, rainwater reuse ratio, annual runoff pollution removal rate, TSS reduction rate, TN reduction rate, TP reduction rate, COD reduction rate, vegetation cover growth rate, construction carbon emissions, green space carbon sequestration, construction cost, maintenance cost, landscape aesthetic value, public space recreational capacity, and heat island effect mitigation rate. See Table 1 for details: Table 1 Basic Evaluation Indicator System

[0025] Step S2: Indicator Selection: Based on the characteristics of the target area and the type of green infrastructure, the existing evaluation indicator system is refined and adjusted, with a focus on optimizing and simplifying the content of the indicator layer. Mandatory indicators include annual runoff control rate, runoff reduction rate, peak flow reduction rate, peak flow delay time, annual runoff pollution removal rate, and maintenance cost. Non-mandatory indicators include groundwater recharge rate, rainwater reuse rate, TSS reduction rate, TN reduction rate, TP reduction rate, COD reduction rate, vegetation cover growth rate, construction carbon emissions, green space carbon sequestration, construction cost, landscape aesthetic value, public space recreational capacity, and urban heat island mitigation rate.

[0026] The properties of the evaluation indicators are shown in Table 2: Table 2 Properties of Evaluation Indicators

[0027] Groundwater recharge ratios are typically used only in construction areas with special geological conditions or when preliminary surveys confirm that groundwater recharge has significant value; rainwater reuse ratios are specifically for projects equipped with rainwater reuse facilities; TSS reduction rates, TN reduction rates, TP reduction rates, and COD reduction rates can be selectively included based on regional pollution control priorities; vegetation cover growth rate is only applicable to project evaluations using green bioretention facilities; construction carbon emissions and green space carbon sequestration require detailed understanding of facility energy consumption and vegetation carbon sequestration characteristics, and it is recommended to strengthen basic data collection in new projects; construction costs can be disregarded in the evaluation of existing projects; social benefit indicators are mainly applicable to public construction projects such as residential parks and wetlands, and not all project evaluations need to include them.

[0028] Step S3: Calculation of indicator weights: The indicator weights are determined based on the fusion of the analytic hierarchy process (AHP), entropy weight method, and DS evidence theory.

[0029] 1. Subjective Weight Determination: An indicator judgment matrix is ​​established to determine the relative importance of each evaluation indicator in the same layer of the criterion layer and the indicator layer, forming a judgment matrix. The 1-9 scale method is used as the standard for confirming the scale. Scale 1 indicates that the two factors are equally important, scale 3 indicates that one factor is slightly more important than the other, scale 5 indicates that one factor is significantly more important than the other, scale 7 indicates that one factor is strongly more important than the other, scale 9 indicates that one factor is extremely more important than the other, and scales 2, 4, 6, and 8 are the median between two adjacent scales. The reciprocal represents the judgment value of factor j on factor i.

[0030] The scales and their meanings are shown in Table 3: Table 3 Scales and their meanings

[0031] Before using the judgment matrix, a consistency check needs to be performed on it, and the consistency index CI needs to be calculated. , where λ maxTo determine the largest eigenvector corresponding to the matrix, where n is the number of indicators, find the average random consistency index RI corresponding to the number of indicators n, and calculate the consistency ratio CR. .

[0032] The average random consistency index RI corresponding to the number of indices n is shown in Table 4: Table 4 Average Random Consistency Index RI Values

[0033] When CR < 0.10, the judgment matrix is ​​acceptable; otherwise, it should be modified appropriately. Based on the judgment matrix, the weights (Wi) of each indicator (i) within each level can be calculated: .

[0034] 2. Objective Weight Determination: Collect a wide range of similar construction projects in the study area. Based on the evaluation index system determined in step S2, calculate the corresponding index values ​​for each project. For qualitative indicators, select their corresponding scores. Assume that m projects corresponding to n indicators are collected, forming an index value matrix X = (x... ij ) m*n .

[0035] Each indicator value is standardized. The standardization of positive indicators uses the following formula: The standardization of negative indicators uses the following formula: .

[0036] After standardization, calculate the weight P of the i-th item in the j-th indicator. ij : Furthermore, the entropy value e of each indicator can be calculated. j : .

[0037] Finally, the objective weights of each indicator were determined: .

[0038] Subjective-objective fusion weight calculation: Based on the DS evidence theory fusion method, using the subjective weight W determined by AHP. AHP The objective weight W determined by the entropy weight method 熵 As two sources of evidence, the basic allocation probability (BPA) is defined as follows: Furthermore, the conflict degree K between the two weighting methods is calculated: When the conflict degree K < 0.7, the fusion weights are calculated using the DS synthesis rule: When the conflict degree K ≥ 0.7, a weighting coefficient λ is introduced to calculate the fusion weight value: λ takes the value 0.7.

[0039] Step S4: Calculation of quantitative indicators: .

[0040] Step S4.1: Calculation of annual runoff control rate (C1). Referencing the region's multi-year average precipitation level and evaporation conditions, or long-sequence annual precipitation and evaporation monitoring data, simulate the annual runoff after the scheme's construction. The calculation formula is as follows: Where Qn is the annual runoff (mm) after the construction of LID facilities, and Pn is the annual precipitation (mm).

[0041] Step S4.2: Annual runoff pollutant removal rate (C7), denoted as SS, is expressed as the product of the total annual runoff removal rate and the average SS removal rate (SS average) of green infrastructure in the region. Step S4.3: Runoff reduction rate (C2), peak flow reduction rate (C3), TSS reduction rate (C8), TN reduction rate (C9), TP reduction rate (C10), and COD reduction rate (C11) are all assessed based on the corresponding return period design storms of concern to the project, calculating the runoff volume and water quality before and after the construction of green infrastructure. The corresponding calculation formulas are as follows: Where X represents one of the above indicators, Q0 represents the runoff (m³), peak flow (m³ / s), and pollutant amount (mg) generated under the design storm conditions before the construction of green facilities, and QLID represents the corresponding value after the construction of green infrastructure.

[0042] Step S4.4: The peak delay time (C4) is also the simulation result for the design storm with the corresponding return period. The corresponding calculation formula is as follows: Where T0 and TLID represent the time (in minutes) of the flood peak before and after the construction of the LID facility, respectively.

[0043] Step S4.5: The groundwater recharge ratio (C5) is based on the annual rainfall, and the corresponding calculation formula is as follows: Where Fn is the annual infiltration recharge (mm) after the construction of the LID facility.

[0044] Step S4.6: The rainwater reuse ratio (C6) is based on the annual runoff, and the corresponding calculation formula is as follows: Where Q_return represents the annual rainwater reuse volume (mm) after the construction of green infrastructure and rainwater reuse facilities.

[0045] Step S4.7: The vegetation cover growth rate (C12) is the change in the proportion of vegetation cover in the region before and after the construction of green infrastructure. The corresponding calculation formula is as follows: Where A0 and ALID represent the vegetation coverage area (m²) of the region before and after the construction of green infrastructure, respectively.

[0046] Step S4.8: Construction carbon emissions (C13) refer to the carbon emissions generated by the energy consumption of construction equipment during the construction process. The corresponding calculation formula is as follows: Where C13 represents the indirect carbon emissions during the construction process, kgCO2; Ti,j,k represents the number of shifts used per unit of work for the i-th type of project, the j-th type of construction equipment, and the k-th type of energy; Vi represents the work volume of the i-th type of project, m³; Rj represents the energy consumption per unit of work for the j-th type of construction equipment, kg / shift or kWh / shift; Fk represents the carbon emission factor of the k-th type of energy, kgCO2 / kg or kgCO2 / kwh.

[0047] Step S4.9: Green space carbon sequestration (C14) refers to the amount of carbon sink that can be generated through vegetation photosynthesis during the operation phase. The corresponding calculation formula is as follows: Where C14 represents the carbon sink generated through green space carbon sequestration, kgCO2; i represents the i-th facility capable of carbon sequestration; Ai represents the area of ​​facility i, m²; F*i represents the carbon sequestration rate of facility i, kgCO2 / (m²·a); Ti represents the operating years of facility i, a.

[0048] Step S4.10: Construction cost (C15) and maintenance cost (C16) refer to the cost per unit area of ​​facilities in the construction plan, and the corresponding calculation formulas are as follows: Where Ai represents the area of ​​facility i, in m²; Mi represents the unit area construction / maintenance cost of facility i, in yuan / m² or yuan / (m²·year).

[0049] Step S4.11: Calculating the heat island effect mitigation rate (C19) requires measuring and statistically analyzing the average temperature (TLID) of the green infrastructure area 6-8 months after the project's completion, the average temperature of unmodified plots within the study area (T-comparison), and the average temperature of plots in the surrounding suburbs (T-background) of the urban area. The final calculation formula is as follows: .

[0050] Step S5 Qualitative Indicator Grading Evaluation: The evaluation of landscape aesthetic value and public space recreationability is conducted through a questionnaire survey of the surrounding community, allowing for subjective evaluation from a public perspective. Questionnaires are distributed and collected using the Wenjuanxing platform, with evaluations categorized into five levels: Excellent, Good, Fair, Poor, and Very Poor. Landscape aesthetic value encompasses environmental biodiversity, vegetation coverage, landscape fragmentation, and the harmony between the constructed area and its surrounding landscape. Public space recreationability includes the construction of facilities such as lawns and benches in park-type projects, and rain gardens and permeable paved plazas in residential areas.

[0051] Step S6 Standardized Scoring: The final performance of the solution is divided into five levels: very high efficiency corresponds to 90-100 points on a 100-point scale, with a median of 95 points; relatively high efficiency corresponds to 80-90 points, with a median of 85 points; average efficiency corresponds to 70-80 points, with a median of 75 points; relatively low efficiency corresponds to 60-70 points, with a median of 65 points; and very low efficiency corresponds to below 60 points, with a median of 30 points.

[0052] The specific scoring ranges and their corresponding levels are shown in Table 5: Table 5 Standardized Scoring Method

[0053] The following rules should be followed when assigning scores to each indicator.

[0054] Step S6.1: The annual runoff control rate (C1) is an important indicator for evaluating the effectiveness of green facilities. Its target value is usually set at 0.5~0.8. For specific evaluation items, we use its expected target as the standard of 85 points; a runoff control rate of 90% as the standard of 100 points; and a relative runoff reduction rate of 20% after construction compared to the pre-construction state as the standard of 30 points. The specific scores are obtained by linear interpolation of the corresponding score ranges.

[0055] Step S6.2: The target value for the annual runoff pollution removal rate (C7) is usually set at 0.4~0.6. For specific evaluation items, we use the expected target as the standard of 85 points, a runoff control rate of 60% (if the target is higher than 60%, then the target value is used) as the standard of 100 points, 40% as the standard of 75 points, and the pre-construction state as the standard of 30 points. The specific score is obtained by linear interpolation of the corresponding score range.

[0056] Step S6.3: Runoff reduction rate (C2), peak reduction rate (C3), peak delay time (C4), groundwater recharge ratio (C5), rainwater reuse ratio (C6), TSS reduction rate (C8), TN reduction rate (C9), TP reduction rate (C10), and COD reduction rate (C11) need to be set with corresponding threshold ranges for the five levels I-V for specific projects and study areas. The specific scores are also calculated by linear interpolation.

[0057] Step S6.4: The vegetation cover growth rate (C12) is set with 0% as the lower threshold, corresponding to 30 points; and with 100% vegetation cover in the green facility construction area as the upper threshold, corresponding to 95 points. The final score is determined by linear interpolation.

[0058] Step S6.5: Construction carbon emissions (C13), green space carbon sequestration (C14), construction cost (C15), and maintenance cost (C16) are calculated by comprehensively considering the situation of various types of green infrastructure in the region. The facility scenario with the highest emissions per unit area, the lowest carbon sequestration, and the highest corresponding economic cost is selected as the lower threshold, and the facility scenario with the lowest emissions per unit area, the highest carbon sequestration, and the lowest corresponding economic cost is selected as the upper threshold. The final score is obtained by linear interpolation.

[0059] Step S6.6: For the heat island mitigation rate (C19), a score of 95 is defined as restoring the meteorological conditions of the green infrastructure construction area and the surrounding suburbs to a consistent level, i.e., C19=1; a score of 30 is defined as the temperature in the area after construction not improving compared to before construction, i.e., C19=0. The specific score is also determined by linear interpolation.

[0060] Step S6.7: Landscape aesthetic value (C17) and public space restability (C18) are scored and their results are matched one-to-one with the five evaluation levels (I-V), and the median score is taken.

[0061] Step S7 Comprehensive Evaluation: The standardized scores corresponding to each level of indicators are weighted and summed according to the comprehensive weight to obtain the applicability evaluation results of the scheme.

[0062] To clarify the subjective and objective weight fusion method mentioned in this invention, we will take the six indicators in the "runoff regulation and storage benefits (B1)" of the criterion layer as an example to demonstrate the specific implementation method of their weight calculation.

[0063] (1) Calculation of subjective weights (AHP): The results of the judgment matrix of indicators C1-C6 are shown in Table 6: Table 6 Matrix Results

[0064] The weight W of each indicator is calculated according to the subjective weighting formula. AHP i The result is W AHP =[0.443,0.222,0.092,0.145,0.039,0.059].

[0065] A consistency check is performed on the calculation results of the indicator weights, and the largest eigenvector of the judgment matrix is ​​λ. max =6.1626, calculate CI=(6.1626-6) / (6-1)=0.0325; look up the table and find that when n=6, RI=1.24; therefore, CR=0.06 / 1.24≈0.0262<0.1.

[0066] (2) Calculation of objective weights (entropy weight method): Three similar construction projects were collected, and their corresponding indicator values ​​are shown in Table 7: Table 7 Indicator Values

[0067] Based on the objective weight calculation steps, the above indicator values ​​are first positively standardized, then the proportion of each item in each indicator and the indicator entropy value are calculated, and finally, the objective weight is calculated as: W 熵 =[0.17,0.16,0.17,0.17,0.16,0.17].

[0068] (3) Calculation of subjective and objective weight integration: Calculate the conflict degree of the two elements according to the conflict degree calculation formula: K=0.83>0.7.

[0069] Therefore, a weighting coefficient λ is introduced to calculate the final comprehensive weight. Considering the emphasis on the annual runoff volume control rate (C1) in the subjective weighting, which aligns with the actual project requirements, we set the weighting coefficient to 0.7, resulting in a final comprehensive weight W. 融合 =[0.36,0.20,0.12,0.15,0.08,0.09].

[0070] (4) Quantitative Indicator Calculation and Standardized Scoring: A green infrastructure construction project in a city park was selected as the evaluation object. This project adopts green bioretention facilities and is equipped with a rainwater reuse system. The area has groundwater recharge value. Therefore, indicators C1-C11, C12-C16, and C17-C19 were selected as evaluation indicators. The quantitative indicator values ​​were obtained by simulation calculation using SWMM5.1 software, and the qualitative indicator evaluation results were obtained through a questionnaire survey. Then, the indicators were scored according to the standardized scoring rules. The scoring results of some indicators are shown in Table 8 below: Table 8 Scoring Results of Some Indicators

[0071] (5) Comprehensive Evaluation Results: The standardized scores of each indicator were weighted and summed according to their comprehensive weights to obtain the comprehensive score S1 for the runoff regulation and storage benefit criterion layer: S1 = 0.36×93 + 0.20×86 + 0.12×80 + 0.15×82 + 0.08×78 + 0.09×81 = 87.25 points, corresponding to a relatively high level of benefit. Similarly, the comprehensive scores of the environmental, economic, and social benefit criterion layers were calculated, and then weighted and summed according to the weights of each criterion layer to obtain the comprehensive evaluation score of the applicability of the green infrastructure construction plan for this project, providing a basis for project decision-making.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights, characterized in that, The process includes the following steps: S1: Establishing a basic evaluation system, which has a three-tiered structure. The top tier is the target tier, which evaluates the applicability of green infrastructure construction plans. The second tier is the criteria tier, which includes runoff regulation benefits, environmental benefits, economic benefits, and social benefits. The third tier is the indicator tier, which includes 19 indicators characterizing the effectiveness of infrastructure construction plans. S2: Indicator selection, based on the characteristics of the target area and the type of green infrastructure, the content of the indicator tier is refined, adjusted, optimized, and simplified. S3: Indicator weight calculation: subjective weights are determined by the analytic hierarchy process (AHP), objective weights are determined by the entropy weight method based on actual data from similar projects, and the comprehensive weights of each indicator are obtained by the DS evidence theory fusion method. S4: Quantitative indicator calculation: Simulate and calculate the construction plan based on the basic environmental conditions of the region to obtain the specific values ​​of each quantitative indicator; S5: Qualitative indicator hierarchical evaluation: Adopt a hierarchical evaluation model for the aesthetic value of the landscape and the restability of public spaces; S6: Standardized scoring: Convert indicators of different dimensions into dimensionless scores under a unified scoring system. S7: Comprehensive evaluation, which involves summing the standardized scores corresponding to each level of indicators according to their comprehensive weights to obtain the facility suitability evaluation results.

2. The method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights as described in claim 1, characterized in that, The 19 indicators in step S1 include annual runoff control rate, runoff reduction rate, peak reduction rate, peak delay time, groundwater recharge ratio, rainwater reuse ratio, annual runoff pollution removal rate, TSS reduction rate, TN reduction rate, TP reduction rate, COD reduction rate, vegetation cover growth rate, carbon emissions from construction, carbon sequestration in green spaces, construction cost, maintenance cost, landscape aesthetic value, public space recreational capacity, and heat island effect mitigation rate.

3. The method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights as described in claim 2, characterized in that, In step S1, the indicators are divided into two categories: mandatory and optional. Mandatory indicators include annual runoff control rate, runoff reduction rate, peak reduction rate, peak delay time, annual runoff pollution removal rate, and maintenance cost. The remaining indicators are optional.

4. The method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights as described in claim 1, characterized in that, In step S2, the subjective weight calculation uses the 1-9 scale method to establish the indicator judgment matrix, calculates the largest eigenvector of the judgment matrix and passes the consistency test. When the consistency ratio CR < 0.10, the judgment matrix is ​​acceptable; otherwise, the judgment matrix is ​​adjusted, and then the subjective weight of each indicator is calculated based on the judgment matrix.

5. The method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights as described in claim 1, characterized in that, The objective weight calculation in step S2 includes the following steps: collecting similar construction projects in the study area, obtaining the corresponding indicator values ​​for each project based on the evaluation indicator system determined in step S2, performing positive or negative standardization on the indicator values, calculating the proportion of each project in each indicator and the indicator entropy value, and finally calculating the objective weight of each indicator based on the entropy value.

6. The method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights as described in claim 5, characterized in that, The specific calculation process for objective weights is as follows: m items were collected, corresponding to n indicators, forming an indicator value matrix X=(x ij ) m*n For each indicator value (x) ij Standardization processing is performed; the standardization formula for positive indicators is: The standardized formula for the negative index is: After standardization, calculate the weight P of the i-th item in the j-th indicator. ij : The entropy value e of each indicator can be calculated. j : The objective weights of each indicator are derived as follows: 。 7. The method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights as described in claim 1, characterized in that, The specific process of the DS evidence theory fusion method in step S3 is as follows: Define the basic allocation probability using subjective and objective weights as two sources of evidence; calculate the conflict degree K between the two weight calculation methods; when the conflict degree K < 0.7, calculate the fused weights using the DS synthesis rule; when K ≥ 0.7, introduce a weight coefficient λ, and calculate the fused weights using the formula... Calculate the fusion weight value.

8. The method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights as described in claim 7, characterized in that, The carbon emissions from construction in step S4 are calculated using the formula. Calculate, where C 13 T represents the indirect carbon emissions during the construction process. i,j,k V represents the number of machine shifts used per unit of work for the i-th type of project, the j-th type of construction equipment, and the k-th type of energy; i R represents the quantity of work for the i-th type of project. j F represents the energy consumption per unit shift of the j-th type of construction equipment. k The carbon emission factor represents the k-th energy type; the carbon sequestration of green spaces is expressed by the formula. Calculate, where C 14 A represents the carbon sink generated through green space carbon sequestration, where i represents the i-th facility capable of carbon sequestration; i The area F representing facility i * i T represents the carbon sequestration rate of facility i. i The representative facility i represents the number of years of operation; the heat island effect mitigation rate is calculated by measuring the average temperature of the green infrastructure area 6-8 months after the construction project, the average temperature of the unmodified area within the study area, and the average temperature of the suburbs surrounding the urban area.

9. The method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights as described in claim 1, characterized in that, In step S5, the qualitative indicator grading evaluation is conducted by the surrounding closely related social public through a questionnaire survey. The evaluation level is divided into five levels: very good, good, fair, poor, and very poor.

10. The method for evaluating the applicability of comprehensive benefits of urban green infrastructure based on subjective and objective weights as described in claim 1, characterized in that, In step S6, the standardized scoring divides the evaluation results into five levels: very high efficiency corresponds to 90-100 points, relatively high efficiency corresponds to 80-90 points, average efficiency corresponds to 70-80 points, low efficiency corresponds to 60-70 points, and very low efficiency corresponds to below 60 points. The quantitative index scores are obtained by linear interpolation of the corresponding score range, and the qualitative index scores are taken as the median of the corresponding evaluation level.

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