Sponge park low-impact development engineering design method based on multi-objective optimization

Abstract

The invention relates to the technical field of sponge park engineering design, in particular to a sponge park low-impact development engineering design method based on multi-objective optimization, and the method comprises the steps: firstly determining rainwater management, ecological and economic objectives and weights, enabling the rainwater management objectives to cover the collection rate and the permeability, enabling the ecological objectives to comprise biodiversity and vegetation coverage, and enabling the economic objectives to comprise the vegetation coverage; the economic target relates to construction and maintenance cost; then collecting various data of the region and analyzing the current situation, constructing a multi-objective optimization model, and optimizing a design scheme through genetic or particle swarm optimization; then generating a plurality of schemes, evaluating the performance of the schemes on each target, screening an optimal scheme by adopting an analytic hierarchy process, and refining the design; and finally, establishing a spongy effect evaluation system, performing regular evaluation, and feeding back optimization according to a result. According to the method, multiple targets can be comprehensively optimized, the design scientificity and accuracy are improved, the park function and adaptability are enhanced, sustainable development is promoted, and effective support is provided for sponge park design.

Description

Technical Field

[0001] The present invention relates to the technical field of sponge park engineering design, and in particular to a sponge park low-impact development engineering design method based on multi-objective optimization. Background Art

[0002] As an important part of the urban ecosystem, sponge parks are of key significance in dealing with rainwater management, ecological protection and urban sustainable development. Traditional design methods often focus on a single goal, such as excessive attention to rainwater storage functions, but ignoring the improvement of ecological benefits and economic cost control. This leads to the inability to achieve efficient use of rainwater resources, effective improvement of the ecological environment and reasonable allocation of economic investment during the construction and operation of sponge parks. Although some parks have set up rainwater gardens, sunken green spaces and other facilities, their functions have not been fully utilized due to the lack of overall planning and optimized design.

[0003] Moreover, during the design process, due to the lack of comprehensive data collection and analysis, the meteorological, hydrological, soil and other conditions of the site were not considered enough, which made the design scheme out of touch with the actual needs. In addition, the existing design methods lack an effective evaluation and feedback mechanism, making it difficult to adjust and optimize according to the actual results, which in turn affects the overall performance and sustainable development capabilities of the sponge park. Therefore, in response to the above problems, a low-impact development engineering design method for sponge parks based on multi-objective optimization is proposed. Summary of the invention

[0004] The purpose of the present invention is to provide a sponge park low-impact development engineering design method based on multi-objective optimization to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A design method for low-impact development engineering of sponge parks based on multi-objective optimization includes the following steps:

[0007] Step S1, determining design goals, which include rainwater management goals, ecological goals and economic goals, and setting corresponding weights for the rainwater management goals, ecological goals and economic goals, wherein the rainwater management goals include rainwater collection rate and infiltration rate, the ecological goals include biodiversity and vegetation coverage, and the economic goals include construction cost and maintenance cost;

[0008] Step S2: Collect regional meteorological, hydrological, soil, vegetation and socio-economic data to conduct status analysis;

[0009] Step S3, establishing a multi-objective optimization model, and optimizing the design scheme using an optimization algorithm;

[0010] Step S4, generating multiple design solutions and evaluating their performance on each objective;

[0011] Step S5: Use a comprehensive evaluation method to select the best solution and conduct detailed design, which includes overall layout design, sponge facility design and rainwater treatment system design;

[0012] Step S6: Establish a sponge effect evaluation system, regularly evaluate the design effect and conduct feedback optimization. The sponge effect evaluation system includes regular evaluation of rainwater management effect, ecological improvement effect and economic benefit. The feedback optimization step includes adjusting and improving the design plan according to the evaluation results.

[0013] As a preferred solution, in step S1, the rainwater management target weight is set to , the ecological target weight is , the economic target weight is ,satisfy , each weight ranges from 0 to 1.

[0014] As a preferred solution, in step S3, the objective function of the multi-objective optimization model constructed is to minimize the construction cost , maximize rainwater collection efficiency , maximize penetration , maximizing biodiversity and maximize vegetation cover , which is expressed as follows: ; in, Represents the design variable vector, and at the same time, the constraints between the objectives must be considered, using the inequality constraint function Equality constraint function Reflect the constraints in actual engineering.

[0015] As a preferred solution, in step S3, the optimization algorithm uses a genetic algorithm to optimize the design solution. In the optimization step:

[0016] The coding method uses binary coding or real number coding to encode the design variables. Encode to form chromosomes to represent individuals. Suppose the length of chromosome is , each gene corresponds to a design variable encoding value fitness function Build as: ;

[0017] in: ; ; ,and , , , Sub-functions related to stormwater management objectives, is the sub-function related to ecological goals, is the sub-function related to economic objectives, are the weight coefficients of rainwater collection rate and infiltration rate in the rainwater management target sub-function, and the sum of the two is 1, which indicates the relative importance of rainwater collection rate and infiltration rate in the rainwater management target. Indicates the design Rainwater collection rate under Indicates the design The permeability under are the weight coefficients of biodiversity and vegetation coverage in the ecological target sub-function, and their sum is 1, which indicates the relative importance of biodiversity and vegetation coverage in the ecological target. Indicates the design biodiversity, Indicates the design The vegetation coverage rate under are the weight coefficients of construction cost and maintenance cost in the economic objective sub-function respectively, and their sum is 1, which indicates the relative importance distribution of construction cost and maintenance cost in the economic objective. Indicates the design The construction cost of Indicates the design The maintenance cost under the condition, the calculation formula of the relevant indicators of each sub-function is as follows:

[0018] Rainwater collection rate : ;in, Indicates during the period Internal design The actual volume of rainwater collected at Indicates during the period The theoretical volume of rainwater that can be collected corresponds to the total rainfall amount. is the total number of rainfall periods;

[0019] Permeability : ;in, is the soil hydraulic conductivity, is the water head difference, is the seepage path length;

[0020] Biodiversity ;in, is the total number of species, For the The proportion of the number of individuals of a species to the total number of individuals, For biodiversity A form of representation;

[0021] Vegetation coverage : ;in, For the Vegetation Type in Design Plan The coverage area below is the total number of vegetation types, is the total area of ​​the sponge park;

[0022] Construction costs : ;in, For the Construction projects are under design The cost of is the total number of construction projects;

[0023] Maintenance costs : ;in, For the Maintenance items in the design plan The cost of The total number of maintenance items;

[0024] Genetic operations include selection, crossover, and mutation. The population is continuously evolved through multiple generations of genetic operations until the convergence conditions are met.

[0025] As a preferred solution, in step S3, the optimization algorithm uses a particle swarm optimization algorithm to optimize the design solution. In the optimization step:

[0026] When initializing, the population size is set to , each particle The position vector represent design variables, the velocity vector Randomly initialize the particle positions and speed ,in, and is the design variable The lower and upper limits of is the speed variable The upper limit value of ;

[0027] During the update process of individual optimal and global optimal, the fitness value of each particle is calculated and the individual historical optimal position is recorded. and the global optimal position of the group particle The speed and position update formulas are: ; ;

[0028] in, is the inertia weight, , and are the maximum and minimum values ​​of the inertia weight, respectively. is the current iteration number, is the maximum number of iterations, and is the learning factor, and yes Random numbers in the interval; update the particle state through continuous iteration until the stopping criterion is met; For particles In Dimension The optimal position of an individual at time ; For groups in dimensions On The global optimal position at time.

[0029] As a preferred solution, in step S4, for rainwater management target evaluation, the rainwater collection rate is calculated respectively and permeability ,Compare the corresponding values ​​under different schemes, and analyze the performance differences of each scheme in rainwater collection and infiltration; For ecological goal evaluation, the Shannon-Wiener diversity index formula is used to calculate biodiversity , and calculated according to the vegetation coverage formula , compare the values ​​of these two indicators under each plan to measure the degree of impact of each plan on ecological improvement; for economic goal evaluation, calculate the construction cost of each plan and maintenance costs , directly compare the construction and operation costs of different schemes.

[0030] As a preferred solution, when the comprehensive evaluation method is used to screen out the optimal solution, the hierarchical analysis method is used to screen out the optimal solution. When the hierarchical analysis method is used to screen out the optimal solution, a hierarchical model including the target layer, the criterion layer and the solution layer is constructed; a judgment matrix is ​​constructed. , its elements Representation Guidelines Relative to the criteria The relative importance of Representation Guidelines Relative to the criteria The relative importance of , ,in, Judgment Matrix The elements on the diagonal represent the criteria The degree of importance relative to itself; calculate the maximum eigenvalue of the judgment matrix and the corresponding eigenvector , and conduct consistency checks, consistency indicators , random consistency ratio ,when When , the judgment matrix is ​​considered to have satisfactory consistency. To determine the matrix order, The average random consistency index is then used to calculate the scores of each solution relative to each target in the criterion layer, and finally the comprehensive evaluation value of each solution is obtained. The solution with the highest evaluation value is selected as the optimal solution.

[0031] As a preferred option, when the design is refined, the overall layout design combines the regional topography, surrounding environment and the functions of each sponge facility to determine the location and connection relationship of each functional area, to ensure that the overall layout of the sponge park is reasonable and rainwater can flow effectively in various areas and realize corresponding functions; the sponge facility design determines the type, specification and location of the facility based on the rainwater management objectives and the site hydrogeological conditions; the rainwater treatment system design determines the treatment process and equipment selection based on the purification and reuse of the collected rainwater.

[0032] As a preferred solution, in step S6, the sponge effect evaluation system includes:

[0033] Stormwater management effectiveness evaluation:

[0034] Stormwater runoff reduction rate The formula is ;in, It is the rainwater runoff under specific rainfall conditions before the construction of the sponge park. To obtain the rainwater runoff under the same rainfall conditions after construction, flow monitoring equipment is installed at the site outlet and other locations to collect flow data in the corresponding period. and The value of

[0035] Peak traffic reduction rate The formula is ;in, is the peak flow during rainfall before construction, It is the peak flow during rainfall after construction;

[0036] Rainwater retention time : For a single stormwater detention facility , average rainwater retention time The calculation formula is: ;in It's time The amount of rainwater retained in the facility (the volume can be calculated by installing monitoring equipment such as water level sensors in the facility and combining the water level changes with the geometric shape of the facility), is the total duration of a complete rainfall event and the subsequent drainage process. is the average water inflow of the facility during this rainfall process, represents the integral variable;

[0037] Ecological improvement effect evaluation:

[0038] Biodiversity changes The formula is ,in, To construct the post-biodiversity index, is the biodiversity index before construction, if , indicating that biodiversity has been improved;

[0039] Changes in vegetation coverage The formula is ,in, is the vegetation coverage rate after construction, The vegetation coverage area after construction is obtained through remote sensing image interpretation or field surveying. is the total area of ​​the park, It is the vegetation coverage rate before construction, which is used to evaluate the impact of sponge park construction on vegetation growth and coverage;

[0040] Economic benefit evaluation:

[0041] Construction cost saving rate The formula is ;in, The actual construction cost of the low-impact development design of the sponge park is is the estimated construction cost of the traditional park construction plan. , indicating that construction costs have been saved;

[0042] Maintenance cost savings The formula is ;in, is the actual annual maintenance cost of the sponge park, Estimated annual maintenance costs for traditional parks to measure savings in maintenance costs over the long term.

[0043] It can be seen from the technical solution provided by the present invention that the present invention provides a low-impact development engineering design method for sponge parks based on multi-objective optimization, which has the following beneficial effects:

[0044] Realize multi-objective comprehensive optimization:

[0045] The present invention determines rainwater management, ecological and economic goals, assigns corresponding weights, and constructs a unified design framework; this approach integrates the relationship between the goals, avoids the one-sided pursuit of a single goal, achieves optimal overall performance, meets social, environmental and economic needs, and achieves multi-objective comprehensive optimization;

[0046] Improve the scientificity and accuracy of design:

[0047] Utilize multi-objective optimization models and advanced algorithms to comprehensively evaluate numerous design options. The algorithm searches for the optimal solution in a complex decision space, considers multiple constraints, and combines accurate data with current situation analysis to ensure that the design solution is scientific and reasonable and fits the site, thus improving the scientificity and accuracy of the design.

[0048] Enhance the function and adaptability of sponge parks:

[0049] Carefully set and optimize rainwater management goals, improve the park's rainwater storage, infiltration, purification and utilization capabilities, reduce runoff and peak flow, reduce the risk of waterlogging, and realize rainwater resource utilization; ecological goals promote the improvement of biodiversity and vegetation coverage, improve the ecological environment, provide habitats, and enhance the stability and service functions of the ecosystem; reasonable economic goal planning ensures economic feasibility and sustainability, so that the sponge park can adapt to the development of different regions and enhance its functions and adaptability;

[0050] Promoting sustainable development and resource recycling:

[0051] The design method implements the concept of sustainable development, covering rainwater resource management, ecological protection and improvement, and economic cost control; the sponge park realizes the natural recycling of rainwater, reduces resource dependence, optimizes the ecological environment, improves the quality of life of residents, promotes ecological balance, promotes the healthy development of urban ecology, forms a virtuous cycle of society, environment and economy, and promotes sustainable development and resource recycling;

[0052] Providing decision support and flexibility:

[0053] A comprehensive evaluation method is used to evaluate design plans, providing decision makers with a comprehensive and objective basis to help them choose the best plan. The method is flexible and can adjust target weights and parameters according to regional conditions and project requirements to adapt to a variety of scenarios, provide support for decision-making and give design flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1It is a schematic diagram of the overall structure of a sponge park low-impact development engineering design method based on multi-objective optimization of the present invention. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0056] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0057] like Figure 1 As shown, an embodiment of the present invention provides a sponge park low-impact development engineering design method based on multi-objective optimization, comprising the following steps:

[0058] Step S1, determine the design objectives, which include rainwater management objectives, ecological objectives and economic objectives, and set corresponding weights for the rainwater management objectives, ecological objectives and economic objectives. The rainwater management objectives include rainwater collection rate and infiltration rate, the ecological objectives include biodiversity and vegetation coverage, and the economic objectives include construction cost and maintenance cost. The specific steps are as follows:

[0059] Step S1-1: Determine rainwater management goals and weights

[0060] Determine rainwater collection rate target:

[0061] Analyze the rainfall characteristics of the project area and collect rainfall data for at least the past 5-10 years, including annual rainfall, rainfall events, distribution frequency of different rainfall intensities (light rain, moderate rain, heavy rain, rainstorm, etc.), and average rainfall duration, and statistically analyze the rainfall patterns in the area;

[0062] Based on the planned area, topography and surrounding drainage system of the sponge park, estimate the theoretical maximum potential of rainwater collection in the park; for example, determine the catchment area based on the topography and calculate the range of rainwater that may flow into the park under different rainfall conditions;

[0063] Refer to the actual data of rainwater collection rate of sponge parks built in the same region or under similar climatic conditions, as well as the requirements for rainwater collection rate in relevant sponge city construction standards, and set the target value of rainwater collection rate of this sponge park; generally speaking, it can be set at around 50%-70% in the initial stage, and can be adjusted and optimized according to actual conditions in the future. The target value is expressed in percentage form, such as the proportion of rainwater that the park can collect under specific rainfall conditions (such as the average annual rainfall) to the total rainfall;

[0064] Determine penetration target:

[0065] Conduct a comprehensive soil survey of the project site, collect soil samples at a certain grid spacing (such as 10m x 10m or 20m x 20m, etc.), analyze parameters such as soil type (such as sand, loam, clay, etc.), soil texture (particle size distribution), porosity, initial permeability, etc., draw a soil parameter distribution map, and clarify the permeability characteristics of the soil at different locations on the site;

[0066] Investigate the existing underlying surface conditions of the site, and count the area proportions of different types of underlying surfaces, such as hard pavement (such as roads, squares, etc.), green space (lawns, woods, etc.), and water bodies. Because the permeability of different underlying surfaces varies greatly, the permeability of hard pavement is low, while the permeability of green space and water bodies is relatively high. According to the permeability standard values ​​and area proportions of different underlying surfaces, estimate the comprehensive initial permeability of the site;

[0067] According to the concept of sponge city construction and site conditions, plan the sponge facilities to be used (such as rain gardens, sunken green spaces, permeable pavements, etc.) and their scale and layout, and estimate the effect of these facilities on the site permeability after construction; set reasonable permeability targets in combination with relevant standards and ecological protection requirements, such as expecting the overall permeability of the site to be increased to a certain value (such as an hourly permeability of 10-30 mm, etc.) after the completion of facility construction, so as to promote rainwater infiltration and reduce surface runoff;

[0068] Determine the weights of stormwater management objectives:

[0069] Organize experts in related fields (including hydrology and water resources experts, urban planners, landscape designers, etc.) to discuss and evaluate, and introduce the project background, site conditions and preliminary ideas of stormwater management goals to the experts;

[0070] Using methods such as the analytic hierarchy process (AHP) or expert scoring method, let experts compare and score the relative importance of the two sub-goals of rainwater collection rate and infiltration rate, for example, using a 1-9 scale (1 means equally important, 9 means extremely important), and construct a judgment matrix;

[0071] By calculating the eigenvector of the judgment matrix, the weights of rainwater collection rate and infiltration rate in the rainwater management target are determined to ensure that the sum of the two weights is 1. The weight value reflects the relative importance of each sub-target in rainwater management and is used for comprehensive consideration of rainwater management targets in the subsequent multi-objective optimization model.

[0072] Step S1-2: Determine ecological goals and weights

[0073] Determine biodiversity targets:

[0074] Conduct a detailed survey of the ecological environment within a certain range (e.g. 1-3 km radius) in and around the project area, using sampling, line sampling, mark-recapture and other ecological survey methods to count the number of species, individuals and distribution of plants and animals (birds, insects, small mammals, etc.), analyze the current biodiversity level, and draw a biodiversity distribution map;

[0075] Combined with the positioning of the sponge park (such as ecological education, ecological restoration, leisure and recreation, etc.) and planning and design concepts, refer to the biodiversity indicators of similar successful cases to determine the target species and community types to be attracted and protected, such as increasing local characteristic plant species, providing bird habitats to attract more birds, etc.;

[0076] Develop a biodiversity improvement plan based on site conditions (such as space size, availability of ecological resources, etc.) and target species needs, and set specific biodiversity goals within a certain period of time (such as 3-5 years) after the park is built, such as increasing species richness by 20%-30%, or reaching a certain value for a specific ecological index (such as the Shannon-Wiener Index), in order to quantitatively evaluate the degree of improvement in biodiversity;

[0077] Determine vegetation coverage target:

[0078] Use high-resolution satellite images or drone aerial photography technology to comprehensively map the existing vegetation on the project site, obtain the exact range of vegetation coverage, vegetation types (trees, shrubs, herbs, etc.) and distribution, and calculate the initial vegetation coverage rate on site;

[0079] According to the functional zoning of the sponge park (such as rainwater purification area, leisure and activity area, ecological protection area, etc.) and landscape design requirements, plan the vegetation layout and planting plan of different areas, and determine the planting area and density of various types of vegetation. For example, increase the planting of water-resistant plants in the rainwater purification area, and configure ornamental flowers and lawns in the leisure and activity area.

[0080] Considering the growth characteristics, survival rate and subsequent maintenance and management level of vegetation, the growth and expansion of vegetation in a certain growth cycle (such as 1-3 years) is estimated, and a reasonable vegetation coverage target value is set, generally expressed as a percentage. For example, it is planned to increase the vegetation coverage rate from the initial 30% to 50%-60% within 2 years after the park is built, so as to achieve the goals of improving the ecological environment and enhancing the landscape effect;

[0081] Determine the ecological target weights:

[0082] Invite ecological experts, landscape designers, environmental scientists and other professionals to form an evaluation team, and explain in detail to the team members the ecological planning intentions of the sponge park, the current status of the site and the preliminary setting of ecological goals;

[0083] Using the Delphi method or analytic hierarchy process, etc., organize experts to evaluate and score the importance of the two sub-goals of biodiversity and vegetation coverage, build a judgment matrix, and determine the weights by calculating the eigenvectors to ensure that the sum of the two weights is 1. The weights reflect the relative importance of each sub-goal in the ecological goal in improving the overall ecological function, and are used to comprehensively evaluate the degree of achievement of the ecological goal;

[0084] Step S1-3: Determine economic goals and weights

[0085] Determine construction cost targets:

[0086] Carry out detailed engineering breakdown of the sponge park construction project, list all the construction contents involved, including site leveling, earthwork, construction of various sponge facilities (rainwater gardens, bioretention ponds, green roofs, etc.), laying of water supply and drainage pipes, landscaping engineering, road and square paving, lighting and ancillary facilities installation, etc., and clarify the bill of quantities of each sub-project;

[0087] Conduct extensive market research on price information of construction materials, equipment (such as water pumps, water quality monitoring instruments, etc.) and labor services, inquire about prices from multiple suppliers and construction companies, obtain price ranges for materials and equipment of different specifications and quality levels, understand the labor cost standards of the local construction industry, and make a preliminary estimate of the construction cost of each sub-project based on the bill of quantities;

[0088] Consider the source of project funds (such as government investment, social capital cooperation, etc.), investment budget restrictions and the project's economic benefit requirements, refer to the cost data of similar sponge park construction, and set a reasonable upper limit for the construction cost target. For example, plan to control the construction cost of the entire sponge park within a certain range (such as RMB 3 million to RMB 8 million, etc.) to ensure that the project is smoothly implemented under the premise of economic feasibility;

[0089] Determine maintenance cost targets:

[0090] Analyze the maintenance needs of various facilities and landscapes after the sponge park is built, including regular cleaning of sponge facilities (such as dredging of rain gardens, cleaning of debris in bioretention ponds, etc.), equipment inspection and replacement (such as maintenance cycles and costs of water pumps, sprinklers and other equipment), vegetation maintenance (watering, fertilizing, pruning, pest control, etc.), maintenance of public facilities (roads, seats, lighting facilities, etc.), etc., and list in detail the list of various maintenance items and the expected maintenance cycle;

[0091] According to the price level of relevant maintenance services in the market, the cost of material consumption and the workload of manual maintenance, the annual expenditure of each maintenance project is estimated, and the estimated annual maintenance cost of the entire sponge park is summarized; for example, the vegetation maintenance cost is estimated based on the quotation of the local greening maintenance company, and the equipment maintenance cost is estimated based on the maintenance manual provided by the equipment manufacturer;

[0092] Combined with the project's operation and management model, expected service life, and economic sustainability requirements, refer to the maintenance costs of similar sponge parks that have been in operation, and set reasonable maintenance cost targets. Generally, they can be set as a certain proportion of the construction cost (such as 5%-10%) or the annual maintenance cost can be controlled within a certain amount range (such as RMB 100,000-300,000, etc.) to ensure the economy and maintainability of the park in the long-term operation process;

[0093] Determine the weights of economic objectives:

[0094] Organize economic analysts, cost engineers, project managers and other professionals to participate in the economic target weight assessment, and introduce the project's financial status, construction and operation plans, and the ideas for setting economic targets to them;

[0095] By using methods such as expert survey or weight allocation model, professionals are asked to evaluate and score the relative importance of the two sub-goals of construction cost and maintenance cost, build a judgment matrix, calculate the weights, and ensure that the sum of the two weights is 1. The weights reflect the relative importance of each sub-goal in the project economic considerations and are used to comprehensively weigh the role of economic goals in the overall design;

[0096] Assume that the target weight of rainwater management is , the ecological target weight is , the economic target weight is ,satisfy , each weight ranges from 0 to 1;

[0097] Step S2: Collect regional meteorological, hydrological, soil, vegetation and socio-economic data to conduct status analysis;

[0098] Step S2-1: Data collection

[0099] Meteorological data collection:

[0100] Determine the time range for meteorological data collection. It is generally recommended to collect at least 5-10 years of historical meteorological data to fully reflect the climate characteristics and changing patterns of the region;

[0101] Cooperate with local meteorological departments to obtain data on rainfall, rainfall intensity, rainfall duration, rainfall frequency, temperature, humidity, wind speed, wind direction, etc. from regular meteorological observation stations; ensure the accuracy and completeness of the data, and the data format should be an electronic document format that can be used for analysis (such as Excel tables, database files, etc.);

[0102] Small meteorological monitoring stations should be set up at appropriate locations in or around the sponge park project site to collect additional local meteorological data, such as the impact of micro-topography on rainfall distribution, local temperature differences, etc. Small meteorological monitoring stations should be equipped with high-precision sensors that can monitor and record meteorological data in real time. The collection frequency can be set according to project requirements (such as collecting data every 10 minutes or every 30 minutes);

[0103] Hydrological data collection:

[0104] Collect water system distribution maps of the project area to clarify the location, flow direction, drainage area and other information of rivers, lakes, ditches and other water bodies. Relevant information can be obtained from local water conservancy departments or query and analyze using geographic information system (GIS) software;

[0105] On-site measurement or acquisition of the diameter, slope, direction, drainage capacity and other parameters of the existing drainage pipes around the site, record the location and elevation information of the drainage outlets, and conduct endoscopic inspection of the drainage pipes if necessary to fully understand the internal conditions of the pipes;

[0106] Hydrological monitoring equipment shall be installed at the main water bodies and drainage nodes in and around the site to monitor water level changes and flow data. The monitoring frequency shall be determined according to the actual situation (e.g., the monitoring frequency shall be increased in the rainy season). For areas lacking long-term monitoring data, short-term hydrological surveys may be conducted to estimate the flow rate by measuring the flow velocity with a flow meter and measuring the cross-sectional area of ​​the water flow.

[0107] Collect historical flood water level records and historical rainstorm runoff data of the region, analyze the frequency of floods, inundation range, runoff coefficient and other information, and provide reference for the design of sponge parks. These data can be obtained from water conservancy departments, hydrological stations or historical archives;

[0108] Soil data collection:

[0109] Soil sampling points should be evenly arranged in the project site according to a certain sampling grid (such as 10m×10m or 20m×20m). The sampling depth should be determined according to the design depth of the sponge facility and the soil stratification. Generally, the sampling depth should be at least 1-2m underground to ensure that the characteristics of soil at different layers can be reflected;

[0110] When collecting soil samples, use professional soil sampling tools (such as soil drills) to collect soil samples at different depths at each sampling point. Mix the samples at different depths at the same point evenly as representative samples of that point, put them into sealed bags and mark the sampling point location, depth and other information;

[0111] Conduct laboratory analysis on the collected soil samples to determine the soil's physical properties (such as soil texture, particle composition, bulk density, porosity, saturated hydraulic conductivity, etc.) and chemical properties (such as pH value, organic matter content, nutrient content such as nitrogen, phosphorus and potassium, heavy metal content, etc.). The analysis method should comply with relevant soil testing standards and specifications;

[0112] Based on the soil analysis results, draw soil type distribution maps, soil physical and chemical property parameter maps, etc., to intuitively display the spatial distribution of site soil characteristics and provide a basis for the site selection and design of sponge facilities;

[0113] Vegetation data collection:

[0114] Use high-resolution satellite images (e.g. images with a resolution better than 0.5 meters) or drone aerial photography technology to obtain the coverage of vegetation in and around the project site, and identify the distribution range and area size of different vegetation types (e.g. arbor forests, shrubs, grasslands, wetland plants, etc.) and the health status of vegetation (e.g. whether there are pests and diseases, withering, etc.) through image interpretation;

[0115] Conduct a field survey of the vegetation in the site, using the sampling method or the transect method, set up a certain number of sample plots (the area of ​​the sample plot is determined according to the vegetation type, such as the area of ​​the tree forest sample plot can be 100 square meters, and the area of ​​the grassland sample plot can be 1 square meter) or transect lines (the length of the transect line is determined according to the site conditions, generally not less than 100 meters), and record in detail the type, quantity, height, breast diameter (for trees), coverage and other information of the plants in the sample plots or transect lines. For rare and endangered plants, their location and growth status must be specially marked;

[0116] Collect information on the growth habits and ecological functions of existing vegetation on the site, such as the ability of plants to withstand flooding, their role in soil improvement, and their attraction to animals such as birds and insects. This can be obtained by consulting flora, consulting plant experts, or conducting field observations.

[0117] According to the results of vegetation survey, draw vegetation distribution map, count the area, quantity and distribution ratio of different vegetation types, analyze the vegetation community structure and ecological function status, and provide basic data for the vegetation planning of sponge park;

[0118] Socioeconomic Data Collection:

[0119] Obtain socio-demographic data such as population size, population density, age structure, income level, employment structure, etc. of the project area from the local government statistics department, as well as economic data such as the regional economic development level (such as GDP, per capita GDP, industrial structure, etc.), fixed asset investment, and real estate price trends. The data time span should be consistent with the planning period of the sponge park (such as the past 5-10 years);

[0120] Investigate the current land use and planning situation around the project site, including the distribution, area, development intensity of various types of land (such as residential land, commercial land, industrial land, agricultural land, etc.), and the future land use planning direction (such as whether there are new development projects, urban renewal plans, etc.). Information can be obtained through field surveys, review of urban planning materials, or communication with relevant planning departments;

[0121] Collect price information from the local construction market, including construction material prices (such as price fluctuations of common materials such as cement, steel, sand and gravel, and wood), labor costs (daily or monthly wages for different types of work), construction equipment rental costs, etc. Data can be obtained by asking building material suppliers and construction companies for prices or by searching construction project cost information websites;

[0122] Understand the needs and expectations of local residents for the construction of sponge parks. Through questionnaire surveys and interviews with residents, collect residents' opinions and suggestions on park functions (such as leisure and entertainment, ecological education, sports and fitness, etc.), landscape features, service facilities, etc., to provide reference for the design and positioning of sponge parks. The questionnaire design should be scientific and reasonable, and the interviewees should be representative to ensure that they can accurately reflect the wishes of residents;

[0123] Step S2-2: Current situation analysis

[0124] Meteorological data analysis:

[0125] Conduct statistical analysis on the collected rainfall data, calculate annual average rainfall, monthly average rainfall, rainfall intensity frequency distribution (such as the proportion of occurrences of different rainfall intensity levels to total rainfall), maximum rainfall duration and other indicators, draw rainfall histograms, rainfall intensity duration curves and other charts to intuitively display rainfall characteristics;

[0126] Analyze the changing patterns of meteorological elements such as temperature, humidity, wind speed, and wind direction, calculate the annual average temperature, monthly average temperature, frequency of extreme temperatures, humidity variation range, dominant wind direction and frequency, etc., and study the impact of these meteorological factors on water evaporation, vegetation growth, and human comfort in the sponge park;

[0127] Combined with rainfall and temperature data, the impact of seasonal climate change on the rainwater management of sponge parks is analyzed, such as the obvious differences between the rainy season and the dry season, to provide a basis for determining the scale and regulation capacity of sponge facilities. For example, a larger rainwater storage space is needed in the rainy season, while the rational use and storage of water resources should be considered in the dry season.

[0128] Hydrological data analysis:

[0129] According to the water system distribution and drainage pipeline information, analyze the drainage path and drainage capacity of the site, use GIS software to perform hydrological simulation analysis, calculate the site's surface runoff coefficient, catchment area, runoff and other parameters under different rainfall conditions, and evaluate the drainage effect and potential risks of the site's existing drainage system in response to extreme weather such as heavy rain;

[0130] Analyze water level changes and flow data, determine the normal water level, maximum water level, minimum water level and water level change cycle of the water body in the site, study the dynamic balance of water resources in the site, provide a reference for the design of water level control of sponge facilities such as wetlands and rainwater ponds, and evaluate the connectivity and interaction between the water body in the site and the surrounding water system;

[0131] Combined with historical flood and storm runoff data, the degree and scope of flood threats to the site are analyzed, and the blocking and diversion effects of existing topography on floods are evaluated to provide a basis for the flood control design of the sponge park (such as setting up flood control embankments, drainage channels, etc.), and determine the role and function of sponge facilities in flood control and disaster reduction;

[0132] Soil data analysis:

[0133] According to the soil type distribution map and physical and chemical property parameter map, the spatial heterogeneity of the site soil is analyzed to determine the suitability and limiting factors of the soil in different areas. For example, some areas have loose soil texture and high permeability, which are suitable for the construction of infiltration sponge facilities such as rain gardens; while some areas have heavy soil and low permeability, which may require soil improvement or the use of other suitable sponge facilities;

[0134] Assess the water storage and fertilizer retention capacity of the soil, calculate the field water holding capacity and effective water storage capacity of the soil through soil porosity, saturated hydraulic conductivity and other parameters, analyze the soil's support for vegetation growth in combination with soil nutrient content, and provide a basis for the design of sponge facilities and vegetation configuration. For example, in areas with poor soil water storage capacity, the scale of rainwater storage facilities can be increased, and in areas with low soil fertility, plant varieties that are resistant to barrenness can be selected or soil improvement can be carried out;

[0135] Analyze the chemical properties of the soil, evaluate the potential impact of soil pH, heavy metal content, etc. on plant growth and groundwater quality, and formulate corresponding improvement measures or treatment plans for soil that does not meet plant growth requirements or may cause environmental pollution to ensure the ecological and environmental safety during the construction and operation of the sponge park;

[0136] Analysis of vegetation status:

[0137] According to the vegetation distribution map and field survey data, analyze the community structure and succession trend of the site vegetation, determine the dominant vegetation species and community types, and evaluate the stability and ecological service functions of the vegetation community (such as carbon sequestration, oxygen release, air purification, habitat provision, etc.). For example, the ecological service function of mature arbor forest communities is relatively high, but certain maintenance management may be required to maintain its stability;

[0138] Study the relationship between vegetation and site hydrology and soil conditions, and analyze the role of vegetation in rainwater interception, soil erosion control, soil improvement, etc. For example, grassland vegetation can effectively reduce surface runoff and soil erosion, and plants with well-developed root systems can help improve soil structure and increase soil permeability, providing a basis for the coordinated design of sponge facilities and vegetation;

[0139] Combined with the ecological function and landscape value of vegetation, the preservation and utilization value of existing vegetation in the sponge park planning should be evaluated. Vegetation with important ecological significance or landscape characteristics should be preserved and protected. For vegetation areas that need to be transformed or supplemented, reasonable vegetation planning plans should be formulated according to the site functional requirements and ecological goals to improve vegetation coverage and ecological diversity;

[0140] Analysis of social and economic status:

[0141] According to social demographic data and economic development data, analyze the social and economic development trends and residents' consumption capacity in the project area, and evaluate the potential service objects and market demand of the sponge park. For example, densely populated and economically developed areas have a greater demand for high-quality leisure space, and diversified leisure and entertainment facilities and service items can be added to the sponge park design;

[0142] Combined with the current land use and planning situation, analyze the coordination and complementarity between the construction of sponge parks and the surrounding land use, and evaluate the potential impact of park construction on the value of surrounding land. For example, the construction of sponge parks may increase the value of surrounding residential and commercial land. The design should consider the integration and interaction with the surrounding environment to promote the overall development of the region.

[0143] According to the construction market price information and the survey results of residents' needs, the cost-effectiveness and social benefits of sponge park construction are analyzed to determine the reasonable construction investment scale and functional positioning. On the premise of meeting the needs of residents, the construction cost is controlled as much as possible to improve the economic feasibility and sustainability of the project. For example, according to the needs of residents for sports and fitness facilities, the number and type of corresponding facilities are reasonably allocated, while considering their construction and maintenance costs;

[0144] Step S3, establishing a multi-objective optimization model, and optimizing the design scheme using an optimization algorithm;

[0145] Step S3-1, construct the objective function of the multi-objective optimization model:

[0146] The objective function of the constructed multi-objective optimization model is to minimize the construction cost , maximize rainwater collection efficiency , maximize penetration , maximizing biodiversity and maximize vegetation cover , which is expressed as follows: ; in, Represents the design variable vector, and at the same time, the constraints between the objectives must be considered, using the inequality constraint function Equality constraint function Reflect the constraints in actual engineering;

[0147] Step S3-2: Select optimization algorithm and optimize

[0148] The coding method uses binary coding or real number coding to encode the design variables. Encode to form chromosomes to represent individuals. Suppose the length of chromosome is , each gene corresponds to a design variable encoding value fitness function Build as: ;

[0149] in: ; ; ;

[0150] and , , , Sub-functions related to stormwater management objectives, is the sub-function related to ecological goals, is the sub-function related to economic objectives, are the weight coefficients of rainwater collection rate and infiltration rate in the rainwater management target sub-function, and the sum of the two is 1, which indicates the relative importance of rainwater collection rate and infiltration rate in the rainwater management target. Indicates the design Rainwater collection rate under Indicates the design The permeability under are the weight coefficients of biodiversity and vegetation coverage in the ecological target sub-function, and their sum is 1, which indicates the relative importance of biodiversity and vegetation coverage in the ecological target. Indicates the design biodiversity, Indicates the design The vegetation coverage rate under are the weight coefficients of construction cost and maintenance cost in the economic objective sub-function respectively, and their sum is 1, which indicates the relative importance distribution of construction cost and maintenance cost in the economic objective. Indicates the design The construction cost of Indicates the design The maintenance cost under the condition, the calculation formula of the relevant indicators of each sub-function is as follows:

[0151] Rainwater collection rate

[0152]

[0153] in, Indicates during the period Internal design The actual volume of rainwater collected at Indicates during the period The theoretical volume of rainwater that can be collected corresponds to the total rainfall amount. is the total number of rainfall periods;

[0154] Permeability :

[0155] in, is the soil hydraulic conductivity, is the water head difference, is the seepage path length;

[0156] Biodiversity :

[0157] in, is the total number of species, For the The proportion of the number of individuals of a species to the total number of individuals, For biodiversity A form of representation;

[0158] Vegetation coverage :

[0159] in, For the Vegetation Type in Design Plan The coverage area below is the total number of vegetation types, is the total area of ​​the sponge park;

[0160] Construction costs :

[0161] in, For the Construction projects are under design The cost of is the total number of construction projects;

[0162] Maintenance costs :

[0163] in, For the Maintenance items in the design plan The cost of The total number of maintenance items;

[0164] Genetic operations include selection, crossover, and mutation. The population is continuously evolved through multiple generations of genetic operations until the convergence condition is met.

[0165] Step S3-3, particle swarm optimization algorithm optimization (optional):

[0166] When initializing, the population size is set to , each particle The position vector represent design variables, the velocity vector Randomly initialize the particle positions and speed ,in, and is the design variable The lower and upper limits of is the speed variable The upper limit value of ;

[0167] During the update process of individual optimal and global optimal, the fitness value of each particle is calculated and the individual historical optimal position is recorded. and the global optimal position of the group particle The speed and position update formulas are: ; ;

[0168] in, is the inertia weight, and:

[0169] and are the maximum and minimum values ​​of the inertia weight, respectively. is the current iteration number, is the maximum number of iterations, and is the learning factor, and yes Random numbers in the interval; update the particle state through continuous iteration until the stopping criterion is met; For particles In Dimension The optimal position of an individual at time ; For groups in dimensions On The global optimal position at the moment;

[0170] Step S4: Generate multiple design solutions and evaluate their performance on each goal. The specific steps are as follows:

[0171] Step S4-1, generating multiple design solutions:

[0172] Generate solutions based on the range of decision variable values:

[0173] According to the decision variables (such as the number and area of ​​rain gardens, the depth of bioretention pools, the proportion of permeable pavement area, the coverage of green roofs, etc.) and their value ranges determined in step S3, Latin Hypercube Sampling (LHS) or uniform design methods are used to generate multiple sample points with different value combinations; each sample point corresponds to a set of decision variable values, thereby generating multiple initial design schemes; for example, for the number of rain gardens with a value range of [3,8], 5 different values ​​(such as 3, 4, 5, 6, 7) are uniformly selected in this interval, and other decision variables are also selected in a similar manner, and then combined into different design schemes;

[0174] Ensure that the generated design solutions have a certain degree of diversity and can cover all areas of the decision variable value space to avoid local concentration of solutions; thereby initially generating a certain number (e.g., 50-100) of design solutions as the basis for subsequent evaluation and screening;

[0175] Adjustment plan based on expert experience and actual cases:

[0176] Experts in the field of sponge city construction were invited to evaluate and analyze the preliminary design plan. With their own experience and professional knowledge, the experts put forward adjustment opinions and suggestions on the layout, selection, scale and other aspects of the sponge facilities in the plan. For example, according to the site topography and drainage direction, it is proposed to adjust the location of the rain garden to make it more suitable for rainwater collection and storage needs.

[0177] Refer to the design features and experience data of similar successful sponge park cases at home and abroad to optimize and improve the generated scheme to make it more in line with actual engineering requirements and best practices; for example, refer to the matching mode of bioretention pool and surrounding vegetation in a successful case to optimize the configuration of vegetation around the bioretention pool in the corresponding scheme;

[0178] According to expert opinions and case experience, some design schemes are manually adjusted and modified to further enrich the diversity and rationality of the design schemes, and finally multiple design schemes for evaluation are determined (such as retaining 80-100 better schemes);

[0179] Step S4-2: Evaluate the performance of each solution on each objective:

[0180] Stormwater Management Objectives Assessment:

[0181] Rainwater collection rate assessment:

[0182] For each design, based on the layout and scale of its sponge facilities (such as the area of ​​rain gardens, the volume of bioretention pools, etc.), site topography, and rainfall data, a rainwater runoff model (such as the SWMM model, etc.) is used to simulate and calculate the amount of rainwater collected under different rainfall conditions (such as different rainfall intensities and durations); then the rainwater collection rate is calculated, that is, the rainwater collection amount is compared with the total rainfall and converted into a percentage, and compared and evaluated with the set rainwater collection rate target;

[0183] Permeability assessment:

[0184] Calculate the overall permeability of the site based on the measures taken by the sponge facilities in each design to improve the soil (such as adding organic materials, improving soil structure, etc.) and the soil types and underlying surface conditions in different areas of the site; calculate the permeability of each area through specific methods (such as relevant calculation methods based on Darcy's law, which need to consider factors such as seepage volume, seepage path length, seepage area, and head difference in different areas), and then obtain the overall permeability of the site by weighted average according to the area of ​​the area, and compare and evaluate it with the set permeability target value;

[0185] Ecological target assessment:

[0186] Biodiversity Assessment:

[0187] Estimate the number and type of organisms that may be attracted and supported based on factors such as vegetation configuration, habitat creation measures (such as setting up bird habitat islands, insect hotels, etc.) and water landscape design in each design plan; use biodiversity indices (such as the Shannon-Wiener Diversity Index, which requires counting the proportion of individuals of different species to the total number of individuals) or species richness (i.e. the number of species) to quantitatively assess biodiversity, and compare and analyze the calculated results with the set biodiversity targets;

[0188] Vegetation coverage assessment:

[0189] Using geographic information system (GIS) or image processing software, calculate the vegetation coverage area according to the vegetation planting plan in the design plan, and then calculate the vegetation coverage rate (i.e. the ratio of the vegetation coverage area to the total area of ​​the sponge park and convert it into a percentage), and compare and evaluate it with the set vegetation coverage rate target to determine whether the vegetation coverage condition meets the expected requirements;

[0190] Economic Objectives Assessment:

[0191] Construction cost assessment:

[0192] For each design scheme, calculate the various construction costs in detail, including the construction costs of sponge facilities (such as civil engineering costs of rainwater gardens, materials and construction costs of bioretention pools, etc.), site leveling costs, landscaping costs, equipment purchase and installation costs (such as rainwater pumps, water quality monitoring equipment, etc.), etc.; based on market price information and the bill of quantities, summarize the total construction cost of each scheme, compare it with the set construction cost target, and evaluate whether it is within the budget;

[0193] Maintenance cost assessment:

[0194] Analyze the maintenance needs of each design during operation and estimate the annual maintenance costs; maintenance costs include regular cleaning and maintenance costs of sponge facilities (such as silting of rain gardens, cleaning of debris in bioretention ponds, etc.), equipment inspection and maintenance costs (such as regular equipment inspections, replacement of wearing parts, etc.), vegetation maintenance costs (such as watering, fertilizing, pruning, pest control, etc.) and maintenance costs of other public facilities (such as roads, seats, lighting facilities, etc.); summarize and calculate the annual maintenance cost of each plan and compare it with the set maintenance cost target to evaluate its economic feasibility for long-term operation;

[0195] Step S5: Use a comprehensive evaluation method to select the best solution and carry out detailed design. The detailed design includes overall layout design, sponge facility design and rainwater treatment system design. The specific steps are as follows:

[0196] Step S5-1: Use the analytic hierarchy process to select the optimal solution:

[0197] Build a hierarchical model:

[0198] Determine the target layer as the optimal solution for the comprehensive performance of the sponge park;

[0199] The criterion layer includes stormwater management goals, ecological goals, and economic goals, and the specific content and weights of these goals have been set in step S1;

[0200] The solution layer is the multiple design solutions generated and evaluated in step S4 (e.g., the 80-100 best solutions retained);

[0201] Construct a judgment matrix:

[0202] Organize a team of experts (such as sponge city construction experts, ecologists, cost engineers, etc.) to compare and judge the relative importance of each goal at the criterion level;

[0203] For rainwater management goals, ecological goals and economic goals, experts use a 1-9 scale to compare and score them pairwise based on the actual needs and focus of the project, and construct a judgment matrix in Representation Guidelines Relative to the criteria The relative importance of Representation Guidelines Relative to the criteria The relative importance of ,in, Judgment Matrix The elements on the diagonal represent the criteria The relative importance of the stormwater management goal to itself; for example, if experts consider the stormwater management goal to be slightly more important than the ecological goal, then ,but ;

[0204] Compute the weight vector and perform a consistency check:

[0205] Calculate the judgment matrix The largest characteristic root and the corresponding eigenvector (in are the relative weights of rainwater management objectives, ecological objectives, and economic objectives respectively); the calculation method can adopt an approximate calculation method, such as the sum method or the root method;

[0206] Calculate consistency index (in is the order of the judgment matrix);

[0207] Find the average random consistency index The value of , calculate the random consistency ratio ;when When , the judgment matrix is ​​considered to have satisfactory consistency and the obtained weight vector is valid; otherwise, experts are required to readjust the judgment matrix until the consistency requirement is met;

[0208] Calculate the score of each solution relative to each goal of the criterion layer:

[0209] For each design scheme, the score of the scheme relative to each target is calculated based on the evaluation results of its rainwater management targets (such as the actual performance of rainwater collection rate, infiltration rate, etc.), ecological targets (biodiversity, vegetation coverage, etc.) and economic targets (construction cost, maintenance cost, etc.), combined with the weights of each target in the criterion layer; for example, the score of a scheme on the rainwater management target is (in is the quantitative evaluation function of the scheme on the rainwater management target, which is calculated based on specific indicators, such as the rainwater collection rate reaches , and the rainwater collection rate target weight ,but ), and similarly calculate the scores on ecological and economic goals and ;

[0210] Calculate the comprehensive evaluation value of each solution and select the best solution:

[0211] Calculate the comprehensive evaluation value of each plan ;

[0212] Compare the comprehensive evaluation values ​​of all options and select the option with the highest evaluation value as the optimal option;

[0213] Step S5-2: Refine the design of the optimal solution:

[0214] Overall layout design:

[0215] Functional zoning is carried out in combination with regional topography; for example, natural confluence paths for rainwater runoff are set up using terrain height differences, low-lying areas are planned as rainwater storage areas (such as rainwater ponds, wetlands, etc.), and highlands or areas with good drainage are set up as activity and leisure areas, vegetation planting areas, etc., to ensure that rainwater can flow effectively in various areas;

[0216] Consider the surrounding environmental factors to determine the location relationship of each functional area; if there are residential areas around, set the leisure and entertainment functional area near the residential area and in a convenient location; if it is close to a traffic artery, set up a buffer green belt on the side of the road to reduce the impact of traffic noise and exhaust pollution on the park, while ensuring the harmonious coexistence of the park and the surrounding environment, and realizing the rationality of the overall layout of the sponge park;

[0217] Sponge facility design:

[0218] Determine the type and size of facilities based on the rainwater management goals; if the rainwater collection rate target is high, increase the number and area of ​​rainwater collection facilities such as rain gardens and bioretention ponds; for the infiltration rate target, select appropriate soil improvement measures (such as adding appropriate amounts of organic materials, sand, etc.) and the area and area of ​​permeable paving according to the site soil conditions and the expected infiltration rate improvement requirements;

[0219] Determine the location of facilities according to the hydrogeological conditions of the site; in areas with high groundwater levels, rationally arrange rainwater storage facilities to avoid adverse effects on groundwater levels; in areas with good soil permeability, give priority to setting up infiltration sponge facilities, such as infiltration wells and infiltration ditches, to make full use of the natural permeability of the soil and improve the effect of rainwater management;

[0220] Stormwater treatment system design:

[0221] The treatment process is determined according to the purification requirements of the collected rainwater; if it is used for landscape water replenishment or irrigation and other reuse purposes with high water quality requirements, deep treatment processes such as multi-stage filtration (such as sand filtration, activated carbon filtration, etc.) and biological treatment (such as artificial wetland purification) are adopted; if it is only used for general road sprinkling within the site, simple sedimentation and filtration treatment processes can be used to remove larger particle impurities and some pollutants in the rainwater;

[0222] Determine the equipment selection based on the reuse demand; for example, calculate the reused water volume to determine the size of the rainwater storage tank, and select the appropriate water pump model according to the required water supply pressure; for water quality monitoring equipment, select monitoring instruments with corresponding accuracy and functions according to the detected pollutant indicators (such as pH, suspended solids, chemical oxygen demand, etc.) to ensure that the rainwater treatment system can meet the requirements of the sponge park for rainwater purification and reuse, and realize the rational use and circulation of water resources;

[0223] Step S6: Establish a sponge effect evaluation system, regularly evaluate the design effect and conduct feedback optimization. The sponge effect evaluation system includes regular evaluation of rainwater management effect, ecological improvement effect and economic benefit. The feedback optimization step includes adjusting and improving the design plan according to the evaluation results. The specific steps are as follows:

[0224] Step S6-1, establishing a sponge effect evaluation system:

[0225] Stormwater management effectiveness evaluation:

[0226] Stormwater runoff reduction rate The formula is ;in, It is the rainwater runoff under specific rainfall conditions before the construction of the sponge park. To obtain the rainwater runoff under the same rainfall conditions after construction, flow monitoring equipment is installed at the site outlet and other locations to collect flow data in the corresponding period. and The value of

[0227] Peak traffic reduction rate The formula is ;in, is the peak flow during rainfall before construction, It is the peak flow during rainfall after construction;

[0228] Rainwater retention time : For a single stormwater detention facility , average rainwater retention time The calculation formula is: ;in It's time The amount of rainwater retained in the facility (the volume can be calculated by installing monitoring equipment such as water level sensors in the facility and combining the water level changes with the geometric shape of the facility), is the total duration of a complete rainfall event and the subsequent drainage process. is the average water inflow of the facility during this rainfall process, represents the integral variable;

[0229] Ecological improvement effect evaluation:

[0230] Biodiversity changes The formula is ,in, To construct the post-biodiversity index, is the biodiversity index before construction, if , indicating that biodiversity has been improved;

[0231] Changes in vegetation coverage The formula is ,in, is the vegetation coverage rate after construction, The vegetation coverage area after construction is obtained through remote sensing image interpretation or field surveying. is the total area of ​​the park, It is the vegetation coverage rate before construction, which is used to evaluate the impact of sponge park construction on vegetation growth and coverage;

[0232] Economic benefit evaluation:

[0233] Construction cost saving rate The formula is ;in, The actual construction cost of the low-impact development design of the sponge park is is the estimated construction cost of the traditional park construction plan. , indicating that construction costs have been saved;

[0234] Maintenance cost savings The formula is ;in, is the actual annual maintenance cost of the sponge park, Estimated annual maintenance costs for traditional parks to measure savings in maintenance costs over the long term;

[0235] Step S6-2: Regularly evaluate the design effect:

[0236] Determine the evaluation cycle: Determine a reasonable evaluation cycle based on the scale, functional positioning, local climate and ecological conditions of the sponge park. Generally, the rainwater management effect and ecological improvement effect can be evaluated every six months or one year. The economic benefit evaluation can be conducted once a year. For the initial stage of construction or after the adjustment of facilities, the evaluation cycle can be appropriately shortened to timely identify problems and make adjustments and optimizations.

[0237] Data collection and collation: In each evaluation cycle, according to the data collection methods of each indicator in the above evaluation system, comprehensive information such as rainwater runoff, peak flow, water level changes, biodiversity survey data, vegetation cover image data, construction and maintenance cost expenditures, etc. is collected, and systematically collated and classified to ensure the accuracy and completeness of the data, providing a reliable basis for subsequent analysis;

[0238] Effect analysis and evaluation: Use statistical methods and professional knowledge to conduct in-depth analysis of the collected data; calculate the actual values ​​of various evaluation indicators (rainwater runoff reduction rate, peak flow reduction rate, biodiversity changes, vegetation coverage changes, construction cost savings rate, maintenance cost savings rate, etc.) during the evaluation period, compare with the previous period or the set target value, analyze the change trend and compliance of each indicator, comprehensively evaluate the actual effects of the sponge park in rainwater management, ecological improvement and economic benefits, and form a detailed evaluation report to clarify the achievements and problems in the construction and operation of the park;

[0239] Step S6-3, feedback optimization:

[0240] Develop adjustment strategies based on the evaluation results:

[0241] Adjustments for rainwater management results that do not meet the standards:

[0242] If the reduction rate of rainwater runoff or peak flow reduction rate is lower than the expected target, the reasons may include insufficient scale of sponge facilities, unreasonable layout, improper operation and maintenance of facilities (such as soil compaction in rain gardens affecting infiltration, blockage of drainage pipes, etc.); formulate corresponding adjustment strategies for these problems, such as appropriately increasing the scale of sponge facilities (such as expanding the area of ​​rain gardens, increasing the volume of bioretention ponds, etc.), optimizing facility layout (replanning rainwater runoff paths and facility locations based on site topography and water catchment conditions), strengthening facility maintenance management (regularly cleaning rain gardens, inspecting and unblocking drainage pipes, etc.), and improving the park's ability to regulate, store and discharge rainwater;

[0243] If the rainwater retention time does not meet the requirements, it may be that the design parameters of the rainwater retention facility are unreasonable (such as too shallow depth, inappropriate water inlet size, etc.) or the connection with other facilities is not smooth; in this case, the design parameters of the rainwater retention facility can be adjusted (such as deepening the pool depth, optimizing the water inlet design, etc.), and the connection method between facilities can be improved (such as increasing the slope of the connecting pipe, setting up a buffer area, etc.) to ensure that rainwater can be fully retained in the facility and discharged in a staggered manner;

[0244] Improvement measures for poor ecological improvement effects:

[0245] When the change in biodiversity does not achieve the expected improvement effect, it may be due to imperfect habitat construction (such as lack of suitable bird nesting sites, insect habitats, etc.), unreasonable vegetation configuration (single plant species, lack of nectar plants, etc.) or large interference from surrounding human activities (such as noise, pollution, etc.); in response to these situations, take corresponding improvement measures, such as increasing habitat types and diversity (setting up artificial bird nests, insect hotels, creating diverse aquatic and terrestrial habitats, etc.), optimizing vegetation configuration (increasing local plant species, enriching plant community structure, planting nectar plants to attract insects, etc.), reducing the interference of surrounding human activities on the park's ecological environment (setting up sound barriers, controlling surrounding pollution sources, etc.), and promoting the improvement of biodiversity;

[0246] If the vegetation coverage rate does not change as expected, it may be due to low survival rate in the early stage of vegetation planting, poor growth in the later stage, or human damage. Vegetation maintenance and management should be strengthened (such as improving planting techniques, watering and fertilizing properly, strengthening pest and disease control, etc.), and damaged or dead vegetation should be replanted in time. At the same time, publicity and education for tourists should be strengthened to enhance public awareness of protection and ensure the achievement of vegetation coverage rate targets.

[0247] Optimization plan for economic benefits that do not meet expectations:

[0248] If the construction cost saving rate does not meet expectations, analysis may be due to unreasonable selection of materials and equipment in the design stage (such as the selection of materials and equipment that are too high standard or expensive), and changes in the construction process that lead to cost increases (such as design changes, construction process problems, etc.); optimization solutions include re-evaluating the selection of materials and equipment (selecting products with higher cost performance while meeting functional requirements), strengthening construction process management (strictly controlling design changes, optimizing construction processes, improving construction efficiency, etc.), and reducing construction costs;

[0249] In the case of unsatisfactory maintenance cost saving rate, it may be that the maintenance plan is unreasonable (such as maintenance frequency is too high or too low, maintenance items are improperly arranged, etc.), the equipment is aging or the selection is not suitable, resulting in high maintenance costs; the maintenance plan should be adjusted (maintenance frequency and items should be reasonably arranged according to the actual operation status and service life of the facilities), the equipment selection should be optimized (select equipment with reliable quality and simple maintenance), and daily operation management should be strengthened (such as reasonable control of water and electricity consumption, reduction of facility damage, etc.) to improve the economic operation efficiency of the park;

[0250] Implementation adjustments and ongoing monitoring:

[0251] According to the formulated adjustment strategy, corresponding adjustments and improvements shall be made to the design plan, facility operation management, vegetation maintenance, cost control and other aspects of the sponge park; the adjustment process shall follow the principles of scientific rationality and economic feasibility to ensure that the adjustment measures can be effectively implemented;

[0252] After the adjustment is implemented, the park’s operating results will be continuously monitored, and data collection, analysis and evaluation will be carried out again according to the established assessment cycle and evaluation system; observe whether various indicators have been improved, verify the effectiveness of the adjustment measures, form a closed-loop management of feedback optimization, continuously improve the construction and operation level of the sponge park, and achieve the sustainable development of the sponge park and maximize its comprehensive benefits.

[0253] In this embodiment, in step S4, for rainwater management target evaluation, the rainwater collection rate is calculated respectively. and permeability ,Compare the corresponding values ​​under different schemes, and analyze the performance differences of each scheme in rainwater collection and infiltration; For ecological goal evaluation, the Shannon-Wiener diversity index formula is used to calculate biodiversity , and calculated according to the vegetation coverage formula , compare the values ​​of these two indicators under each plan to measure the degree of impact of each plan on ecological improvement; for economic goal evaluation, calculate the construction cost of each plan and maintenance costs , directly compare the construction and operation costs of different schemes.

[0254] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A design method for low-impact development engineering of sponge parks based on multi-objective optimization, characterized by: The following steps are involved: Step S1, determining design goals, wherein the design goals include rainwater management goals, ecological goals and economic goals, and setting corresponding weights for the rainwater management goals, ecological goals and economic goals, wherein the rainwater management goals include rainwater collection rate and infiltration rate, the ecological goals include biodiversity and vegetation coverage, and the economic goals include construction cost and maintenance cost; Step S2: Collect regional meteorological, hydrological, soil, vegetation and socio-economic data to conduct status analysis; Step S3, establishing a multi-objective optimization model, and optimizing the design scheme using an optimization algorithm; Step S4, generating multiple design solutions and evaluating their performance on each objective; Step S5: Use a comprehensive evaluation method to select the best solution and carry out detailed design, wherein the detailed design includes overall layout design, sponge facility design and rainwater treatment system design; Step S6: Establish a sponge effect evaluation system, regularly evaluate the design effect and perform feedback optimization. The sponge effect evaluation system includes regular evaluation of rainwater management effect, ecological improvement effect and economic benefit. The feedback optimization step includes adjusting and improving the design plan according to the evaluation results.

2. A method for designing a low-impact development project of a sponge park based on multi-objective optimization according to claim 1, characterized in that: In step S1, the rainwater management target weight is set to , the ecological target weight is , the economic target weight is ,satisfy , each weight ranges from 0 to 1.

3. The method for designing a low-impact development project of a sponge park based on multi-objective optimization according to claim 1 is characterized in that: In step S3, the objective function of the constructed multi-objective optimization model is to minimize the construction cost. , maximize rainwater collection efficiency , maximize penetration , maximizing biodiversity and maximize vegetation cover , which is expressed as follows: ； in, Represents the design variable vector, and at the same time, the constraints between the objectives must be considered, using the inequality constraint function Equality constraint function Reflect the constraints in actual engineering.

4. A method for designing a low-impact development project of a sponge park based on multi-objective optimization according to claim 3, characterized in that: In step S3, the optimization algorithm uses a genetic algorithm to optimize the design solution. In the optimization step: The coding method uses binary coding or real number coding to encode the design variables. Encode to form chromosomes to represent individuals. Suppose the length of chromosome is , each gene corresponds to a design variable encoding value fitness function Build as: ； in: ; ; ,and , , , Sub-functions related to stormwater management objectives, is the sub-function related to ecological goals, is the sub-function related to economic objectives, are the weight coefficients of rainwater collection rate and infiltration rate in the rainwater management target sub-function, and the sum of the two is 1, which indicates the relative importance of rainwater collection rate and infiltration rate in the rainwater management target. Indicates the design plan Rainwater collection rate under Indicates the design The permeability under are the weight coefficients of biodiversity and vegetation coverage in the ecological target sub-function, and their sum is 1, which indicates the relative importance of biodiversity and vegetation coverage in the ecological target. Indicates the design plan biodiversity, Indicates the design plan The vegetation coverage rate under are the weight coefficients of construction cost and maintenance cost in the economic objective sub-function respectively, and their sum is 1, which indicates the relative importance distribution of construction cost and maintenance cost in the economic objective. Indicates the design The construction cost of Indicates the design The maintenance cost under the condition, the calculation formula of the relevant indicators of each sub-function is as follows: Rainwater collection rate : ;in, Indicates during the period Internal design The actual volume of rainwater collected at Indicates during the period The theoretical volume of rainwater that can be collected corresponds to the total rainfall amount. is the total number of rainfall periods; Permeability : ;in, is the soil hydraulic conductivity, is the water head difference, is the seepage path length; Biodiversity : ;in, is the total number of species, For the The proportion of the number of individuals of a species to the total number of individuals, For biodiversity A form of representation; Vegetation coverage : ;in, For the Vegetation Type in Design Plan The coverage area below is the total number of vegetation types, is the total area of ​​the sponge park; Construction costs : ;in, For the Construction projects are under design The cost of is the total number of construction projects; Maintenance costs : ;in, For the Maintenance items in the design plan The cost of The total number of maintenance items; Genetic operations include selection, crossover, and mutation. The population is continuously evolved through multiple generations of genetic operations until the convergence conditions are met.

5. A method for designing a low-impact development project of a sponge park based on multi-objective optimization according to claim 4, characterized in that: In step S3, the optimization algorithm uses a particle swarm optimization algorithm to optimize the design solution. In the optimization step: When initializing, the population size is set to , each particle The position vector represent design variables, the velocity vector Randomly initialize the particle positions and speed ,in, and is the design variable The lower and upper limits of is the speed variable The upper limit value of ; During the update process of individual optimal and global optimal, the fitness value of each particle is calculated and the individual historical optimal position is recorded. and the global optimal position of the group particle The speed and position update formulas are: ； ； in, is the inertia weight, , and are the maximum and minimum values ​​of the inertia weight, respectively. is the current iteration number, is the maximum number of iterations, and is the learning factor, and yes Random numbers in the interval; update the particle state through continuous iteration until the stopping criterion is met; For particles In Dimension The optimal position of an individual at time ; For groups in dimensions On The global optimal position at time.

6. The design method of a sponge park low-impact development project based on multi-objective optimization according to claim 1 is characterized by: In step S4, for rainwater management target evaluation, the rainwater collection rate is calculated respectively. and permeability ,Compare the corresponding values ​​under different schemes, and analyze the performance differences of each scheme in rainwater collection and infiltration; For ecological goal evaluation, the Shannon-Wiener diversity index formula is used to calculate biodiversity , and calculated according to the vegetation coverage formula , compare the values ​​of these two indicators under each plan to measure the degree of impact of each plan on ecological improvement; for economic goal evaluation, calculate the construction cost of each plan and maintenance costs , directly compare the construction and operation costs of different schemes.

7. The design method of a sponge park low-impact development project based on multi-objective optimization according to claim 1 is characterized by: When the comprehensive evaluation method is used to screen out the optimal solution, the hierarchical analysis method is used to screen out the optimal solution. When the hierarchical analysis method is used to screen out the optimal solution, a hierarchical model including the target layer, the criterion layer and the solution layer is constructed; a judgment matrix is ​​constructed. , its elements Representation Guidelines Relative to the criteria The relative importance of Representation Guidelines Relative to the criteria The relative importance of , ,in, Judgment Matrix The elements on the diagonal represent the criteria The degree of importance relative to itself; calculate the maximum eigenvalue of the judgment matrix and the corresponding eigenvector , and conduct consistency checks, consistency indicators , random consistency ratio ,when When , the judgment matrix is ​​considered to have satisfactory consistency. To determine the matrix order, The average random consistency index is then used to calculate the scores of each solution relative to each target in the criterion layer, and finally the comprehensive evaluation value of each solution is obtained. The solution with the highest evaluation value is selected as the optimal solution.

8. The design method of a sponge park low-impact development project based on multi-objective optimization according to claim 7 is characterized by: When the design is refined, the overall layout design combines the regional topography, surrounding environment and the functions of each sponge facility to determine the location and connection relationship of each functional area, to ensure that the overall layout of the sponge park is reasonable and rainwater can flow effectively in each area and realize the corresponding functions; the sponge facility design determines the type, specification and location of the facility based on the rainwater management objectives and the site hydrogeological conditions; the rainwater treatment system design determines the treatment process and equipment selection based on the purification and reuse of the collected rainwater.

9. The design method of a sponge park low-impact development project based on multi-objective optimization according to claim 1, characterized in that: In step S6, the sponge effect evaluation system includes: Stormwater management effectiveness evaluation: Stormwater runoff reduction rate The formula is ;in, It is the rainwater runoff under specific rainfall conditions before the construction of the sponge park. To obtain the rainwater runoff under the same rainfall conditions after construction, flow monitoring equipment is installed at the site outlet and other locations to collect flow data in the corresponding period. and The value of Peak traffic reduction rate The formula is ;in, is the peak flow during rainfall before construction, It is the peak flow during rainfall after construction; Rainwater retention time : For a single stormwater detention facility , average rainwater retention time The calculation formula is: ;in, It's time The amount of rainwater retained in the facility, is the total duration of a complete rainfall event and the subsequent drainage process. is the average water inflow of the facility during this rainfall process, represents the integral variable; Ecological improvement effect evaluation: Biodiversity changes The formula is ,in, To construct the post-biodiversity index, is the biodiversity index before construction, if , indicating that biodiversity has been improved; Changes in vegetation coverage The formula is ,in, is the vegetation coverage rate after construction, The vegetation coverage area after construction is obtained through remote sensing image interpretation or field surveying. is the total area of ​​the park, It is the vegetation coverage rate before construction, which is used to evaluate the impact of sponge park construction on vegetation growth and coverage; Economic benefit evaluation: Construction cost saving rate The formula is ;in, The actual construction cost of the low-impact development design of the sponge park is is the estimated construction cost of the traditional park construction plan. , indicating that construction costs have been saved; Maintenance cost savings The formula is ;in, is the actual annual maintenance cost of the sponge park, Estimated annual maintenance costs for traditional parks to measure savings in maintenance costs over the long term.

Images