Park green land accessibility evaluation method and system integrated with ecological system service

Abstract

The invention discloses a park green land accessibility evaluation method and system integrated with ecological system service, and relates to the technical field of ecological environment evaluation, and the method comprises the steps: determining a park green land range, constructing an ecological system service word library, and calculating a cultural ecological service perception intensity index; quantitatively adjusting service indexes by comprehensively using the urban flood risk model, the urban cooling model and the dry settlement model; integrating the cultural ecological service perception intensity index and the adjustment service index, and calculating a park quality evaluation index; and based on the park quality evaluation index, using a Gaussian moving two-step search method to quantify the park green space service accessibility, and calculating to obtain a green space service accessibility result. On the basis of a Gaussian two-step mobile search method, the park green land reachability evaluation method combining the adjustment service and the culture service is developed, the park reachability analysis technology is perfected through the ecological adjustment service and the culture ecological service, and the spatial pattern of urban park reachability is better revealed.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological environment assessment, and more specifically, to an assessment method and system for park green space accessibility integrating ecosystem services. Background Art

[0002] In the process of rapid urbanization globally, the role of urban parks as "natural healing spaces" has become increasingly prominent. As the core space for residents to contact nature, urban parks not only provide ecological regulation functions, but also are important carriers for relieving mental stress and promoting physical and mental health. As the intersection of the urban natural system and human activities, urban parks are not only the physical carriers of ecological regulation, but also the core spaces for residents to obtain cultural ecosystem services. Recent studies have generally confirmed that park accessibility is significantly positively correlated with the mental health level of residents, especially playing an irreplaceable role in relieving stress and promoting social interaction. In the initial stage of greening construction in China, the evaluation indicators of green space planning were mainly limited to two-dimensional basic data such as the quantity and area of green spaces. Since the concept of "greening coverage rate" was proposed, the evaluation of urban green space planning has mainly been carried out with indicators such as "urban green space rate", "urban greening coverage rate", and "per capita park green space area".

[0003] Traditional urban green space evaluation indicators mainly reflect the quantity and quality characteristics of parks. The understanding of the development of urban park green spaces is mainly based on the increase in the number of parks, the optimization of public facilities, and the improvement of greening quality, and cannot reflect practical problems such as the rationality of the layout of green public spaces and the balance of services provided to citizens. "Accessibility" can comprehensively measure the service supply capacity, traffic convenience, and spatial accessibility of park green spaces considering various factors, and scientifically evaluate the construction level and layout rationality of urban green spaces. The accessibility of urban park green spaces represents the convenience degree for residents to reach urban park green spaces by overcoming resistance factors such as distance and cost, and is an important indicator for quantitatively evaluating the service function of park green spaces. Compared with traditional evaluation indicators, it is more user-friendly, focusing on the rationality of the layout of park green spaces and the evaluation of recreation opportunities. If park green spaces are easily accessible, urban residents can more effectively enjoy the benefits brought by urban green spaces. However, when calculating the supply capacity of park green spaces, traditional accessibility calculation models often only use the area of park green spaces as the evaluation indicator, and this evaluation method cannot fully reflect the quality of park green spaces. Ecological regulation services and cultural ecological services, as two important functions of urban park green spaces, can better reflect the quality of parks.

[0004] Therefore, how to propose an evaluation method and system for the accessibility of park green spaces integrating ecosystem services, on the basis of quantifying the ecosystem services of parks, using ecosystem services to characterize park quality and integrating it into the accessibility analysis, and improving the accessibility analysis technology of parks through ecological regulation services and cultural ecosystem services, so as to better reveal the spatial pattern of the accessibility of urban parks is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides an evaluation method and system for the accessibility of park green spaces integrating ecosystem services. On the basis of quantifying the ecosystem services of parks, using ecosystem services to characterize park quality and integrating it into the accessibility analysis, and improving the accessibility analysis technology of parks through ecological regulation services and cultural ecosystem services, so as to better reveal the spatial pattern of the accessibility of urban parks, and provide a theoretical basis for urban green space system planning and improving residents' well-being. To achieve the above object, the present invention adopts the following technical solutions:

[0006] An evaluation method for the accessibility of park green spaces integrating ecosystem services, comprising:

[0007] Determine the scope of park green spaces, construct an ecosystem service thesaurus and calculate the cultural ecosystem service perception intensity index;

[0008] Quantify the regulation service index by comprehensively using the urban flood risk model, the urban cooling model and the dry deposition model;

[0009] Integrate the cultural ecosystem service perception intensity index and the regulation service index, and calculate the park quality evaluation index;

[0010] Quantify the accessibility of park green space services based on the park quality evaluation index by using the Gaussian moving two-step search method, and calculate the green space service accessibility result.

[0011] Optionally, the construction of the ecosystem service thesaurus includes:

[0012] Select the park cultural service data indicators of aesthetic appreciation, physical and mental recovery and entertainment, perform data preprocessing, segment the data based on the Jieba package of Python, vectorize the text information using the word2vec model; combine the segmented text, perform word frequency statistics on the review text, and extract the vocabulary related to park cultural services from the high-frequency words to form an essential vocabulary list, use the word2vec module of Python to expand the scope of high-frequency words, and finally classify the expanded words into ecosystem service categories to obtain the ecosystem service thesaurus.

[0013] Optionally, the calculation of the perceived intensity index of cultural ecosystem services includes: preprocessing the ecosystem service thesaurus, analyzing each comment sample based on the preprocessed ecosystem service thesaurus through a word matching method. When the content of a comment matches a word in a certain item of the ecosystem cultural service thesaurus, it is recorded that the service is perceived. The number of times a matching word appears in the comment is recorded as the number of times the service is perceived. If there is no match, it is regarded as an invalid sample.

[0014] Optionally, it further includes: using the perceived intensity of ecosystem service indicators as the perceived intensity index of cultural ecosystem services:

[0015] Among them, P i is the perceived intensity of each subclass of ecosystem service indicators by users, i is the number of each subclass of indicators, S i is the number of occurrences of each subclass of ecosystem service indicators, C i is the total number of comments on the i-th park.

[0016] Optionally, the quantification of regulation service indicators by comprehensively using urban flood risk models, urban cooling models, and dry deposition models includes:

[0017] Obtaining the park's waterlogging regulation service capacity, and the calculation formula for waterlogging regulation service supply is as follows:

[0018] Z if = 25400 / CN if - 254;

[0019]

[0020] R if = 1 - Q if / P;

[0021] S FR = R if ×P×A if / 1000;

[0022] Among them, Z if is the possible maximum retention volume of land use type f in grid i; CN if is the CN value of land use type f in grid i; Q if is the surface runoff depth of land use type f in grid i; P is the designed storm depth of the study area; λ is the soil infiltration coefficient; R if is the runoff retention volume of land use type f in grid i; S FR is the waterlogging regulation service supply, A if is the land use type f in grid i.

[0023] Optionally, it further includes: evaluating the heat island mitigation service capacity of central urban parks, and calculating the heat mitigation index HMI based on vegetation shade, evapotranspiration, albedo, and the distance weight from the cooling area;

[0024] S11: Calculate the cooling capacity index CC of each pixel based on local shade, evapotranspiration, and albedo;

[0025] CC i = 0.6×shade + 0.2×albedo + 0.2×ETI;

[0026] Among them, CC i is the cooling value of the i-th pixel, shade is the shading factor, albedo is the surface albedo, that is, the proportion of solar radiation reflected by the ground surface, and ETI is the evapotranspiration index, representing the standardized value of potential evapotranspiration; ET0 is the pixel value of the monthly potential evapotranspiration dataset; K c is the crop coefficient, related to the land cover type, and ET max is the maximum value of the ET0 raster;

[0027] S12: If the pixel is not affected by any large green spaces, its heat mitigation index HMI is the same as the cooling capacity index CC value; if affected, set the distance weight and use the CC value to calculate the HMI value. The green space area GA i within the cooling radiation range around the pixel is calculated as follows:

[0028] GA i = cell area ×∑ j∈dradiusfromigi g i ;

[0029] The calculation formula for the cooling capacity index of the pixel is as follows:

[0030]

[0031] Among them, cell area is the pixel area; g i is the patch attribute, 1 for green space and 0 for non-green space, and d (i,j) is the distance between pixel i and pixel j; d cool is the cooling radiation range;

[0032] S13: By analyzing the cooling effect of large green spaces, obtain HMI, and the calculation formula is as follows:

[0033] Among them, HMI i is the cooling service index of the green space.

[0034] Optionally, it further includes obtaining the air purification service capacity using a dry deposition model in the evaluation area:

[0035] S21: For forest land, the calculation formula for leaf area index is:

[0036] LAI i = 9.7471 × NDVI i + 0.3718;

[0037] For grassland, the calculation formula for leaf area index is:

[0038]

[0039] Among them, LAI i is the leaf area index of the i-th green space pixel; NDVI i is the normalized difference vegetation index of the i-th green space pixel; NDVI avg is the average normalized difference vegetation index of the study area and grassland; 3.227 is the average leaf area index of grassland in the study area;

[0040] S22: Based on the dry deposition model, the formula for the daily reduction of PM2.5 by green space is as follows:

[0041] q d = F × LAI × T × (1 - R);

[0042] Among them, q d is the daily reduction of PM2.5 by green space; F is the dry deposition flux of PM2.5; LAI is the leaf surface area index; T is the evaluation duration; R is the resuspension rate, and the calculation formula for the dry deposition flux F is: F = V d × C p × 3600, where, V d is the sedimentation rate of PM2.5; C p is the concentration of PM2.5;

[0043] S23: For the study area, the calculation formula for the annual reduction of PM2.5 per unit area of each grid of green space is as follows: q pi = D × V d × C p × 3600 × LAI i × 24 × (1 - R); where, q pi is the annual reduction index of PM2.5 by area, and D is the number of days without rainfall in a year.

[0044] Optionally, integrating the perceived intensity index of cultural ecosystem services and the regulation service index, calculating the park quality evaluation index includes: equally weighting and superimposing each index of the obtained ecosystem services to obtain the park quality evaluation index:

[0045] Sj = P i + S FR + HMI i + q pi ;

[0046] Among them, S j is the service supply capacity of park green space, P i is the perceived intensity index of cultural and ecological services, S FR is the service supply index for waterlogging regulation, HMI i is the service index for temperature reduction and cooling of green space, q pi is the annual reduction index of PM2.5 by area.

[0047] Optionally, the service accessibility of park green space is quantified using the Gaussian moving two-step search method based on the park quality evaluation index, and the calculated service accessibility results include:

[0048] S31: Calculate the supply-demand ratio R j , take the centroid of each supply location j, select or assume a spatial distance d0, form its spatial scope of influence, calculate the number of demanders at each demand point k falling within the spatial scope of influence, assign weights using the Gaussian equation and accumulate them to obtain the potential number of demanders at supply location j Then divide the service capacity S j of supply location j by the total number of its potential demanders to obtain the supply-demand ratio R j , and the calculation formula is as follows:

[0049]

[0050] Among them, d kj is the distance between demand point k and supply location j; d0 is the spatial distance set for the supply location; P k is the number of demanders in the search area; S j is the total supply at point j; G(d kj , d0) is the distance attenuation function of the influence of point source elements on spatial elements, that is, the Gaussian equation, and the calculation formula is as follows:

[0051]

[0052] S32: For each demand location k, given the spatial distance d0, form its spatial scope of influence, assign weights to the supply-demand ratio R j of supply location j falling within this scope of influence using the Gaussian equation, and then sum up the weighted ratios to obtain the spatial accessibility A i of demand location k, and the calculation formula is as follows:

[0053] A i The larger A is, the better the spatial accessibility.

[0054] Optionally, an evaluation system for the accessibility of park green spaces incorporating ecosystem services, comprising:

[0055] A cultural service index calculation module: used to determine the scope of park green spaces and calculate cultural service indexes by using the perception intensity;

[0056] A regulating service index calculation module: used to quantify regulating service indexes by comprehensively using an urban flood risk model, an urban cooling model and a dry deposition model;

[0057] A park quality evaluation index integration module: used to integrate cultural service indexes and regulating service indexes and calculate park quality evaluation indexes;

[0058] A green space service accessibility result calculation module: used to quantify the accessibility of park green space services by using the Gaussian moving two-step search method based on park quality evaluation indexes and calculate the green space service accessibility result.

[0059] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses an evaluation method and system for the accessibility of park green spaces incorporating ecosystem services, having the following beneficial effects:

[0060] The present invention provides an evaluation method for the accessibility of park green spaces incorporating ecosystem services, comprising: determining the scope of park green spaces, constructing an ecosystem service thesaurus and calculating cultural ecosystem service perception intensity indexes; quantifying regulating service indexes by comprehensively using an urban flood risk model, an urban cooling model and a dry deposition model; integrating cultural ecosystem service perception intensity indexes and regulating service indexes and calculating park quality evaluation indexes; quantifying the accessibility of park green space services by using the Gaussian moving two-step search method based on park quality evaluation indexes and calculating the green space service accessibility result. On the basis of the Gaussian two-step moving search method, the present invention develops an evaluation method for the accessibility of park green spaces combining regulating services and cultural services. On the basis of quantifying the ecosystem services of parks, the ecosystem services are used to characterize park quality and integrated into the accessibility analysis. The park accessibility analysis technology is improved through ecological regulating services and cultural ecosystem services, so as to better reveal the spatial pattern of urban park accessibility, provide a theoretical basis for urban green space system planning and improving residents' well-being, and provide strong support for optimizing the evaluation of the supply capacity of park green space services and improving the accuracy of park accessibility evaluation. Description of the Drawings

[0061] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0062] Figure 1 Schematic diagram of a method and system for evaluating the accessibility of park green spaces incorporating ecosystem services provided by the present invention.

[0063] Figure 2(a) is a schematic diagram of the cultural service capacity of the park ecosystem in the central urban area of Chengdu provided by the present invention.

[0064] Figure 2(b) is a schematic diagram of the waterlogging regulation service capacity of the parks in the central urban area of Chengdu provided by the present invention.

[0065] Figure 2(c) is a schematic diagram of the cooling service capacity of the parks in the central urban area of Chengdu provided by the present invention.

[0066] Figure 2(d) is a schematic diagram of the air purification service capacity of the grasslands in the parks in the central urban area of Chengdu provided by the present invention.

[0067] Figure 2(e) is a schematic diagram of the air purification service capacity of the woodlands in the parks in the central urban area of Chengdu provided by the present invention.

[0068] Figure 2(f) is a schematic diagram of the population distribution in the residential areas in the central urban area of Chengdu provided by the present invention.

[0069] Figure 3 Schematic diagram of the accessibility of ecosystem services in the central urban area of Chengdu provided by the present invention. Detailed implementation manners

[0070] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0071] The embodiments of the present invention disclose a method for evaluating the accessibility of park green spaces incorporating ecosystem services, as Figure 1 shown, including:

[0072] Determine the scope of park green spaces, construct an ecosystem service thesaurus, and calculate the cultural ecosystem service perception intensity index;

[0073] Quantify the regulating service indicators by comprehensively using the urban flood risk model, urban cooling model, and dry deposition model;

[0074] Integrate the cultural ecosystem service perception intensity indicators and regulating service indicators to calculate the park quality evaluation indicators;

[0075] Quantify the accessibility of park green space services using the Gaussian moving two-step search method based on the park quality evaluation indicators, and calculate the green space service accessibility results.

[0076] In the specific implementation manner, an evaluation method for the accessibility of park green space integrating ecosystem services, based on the Gaussian two-step moving search method, develops an evaluation method for the accessibility of park green space combining regulating services and cultural services, providing a theoretical basis for optimizing the evaluation of the service supply capacity of park green space and improving the accuracy of park accessibility evaluation. The specific steps are as follows:

[0077] Step 1: Determine the scope of park green space in the central urban area of Chengdu, and evaluate the ecological system cultural services of urban parks in the central urban area of Chengdu. Construct a structured text thesaurus through index selection and thesaurus development, and on this basis, conduct word matching analysis to construct a calculation formula for perception intensity, realizing the quantification of cultural service perception intensity.

[0078] Step 2: Quantify the park ecological regulation service intensity and the regulating service intensity indicators by using the urban flood risk model, urban cooling model, and dry deposition model.

[0079] Step 3: Calculate the park ecosystem service quality in the central urban area of Chengdu by integrating the cultural service indicators and regulating service indicators, and obtain the park cultural service intensity indicators.

[0080] Step 4: Quantify the accessibility of park green space in the central urban area of Chengdu using the Gaussian moving two-step search method, and calculate the green space service accessibility results.

[0081] In the specific implementation manner, the specific steps of the first step include: in the evaluation area, referring to the classification of the "Common International Classification of Ecosystem Services" (CICES V5.1) and the relevant research on ecosystem cultural services, and finally selecting three indicators suitable for park cultural services through consulting experts in related majors such as landscape architecture, including aesthetic appreciation, physical and mental recovery, and entertainment. The indicator selection and sources are shown in Table 1. In terms of lexicon development, after data preprocessing, the Jieba package based on Python is used to segment the data. After that, the word2vec model is used to vectorize the text information. Secondly, combined with the segmented text, the word frequency of the review text is counted, and the words related to park cultural services are extracted from the high-frequency words to form an essential word list. In addition, the Python word2vec module is further used to expand the range of high-frequency words. Finally, the expanded words are manually classified into n ecosystem service categories to form an ecosystem service lexicon.

[0082] Table 1 Indicator Selection and Sources

[0083]

[0084] Furthermore, the word matching method analyzes each comment sample based on the preprocessed ecosystem service lexicon. If the content of a certain comment matches the words in a certain ecosystem cultural service lexicon, it is recorded that this service is perceived, and the number of times the words matching a certain service appear in the comment is recorded as the number of times this service is perceived; if there is no match, it is regarded as an invalid sample. As shown in Figure 2(a), the perception intensity is used as the perception index of park ecosystem services, and the calculation formula is:

[0085]

[0086] Among them, P i represents the perception intensity of users for each subclass of ecosystem service indicators, i is the number of each subclass of indicators, S i represents the number of times each subclass of ecosystem service indicators appears, C i represents the total number of reviews of the i-th park, and is classified into four seasons.

[0087] In the specific implementation manner, as shown in Figures 2(b) and 2(f), the specific steps of the second step include: using the InVEST urban flood risk model to obtain the park's waterlogging regulation service capacity.

[0088] By means of remote sensing interpretation and other methods, the land use types in the core area of the central urban area of Chengdu are divided into forest land, grassland, cultivated land, water body and construction land. According to the global soil hydrology grid HYSOGs250m, the soil hydrology types in the study area are determined. This dataset describes the rainfall runoff potential at a spatial resolution of 250m, and is divided into four standard levels: A, B, C, D, corresponding to soils with low, medium - low, medium - high and high runoff potential respectively. Since there is a water table within 60cm of the ground surface, wet soils have a high runoff potential, so these soils have a dual HSG (hydrologic soil group). In the study, according to the specifications of the dataset user manual and the model input requirements, the soil hydrology types in the study area are finally determined to be types C and D.

[0089] Then, according to the curve number (CN) compiled by the US Department of Agriculture as shown in Table 2, the CN values corresponding to each land use type in the two types of partitions are determined. The formula for calculating the supply of waterlogging regulation services is as follows:

[0090] Z if = 25400 / CN if - 254;

[0091]

[0092] R if = 1 - Q if / P;

[0093] S FR = R if × P × A if / 1000;

[0094] In the formula: Z if is the possible maximum retention amount (mm) of land use type f in grid i; CN if is the CN value of land use type f in grid i; Q if is the surface runoff depth (mm) of land use type f in grid i; P is the designed storm depth (mm) of the study area; λ is the soil infiltration coefficient, generally taking a value of 0.2; R if is the runoff retention amount of land use type f in grid i; S FR is the supply of waterlogging regulation services (m 3 ); A if is land use type f in grid i;

[0095] Table 2 Runoff curve numbers of the evaluation area

[0096]

[0097]

[0098] In the specific implementation, based on the calculated design storm depth, the model rainfall value is set to simulate the supply capacity of urban waterlogging regulation services during extreme rainstorm disasters. According to the "Announcement on the Release of the Revised Rainstorm Intensity Formula for the Central Urban Area of Chengdu" by the Chengdu Water Affairs Bureau, the revised rainstorm intensity formula is as follows:

[0099]

[0100] In the formula, P is the design rainfall intensity (mm / min); t is the rainfall duration (min); is the recurrence interval (years). In the general design calculation of urban drainage pipe systems, the rainfall duration is taken as 1 h. Therefore, when is 100 (years) and t is 1 h (60 min), the rainfall depth of the once-in-a-century rainstorm in the central urban area of Chengdu is 91.387 mm.

[0101] Furthermore, as shown in Figure 2(c), the Urban Cooling module of the InVEST model is used to evaluate the heat island mitigation service capacity of parks in the central urban area of Chengdu. Its principle is to calculate the HMI (Heat Mitigation Index) based on vegetation shadow, evapotranspiration, albedo, and the distance weight from the cooling area (such as green space). The model first calculates the CC (Cooling Capacity) index of each pixel based on local shadow, evapotranspiration, and albedo. The calculation formula is as follows:

[0102] CC i = 0.6×shade + 0.2×albedo + 0.2×ETI;

[0103] In the formula: CC i is the cooling value of the i-th pixel, with a value range of [0, 1]. When the value is 0, it represents no cooling capacity, and when the value is 1, it represents the maximum cooling capacity; shade is the shading factor, representing the proportion of the area with a tree canopy higher than 2 m in each land use type. When the tree canopy is higher than 2 m, it is assigned a value of 1, and when it is lower than 2 m, it is assigned a value of 0. In the study, the shade of the forest land use type is assigned a value of 1, and the shade of the remaining land use types is assigned a value of 0; albedo is the surface albedo, that is, the proportion of the solar radiation reflected by the ground surface; ETI is the evapotranspiration index, representing the standardized value of potential evapotranspiration.

[0104]

[0105] The reference evapotranspiration ET0 is the pixel value of the monthly potential evapotranspiration dataset; K c is the crop coefficient, which is related to the land cover type. The values of shade, K c , and albedo are shown in Table 3; ET max is the maximum value of the ET0 raster.

[0106] Table 3 Biophysical Table

[0107] Land use type Shading factor Crop coefficient Albedo Green space attribute Grassland 0 0.7 0.19 1 Cultivated land 0 0.75 0.19 1 Forest land 1 0.96 0.16 1 Construction land 0 0.29 0.16 0 Water body 0 0.7 0.11 0

[0108] If a pixel is not affected by any large green space, its HMI is the same as the CC value; if it is affected, the HMI is calculated using the CC value by setting the distance weight. Large green spaces with an area greater than 2 hm 2 have a cooling effect on the surrounding area. Referring to previous studies and conducting multiple model tests, when the distance weight of the large green space is set to 400 m, the model performance is good. The green space area GA i within the cooling radiation range around the pixel is calculated as follows:

[0109] GA i = cell area × ∑ j∈dradiusfromi g i .

[0110] Furthermore, the cooling capacity index CC parki of the pixel is calculated as follows:

[0111]

[0112] In the formula: cell area is the pixel area; g i is the patch attribute, 1 for green space and 0 for non-green space, dimensionless; d (i,j) is the distance between pixel i and pixel j; d cool is the cooling radiation range. The model obtains the HMI by analyzing the temperature reduction and cooling effect of large green spaces. The HMI i is calculated as follows:

[0113]

[0114] Furthermore, a dry deposition model is used to obtain the air purification service capacity of the central urban area of Chengdu. The reduction of PM2.5 by different vegetation is used as the quantitative basis for the air purification service supply in the study area. The study uses remote sensing images to simulate the leaf area index of green spaces in the study area and calculates the reduction of PM2.5 by green spaces in the study area according to the dry deposition model. Among them, as shown in Figure 2(e), for forest land, the formula for calculating the leaf area index is:

[0115] LAI i = 9.7471 × NDVI i + 0.3718;

[0116] As shown in Figure 2(d), for grassland, the formula for calculating the leaf area index is:

[0117]

[0118] Where: LAI i is the leaf area index of the i-th green space pixel (m 2 / m 2 ); NDVI i is the normalized difference vegetation index of the i-th green space pixel; NDVI avg is the average normalized difference vegetation index of the study area and grassland; 3.227 is the average leaf area index of grassland in the study area.

[0119] Based on the dry deposition model, the formula for the daily reduction of PM2.5 by green space is as follows:

[0120] q d = F × LAI × T × (1 - R);

[0121] Where, q d is the daily reduction of PM2.5 by green space (g / m 2 ); F is the dry deposition flux of PM2.5 g / (m 2 ·h); LAI is the leaf surface area index (m 2 / m 2 ); T is the evaluation duration, 24 hours per day; R is the resuspension rate. Among them, the calculation formula for the dry deposition flux F is:

[0122] F = V d × C p × 3600;

[0123] Where, V d is the deposition rate of PM2.5 (m / s); C p is the concentration of PM2.5 (g / m 3 ). For the study area, the formula for the annual reduction of PM2.5 per unit area of each grid of green space (q pi ) is as follows:

[0124] q pi = D × V d × C p × 3600 × LAI i × 24 × (1 - R);

[0125] Where, D is the number of days without rainfall in a year, and the number of days without rainfall in 2023 is 231; V d for forest land and V d for grassland, referring to relevant literature, the values are 0.09 and 0.018 respectively; the average annual concentration of PM2.5 in 2023 is 0.000039 g / m 3 , C p takes the value of 0.000039; R takes the value of 0.03 according to relevant references.

[0126] In the specific implementation manner, step three specifically includes: in the evaluation area, equally weighted superposition of each index of the ecosystem services obtained is performed to obtain the park quality evaluation index. The specific formula is as follows:

[0127] S j = Pi + S FR + HMI i + q pi ;

[0128] In the formula, Pi is the cultural ecosystem service perception intensity index, S FR is the waterlogging regulation service supply index, HMI i is the temperature reduction and cooling service index of the green space, q pi is the annual reduction of PM2.5 index by area, and S j is the service supply capacity of the park green space.

[0129] In the specific implementation manner, the Gaussian two-step moving search method can more accurately describe the urban park accessibility index because it comprehensively considers both the supply and demand sides, distance decay, and is easy to operate. As Figure 3 shown, step four specifically includes:

[0130] First, calculate the supply-demand ratio R j . Take the centroid of each supply location j, select or assume a spatial distance d0 to form its spatial scope of influence, calculate the number of demanders at each demand point k falling within this scope of influence, assign weights by referring to the Gaussian equation and accumulate them to obtain the potential number of demanders at the supply location j Then divide the service capacity S j of the supply location j by the total number of its potential demanders to obtain the supply-demand ratio R j . The calculation formula is as follows:

[0131]

[0132] In the formula: d kj is the distance between the demand point k and the supply location j; d0 is the spatial distance set for the supply location; P k is the number of demanders in the search area (i.e., d kj ≤ d0); S j is the total supply at point j; G(d kj , d0) is the distance decay function of the influence of the point source element on the spatial element, that is, the Gaussian equation. The calculation formula is as follows:

[0133]

[0134] Secondly, for each demand location k, given the spatial distance d0, its spatial scope of influence is formed, and the supply-demand ratio R jAssign weights using the Gaussian equation, then sum the weighted ratios to obtain the spatial accessibility A of demand location k i , and the calculation formula is as follows:

[0135]

[0136] In the formula, R j is the supply-demand ratio of supply point j within the search area of demand location (k) (i.e., d kj ≤d0); d kj is the distance between demand point k and the centroid j of the supply area. The larger A i is, the better the accessibility. The Gaussian two-step floating catchment area method adds a Gaussian function to the traditional two-step floating catchment area method to simulate the distance decay effect of residents' travel within the search threshold, considering the mutual relationship between supply and demand.

[0137] In a specific embodiment, a park green space accessibility evaluation system integrating ecosystem services includes:

[0138] Cultural service index calculation module: used to determine the park green space range and calculate the cultural service index using the perception intensity;

[0139] Regulating service index calculation module: used to quantify the regulating service index by comprehensively using the urban flood risk model, urban cooling model, and dry deposition model;

[0140] Park quality evaluation index integration module: used to integrate the cultural service index and the regulating service index and calculate the park quality evaluation index;

[0141] Green space service accessibility result calculation module: used to quantify the park green space service accessibility using the Gaussian two-step floating catchment area method based on the park quality evaluation index and calculate the green space service accessibility result

[0142] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0143] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can 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 these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An evaluation method for the accessibility of park green spaces incorporating ecosystem services, characterized in that, Including: Determine the scope of park green space, construct an ecosystem service thesaurus, and calculate the cultural ecosystem service perception intensity index; Quantify the regulation service index by comprehensively using the urban flood risk model, urban cooling model, and dry deposition model; Integrate the cultural ecosystem service perception intensity index and the regulation service index, and calculate the park quality evaluation index; Based on the park quality evaluation index, use the Gaussian moving two-step search method to quantify the accessibility of park green space services, and calculate the green space service accessibility result.

2. The accessibility assessment method of park green space integrating ecosystem services according to claim 1, characterized in that The construction of the ecosystem service thesaurus includes: Select the park cultural service data indicators of aesthetic appreciation, physical and mental recovery, and entertainment, perform data preprocessing, segment the data based on the Jieba package in Python, and vectorize the text information using the word2vec model; combine the segmented text, perform word frequency statistics on the review text, extract the vocabulary related to park cultural services from the high-frequency words to form an essential vocabulary list, use the word2vec module in Python to expand the scope of high-frequency words, and finally classify the expanded words into ecosystem service categories to obtain the ecosystem service thesaurus.

3. The accessibility assessment method of park green space integrating ecosystem services according to claim 1, characterized in that, The calculation of the cultural ecosystem service perception intensity index includes: preprocessing the ecosystem service thesaurus, analyzing each comment sample based on the preprocessed ecosystem service thesaurus through the word matching method. When the content of a certain comment matches the words in a certain ecosystem cultural service thesaurus, it is recorded that the service is perceived, and the number of times the matching words of a certain service appear in the comment is recorded as the number of times the service is perceived. If there is no match, it is regarded as an invalid sample.

4. The accessibility assessment method of park green space integrating ecosystem services according to claim 3, characterized in that, Also included: Adopt the perception intensity of the ecosystem service index as the cultural ecosystem service perception intensity index: Among them, P i is the perceived intensity of the user for each subclass ecosystem service index, i is the number of each subclass index, and S i is the number of occurrences of each subclass ecosystem service index, and C i is the total number of comments on the i-th park.

5. The accessibility evaluation method of park green space integrating ecosystem services according to claim 1, characterized in that, The quantification of the regulation service index by comprehensively using the urban flood risk model, urban cooling model, and dry deposition model includes: Obtain the park waterlogging regulation service capacity, and the calculation formula for the waterlogging regulation service supply is as follows: Z if = 25400 / CN if -254; R if = 1 - Q if / P; S FR = R if × P × A if / 1000; Among them, Z if is the possible maximum retention volume of land use type f in grid i; CN if is the CN value of land use type f in grid i; Q if is the surface runoff depth of land use type f in grid i; P is the designed storm depth of the study area; λ is the soil infiltration coefficient; R if is the runoff retention volume of land use type f in grid i; S FR is the supply of waterlogging regulation service, A if is the land use type f in grid i.

6. The accessibility assessment method of park green space integrating ecosystem services according to claim 5, characterized in that, Also included: Evaluate the heat island mitigation service capacity of the central urban area parks, and calculate the heat mitigation index HMI according to the vegetation shadow, evapotranspiration, albedo, and the distance weight from the cooling area; S11: Calculate the cooling capacity index CC of each pixel based on the local shadow, evapotranspiration, and albedo; CC i = 0.6 × shade + 0.2 × albedo + 0.2 × ETI; Among them, CC i is the cooling value of the i-th pixel, shade is the shading factor, albedo is the surface albedo, that is, the proportion of solar radiation reflected by the surface, and ETI is the evapotranspiration index, representing the standardized value of potential evapotranspiration; ET0 is the pixel value of the monthly potential evapotranspiration dataset; K c is the crop coefficient, related to the land cover type, and ET max is the maximum value of the ET0 raster; S12: If a pixel is not affected by any large green space, its heat mitigation index HMI is the same as the cooling capacity index CC value; if it is affected, by setting the distance weight and using the CC value to calculate the HMI value, the green space area GA within the cooling radiation range around the pixel i The calculation formula is as follows: GA i = cell area × ∑ j∈d radius from i g i ; Cooling capacity index of pixels The calculation formula is as follows: where cell area is the pixel area; g i is the patch attribute, 1 for green space and 0 for non-green space, d (i,j) is the distance between pixel i and pixel j; d cool is the cooling radiation range; S13: Obtain HMI by analyzing the temperature reduction and cooling effect of large green spaces, and the calculation formula is as follows: Among them, the HMI i is the temperature reduction and cooling service index for the green space.

7. The accessibility evaluation method of park green space integrating ecosystem services according to claim 5, characterized in that Also included, in the evaluation area, use the dry deposition model to obtain the air purification service capacity: S21: For forest land, the calculation formula for the leaf area index is: LAI i = 9.7471 × NDVI i + 0.3718; For grassland, the calculation formula for the leaf area index is: where LAI i is the leaf area index of the i-th green space pixel; NDVI i is the normalized difference vegetation index of the i-th green space pixel; NDVI avg is the average normalized difference vegetation index of the study area and the grassland; 3.227 is the average leaf area index of the grassland in the study area; S22: Based on the dry deposition model, the daily reduction amount formula of green space for PM2.5 is as follows: q d = F × LAI × T × (1 - R); Among them, q d is the daily reduction amount of PM2.5 in the green space; F is the dry deposition flux of PM2.5; LAI is the leaf area index; T is the evaluation duration; R is the resuspension rate. The calculation formula for the dry deposition flux F is: F = V d ×C p ×3600. Among them, V d is the PM2.5 deposition rate; C p is the PM2.5 concentration; S23: For the study area, the formula for calculating the annual PM2.5 reduction per unit area of each grid in the green space is as follows: q pi = D × V d × C p × 3600 × LAI i × 24 × (1 - R); where q pi is the annual PM2.5 reduction index, and D is the number of days without rainfall in a year.

8. The accessibility evaluation method of park green space integrating ecosystem services according to claim 1, characterized in that The integration of the cultural ecosystem service perception intensity index and the regulation service index, and the calculation of the park quality evaluation index include: equally weighted superposition of each index of the obtained ecosystem service to obtain the park quality evaluation index: S j = P i + S FR + HMI i + q pi ; Among them, S j is the service supply capacity of park green space, P i is the perceived intensity index of cultural and ecological services, S FR is the service supply index for waterlogging regulation, HMI i is the service index for temperature reduction and cooling of green space, q pi is the annual area reduction index of PM2.

5.

9. The accessibility assessment method of park green space integrating ecosystem services according to claim 1, characterized in that, The quantification of the accessibility of park green space services based on the park quality evaluation index using the Gaussian moving two-step search method and the calculation of the green space service accessibility result include: S31: Calculate the supply-demand ratio R j , take the centroid of each supply location j, select or assume a spatial distance d0 to form its spatial scope of influence, calculate the number of demanders at each demand point k within the spatial scope of influence, assign weights by referring to the Gaussian equation and accumulate them to obtain the number of potential demanders at supply location j Then divide the service capacity S of supply location j j by the total number of its potential demanders to obtain the supply-demand ratio R j , and the calculation formula is as follows: Among them, d kj is the distance between demand point k and supply place j; d0 is the spatial distance set by the supply place; P k is the number of demanders in the search area; S j is the total supply at point j; G(d kj , d0) is the distance attenuation function of the influence of point source elements on spatial elements, that is, the Gaussian equation, and the calculation formula is as follows: S32: For each demand location k, given a spatial distance d0, form its spatial scope of influence, and calculate the supply-demand ratio R of supply location j that falls within this scope of influence j Assign weights using the Gaussian equation, and then sum the weighted ratios to obtain the spatial accessibility A of demand location k i , and the calculation formula is as follows: A i The larger it is, the better the spatial accessibility.

10. An evaluation system for the accessibility of park green spaces integrating ecosystem services, characterized in that, Including: Cultural service index calculation module: used to determine the scope of park green space and calculate the cultural service index using the perception intensity; Regulation Service Index Calculation Module: It is used to quantify the regulation service index by comprehensively using the urban flood risk model, urban cooling model, and dry deposition model; Park Quality Evaluation Index Integration Module: It is used to integrate the cultural service index and the regulation service index and calculate the park quality evaluation index; Green Space Service Accessibility Result Calculation Module: It is used to quantify the accessibility of park green space services using the Gaussian moving two-step search method based on the park quality evaluation index and calculate the green space service accessibility result.

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