Multi-objective coupling optimization and decision-making method and device for new sewage outlet location and discharge intensity

Abstract

The present invention provides a multi-objective coupling optimization and decision-making method and device for the location and discharge intensity of a newly built sewage outlet. The method includes: Step 1, constructing a coupling optimization multi-objective model for the location and discharge amount of the sewage outlet considering three objectives of regional economy, regional water quality, and regional ecological environment impact; Step 2, using the adjoint method to derive the accuracy lossless replacement expressions of the average concentration of the research period at the center point of the water quality control section in the regional water quality objective function and the regional ecological environment impact objective function, and performing objective function calculation; Step 3, using the multi-objective genetic algorithm NSGA-II to solve the multi-objective model to obtain all feasible solutions; Step 4, using the trade-off rate method to screen the feasible solutions that meet the trade-off rate requirements, given multiple groups of trade-off rates, and obtaining the optimal solutions corresponding to each group of trade-off rates; Step 5, determining the risk values of the optimal solutions corresponding to each group of trade-off rates through risk analysis, and finally determining the best multi-objective optimization plan for the sewage outlet with the lowest risk value.

Description

Technical Field

[0001] The present invention belongs to the field of environmental hydraulics, and particularly relates to a multi-objective coupling optimization and decision-making method and device for the location and discharge intensity of newly built sewage outfalls that coordinate the regional social and economic development and water ecological environment protection. Background Art

[0002] The setting of sewage outfalls into rivers will have a greater impact on the water quality, ecological protection areas, residential areas, water intakes, etc. of the downstream river sections. Therefore, the demonstration of sewage outfalls into rivers has always been an important topic in the engineering field. Optimizing the demonstration of sewage outfalls can coordinate the impacts of sewage outfalls on multiple aspects such as regional economy, water quality status, and ecological environment. The optimization of sewage outfalls needs to be based on the water quality standards of downstream monitoring sections or the requirements of water function areas.

[0003] However, the current sewage outfall optimization demonstration technology only optimizes the discharge intensity, and only selects the sewage outfall location according to the analytic hierarchy process for scheme comparison, lacking the coupling optimization of the sewage outfall location and discharge intensity; and the current sewage outfall optimization demonstration model only considers the impact of water quality and ignores the impacts of sewage outfalls on multiple aspects such as economy, ecological environment, and social impacts. Summary of the Invention

[0004] The present invention is carried out to solve the above problems, and aims to provide a multi-objective coupling optimization and decision-making method and device for the location and discharge intensity of newly built sewage outfalls, which can effectively coordinate the impacts of newly built sewage outfalls into rivers on multiple aspects such as regional economy, regional water quality, and regional ecological environment, establish a multi-objective coupling model that simultaneously optimizes the sewage outfall location and discharge intensity, and efficiently obtain the optimal result. To achieve the above object, the present invention adopts the following solutions:

[0005] <Method>

[0006] As Figure 1 shown, the present invention provides a multi-objective coupling optimization and decision-making method for the location and discharge intensity of newly built sewage outfalls, which is characterized by including the following steps:

[0007] Step 1, construct a multi-objective model for coupling optimization of the sewage outfall location and discharge volume considering three objectives of regional economy, regional water quality, and regional ecological environment impact; the multi-objective model includes three objective functions of regional economy, regional water quality, and regional ecological environment impact, and two independent variables of the discharge location and discharge intensity of the sewage outfall;

[0008] Let the spatial region of the research river section be Ω, and assume that there are several existing sewage outfalls or pollution sources in the research area, which are located at points x i ∈Ω (i = 1, 2,..., N1) respectively, and have discharge intensities of m i (t) (i = 1, 2,..., N1);

[0009] Let the discharge position of the new sewage outlet to be optimized be represented by the symbol x0, and its value range is determined according to the results of the water function zoning. Assume the value range is x0 ∈ x ad ; There are N2 types of pollutant indicators discharged from the new sewage outlet to be optimized, and the discharge intensity is represented by the symbol m0(t). Then we have:

[0010]

[0011] In the formula, represents the discharge intensity function of the j-th type of pollutant from the new sewage outlet, and its value range is determined according to the calculation results of the pollutant assimilation capacity of the functional area water body. Assume the value range is m0(t) ∈ m ad ;

[0012] The regional water quality objective function is defined as the average value of the pollutant spatio-temporal concentration in the water quality control section (such as the section near the water intake, the ecological protection area section, the aquatic organism gathering area section, etc.). As Figure 2 shown, it is restricted by the discharge intensity and discharge position of the new sewage outlet; if there are N3 water quality control sections, then the water quality objective function of the j-th type of pollutant on the k-th water quality control section is as follows:

[0013]

[0014] In the formula, f2 is the regional water quality objective function; |L k | represents the length of the k water quality control sections; d is the weight coefficient of the water quality control section, which can reflect different emphases in space and time; for example, the weight of the core area of the ecological protection area section can be set larger, and the weight of the edge area can be set smaller; the weight of the aquatic organism breeding period can be set larger, and the weight of other periods can be set smaller, etc.; C j is the water quality concentration of the j-th type of pollutant;

[0015] As Figure 3 shown, the regional ecological environment impact objective function is defined as the sum of the product of the average concentration at the center point of the water quality control section during the research period and the distance coefficient S k representing the distance from the sewage outlet position to the center point, and it satisfies that when the sewage outlet position is farther away from the center point, the ecological environment impact is smaller, and when the center point concentration is smaller, the ecological environment impact is smaller; the regional ecological environment impact objective function of the j-th type of pollutant on the k-th water quality control section is as follows:

[0016]

[0017] In the formula, f3 is the regional ecological environment impact objective function; is the average concentration at the center point of the water quality control section during the study period; S is the distance coefficient representing the distance from the sewage outfall location to the center point of the water quality control section;

[0018] The expression for the average concentration at the center point of the water quality control section during the study period is as follows:

[0019]

[0020] The expression for the distance coefficient S representing the distance from the sewage outfall location to the center point is:

[0021]

[0022] In the formula, x p is the coordinate of the center point of the water quality control section; σ is the variance coefficient, used to adjust the distribution of the distance coefficient in the entire water quality control section, and can be determined according to specific problems;

[0023] Step 2: Use the adjoint method to derive the precision lossless replacement expressions of the average concentration at the center point of the water quality control section in the regional water quality objective function and the regional ecological environment impact objective function, and perform objective function calculations;

[0024] Step 3: Use the multi-objective genetic algorithm NSGA-II to solve the multi-objective model to obtain all feasible solutions;

[0025] Step 4: Use the trade-off rate method to screen the feasible solutions that meet the trade-off rate requirements, given multiple groups of trade-off rates, and obtain the optimal solutions corresponding to each group of trade-off rates;

[0026] Step 5: Determine the risk values of the optimal solutions corresponding to each group of trade-off rates through risk analysis, and finally determine the best multi-objective optimization plan for the sewage outfall with the lowest risk value.

[0027] Preferably, the multi-objective coupling optimization and decision-making method for the location and discharge intensity of the newly built sewage outfall provided by the present invention may also have the following characteristics: In step 1, as Figure 4 shown, the regional economic objective function includes three parts: discharge benefit, sewage outfall construction cost, and operation cost, specifically as follows:

[0028]

[0029] In the formula, f1 is the economic objective function value, and the smaller this function value is, the greater the economic benefit; T is the length of the study period; XY represents the economic benefit value related only to the discharge intensity brought by the pollutant discharge of the newly built sewage outfall per unit time, which can be set according to the actual project; JS represents the construction cost of the sewage outfall, which is only related to the construction location of the newly built sewage outfall; YY represents the operation cost of the sewage outfall per unit time, which is related to both the construction location and the discharge intensity of the newly built sewage outfall;

[0030] The construction cost function JS of the economic objective function for the sewage outlet is as follows:

[0031] JS(x0) = JS max ×pd(x0)ptd(x0)td(x0) (1 - 7)

[0032] In the formula, JS max is the upper limit value of the construction cost, which is determined by the actual problem; pd is the slope coefficient; ptd is the flatness coefficient; td is the land use type coefficient; pd, ptd, and td can be obtained from the actual terrain data;

[0033] The operating cost function YY per unit time in the economic objective function is as follows:

[0034] YY(m0(t), x0) = D(m0(t))l(x0) (1 - 8)

[0035] In the formula, D is a function representing the relationship between the operating cost per unit time and the emission intensity m0(t), which is determined by the actual problem; l is a function representing the relationship between the operating cost per unit time and the location x0 of the sewage outlet, which is determined by the actual problem.

[0036] Preferably, the multi-objective coupling optimization and decision-making method for the location and emission intensity of the newly built sewage outlet provided by the present invention may further have the following characteristics: In step 2, when calculating the regional water quality objective function value and the regional ecological environment impact objective function value in step 1, the river water quality information of the water quality control section is required; if the numerical solution of the convection-diffusion equation is directly used to calculate the river water quality information, then every time the emission location and emission time of the newly built sewage outlet are modified, the numerical solution of the convection-diffusion equation needs to be solved again, which takes almost several hundred days in the multi-objective genetic algorithm. In order to improve the calculation efficiency, the adjoint system of the convection-diffusion equation is introduced to replace the calculation method of the river water quality information without loss of accuracy:

[0037] The regional water quality objective function is:

[0038]

[0039] The calculation method of the average concentration at the center point of the control section during the research period is:

[0040]

[0041] In the above calculation formulas of the regional water quality objective function and the average concentration, only the initial conditions and boundary conditions of the concentration C are used, and these are all known quantities. The only variable is the adjoint variable λ, and the adjoint variable λ is directly calculated by calculating the following adjoint equation:

[0042]

[0043] In the formula, A is the cross-sectional area of the river; Q is the flow rate; E is the longitudinal dispersion coefficient; K is the first-order decay coefficient of the pollutant; x is the coordinate along the river flow direction; t is the time; C(x) is the spatial distribution of the pollutant concentration at the initial moment; V is an undetermined function. If the water quality objective function of the area to be calculated, that is, the spatio-temporal average concentration of the water quality control section, then the undetermined function V is given as:

[0044]

[0045] In the formula, I is the index function. When I is 1, when it is within the water quality control section, that is, when x ∈ L, the value of the index function is 1, otherwise it is 0; |L| is the length of the water quality control section;

[0046] If what needs to be calculated is the average concentration of the research period at the center point of the water quality control section in the regional ecological and social impact objective function, then the undetermined function V is given as:

[0047]

[0048] In the formula, x p is the coordinate of the center point of the water quality control section, and δ(·) is the Dirac function.

[0049] When using the above formula (2-1) to calculate the regional water quality objective function and formula (2-2) to calculate the average concentration of the research period at the center point of the control section, even if the discharge position and discharge intensity of the newly built sewage outfall are adjusted, it is not necessary to recalculate the numerical solution C(x,t) of the convection-diffusion equation. This greatly improves the calculation efficiency and makes it possible to perform multi-objective optimization for the sewage outfall.

[0050] In addition, the specific derivation of the above formula is as follows:

[0051] The convection-diffusion equation and its initial value conditions and boundary conditions are as follows:

[0052]

[0053] In the formula, A is the cross-sectional area of the river; Q is the flow rate; E is the longitudinal dispersion coefficient; K is the first-order decay coefficient of the pollutant; δ(·) is the Dirac function; x is the coordinate along the river flow direction; t is the time; C(x) is the spatial distribution of the pollutant concentration at the initial moment; C in (t) is the upstream water quality boundary condition; the downstream water quality boundary condition is that the diffusion flux is 0;

[0054] Introduce the adjoint variable λ and take the inner product of λ with both sides of the convection-diffusion equation as follows:

[0055]

[0056] Integrate the above formula by parts and assume that:

[0057]

[0058]

[0059] λ = 0 at t = T (2e)

[0060] It should be noted that in the above formula, V is an undetermined function, that is, an arbitrarily set unknown function, and its actual meaning will be given according to the research content later;

[0061] Combining the initial value conditions and boundary conditions of formula (2a), formula (2b) is sorted out, and the result is as follows:

[0062]

[0063] In the above formula, since the undetermined function V is an arbitrary function, then, for the calculation of river water quality information, if the water quality objective function of the area to be calculated, that is, the spatio-temporal average concentration of the water quality control section, then the undetermined function V can be given as:

[0064]

[0065] In the formula, I is the index function. When I is 1, when in the water quality control section, that is, when x ∈ L, the index function value is 1, otherwise it is 0; |L| is the length of the water quality control section;

[0066] Substitute formula (2h) into formula (2g), and we can get:

[0067]

[0068] Since:

[0069]

[0070] The right side of the above formula is the regional water quality objective function in step 1, that is, the expression of the spatio-temporal average concentration in the control section; therefore, another calculation method of the regional water quality objective function is:

[0071]

[0072] If what needs to be calculated is the average concentration of the research period at the center point of the water quality control section in the regional ecological and social impact objective function, then the undetermined function V can be given as:

[0073]

[0074] where x p is the coordinate of the center point of the water quality control section;

[0075] Substituting formula (2k) into formula (2f), we can obtain:

[0076]

[0077] Since:

[0078]

[0079] The right side of the above formula is the expression of the average concentration of the research period at the center point of the control section in the regional ecological and social impact objective function in step 1; therefore, another calculation method for the average concentration of the research period at the center point of the control section is:

[0080]

[0081] Preferably, the multi-objective coupling optimization and decision-making method for the location and discharge intensity of the newly built sewage outfall provided by the present invention may further have the following characteristics: the trade-off rate ν in step 4 ij refers to the degree of increase in the benefit of objective i when reducing the unit benefit of objective j while keeping the other objective functions unchanged; the specific operation of the trade-off analysis is as follows:

[0082] Step 4-1, normalize the objective function values corresponding to the feasible solutions obtained in step 3, and the normalization formula is as follows:

[0083]

[0084] where f represents the objective function; represents the normalized objective function value of the r-th objective function of the s-th feasible solution;

[0085] Step 4-2, select the optimal solution of the regional economic objective as the initial solution X 0 , and denote its corresponding normalized objective function as g 0 , and given the trade-off rates of the regional water quality objective and the regional ecological environment impact objective relative to the economic objective and trade-off rate and satisfy the following conditions:

[0086]

[0087] Step 4-3, use the given trade-off rates and to screen the feasible solutions that meet the conditions, and the specific conditions are as follows:

[0088]

[0089] Step 4-4, from the trade-off ratios and among the feasible solutions screened out, find the optimal solution corresponding to this set of trade-off ratios that satisfies the following conditions:

[0090]

[0091] Step 4-5, given the range of each trade-off ratio, select a number from each range to form multiple sets of trade-off ratios, and obtain the optimal solution corresponding to each set of trade-off ratios according to the previous operation method.

[0092] Preferably, for the multi-objective coupling optimization and decision-making method for the location and discharge intensity of a new sewage outlet provided by the present invention, the specific operation of the risk assessment in Step 5 is as follows:

[0093] Step 5-1, define the water quality risk and obtain the probability cumulative distribution curve of the water quality risk; when the water quality benchmark concentration of the water quality control section reaches the predetermined standard (the predetermined standard can be: for example, for Class I water, COD = 15 mg / L), calculate the regional water quality objective function at this time. For all feasible solutions in Step 3, when the corresponding regional water quality objective function is less than or equal to this value, the water quality risk is 0; count the number of feasible solutions with a regional water quality objective function greater than this value, denoted as N4, sort these feasible solutions in ascending order according to the value of the water quality objective function, and the water quality risk probability corresponding to the s-th feasible solution is:

[0094]

[0095] Step 5-2, define the ecological risk and obtain the probability cumulative distribution curve of the ecological environment risk; when the average concentration of the research period at the center point of the water quality control section is the predetermined standard and the distance between the location of the new sewage outlet and the center point of the water quality control section is 2 - 5 km (the best is 3 km), calculate the value of the regional ecological environment impact objective function at this time, and set the ecological environment risk to 0 when the regional ecological environment impact objective function of all feasible solutions in Step 3 is less than this value; count the number of feasible solutions with a regional ecological environment impact objective function greater than this value, assumed to be N5, sort these feasible solutions in ascending order according to the value of the regional ecological environment impact objective function, then the ecological environment risk probability corresponding to the s-th feasible solution is:

[0096]

[0097] Step 5-3: Interpolate the water quality risk probability and ecological environment risk probability of the optimal solution corresponding to each trade-off rate obtained in Step 4 on the risk probability cumulative distribution curve according to the size of the objective function to obtain the corresponding risk probability, and sum them to obtain the total risk; arrange the optimal solutions corresponding to each trade-off rate in ascending order according to the total risk, and take the solution with the minimum total risk as the best multi-objective optimization plan for the sewage outfall.

[0098] <Device>

[0099] Furthermore, the present invention also provides a device for calculating the optimal emergency dispatch flow for river water pollution accidents considering uncertainty, which is characterized by including:

[0100] A model initial construction unit that constructs a multi-objective model for coupling optimization of the sewage outfall location and discharge amount considering three objectives of regional economy, regional water quality, and regional ecological environment impact; the multi-objective model includes three objective functions of regional economy, regional water quality, and regional ecological environment impact, as well as two independent variables of the discharge location and discharge intensity of the sewage outfall; let the spatial region of the research river section be Ω, and assume that there are several existing sewage outfalls or pollution sources in the research area, which are located at points x i ∈Ω (i = 1, 2,..., N1), respectively having m i (t) (i = 1, 2,..., N1) of discharge intensity; represent the discharge location of the newly built sewage outfall to be optimized with the symbol x0, and its value range is determined according to the water function zoning result, assuming the value range is x0 ∈ x ad ; there are N2 types of pollutant indicators discharged by the newly built sewage outfall to be optimized, and the discharge intensity is represented by the symbol m0(t), then there is:

[0101]

[0102] In the formula, represents the discharge intensity function of the jth pollutant of the newly built sewage outfall, and assume the value range is m0(t) ∈ m ad ;

[0103] The regional water quality objective function is the average value of the temporal and spatial concentration of pollutants in the water quality control section, which is subject to the discharge intensity and discharge location of the newly built sewage outfall. For N3 water quality control sections, the water quality objective function of the jth pollutant on the kth water quality control section is as follows:

[0104]

[0105] In the formula, f2 is the regional water quality objective function; |L k | represents the length of the k water quality control sections; d is the weight coefficient of the water quality control section, reflecting the temporal and spatial emphasis differences; C j is the water quality concentration of the jth pollutant;

[0106] The regional ecological environment impact objective function is the average concentration at the center point of the water quality control section during the study period and the distance coefficient S representing the distance between the sewage outlet location and the center point k The sum of the products, and it satisfies that when the sewage outlet location is farther away from the center point, the ecological environment impact is smaller, and when the center point concentration is smaller, the ecological environment impact is smaller; the regional ecological environment impact objective function for the jth pollutant in the kth water quality control section is as follows:

[0107]

[0108] In the formula, f3 is the regional ecological environment impact objective function; is the average concentration at the center point of the water quality control section during the study period; S is the distance coefficient representing the distance between the sewage outlet location and the center point of the water quality control section;

[0109] The expression of the average concentration at the center point of the water quality control section during the study period is as follows:

[0110]

[0111] The expression of the distance coefficient S representing the distance between the sewage outlet location and the center point is:

[0112]

[0113] In the formula, x p is the coordinate of the center point of the water quality control section; σ is the variance coefficient used to adjust the distribution of the distance coefficient in the entire water quality control section;

[0114] The model calculation unit uses the adjoint method to derive the precision-lossless replacement expression of the average concentration at the center point of the water quality control section in the regional water quality objective function and the regional ecological environment impact objective function, and performs the objective function calculation;

[0115] The model solution unit uses the multi-objective genetic algorithm NSGA-II to solve the multi-objective model and obtain all feasible solutions;

[0116] The trade-off analysis unit uses the trade-off rate method to screen the feasible solutions that meet the trade-off rate requirements, gives multiple sets of trade-off rates, and obtains the optimal solutions corresponding to each set of trade-off rates;

[0117] The optimal solution acquisition unit determines the risk values of the optimal solutions corresponding to each set of trade-off rates through risk analysis, and finally determines the best multi-objective optimization plan for the sewage outlet with the lowest risk value;

[0118] The control unit is communicatively connected to the model initial construction unit, the model calculation unit, the model solution unit, the trade-off analysis unit, and the optimal solution acquisition unit, and controls their operations.

[0119] Preferably, the optimal emergency dispatch flow calculation device for river water pollution accidents considering uncertainty provided by the present invention may further include: an input and display unit, communicatively connected to the control unit, for allowing a user to input operation instructions and performing corresponding displays.

[0120] Preferably, the optimal emergency dispatch flow calculation device for river water pollution accidents considering uncertainty provided by the present invention may further have the following characteristics: the input and display unit can display the multi-objective model constructed by the model initial construction unit and the model calculation unit, and can display all feasible solutions obtained by the model solution unit, display all groups of optimal solutions obtained by the trade-off analysis unit, and display the best multi-objective optimization solution of the sewage outfall determined by the optimal solution acquisition unit in the form of a data table or a graph.

[0121] Preferably, the optimal emergency dispatch flow calculation device for river water pollution accidents considering uncertainty provided by the present invention may further have the following characteristics: in the model initial construction unit, the regional economic objective function includes three parts: emission benefit, sewage outfall construction cost, and operation cost, which are specifically as follows:

[0122]

[0123] In the formula, f1 is the value of the economic objective function; T is the length of the research period; XY represents the economic benefit value related only to the emission intensity brought by the pollutant emission of the newly built sewage outfall per unit time; JS represents the construction cost of the sewage outfall, which is only related to the construction location of the newly built sewage outfall; YY represents the operation cost of the sewage outfall per unit time, which is related to both the construction location and the emission intensity of the newly built sewage outfall.

[0124] The sewage outfall construction cost function JS in the economic objective function is:

[0125] JS(x0) = JS max ×pd(x0)ptd(x0)td(x0) (1 - 7)

[0126] In the formula, JS max is the upper limit value of the construction cost; pd is the slope coefficient; ptd is the flatness coefficient; td is the land use type coefficient.

[0127] The operation cost function YY per unit time in the economic objective function is:

[0128] YY(m0(t), x0) = D(m0(t))l(x0) (1 - 8)

[0129] In the formula, D is a function representing the relationship between the operation cost per unit time and the emission intensity m0(t), which is determined by the actual problem; l is a function representing the relationship between the operation cost per unit time and the sewage outfall location x0.

[0130] Preferably, the optimal emergency scheduling flow calculation device for river water pollution accidents considering uncertainty provided by the present invention may further have the following characteristics: In the model calculation unit, the river water quality information of the water quality control section is adopted, and the regional water quality objective function is:

[0131]

[0132] The calculation method of the average concentration at the center point of the control section during the study period is:

[0133]

[0134] In the above calculation formulas of the regional water quality objective function and the average concentration, only the initial conditions and boundary conditions of the concentration C are used, and these are all known quantities. The only variable is the adjoint variable λ, and the adjoint variable λ is directly calculated by calculating the following adjoint equation:

[0135]

[0136] In the formula, A is the cross-sectional area of the river; Q is the flow rate; E is the longitudinal dispersion coefficient; K is the first-order decay coefficient of the pollutant; x is the coordinate along the river flow direction; t is the time; C(x) is the spatial distribution of the pollutant concentration at the initial moment; V is an undetermined function. If the regional water quality objective function to be calculated, that is, the spatio-temporal average concentration of the water quality control section, is required, the undetermined function V is given as:

[0137]

[0138] In the formula, I is the index function. When I is 1, when it is within the water quality control section, that is, when x ∈ L, the index function value is 1, otherwise it is 0; |L| is the length of the water quality control section;

[0139] If what needs to be calculated is the average concentration at the center point of the water quality control section in the regional ecological and social impact objective function, the undetermined function V is given as:

[0140]

[0141] In the formula, x p is the coordinate of the center point of the water quality control section, and δ(·) is the Dirac function.

[0142] Functions and effects of the invention

[0143] The multi-objective coupling optimization and decision-making method and device for the location and discharge intensity of newly built sewage outfalls provided by the present invention realize the coupling optimization of the location and discharge intensity of newly built sewage outfalls considering three objectives: regional economy, regional water quality, and regional ecological environment impact, and obtain the best solution for the coupling multi-objective optimization demonstration of the discharge location and discharge intensity of newly built sewage outfalls, solving the problems that previous methods or models cannot achieve coupling optimization, multi-objective optimization only optimizes without making decisions, and only considers the economic cost of sewage outfall construction; moreover, this model avoids the problem of needing to recalculate the numerical solution of the convection-diffusion equation every time the sewage outfall parameters are changed, improving the calculation efficiency of multi-objective optimization. It not only has high calculation efficiency but also has no loss of calculation accuracy; based on this, the present invention provides broad reference and guidance for the multi-objective optimization demonstration of newly built river sewage outfalls. The best multi-objective optimization solution of the sewage outfall with the lowest determined risk value is beneficial to improving the water quality and ecological environment of the river section and provides a scientific guarantee for the safe and reasonable regulation of domestic and agricultural water intake. BRIEF DESCRIPTION OF THE DRAWINGS

[0144] Figure 1 It is a flowchart of the multi-objective coupling optimization and decision-making method (model construction and solution process) for the location and discharge intensity of newly built sewage outfalls involved in the present invention;

[0145] Figure 2 It is a schematic diagram of the composition of the regional water quality objective function involved in the present invention;

[0146] Figure 3 It is a schematic diagram of the composition of the regional ecological environment impact objective function involved in the present invention;

[0147] Figure 4 It is a schematic diagram of the composition of the regional economic objective function involved in the present invention;

[0148] Figure 5 It is a longitudinal sectional view of the A1 river section involved in the embodiment of the present invention;

[0149] Figure 6 It is a typical cross-sectional view of the A1 river section involved in the embodiment of the present invention;

[0150] Figure 7 It is a distribution diagram of the distance coefficient of the ecological and social impact objective function along the river section of the Xinzhou section of the Jushui River involved in the embodiment of the present invention;

[0151] Figure 8 It is a relationship diagram between the regional economic objective function and the regional water quality objective function of the feasible solutions involved in the embodiment of the present invention;

[0152] Figure 9 It is a relationship diagram between the regional economic objective function and the regional ecological environment impact objective function of the feasible solutions involved in the embodiment of the present invention;

[0153] Figure 10 It is a relationship diagram between the regional water quality objective function and the regional ecological environment impact objective function of the feasible solution involved in the embodiment of the present invention;

[0154] Figure 11 It is a schematic diagram of the normalized regional economic objective function, the normalized regional water quality objective function, and the corresponding screened solutions and optimal solutions involved in the embodiment of the present invention;

[0155] Figure 12 It is a schematic diagram of the normalized regional economic objective function, the normalized regional ecological environment impact objective function, and the corresponding screened solutions and optimal solutions involved in the embodiment of the present invention;

[0156] Figure 13 It is a schematic diagram of the normalized regional water quality objective function, the normalized regional ecological environment impact objective function, and the corresponding screened solutions and optimal solutions involved in the embodiment of the present invention;

[0157] Figure 14 It is a cumulative distribution curve of water quality risk probability involved in the embodiment of the present invention;

[0158] Figure 15 It is a cumulative distribution curve of ecological environment risk probability involved in the embodiment of the present invention. Detailed implementation manners

[0159] The following will combine the accompanying drawings to detail the specific implementation schemes of the multi-objective coupling optimization and decision-making method and device for the location and discharge intensity of the newly built sewage outfall involved in the present invention.

[0160] <Embodiment>

[0161] A sewage outfall is to be built at the A1 river section in City A. Suppose there are two existing sewage outfalls (N1 = 2) at the A1 river section, with positions at 2 km (x1) and 4 km (x2) respectively. Only one type of pollutant, COD (N2 = 1), is considered. Both outfalls discharge at a constant rate, with discharge concentrations of 40 mg / L and 30 mg / L respectively, and the daily discharge amounts are both 43,200 m 3 (0.5 m 3 / s), that is, the discharge intensities are m1(t) = 20 g / s and m2(t) = 15 g / s respectively. There is a residential area (water quality control section 1) at 10 km (x p,1 ) from the starting section in the middle of the river; downstream from 25 km to 26 km (L = 1000 m, x p,2 = 25.5) from the starting section is the fish spawning ground (water quality control section 2). Taking the dry season of the A1 river section as the research period, with the typical flow rate Q = 20 m 3 / s is used as the river channel flow during the research, and the downstream water level is set to 8.185 m (calculated from the water level - discharge curve at the downstream boundary). The upstream inflow is assumed to be Class III water (COD = 20 mg / L), and the calculation duration is one month. In the numerical simulation of this example, the spatial step is 100 m, the length of the calculation domain is 27000 m (X = 27000 m), the time step is 1 hour, and the total calculation duration is 30 days (T = 30 days). The longitudinal profile of the selected research river reach is shown in Figure 5 , and the typical cross - section of Reach A1 is shown in Figure 6 . Assuming according to the water function zoning results and the water pollutant assimilation capacity accounting results of the Jushui River, the discharge intensity of this newly built outfall shall not exceed 17.28 tons per day (200 g / s). At the same time, the sewage discharge task of this sewage outfall needs to be greater than 345.6 kg / day (4 g / s), that is, m(t) ∈ m ad = [4, 200]. The location of this outfall is restricted within the range of 2 km to 25 km, that is, x0 ∈ x ad = [2000, 25000].

[0162] In the embodiment, the multi - objective coupling optimization and decision - making technology for the location and discharge intensity of a newly built sewage outfall that coordinates regional social and economic development and water ecological environment protection provided by the present invention includes the following steps:

[0163] Step 1, construct a coupling optimization multi - objective model for the location and discharge amount of the sewage outfall considering three objectives: regional economy, regional water quality, and regional ecological environment impact;

[0164] For this embodiment, in the regional economic objective function, the discharge benefit function is given as follows according to the situation of this example:

[0165] XY(m0(t)) = - 0.001[m(t)] 2 (1)

[0166] The upper limit of the construction cost JS in the regional economic objective function max is given as 100, then the construction cost can be written as:

[0167] JS(x0) = 100pd(x0)ptd(x0)td(x0) (2)

[0168] The operation cost function in the regional economic objective function is:

[0169]

[0170] Then, the expression of the regional economic objective function of the newly built sewage outfall in Reach A1 is as follows:

[0171]

[0172] Assume that for water quality control section 2 of reach A1, the weight coefficient d(x,t) is uniformly distributed in space and time, i.e., d(x,t) = 1. Then, the regional water quality objective function for the newly built sewage outfall in reach A1 is as follows:

[0173]

[0174] In the regional ecological environment impact objective function for the newly built sewage outfall in reach A1, water quality control section 1 is a single cross-section, and the average concentration during the study period of this cross-section is used. The center point is the point x where this cross-section is located. p,1 = 10; Water quality control section 2 is a reach, and the average concentration during the study period of the center point of this reach is used. The center point is x p,2 = 25.5. For the example calculation of the newly built sewage outfall in reach A1, the distance coefficient S representing the distance of the sewage outfall location from the center point in the two water quality control sections is given by the following formula, and the specific distribution is shown in Figure 7 :

[0175]

[0176] Then, the expression of the regional ecological environment impact objective function for the example calculation of the newly built sewage outfall in reach A1 is as follows:

[0177]

[0178] In summary, the multi-objective model for reach A1 is as follows:

[0179]

[0180] Step 2: Use the adjoint method to derive the precision-lossless replacement expressions for the average concentration during the study period of the center points of the water quality control sections in the regional water quality objective function and the regional ecological environment impact objective function, and perform the objective function calculation.

[0181] According to the derivation in Step 2, the regional water quality objective function for the example calculation of the newly built sewage outfall in reach A1 can be replaced with a precision-lossless expression using the adjoint method. It is necessary to first solve the adjoint equation:

[0182]

[0183] Discretize the above equation numerically and solve it once to obtain the adjoint operator λ1. Then, the precision-lossless replacement expression of the regional water quality objective function for the example calculation of the newly built sewage outfall in reach A1 is specifically as follows:

[0184]

[0185] The average concentration during the study period of the center point of the water quality control section in the regional ecological environment impact objective function for the example calculation of the newly built sewage outfall in reach A1 and Expression substitution without loss of precision can also be performed. It is necessary to first solve the following adjoint equations separately:

[0186]

[0187] Discretize the above formula numerically and solve it once respectively to obtain the adjoint operators λ2 and λ3. Then, for the average concentration at the center point of the water quality control section during the study period in the regional ecological environment impact objective function of the new pollution discharge calculation example in the A1 river section and The expression for substitution without loss of precision is as follows:

[0188]

[0189] Step 3: Use the multi-objective genetic algorithm NSGA-II to solve the multi-objective model and obtain all feasible solutions;

[0190] Using the multi-objective genetic algorithm NSGA-II to solve the multi-objective model of the new pollution discharge calculation example in the A1 river section, the relationship between the various objective functions corresponding to the obtained feasible solutions is shown in Figures 8 - 10 . It can be seen from the figure that there is a certain negative correlation between the regional economic objective and the regional water quality objective. When the value of the regional economic objective function increases (the economic benefit becomes worse), the value of the regional water quality objective function decreases (the water quality condition improves), and the value of the regional ecological environment impact objective function decreases (the degree of ecological environment impact decreases); however, when the regional economic objective function increases to be greater than 0, that is, when the economic benefit is poor to a certain extent, even if the economic benefit becomes worse again, it will basically not bring a significant improvement to the water quality condition, nor will it significantly reduce the degree of ecological environment impact.

[0191] Under the same computer configuration scenario, during the process of multi-objective optimization solution using the model constructed by the present invention, the target function calculation program was called a total of 476,049 times, taking 11.75 s; while running the MIKE11 water quality calculation program once takes 94 s, and running 476,049 times requires 518 days; therefore, compared with the traditional method, the calculation time of the model of the present invention in multi-objective optimization calculation can be ignored.

[0192] Step 4: Trade-off analysis, that is, use the trade-off rate method to screen the feasible solutions that meet the trade-off rate requirements, and given multiple sets of trade-off rates, obtain the optimal solutions corresponding to each set of trade-off rates;

[0193] Assume that the range of the trade-off rate preferred by the decision maker for the new pollution discharge in the A1 river section is [0.5, 1], that is and Discretize this range with a step size of 0.05 to obtain combinations of all possible trade-off rates, and substitute them into the trade-off rate method to screen out the optimal solutions corresponding to each set of trade-off rates. and are used as examples for demonstration, as shown specifically in Figures 11 - 13 .

[0194] Step 5, risk assessment, that is, determine the risk values of the optimal solutions corresponding to each set of trade-off rates through risk analysis, and finally determine the best multi-objective optimization plan for the sewage outfall with the lowest risk value.

[0195] Draw the cumulative distribution curve of water quality risk probability and the cumulative distribution curve of ecological environment risk probability for the example of the newly built sewage outfall in the A1 river section according to the specific operations in Step 5, as shown specifically in Figure 14 and 15 .

[0196] Interpolate the optimal solutions corresponding to each set of trade-off rates obtained in Step 4 on the cumulative distribution curve of water quality risk probability and the cumulative distribution curve of ecological environment risk probability according to the regional water quality objective function and the regional ecological objective function respectively, obtain the water quality risk and ecological environment risk corresponding to this optimal solution, and add the two to obtain the total risk of this optimal solution. Finally, arrange all the optimal solutions in ascending order of the overall risk value to obtain the plan with the smallest risk value. The best multi-objective coupling optimization plan for the example of the newly built sewage outfall in the A1 river section finally determined is Plan 1.

[0197] The data involved in the above calculation process of the embodiment are shown in Tables 1 and 2 below:

[0198] Table 1 Classification standards and coefficients of slope, flatness, and land use type

[0199]

[0200] Table 1 Optimal solutions corresponding to the given trade-off rates and risk assessment

[0201]

[0202]

[0203] After testing, the method of the present invention can not only coordinate the impacts of the newly built sewage outfall on regional economy, water quality, ecological environment, etc., realize the multi-objective coupling optimization and decision-making of the location and discharge intensity of the newly built sewage outfall, but also save a large amount of calculation time and improve the calculation efficiency compared with the traditional method, and the calculation accuracy is not damaged. Those skilled in the art can use this technology to demonstrate the impacts of the newly built sewage outfall on regional economy, water quality, ecological environment, etc., so as to obtain the best multi-objective coupling optimization plan for the location and discharge intensity of the newly built sewage outfall.

[0204] Furthermore, this embodiment also provides a device for calculating the optimal emergency dispatch flow of river water pollution accidents that can automatically implement the above method. The device includes a model initial construction unit, a model calculation unit, a model solution unit, a trade-off analysis unit, an optimal solution acquisition unit, an input display unit, and a control unit.

[0205] The model initial construction unit constructs a coupled optimization multi-objective model of the sewage outlet location and discharge volume considering three objectives of regional economy, regional water quality, and regional ecological environment impact according to the description of step 1 above.

[0206] The model calculation unit derives the precision lossless replacement expressions of the average concentration of the research period at the center point of the water quality control section in the regional water quality objective function and the regional ecological environment impact objective function using the adjoint method according to the description of step 2 above, and performs objective function calculation.

[0207] The model solution unit uses the multi-objective genetic algorithm NSGA-II to solve the multi-objective model according to the description of step 3 above, and obtains all feasible solutions.

[0208] The trade-off analysis unit screens the feasible solutions that meet the trade-off rate requirements using the trade-off rate method according to the description of step 4 above, gives multiple sets of trade-off rates, and obtains the optimal solutions corresponding to each set of trade-off rates.

[0209] The optimal solution acquisition unit determines the risk values of the optimal solutions corresponding to each set of trade-off rates through risk analysis according to the description of step 5 above, and finally determines the best multi-objective optimization plan for the sewage outlet with the lowest risk value.

[0210] The input display unit is used to allow the user to input operation instructions and perform corresponding displays. For example, the input display unit can display the multi-objective model constructed by the model initial construction unit and the model calculation unit, can display all the feasible solutions obtained by the model solution unit, display all the sets of optimal solutions obtained by the trade-off analysis unit, and display the best multi-objective optimization plan for the sewage outlet determined by the optimal solution acquisition unit in the form of a data table or a graph.

[0211] The control unit is communicatively connected to the model initial construction unit, the model calculation unit, the model solution unit, the trade-off analysis unit, the optimal solution acquisition unit, and the input display unit, and controls their operations.

[0212] The above embodiments are only illustrative examples of the technical solutions of the present invention. The multi-objective coupling optimization and decision-making method and device for the location and discharge intensity of newly built sewage outlets involved in the present invention are not limited to the content described in the above embodiments, but are subject to the scope defined by the claims. Any modification, supplement, or equivalent replacement made by those skilled in the art in the field of the present invention based on this embodiment is within the scope protected by the claims of the present invention.

Claims

1. A multi-objective coupling optimization and decision-making method for the location and discharge intensity of a newly built sewage outlet, characterized in that, It includes the following steps: Step 1, construct a multi-objective model for coupling optimization of the discharge outlet location and discharge volume considering three objectives of regional economy, regional water quality, and regional ecological environment impact; the multi-objective model includes three objective functions of regional economy, regional water quality, and regional ecological environment impact, as well as two independent variables of the discharge location and discharge intensity of the discharge outlet; Let the spatial region of the study reach be Ω. Suppose there are several sewage outfalls or pollution sources existing in the study area, and they are located at points x i ∈Ω (i = 1, 2,..., N1) respectively, with discharge intensities of m i (t) (i = 1, 2,..., N1). Use the symbol \(x_0\) to represent the discharge location of the newly built sewage outfall to be optimized, and its value range is determined according to the results of the water function zoning, set as \(x_0\in X\). ad There are \(N_2\) types of pollutant indicators for the discharge of the newly built sewage outfall to be optimized, and the discharge intensity is represented by the symbol \(m_0(t)\), then there is: In the formula, represents the emission intensity function of the j-th pollutant from the newly built sewage outlet, and it is assumed that the value range is m0(t) ∈ m ad ; The regional water quality objective function is the average value of the temporal and spatial concentrations of pollutants in the water quality control section, which is subject to the discharge intensity and discharge location of the newly built discharge outlet. For N3 water quality control sections, the water quality objective function of the jth pollutant on the kth water quality control section is as follows: In the formula, f2 is the regional water quality objective function; |L k | represents the lengths of k water quality control river reaches; d is the weight coefficient of the water quality control river reach, reflecting the spatio-temporal emphasis difference; C j is the water quality concentration of the jth pollutant; The regional ecological environment impact objective function is the average concentration at the center point of the water quality control section during the study period and the distance coefficient S representing the distance between the sewage outlet location and the center point k The sum of the products, and it satisfies that when the sewage outlet location is farther away from the center point, the ecological environment impact is smaller, and when the center point concentration is smaller, the ecological environment impact is smaller; the regional ecological environment impact objective function of the jth pollutant in the kth water quality control section is as follows: In the formula, f3 is the objective function of the regional ecological environment impact; is the average concentration at the center point of the water quality control section during the study period; S is the distance coefficient representing the distance from the sewage outlet to the center point of the water quality control section; The expression of the average concentration at the center point of the water quality control section during the research period is as follows: The expression of the distance coefficient S representing the distance from the discharge outlet location to the center point is: where x p is the coordinate of the center point of the water quality control section; σ is the variance coefficient used to adjust the distribution of the distance coefficient in the entire water quality control section; Step 2, use the adjoint method to derive the accuracy lossless replacement expressions of the average concentration at the center point of the water quality control section in the regional water quality objective function and the regional ecological environment impact objective function, and perform objective function calculations; Step 3, use the multi-objective genetic algorithm NSGA-II to solve the multi-objective model to obtain all feasible solutions; Step 4, use the trade-off rate method to screen the feasible solutions that meet the trade-off rate requirements, and given multiple groups of trade-off rates, obtain the optimal solutions corresponding to each group of trade-off rates; Step 5, determine the risk values of the optimal solutions corresponding to each group of trade-off rates through risk analysis, and finally determine the best multi-objective optimization plan for the discharge outlet with the lowest risk value.

2. The multi-objective coupling optimization and decision-making method for the location and discharge intensity of the newly built discharge outlet according to claim 1, wherein: Among them, In step 1, the regional economic objective function includes three parts: discharge benefit, discharge outlet construction cost, and operation cost, specifically as follows: In the formula, f1 is the value of the economic objective function; T is the length of the research period; XY represents the economic benefit value related only to the discharge intensity brought by the pollutant discharge of the newly built discharge outlet per unit time; JS represents the construction cost of the discharge outlet, which is only related to the construction location of the newly built discharge outlet; YY represents the operation cost per unit time of the discharge outlet, which is related to both the construction location and discharge intensity of the newly built discharge outlet; The discharge outlet construction cost function JS in the economic objective function is: JS(x0) = JS max ×pd(x0)ptd(x0)td(x0) (1 - 7) In the formula, JS max is the upper limit value of construction cost; pd is the slope coefficient; ptd is the flatness coefficient; td is the land use type coefficient; The operation cost function YY per unit time in the economic objective function is: YY(m0(t),x0)=D(m0(t))l(x0) (1-8) In the formula, D is a function representing the relationship between the operation cost per unit time and the discharge intensity m0(t), which is determined by the actual problem; l is a function representing the relationship between the operation cost per unit time and the discharge outlet location x0.

3. The multi-objective coupling optimization and decision-making method for the location and discharge intensity of the newly built discharge outlet according to claim 1, wherein: Among them, In step 2, the river water quality information of the water quality control section is adopted: The regional water quality objective function is: The calculation method of the average concentration at the center point of the control section during the research period is: In the above calculation formulas of the regional water quality objective function and the average concentration, only the initial conditions and boundary conditions of the concentration C are used, and these are all known quantities. The only variable is the adjoint variable λ, and the adjoint variable λ is directly calculated by calculating the following adjoint equation: Wherein, A is the cross-sectional area of the river; Q is the flow rate; E is the longitudinal dispersion coefficient; K is the first-order decay coefficient of the pollutant; x is the coordinate along the river flow direction; t is the time; C(x) is the spatial distribution of the pollutant concentration at the initial moment; V is an undetermined function. If the water quality objective function of the area to be calculated, i.e., the spatio-temporal average concentration of the water quality control section, is required, the undetermined function V is given as: Wherein, I is the index function. When I is 1, when it is within the water quality control section, i.e., when x ∈ L, the value of the index function is 1, otherwise it is 0; |L| is the length of the water quality control section; If what needs to be calculated is the average concentration of the research period at the center point of the water quality control section in the regional ecological and social impact objective function, the undetermined function V is given as: where x p is the coordinate of the center point of the water quality control section, and δ(·) is the Dirac function.

4. The multi-objective coupling optimization and decision-making method for the location and discharge intensity of a new sewage outlet according to claim 1, characterized in that: Among them, The trade-off rate ν in step 4 ij refers to the degree to which, while keeping other objective functions from decreasing, reducing the unit benefit of objective j increases the benefit of objective i. The specific operation of the trade-off analysis is as follows: Step 4-1, perform normalization processing on the objective function values corresponding to the feasible solutions obtained in step 3. The normalization formula is as follows: In the formula, f represents the objective function; represents the objective function value after normalization of the r-th objective function of the s-th feasible solution; Step 4-2: Select the optimal solution of the regional economic objective as the initial solution X 0 , and denote the corresponding normalized objective function as g 0 . Given the trade-off rates and of the regional water quality objective and the regional ecological environment impact objective with respect to the economic objective and satisfy the following conditions: Step 4-3, using the given trade-off ratio and screen the feasible solutions that meet the conditions, and the specific conditions are as follows: Step 4-4, from the trade-off ratios and among the feasible solutions selected, find the optimal solution corresponding to this set of trade-off ratios that satisfies the following conditions: Step 4-5, given the range of each trade-off rate, select a number from each range to form multiple groups of trade-off rates, and obtain the optimal solution corresponding to each group of trade-off rates according to the previous operation method.

5. The multi-objective coupling optimization and decision-making method for the location and discharge intensity of a new sewage outlet according to claim 1, characterized in that: Among them, The specific operation of the risk assessment in step 5 is as follows: Step 5-1, define the water quality risk and obtain the cumulative distribution curve of the water quality risk probability; when the water quality benchmark concentration of the water quality control section reaches the predetermined standard, calculate the regional water quality objective function at this time. For all the feasible solutions in step 3, when the corresponding regional water quality objective function is less than or equal to this value, the water quality risk is 0; count the number of feasible solutions with the regional water quality objective function greater than this value, denoted as N4, and arrange these feasible solutions in ascending order according to the value of the water quality objective function. The water quality risk probability corresponding to the s-th feasible solution is: Step 5-2, define the ecological risk and obtain the cumulative distribution curve of the ecological environment risk probability; when the average concentration of the research period at the center point of the water quality control section is the predetermined standard and the distance between the location of the new sewage outlet and the center point of the water quality control section is 2 - 5 km, calculate the value of the regional ecological environment impact objective function at this time, and set the ecological environment risk corresponding to when the regional ecological environment impact objective function of all the feasible solutions in step 3 is less than this value to be 0; count the number of feasible solutions with the regional ecological environment impact objective function greater than this value, denoted as N5, and arrange these feasible solutions in ascending order according to the value of the regional ecological environment impact objective function. Then the ecological environment risk probability corresponding to the s-th feasible solution is: Step 5-3, interpolate the water quality risk probability and the ecological environment risk probability of the optimal solution corresponding to each group of trade-off rates obtained in step 4 on the risk probability cumulative distribution curve according to the size of the objective function to obtain the corresponding risk probability, and add them to get the total risk; arrange the optimal solutions corresponding to each group of trade-off rates in ascending order according to the total risk, and take the solution with the minimum total risk as the best multi-objective optimization plan for the sewage outlet.

6. A multi-objective coupling optimization and decision-making device for the location and emission intensity of a newly built sewage outlet, characterized in that, Including: The initial model construction department constructs a multi-objective model for coupling optimization of the discharge port location and discharge volume considering three objectives: regional economy, regional water quality, and regional ecological environment impact. The multi-objective model includes three objective functions: regional economy, regional water quality, and regional ecological environment impact, as well as two independent variables: the discharge location and discharge intensity of the discharge port. Let the spatial region of the research river section be Ω, and assume that there are several existing discharge ports or pollution sources in the research area, which are located at points x i ∈θ (i = 1, 2,..., N1), respectively having m i (t) (i = 1, 2,..., N1) of discharge intensity; the discharge location of the newly built discharge port to be optimized is represented by the symbol x0, and its value range is determined according to the results of the water function zoning. Assume the value range is x0 ∈ x ad ; there are N2 types of pollutant indicators for the discharge of the newly built discharge port to be optimized, and the discharge intensity is represented by the symbol m0(t). Then there is: In the formula, represents the emission intensity function of the jth pollutant from the newly built sewage outlet, and it is assumed that the value range is m0(t) ∈ m ad ; The regional water quality objective function is the spatio-temporal concentration average of pollutants in the water quality control section, which is subject to the emission intensity and emission location of the newly built sewage outfall. For N3 water quality control sections, the water quality objective function of the jth pollutant in the kth water quality control section is as follows: In the formula, f2 is the regional water quality objective function; |L k | represents the lengths of k water quality control river reaches; d is the weight coefficient of the water quality control river reach, reflecting the spatio-temporal emphasis difference; C j is the water quality concentration of the jth pollutant; The regional ecological environment impact objective function is the average concentration of the center point of the water quality control section during the research period and the distance coefficient S representing the distance between the pollutant discharge outlet location and the center point k The sum of the products, and it satisfies that when the pollutant discharge outlet location is farther away from the center point, the ecological environment impact is smaller, and when the center point concentration is smaller, the ecological environment impact is smaller; the regional ecological environment impact objective function of the jth pollutant in the kth water quality control section is as follows: where f3 is the objective function of the regional ecological environment impact; is the average concentration at the center point of the water quality control section during the study period; S is the distance coefficient representing the distance from the sewage outlet to the center point of the water quality control section; The expression of the average concentration at the center point of the water quality control section during the research period is as follows: The expression of the distance coefficient S representing the distance between the sewage outfall location and the center point is: where x p is the coordinate of the center point of the water quality control section; σ is the variance coefficient used to adjust the distribution of the distance coefficient in the entire water quality control section; The model calculation unit uses the adjoint method to derive the precision-lossless replacement expressions of the average concentration at the center point of the water quality control section in the regional water quality objective function and the regional ecological environment impact objective function, and performs the objective function calculation; The model solution unit uses the multi-objective genetic algorithm NSGA-II to solve the multi-objective model and obtain all feasible solutions; The trade-off analysis unit uses the trade-off rate method to screen the feasible solutions that meet the trade-off rate requirements, gives multiple sets of trade-off rates, and obtains the optimal solutions corresponding to each set of trade-off rates; The optimal solution acquisition unit determines the risk values of the optimal solutions corresponding to each set of trade-off rates through risk analysis, and finally determines the best multi-objective optimization solution of the sewage outfall with the lowest risk value; The control unit is communicatively connected to the model initial construction unit, the model calculation unit, the model solution unit, the trade-off analysis unit, and the optimal solution acquisition unit, and controls their operations.

7. The multi-objective coupling optimization and decision-making device for the location and discharge intensity of a newly built sewage outlet according to claim 6, characterized in that It further includes: The input display unit is communicatively connected to the control unit, and is used for the user to input operation instructions and perform corresponding displays.

8. The multi-objective coupling optimization and decision-making device for the location and emission intensity of the newly built sewage outfall according to claim 7, wherein: Among them, The input display unit can display the multi-objective model of the model initial construction unit and the model calculation unit components, can display all feasible solutions obtained by the model solution unit, display all groups of optimal solutions obtained by the trade-off analysis unit, and display the best multi-objective optimization solution of the sewage outfall determined by the optimal solution acquisition unit in the form of a data table or a graph.

9. The multi-objective coupling optimization and decision-making device for the location and emission intensity of the newly built sewage outfall according to claim 6, wherein: Among them, In the model initial construction unit, the regional economic objective function includes three parts: emission benefit, sewage outfall construction cost, and operation cost, specifically as follows: In the formula, f1 is the economic objective function value; T is the length of the research period; XY represents the economic benefit value related only to the emission intensity brought by the pollutant emission of the newly built sewage outfall per unit time; JS represents the construction cost of the sewage outfall, which is only related to the construction location of the newly built sewage outfall; YY represents the operation cost per unit time of the sewage outfall, which is related to both the construction location and the emission intensity of the newly built sewage outfall; The sewage outfall construction cost function JS in the economic objective function is: JS(x0) = JS max ×pd(x0)ptd(x0)td(x0) (1-7) In the formula, JS max is the upper limit value of construction cost; pd is the slope coefficient; ptd is the flatness coefficient; td is the land use type coefficient; The operation cost function YY per unit time in the economic objective function is: YY(m0(t),x0)=D(m0(t))l(x0) (1-8) In the formula, D is a function representing the relationship between the operation cost per unit time and the emission intensity m0(t), which is determined by the actual problem; l is a function representing the relationship between the operation cost per unit time and the sewage outfall location x0.

10. The multi-objective coupling optimization and decision-making device for the location and discharge intensity of a new sewage outlet according to claim 6, characterized in that: Among them, In the model calculation part, the river water quality information of the water quality control section is used, and the regional water quality objective function is: The calculation method of the average concentration at the center point of the control section during the study period is: In the above calculation formulas of the regional water quality objective function and the average concentration, only the initial conditions and boundary conditions of the concentration C are used, and these are all known quantities. The only variable is the adjoint variable λ, and the adjoint variable λ is directly calculated by calculating the following adjoint equation: In the formula, A is the cross-sectional area of the river; Q is the flow rate; E is the longitudinal dispersion coefficient; K is the first-order decay coefficient of the pollutant; x is the coordinate along the river flow direction; t is the time; C(x) is the spatial distribution of the pollutant concentration at the initial moment; V is an undetermined function. If the regional water quality objective function to be calculated, that is, the spatio-temporal average concentration of the water quality control section, then the undetermined function V is given as: In the formula, I is the index function. When I is 1, when it is within the water quality control section, that is, when x ∈ L, the index function value is 1, otherwise it is 0; |L| is the length of the water quality control section; If what needs to be calculated is the average concentration at the center point of the water quality control section in the regional ecological and social impact objective function during the study period, then the undetermined function V is given as: where x p is the coordinate of the center point of the water quality control section, and δ(·) is the Dirac function.

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