A method for evaluating watershed pollution reduction and carbon reduction coupling synergy and watershed attraction

Abstract

The present application relates to the technical field of river basin pollution reduction and carbon reduction, and particularly relates to a method for evaluating the coupling synergy relationship and the attraction between river basins for pollution reduction and carbon reduction, which specifically comprises the following steps: collecting the pollution data and carbon emission data of a river basin at a grid scale, collecting the "nature-economy-society" factor data of the river basin, and calculating the annual reduction / increase of the pollution and carbon; calculating the coupling degree and the synergy degree of the pollution reduction and carbon reduction of the river basin according to the reduction / increase of the pollution and carbon, and obtaining the coupling synergy relationship of the pollution reduction and carbon reduction of the river basin; analyzing the "nature-economy-society" factor data of the river basin, and obtaining the comprehensive influence index of the "nature-economy-society"; obtaining the gravity center coordinates of the pollution reduction and carbon reduction of the river basin and the distance between the river basins according to the gravity center method, and combining the coupling degree and the comprehensive influence index of the "nature-economy-society" to obtain the attraction strength between the river basins for pollution reduction and carbon reduction. The present application fully considers the influence of the nature, economy and society factors, can accurately determine the coupling synergy relationship of the pollution reduction and carbon reduction of the river basins and the attraction strength between the river basins, and provides a scientific basis for promoting the synergy cooperation between the river basins and establishing the cross-river basin cooperation mechanism for pollution reduction and carbon reduction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of watershed pollution reduction and carbon reduction, and particularly relates to a method for evaluating the coupling synergy of watershed pollution reduction and carbon reduction and the watershed attraction. BACKGROUND

[0002] With the intensification of global climate change and ecological environmental pressure, watershed pollution reduction and carbon reduction have become the focus of attention of countries around the world. Because pollutants and greenhouse gases often come from similar industrial activities or economic behaviors, they show a synergistic effect in some cases. However, in other situations, pollution reduction and carbon reduction may conflict. For example, some pollution control technologies may increase carbon emissions. Therefore, the quantitative study of the coupling synergy of watershed pollution reduction and carbon reduction has become a key to ecological environmental governance. Most of the current methods for evaluating the coupling synergy of watershed pollution reduction and carbon reduction focus on the overall state evaluation, and the dominant situation of pollution reduction or carbon reduction is not clear, which makes it difficult to accurately develop effective measures to achieve the dual goals of pollution reduction and carbon reduction in the actual watershed governance process.

[0003] Secondly, the watershed is an important unit of water resources and ecological system, and different watersheds mostly contain multiple cities and the connection between nature, economy and society is more complex, resulting in complex interaction between watersheds. Studying the attraction of pollution reduction and carbon reduction between watersheds can help scientists and decision-makers better understand the collaborative governance mechanism between watersheds and promote cross-regional environmental cooperation. However, the gravity strength algorithm is currently only used for the analysis of carbon emission relationships between cities, and its application at the watershed level is still in the initial exploration stage, and the influence of natural, economic and social factors on the system is not considered. This limitation makes it impossible to comprehensively and accurately describe and calculate the attraction of pollution reduction and carbon reduction between watersheds through quantitative methods. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a method for evaluating the coupling synergy of watershed pollution reduction and carbon reduction and the watershed attraction.

[0005] The technical solution of the present application to solve the above technical problems is:

[0006] A method for evaluating the coupling synergy of watershed pollution reduction and carbon reduction and the watershed attraction, comprising the following steps:

[0007] Step S1: Obtain multi-year time series data of watershed pollutant and carbon emission at the grid scale; obtain time series data of "nature-economy-society" factors of the watershed; accumulate the pollutant and carbon emission data in each grid of each watershed per year, respectively, to obtain the total amount of pollutants and carbon emissions in each watershed; calculate the reduction / increase of pollutants and carbon emissions per year according to the multi-year time series data of pollutants and carbon emissions;

[0008] Step S2: standardize the pollutant and carbon emission / reduction data of each year; according to the standardized data set, the coupling degree model is used to calculate the coupling degree between pollution reduction and carbon reduction in each basin, and then the coupling degree of pollution reduction and carbon reduction in each basin is obtained;

[0009] Step S3: according to the pollutant data and carbon emission / reduction data of each year, the pollution reduction and carbon reduction synergy efficiency coefficient is used to calculate the synergy degree between pollution reduction and carbon reduction in each basin; then, the coupling degree between pollution reduction and carbon reduction in each basin obtained in step S2 is combined to quantitatively evaluate the coupling and synergy state of pollution reduction and carbon reduction in each basin;

[0010] Step S4: according to the center coordinates of each grid and the pollutant and carbon emission data in each grid, the center coordinates of the pollutant and carbon emission of each basin are determined; the center coordinates of the two basins are connected to obtain the straight line distance between the center coordinates of the two basins and standardize the straight line distance data;

[0011] Step S5: according to the time series data of the "nature-economy-society" factor of the basin, the "nature-economy-society" comprehensive influence index of each basin is constructed;

[0012] Step S6: based on the coupling degree, the "nature-economy-society" comprehensive influence index and the straight line distance between the centers of the basins, the attraction strength of pollution reduction and carbon reduction between the basins is calculated.

[0013] As a preferred scheme of the present application: in step S1, the time series data of the "nature-economy-society" factor of the basin includes: nature: flow of basin trunk stream, annual average precipitation, vegetation coverage, number of species in basin; economy: basin GDP, average utilization rate of basin resources, export trade volume of basin, ecological compensation fund flow; society: population flow, basin material flow, road mileage of basin, urbanization rate. For the natural factor, the flow of basin trunk stream and the annual average precipitation reflect the flow-through strength of pollutants and carbon between basins as water medium, the vegetation coverage reflects the carbon storage capacity between basins, and the number of species in the basin reflects the negative impact of pollutants and carbon on the basin; for the economic factor, the basin GDP and the average utilization rate of basin resources reflect the emission intensity of pollutants and carbon in the basin, the export trade volume of the basin reflects the flow-through strength of pollutants and carbon between basins as economic exchange medium, and the ecological compensation fund flow reflects the ecological management strength of the basin; for the social factor, the population flow, the basin material flow and the road mileage of the basin reflect the flow-through strength of pollutants and carbon between basins as medium of people and materials, and the urbanization rate reflects the emission intensity of pollutants and carbon in the basin.

[0014] As a preferred scheme of the present application: in step S1, the total amount of pollutants and the total amount of carbon emission are calculated as follows:

[0015]

[0016]

[0017] Among them, POL i is the total amount of pollutant emissions in year i; POL ij is the emission of pollutants in the jth grid in the i-th year; CAR i is the total carbon emissions in year i; CAR ij is the carbon emission in the jth grid in year i; n is the total number of grids in each basin.

[0018] As a preferred solution of the present invention: in step S1, the annual reduction / increase in pollutant and carbon emissions is calculated, and the specific calculation formula is:

[0019] ΔPOL i =POL i-1 -POL i ;

[0020] ΔCAR i =CAR i-1 -CAR i ;

[0021] Where ΔPOL i is the difference in pollutant emissions between year i and year (i-1), where ΔPOL i >0 means pollutant emission reduction, ΔPOL i <0 means pollutant emissions increase; POL i-1 is the total amount of pollutant emissions in year (i-1); POL i is the total amount of pollutant emissions in year i; ΔCAR i is the difference in carbon emissions between year i and year (i-1), where ΔCAR i >0 means carbon emission reduction, ΔCAR i <0 means carbon emission increase; CAR i-1 is the total carbon emissions in year (i-1), CAR i is the total carbon emissions in year i.

[0022] As a preferred solution of the present invention: in step S2, the specific formula for normalizing the pollutant and carbon emission reduction / increase data is as follows:

[0023]

[0024]

[0025] Among them, U is the normalized reduction / increase of pollutant emissions, ΔPOL iB is the normalized carbon emission reduction / increase, and ΔCAR is the normalized carbon emission reduction / increase. i B is the normalized carbon emission reduction / increase, and ΔCAR is the normalized carbon emission reduction / increase.

[0026] As a preferred scheme of the present application: in step S2, the coupling degree model is:

[0027]

[0028] wherein, C i is the coupling degree of pollution reduction and carbon reduction in the i-th year, and the value range is [0, 1]; C i The closer to 1, the higher the coupling degree; U i is the normalized pollution emission difference in the i-th year; B i is the normalized carbon emission difference in the i-th year.

[0029] As a preferred scheme of the present application: in step S3, the synergistic degree between pollution reduction and carbon reduction in each watershed is calculated by using the pollution reduction and carbon reduction synergistic efficiency coefficient, and the specific formula is as follows:

[0030]

[0031] wherein, S i is the synergistic degree of pollution reduction and carbon reduction in the i-th year; ΔPOL i is the pollution emission difference of the i-th year relative to the (i-1)-th year; POL i is the total pollution emission in the i-th year; ΔCAR i is the carbon emission difference of the i-th year relative to the (i-1)-th year; CAR i is the total carbon emission in the i-th year.

[0032] S i The value range of S i is (-∞, +∞), when S i < 0, it indicates that the pollution reduction and carbon reduction are not synergistic; when 0 ≤ S i ≤ 1.2, it indicates that the pollution reduction and carbon reduction are driven by both; when S i > 1.2, it indicates that the pollution reduction is dominant.

[0033] As a preferred scheme of the present application: in step S4, the gravity center method is used to determine the gravity center of pollution and carbon emission in each watershed, and the specific formula is as follows:

[0034]

[0035]

[0036] Among them, X i , Y i are the horizontal and vertical coordinates of the center of gravity of pollutant and carbon emissions in the basin in year i, respectively; j ,y j is the horizontal and vertical coordinates of the jth grid cell; POL ij is the emission of pollutants in the jth grid in the i-th year; CAR ij is the carbon emission in the jth grid in year i; n is the total number of grids in each basin.

[0037] As a preferred solution of the present invention: in step S5, an improved CRITIC method is used to calculate the "nature-economy-society" comprehensive impact index. The improved CRITIC method can fully consider the variability and conflict between the 12 "nature-economy-society" factors selected in step S1, making the weighting of each factor more scientific, and then calculating the "nature-economy-society" comprehensive impact index. The specific steps are:

[0038] Step S501: Construct an initial factor matrix:

[0039]

[0040] Step S502: Standardize the “nature-economy-society” factor data to obtain a standardized matrix:

[0041]

[0042] Among them, for a certain basin, a ij , a′ ij are the jth “natural-economic-social” factor in the i-th year before and after standardization, respectively;

[0043] Step S503: Calculate the variability of each factor based on the standardized "natural-economic-social" factors. Variability refers to the volatility of the same factor over time. The larger the value, the greater the volatility of the factor over time, and therefore the greater the weight assigned. The specific formula is as follows:

[0044]

[0045] Among them, E j is the variation index of the jth “nature-economy-society” factor; a′ ij is the jth “natural-economic-social” factor in the i-th year after standardization; is the average value of the jth factor; m is the number of factors;

[0046] Step S504: the correlation between each "nature-economy-society" factor is calculated by using Pearson correlation coefficient method, and the conflict of each factor is calculated, the conflict between each factor refers to the correlation degree between different factors, the greater the conflict between two factors, the weaker the correlation between the two factors, the more different points of the reflected information, so the greater the weight allocated, the specific formula is as follows:

[0047]

[0048] Wherein, R j is the conflict index of the jth "nature-economy-society" factor; |r qj | is the absolute value of the Pearson correlation coefficient between the qth factor and the jth factor; m is the number of factors;

[0049] Step S505: the weight of each factor is calculated according to the variation index and conflict index of each "nature-economy-society" factor, and the specific formula is as follows:

[0050]

[0051] Wherein, W j is the weight of the jth "nature-economy-society" factor; E j is the variation index of the jth "nature-economy-society" factor; R j is the conflict index of the jth "nature-economy-society" factor; m is the number of factors;

[0052] Step S506: the "nature-economy-society" comprehensive influence index is calculated according to the weight of each "nature-economy-society" factor, and the specific formula is as follows:

[0053]

[0054] Wherein, V z is the "nature-economy-society" comprehensive influence index of the zth basin; W j is the weight of the jth "nature-economy-society" factor; a′ ij is the standardized jth "nature-economy-society" factor in the ith year; m is the number of factors.

[0055] As a preferred scheme of the application: in step S6, the calculation formula of the attractive strength is:

[0056]

[0057]

[0058] Wherein, G ijis the gravity strength of the basin i to the basin j, the larger the value is, the stronger the mutual relationship, the influence degree and the coupling effect between the basins and the pollution reduction and carbon reduction are;C ij is the gravity coefficient of the basin i to the basin j;C i , C j respectively, the coupling degree of the basin i, the basin j;V i , V j is the "nature-economy-society" comprehensive influence index of the basin i and the basin j;D ij is the straight line distance of the basin gravity center.

[0059] Compared with the prior art, the present application has the following beneficial effects:

[0060] 1. The method for evaluating the coupling and synergy relationship of basin pollution reduction and carbon reduction and the basin gravity of the present application can clearly evaluate the coupling relationship of pollution reduction and carbon reduction between basins and accurately judge the synergy dominant relationship by collecting and analyzing the basin pollutant and carbon emission data, using the coupling degree model and the synergy efficiency coefficient to calculate the coupling degree and synergy degree of the basin pollution reduction and carbon reduction.

[0061] 2. The method for evaluating the coupling and synergy relationship of basin pollution reduction and carbon reduction and the basin gravity of the present application uses the coupling degree of pollution reduction and carbon reduction, fully considers the influence of nature, economy and society, analyzes and calculates the gravity strength of pollution reduction and carbon reduction between basins, can help to understand the gravity radiation relationship of pollution reduction and carbon reduction between basins, is beneficial to timely adjust the pollution reduction and carbon reduction policy according to the gravity relationship, promotes the synergy and cooperation between basins, establishes the cross-basin pollution reduction and carbon reduction cooperation mechanism, improves the overall effect of pollution reduction and carbon reduction, and provides a more scientific decision basis for sustainable development and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 is the flowchart of the method for evaluating the coupling and synergy relationship of basin pollution reduction and carbon reduction and the basin gravity of the present application.

[0063] Figure 2 is the schematic diagram of the grid coordinate position in the basin 1 and the basin 2.

[0064] Figure 3 is the pollutant discharge and carbon discharge parameter table of each grid in the basin 1 and the basin 2 from 2019 to 2023.

[0065] Figure 4 is the "nature-economy-society" factor time series data table of each grid in the basin 1 and the basin 2 from 2019 to 2023.

[0066] Figure 5 is the gravity center and straight line distance connection schematic diagram in the basin 1 and the basin 2.

[0067] Figure 6The variation index calculation results of each "nature-economy-society" factor of the basin.

[0068] Figure 7 The Pearson correlation coefficient calculation results between each "nature-economy-society" factor of the basin.

[0069] Figure 8 The conflict index calculation results of each "nature-economy-society" factor of the basin.

[0070] Figure 9 The weight calculation results of each "nature-economy-society" factor of the basin.

[0071] Figure 10 The comprehensive influence index calculation results of each "nature-economy-society" factor of the basin. DETAILED DESCRIPTION

[0072] The present application will be further described in conjunction with the embodiments and the accompanying drawings, but the implementation of the present application is not limited thereto.

[0073] Please refer to Figure 1 The method for evaluating the coupling synergy of pollution reduction and carbon reduction of a basin and the basin attraction according to the present application comprises the following steps:

[0074] Step S1: Obtain the multi-year time series data of pollutant and carbon emission of the basin at the grid scale; obtain the time series data of "nature-economy-society" factors of the basin; accumulate the pollutant and carbon emission data in each grid of each basin every year respectively to obtain the total amount of pollutant and carbon emission of each basin in the year; calculate the pollutant and carbon emission reduction (increase) amount every year according to the multi-year time series data of pollutant and carbon emission.

[0075] In the present embodiment, the time series data of "nature-economy-society" factors of the basin includes: nature: flow of the main stream of the basin, average annual precipitation, vegetation coverage, number of species in the basin; economy: GDP of the basin, average utilization rate of resources in the basin, export trade volume of the basin, ecological compensation fund flow; society: population flow, material flow in the basin, road mileage in the basin, urbanization rate. For the nature factors, the flow of the main stream of the basin and the average annual precipitation reflect the flow-through strength of pollutants and carbon between basins with water as the medium, the vegetation coverage reflects the carbon storage capacity between basins, and the number of species in the basin reflects the negative impact of pollutants and carbon on the basin; for the economic factors, the GDP of the basin and the average utilization rate of resources in the basin reflect the emission intensity of pollutants and carbon in the basin, the export trade volume of the basin reflects the flow-through strength of pollutants and carbon between basins with economic exchange as the medium, and the ecological compensation fund flow reflects the ecological management strength of the basin; for the social factors, the population flow, the material flow in the basin, and the road mileage in the basin reflect the flow-through strength of pollutants and carbon between basins with people and materials as the medium, and the urbanization rate reflects the emission intensity of pollutants and carbon in the basin.

[0076] The accumulation method of pollutants and total carbon emissions uses the following specific formulas respectively:

[0077]

[0078]

[0079] Wherein, POL i is the total pollutant emissions in the i year; POL ij is the pollutant emissions in the jth grid in the i year; CAR i is the total carbon emissions in the i year; CAR ij is the carbon emissions in the jth grid in the i year; and n is the total number of grids in each watershed.

[0080] The specific formulas used to calculate the annual pollutant and carbon emission reduction (increase) are as follows:

[0081] ΔPOL i = POL i-1 - POL i ;

[0082] ΔCAR i = CAR i-1 - CAR i ;

[0083] Wherein, ΔPOL i is the pollutant emission difference between the i year and the (i-1) year; ΔPOL i > 0 is pollutant emission reduction, ΔPOL i < 0 is pollutant emission increase; POL i-1 is the total pollutant emissions in the (i-1) year; POL i is the total pollutant emissions in the i year; ΔCAR i is the carbon emission difference between the i year and the (i-1) year, ΔCAR i > 0 is carbon emission reduction, ΔCAR i < 0 is carbon emission increase; CAR i-1 is the total carbon emissions in the (i-1) year; CAR i is the total carbon emissions in the i year.

[0084] Suppose that watershed 1 and watershed 2 both contain 6 grids (grid distribution and each grid coordinate point position are as shown in Figure 2 ), the parameter (unit, t) composition and “nature-economy-society” factor parameters of each grid in 2019-2023 are as shown in Figure 3 and Figure 4 , the accumulation method is used to calculate the total pollutant and carbon emissions of the two watersheds respectively:

[0085] Total pollutant and carbon emissions (t) of watershed 1:

[0086] POL 2019 = 63 + 59 + 59 + 56 + 57 + 65 = 359 (and similarly for others, the calculation method is omitted);

[0087] POL 2020 = 308; POL 2021 = 234; POL 2022 = 227; POL 2023 = 180;

[0088] CAR 2019 = 358; CAR 2020 = 299; CAR 2021 = 237; CAR 2022 = 225; CAR 2023 = 181;

[0089] Total pollutant and carbon emissions (t) of watershed 2:

[0090] POL 2019 = 841; POL 2020 = 779; POL 2021 = 725; POL 2022 = 702; POL 2023 = 673;

[0091] CAR 2019 = 505; CAR 2020 = 437; CAR 2021 = 386; CAR 2022 = 702; CAR 2023 = 673;

[0092] According to the cumulative results of pollutant and carbon emissions of watershed 1 and watershed 2, the difference in pollutant and carbon emissions between the two watersheds from 2019 to 2023 is calculated. Since no data before 2019 is assumed, the difference is calculated from 2020:

[0093] Difference in pollutant and carbon emissions (t) of watershed 1:

[0094] ΔPOL 2020 = 359 - 308 = 51 (and similarly for others, the calculation method is omitted);

[0095] ΔPOL 2021 = 74; ΔPOL 2022 = 7; ΔPOL 2023 = 47;

[0096] Delta CAR 2020 = 59; Delta CAR 2021 = 62; Delta CAR 2022 = 12; Delta CAR 2023 = 44;

[0097] Delta POL

[0098] Delta POL 2020 = 62; Delta POL 2021 = 54; Delta POL 2022 = 23; Delta POL 2023 = 29;

[0099] Delta CAR 2020 = 68; Delta CAR 2021 = 51; Delta CAR 2022 = 65; Delta CAR 2023 = 52.

[0100] Step S2: standardize the pollutant and carbon emission reduction (increase) data of each year; according to the standardized data set, the coupling degree model is used to calculate the coupling degree between the pollution reduction and carbon reduction of each basin, and then the coupling degree grade of the pollution reduction and carbon reduction of each basin is obtained;

[0101] The specific formula for standardizing the pollutant and carbon emission reduction (increase) data used in the application is as follows:

[0102]

[0103]

[0104] Wherein, U is the standardized pollutant emission reduction (increase) ; Delta POL i is the pollutant emission reduction (increase) before standardization; B is the standardized carbon emission reduction (increase) ; Delta CAR i is the carbon emission reduction (increase) before standardization; k is the total number of pollutant data;

[0105] The coupling degree model is used to calculate the coupling degree between the pollution reduction and carbon reduction of each basin, and the specific formula is as follows:

[0106]

[0107] Wherein, C i is the pollution reduction and carbon reduction coupling degree of the i-th year, the value range is [0, 1], C i is closer to 1, the coupling degree is higher; U i is the standardized pollutant emission difference of the i-th year; B i is the standardized carbon emission difference of the i-th year.

[0108] The emission difference of pollutants and carbon in each watershed calculated in step S1 is standardized:

[0109] The standardized emission difference of watershed 1:

[0110]

[0111] U 2021 = 0.545; U 2021 = 0.052; U 2021 = 0.346;

[0112] B 2020 = 0.384; B 2020 = 0.404; B 2020 = 0.078; B 2020 = 0.287;

[0113] The standardized emission difference of watershed 2:

[0114] U 2020 = 0.456; U 2021 = 0.397; U 2021 = 0.169; U 2021 = 0.213;

[0115] B 2020 = 0.443; B 2020 = 0.332; B 2020 = 0.423; B 2020 = 0.339;

[0116] Then, the coupling degree model is used to calculate the coupling degree between pollution reduction and carbon reduction in watershed 1 and watershed 2 from 2020 to 2023:

[0117] The coupling degree of pollution reduction and carbon reduction in watershed 1 each year:

[0118]

[0119] C 2021 = 0.989; C 2022 = 0.979; C 2023 = 0.996;

[0120] The coupling degree of pollution reduction and carbon reduction in watershed 2 each year:

[0121] C 2020 = 1.000; C 2021 = 0.996; C 2022 = 0.903; C 2023 = 0.974.

[0122] According to the calculation results of the pollution reduction and carbon reduction coupling degree of each basin, the coupling degree level of each basin can be analyzed, and the coupling degree value range is [0, 1], the closer to 1 indicates that the coupling degree of the basin is higher, and the correlation degree of pollution reduction and carbon reduction is stronger, for example, in the embodiment, the coupling degrees of basin 1 in four years are 1.000, 0.989, 0.979 and 0.996, and the coupling degrees of basin 2 in four years are 1.000, 0.996, 0.903 and 0.974.

[0123] Step S3: According to the pollution and carbon reduction (increase) data of each year, the pollution reduction and carbon reduction synergy degree of each basin is calculated by using the pollution reduction and carbon reduction synergy efficiency coefficient; and then the coupling degree of pollution reduction and carbon reduction of each basin in step S2 is combined to quantitatively evaluate the coupling synergy state of pollution reduction and carbon reduction of each basin.

[0124] The pollution reduction and carbon reduction synergy efficiency coefficient is used to calculate the synergy degree between pollution reduction and carbon reduction of each basin, and the specific formula is as follows:

[0125]

[0126] Wherein, S i is the pollution reduction and carbon reduction synergy degree of the i-th year; ΔPOL i is the pollution discharge difference value of the i-th year relative to the (i-1)-th year; POL i is the total pollution discharge of the i-th year; ΔCAR i is the carbon discharge difference value of the i-th year relative to the (i-1)-th year; CAR i is the total carbon discharge of the i-th year.

[0127] The value range of S i is (-∞, +∞), when S i <0, it indicates that the pollution reduction and carbon reduction are not synergistic; when 0≤S i <0.8, it indicates that the carbon reduction is dominant; when 0.8≤S i ≤1.2, it indicates that the pollution reduction and carbon reduction are driven by both; and when S i >1.2, it indicates that the pollution reduction is dominant.

[0128] The coupling degree of pollution reduction and carbon reduction of each basin in step S2 is combined to quantitatively evaluate the coupling synergy state of pollution reduction and carbon reduction of each basin, and the coupling synergy state corresponding to the value interval of coupling degree and synergy degree is shown in Table 1.

[0129] Table 1: Coupling synergy state table

[0130]

[0131]

[0132] The synergistic degree between pollution reduction and carbon reduction of basin 1 and basin 2 in 2020-2023 is calculated by using the pollution reduction and carbon reduction synergistic efficiency coefficient respectively:

[0133] The synergistic degree of pollution reduction and carbon reduction of basin 1 every year is:

[0134]

[0135] S 2021 =1.209;S 2022 =0.578;S 2023 =1.074;

[0136] The synergistic degree of pollution reduction and carbon reduction of basin 2 every year is:

[0137] S 2020 =0.511;S 2021 =0.564;S 2022 =0.162;S 2023 =0.223;

[0138] The coupling degree of pollution reduction and carbon reduction of basin 1 and basin 2 calculated in step S2 is combined, and the coupling synergistic state table (i.e., table 1) is referred to, to determine the coupling synergistic state of pollution reduction and carbon reduction of basin 1 and basin 2 in 2020-2023; that is:

[0139] The coupling synergistic states of basin 1 in four years are: high coupling and synergistic emission reduction driven by pollution reduction and carbon reduction, high coupling and synergistic emission reduction driven by pollution reduction, high coupling and synergistic emission reduction driven by carbon reduction, and high coupling and synergistic emission reduction driven by pollution reduction and carbon reduction.

[0140] The coupling synergistic states of basin 2 in four years are all: high coupling and synergistic emission reduction driven by carbon reduction.

[0141] Step S4: According to the center coordinates of each grid (the center coordinates of the irregular boundary grid are determined by the center of the maximum inscribed circle) and the pollution and carbon emission data in each grid, the barycentric method is used to determine the barycenter of pollution and carbon emission of each basin; the barycenter coordinates of the two basins are connected to obtain the straight line distance of the barycenter of the two basins and standardize the straight line distance data.

[0142] The barycentric method is used to determine the barycenter of pollution and carbon emission of each basin, and the specific formula is as follows:

[0143]

[0144]

[0145] Wherein, X i , Y i are the horizontal coordinate and vertical coordinate of the barycenter of pollution and carbon emission of the i-th year basin; xj ,y j is the horizontal and vertical coordinates of the jth grid cell; POL ij is the emission of pollutants in the jth grid in the i-th year; CAR ij is the carbon emission in the jth grid in year i; n is the total number of grids in each basin.

[0146] According to the watershed grid parameter table from 2019 to 2023 in step S1, the horizontal and vertical coordinates of the center of each grid in each watershed are determined (the coordinates of the center of the maximum inscribed circle are used for grids with irregular boundaries); the center of gravity coordinates of the entire watershed are calculated using the center of gravity method:

[0147] The horizontal and vertical coordinates of the annual discharge center in Basin 1:

[0148]

[0149] X 2021 =4.333;X 2022 =4.314;X 2023 =4.285;

[0150] Y 2020 =7.283; Y 2021 =7.237; Y 2022 =7.218; Y 2023 =7.281;

[0151] The horizontal and vertical coordinates of the annual discharge center in Basin 2:

[0152] X 2020 =11.742;X 2021 =11.725;X 2022 =11.748;X 2023 =11.752;

[0153] Y 2020 =11.190;Y 2021 =11.226;Y 2022 =11.217; Y 2023 =11.235;

[0154] Then connect the centroid coordinates of the two basins calculated by the centroid method to obtain the centroid distance between the two basins ( Figure 5 The centroid distances were normalized and the normalized distances were 0.497, 0.500, 0.502 and 0.500 respectively.

[0155] Step S5: Construct the “natural-economic-social” comprehensive impact index of each basin based on the time series data of the “natural-economic-social” factors of the basin;

[0156] The improved CRITIC method is used to calculate the "nature-economy-society" comprehensive influence index, and the improved CRITIC method can fully consider the variability and conflict between the 12 "nature-economy-society" factors selected in step S1, so that the weighting of each factor is more scientific, and then the "nature-economy-society" comprehensive influence index is calculated, and the specific steps are as follows:

[0157] Step S501: Construct an initial factor matrix:

[0158]

[0159] Step S502: After standardizing the "nature-economy-society" factor data, a standardized matrix is obtained:

[0160]

[0161] Among them, for a certain basin, a ij , a′ ij are the jth "nature-economy-society" factor of the ith year before and after standardization respectively;

[0162] Step S503: According to the standardized "nature-economy-society" factor, the variability of each factor is calculated, which refers to the volatility of the same factor over time. The greater the value, the stronger the volatility of the factor over time, and the greater the weight allocated. The specific formula is as follows:

[0163]

[0164] Among them, E j is the variability index of the jth "nature-economy-society" factor; a′ ij is the jth "nature-economy-society" factor of the ith year after standardization; is the average value of the jth factor; m is the number of factors;

[0165] Step S504: The Pearson correlation coefficient method is used to calculate the correlation between each "nature-economy-society" factor, and then the conflict of each factor is calculated. The conflict between factors refers to the degree of association between different factors. The greater the conflict between two factors, the weaker the association between the two factors, the more different points of information reflected, and the greater the weight allocated. The specific formula is as follows:

[0166]

[0167] Among them, R j is the conflict index of the jth "nature-economy-society" factor; |r qj| is the absolute value of Pearson correlation coefficient between the qth factor and the jth factor; m is the number of factors;

[0168] Step S505: Calculate the weight of each factor according to the variation index and conflict index of each "nature-economy-society" factor, and the specific formula is as follows:

[0169]

[0170] Wherein, W j is the weight of the jth "nature-economy-society" factor; E j is the variation index of the jth "nature-economy-society" factor; R j is the conflict index of the jth "nature-economy-society" factor; m is the number of factors;

[0171] Step S506: Calculate the "nature-economy-society" comprehensive influence index according to the weight of each "nature-economy-society" factor, and the specific formula is as follows:

[0172]

[0173] Wherein, V z is the "nature-economy-society" comprehensive influence index of the zth basin; W j is the weight of the jth "nature-economy-society" factor; a′ ij is the standardized jth "nature-economy-society" factor in the ith year; m is the number of factors.

[0174] According to the "nature-economy-society" factors selected in step S1: nature: basin mainstream flow, annual average rainfall, vegetation coverage, number of species in the basin; economy: basin GDP, average utilization rate of basin resources, basin export trade volume, ecological compensation fund flow; society: population flow, basin water flow, road mileage in the basin, urbanization rate data, the initial "nature-economy-society" factor matrix from 2020 to 2023 is constructed:

[0175] Basin 1:

[0176]

[0177] Basin 2:

[0178]

[0179] The "nature-economy-society" factor data is standardized to obtain the standardized matrix, and the standardized matrix is as follows:

[0180] Basin 1:

[0181]

[0182] Basin 2:

[0183]

[0184] Then, the variation index of each factor in each year is calculated based on the standardized "natural-economic-social" factors:

[0185] For example, the variation index of the main stream flow of Basin 1 is:

[0186]

[0187]

[0188] According to the correlation between the “nature-economy-society” factors, the conflict index of each factor is calculated. The Pearson correlation coefficient is as follows: Figure 7 As shown:

[0189] For example, the conflict index of the main stream flow of Basin 1 is:

[0190]

[0191] Then, the weight of each factor is calculated based on the variation index and conflict index of each "natural-economic-social" factor in the two basins:

[0192] For example, the weight of the main stream flow of Basin 1 is:

[0193]

[0194] Then, based on the weights of each “natural-economic-social” factor, the annual “natural-economic-social” comprehensive impact index of the two basins is calculated:

[0195] For example, the 2020 “Nature-Economy-Society” comprehensive impact index of Basin 1 is:

[0196]

[0197] Step S6: Based on the coupling degree of each river basin, the "natural-economic-social" comprehensive impact index and the center of gravity distance, the gravitational intensity of pollution reduction and carbon reduction between river basins is calculated.

[0198] In this embodiment, the specific formula used to calculate the gravitational strength of pollution reduction and carbon reduction between river basins is as follows:

[0199]

[0200]

[0201] Among them, G ijGijis the gravity strength of basin i to basin j, the greater the value, the stronger the mutual relationship, influence degree and coupling effect between the basins and pollution reduction and carbon reduction;C ij Gijis the gravity coefficient of basin i to basin j;C i , C j Vijand Vjare the coupling degrees of basin i and basin j respectively;V i , V j Vijand Vjare the coupling degrees of basin i and basin j respectively;D ij is the straight-line distance of the basin gravity center.

[0202] In this embodiment, the gravity strength of basin 1 to basin 2 is calculated. First, the gravity coefficient of basin 1 to basin 2 is calculated every year:

[0203] In 2020:

[0204] In 2021:C 12 = 0.498;

[0205] In 2022:C 12 = 0.520;

[0206] In 2023:C 12 = 0.506;

[0207] Then, according to the gravity coefficient of basin 1 to basin 2, combined with the "nature-economy-society" comprehensive influence index, coupling degree and basin gravity center distance every year, the gravity strength of basin 1 to basin 2 is calculated every year:

[0208] In 2020:

[0209] In 2021:G 12 = 36.339;

[0210] In 2022:G 12 = 8.896;

[0211] In 2023:G 12 = 18.706.

[0212] From the results, the gravity strength of basin 1 to basin 2 is the strongest in 2021 and the weakest in 2022, and the overall development trend is fluctuating.

[0213] The embodiment first presets the grid data sets of two basins from 2019 to 2023 (the parameters of each grid include pollutant emission, carbon emission and center coordinates) and the 'nature-economy-society' factor data sets of two basins (including: nature: flow of trunk stream of basin, annual average precipitation, vegetation coverage, number of species in basin; economy: GDP of basin, average utilization rate of resources in basin, export trade volume of basin, ecological compensation fund flow; society: population flow, material flow in basin, road mileage in basin, urbanization rate), the coupling and synergy degree method is used to calculate the coupling and synergy degrees of pollution reduction and carbon reduction of two basins, the coupling relationship of pollution reduction and carbon reduction of the basins is clearly evaluated, and the synergistic dominant relationship is accurately judged; in combination with the 'nature-economy-society' comprehensive influence index, the coupling degree and the distance between the gravity centers of pollutants and carbon emissions, the attraction strength between the two basins is analyzed and calculated, which can help to understand the radiation relationship of pollution reduction and carbon reduction between the basins, is beneficial to promote the collaborative cooperation of pollution reduction and carbon reduction between the basins, and provides a scientific basis for formulating pollution reduction and carbon reduction policies between the basins.

[0214] The above is the preferred embodiment of the present application, but the embodiments of the present application are not limited by the above, and any change, modification, replacement, combination, simplification made without departing from the spirit and principles of the present application should be an equivalent replacement method, which is included in the protection scope of the present application.

Claims

1. A method for evaluating the coupled synergy relationship of pollution reduction and carbon reduction in a watershed and its gravity, characterized by: The following steps are involved: Step S1: Obtain multi-year time series data of pollutants and carbon emissions in the watershed at a grid scale; obtain time series data of the "natural-economic-social" factors of the watershed; accumulate the pollutant and carbon emission data in the grid of each watershed each year to obtain the total pollutant and carbon emissions of each watershed in that year; calculate the annual reduction or increase in pollutant and carbon emissions based on the multi-year time series data of pollutants and carbon emissions; the time series data of the "natural-economic-social" factors of the watershed include natural factors, which include the flow of the main stream of the watershed, the average annual precipitation, the vegetation cover, and the number of species in the watershed; among them, the flow of the main stream of the watershed and the average annual precipitation reflect the flow intensity of pollutants and carbon between watersheds with water as the medium; the vegetation cover reflects the carbon storage capacity between watersheds; and the number of species in the watershed reflects the degree to which the watershed is negatively affected by pollutants and carbon; Step S2: Standardize the annual pollutant and carbon emission reduction or increase data; based on the standardized data set, use the coupling degree model to calculate the coupling degree between pollution reduction and carbon reduction in each river basin, and then obtain the pollution reduction and carbon reduction coupling degree level of each river basin; The coupling degree model is: Among them, C i is the coupling degree of pollution reduction and carbon reduction in year i, and its value range is [0,1]; C i The closer it is to 1, the higher the coupling degree; i is the emission reduction or increase of pollutants in year i after standardization; B i is the standardized carbon emission reduction or increase in year i; Step S3: Based on the annual pollutant data and carbon emission reduction or increase data, the pollution reduction and carbon reduction synergy efficiency coefficient is used to calculate the synergy between pollution reduction and carbon reduction in each river basin; then, combined with the coupling degree between pollution reduction and carbon reduction in each river basin obtained in step S2, the synergy status of pollution reduction and carbon reduction in each river basin is quantitatively evaluated; wherein, The synergy efficiency coefficient of pollution reduction and carbon reduction is used to calculate the synergy between pollution reduction and carbon reduction in each river basin. The specific formula is as follows: Among them, S i is the synergy degree of pollution reduction and carbon reduction in year i; ΔPOL i POL is the difference in pollutant emissions between year i and year (i-1); i is the total amount of pollutant emissions in year i; ΔCAR i The carbon emission difference between year i and year (i-1); CAR i is the total carbon emissions in year i; S i The value range is (-∞,+∞), when S i <0, it means that pollution reduction and carbon reduction are not coordinated; when 0≤S i When <0.8, it indicates synergy dominated by carbon reduction; when 0.8≤S i When ≤1.2, it indicates the synergy of pollution reduction and carbon reduction; when S i When it is >1.2, it indicates coordination dominated by pollution reduction; Step S4: Determine the centroid coordinates of pollutants and carbon emissions in each watershed based on the center coordinates of each grid and the pollutant and carbon emission data in each grid; connect the centroid coordinates of two watersheds to obtain the straight-line distance between the centroids of the two watersheds and standardize the straight-line distance data; Step S5: Based on the time series data of the "natural-economic-social" factors of the watershed, construct the "natural-economic-social" comprehensive impact index of each watershed; Step S6: Based on the coupling degree of each river basin, the "natural-economic-social" comprehensive impact index, and the straight-line distance between the centers of gravity, the gravitational strength of pollution reduction and carbon reduction between river basins is calculated, where: The formula for calculating gravitational strength is: Among them, G ij is the gravitational pull of basin i on basin j. The larger the value, the stronger the relationship, influence and coupling effect between basins in pollution reduction and carbon reduction. ij is the gravity coefficient of basin i to basin j; C i , C j are the coupling degrees of basin i and basin j respectively; V i 、V j are the comprehensive impact indexes of "nature-economy-society" of basin i and basin j respectively; D ij is the straight-line distance to the centroid of the watershed.

2. The method for evaluating the coupled synergy relationship and watershed gravity of pollution reduction and carbon reduction in a watershed according to claim 1 is characterized in that: In step S1, the watershed "natural-economic-social" factor time series data also includes economic factors and social factors, where: The economic factors include basin GDP, average basin resource utilization rate, basin export trade volume, and ecological compensation fund flow. Basin GDP and average basin resource utilization rate reflect the intensity of pollutant and carbon emissions in the basin, while basin export trade volume reflects the intensity of inter-basin pollutant and carbon circulation through economic exchange. Ecological compensation fund flow reflects the intensity of basin ecological governance. The social factors include population mobility, watershed logistics volume, watershed road mileage, and urbanization rate. Among them, population mobility, watershed logistics volume, and watershed road mileage reflect the circulation intensity of pollutants and carbon between watersheds with people and materials as the medium; the urbanization rate reflects the emission intensity of pollutants and carbon in the watershed.

3. The method for evaluating the coupled synergy relationship and watershed gravity of pollution reduction and carbon reduction in a watershed according to claim 1 is characterized in that: In step S1, the total amount of pollutants and total carbon emissions are calculated as follows: Among them, POL i is the total amount of pollutant emissions in year i; POL ij is the emission of pollutants in the jth grid in the i-th year; CAR i is the total carbon emissions in year i; CAR ij is the carbon emission in the jth grid in year i; n is the total number of grids in each basin.

4. The method for evaluating the coupled synergistic relationship and watershed gravity of pollution reduction and carbon reduction in a watershed according to claim 3 is characterized in that: In step S1, the annual reduction or increase in pollutant and carbon emissions is calculated. The specific calculation formula is: ΔPOL i =POL i-1 -POL i ; ΔCAR i =CAR i-1 -CAR i ; Where ΔPOL i is the difference in pollutant emissions between year i and year (i-1), where ΔPOL i >0 means pollutant emission reduction, ΔPOL i <0 means pollutant emissions increase; POL i-1 is the total amount of pollutant emissions in year (i-1); POL i is the total amount of pollutant emissions in year i; ΔCAR i is the difference in carbon emissions between year i and year (i-1), where ΔCAR i >0 means carbon emission reduction, ΔCAR i <0 means carbon emission increase; CAR i-1 is the total carbon emissions in year (i-1), CAR i is the total carbon emissions in year i.

5. The method for evaluating the coupled synergistic relationship and watershed gravity of pollution reduction and carbon reduction in a watershed according to claim 4 is characterized in that: In step S2, the specific formula for normalizing the pollutant and carbon emission reduction or increase data is as follows: Among them, U i is the standardized reduction or increase in pollutant emissions in year i, ΔPOL i is the reduction or increase in pollutant emissions before standardization, B i is the standardized carbon emission reduction or increase in year i, ΔCAR i is the carbon emission reduction or increase before normalization, and k is the total number of pollutant data.

6. The method for evaluating the coupled synergy relationship and watershed gravity for pollution reduction and carbon reduction in a watershed according to claim 5, characterized in that: In step S4, the center of gravity method is used to determine the center of gravity of pollutants and carbon emissions in each basin. The specific formula is as follows: Among them, X i , Y i are the horizontal and vertical coordinates of the center of gravity of pollutant and carbon emissions in the basin in year i, respectively; j ,y j are the horizontal and vertical coordinates of the jth grid cell respectively; POL ij is the emission of pollutants in the jth grid in the i-th year; CAR ij is the carbon emission in the jth grid in year i; n is the total number of grids in each basin.

7. The method for evaluating the coupled synergistic relationship and watershed gravity of pollution reduction and carbon reduction in a watershed according to claim 6 is characterized in that: In step S5, the improved CRITIC method is used to calculate the "nature-economy-society" comprehensive impact index. The improved CRITIC method can fully consider the variability and conflict between the 12 "nature-economy-society" factors selected in step S1, and then calculate the "nature-economy-society" comprehensive impact index. The specific steps are as follows: Step S501: Construct an initial factor matrix: Step S502: Standardize the "nature-economy-society" factor data to obtain a standardized matrix: Among them, for a certain basin, a ij , a′ ij are the jth "natural-economic-social" factor in the i-th year before and after standardization, respectively; Step S503: Calculate the variability of each factor based on the standardized "Natural-Economic-Social" factor. Variability refers to the volatility of a factor over time. A larger value indicates a greater volatility over time, and thus a greater weight is assigned. The specific formula is as follows: Among them, E j is the variation index of the jth "nature-economy-society" factor; a i ' j is the jth "natural-economic-social" factor in the i-th year after standardization; is the average value of the jth factor; m is the number of factors; Step S504: The Pearson correlation coefficient method is used to calculate the correlation between the "Nature-Economy-Society" factors, and then calculate the conflict of each factor. The conflict between factors refers to the degree of association between different factors. The greater the conflict between two factors, the weaker the association between the two factors, and the more different points of information reflected, so the greater the weight assigned. The specific formula is as follows: Among them, R j is the conflict index of the jth "nature-economy-society" factor; |r qj | is the absolute value of the Pearson correlation coefficient between the qth factor and the jth factor; m is the number of factors; Step S505: Calculate the weight of each factor based on the variation index and conflict index of each "nature-economy-society" factor. The specific formula is as follows: Among them, W j is the weight of the jth "nature-economy-society" factor; E j is the variation index of the jth "nature-economy-society" factor; R j is the conflict index of the jth "nature-economy-society" factor; m is the number of factors; Step S506: Calculate the comprehensive impact index of "Nature-Economy-Society" based on the weights of each "Nature-Economy-Society" factor. The specific formula is as follows: Among them, V z is the comprehensive impact index of "nature-economy-society" of the zth basin; W j is the weight of the jth "nature-economy-society" factor; a′ ij is the jth "natural-economic-social" factor in the i-th year after standardization; m is the number of factors.

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