River water balance calculation method

Abstract

The invention provides a water balance calculation method for a river, which fully considers the influence of rainfall runoff, underground water infiltration, external flow in a research range and human activities on the water amount of the river, and carries out quantitative calculation on the in-river amount of an analysis unit, the flow of a base flow and the flow of the external flow in the range. And the water balance calculation data of the calculation object river is obtained after summarizing statistics, so that the health condition and the recovery potential of the ecological environment in the drainage basin are evaluated, the distribution and change rules of the water resources are mastered, and the method has important significance for reasonably utilizing and protecting the river water resources.

Description

Technical Field

[0001] The present invention belongs to the technical field of water environment and water resource management and supervision, and particularly relates to a method for calculating the water balance of a river. Background Art

[0002] The calculation of water balance can evaluate the ecological environment status of a basin. Through the calculation results of the water balance of water resources, we can understand the changes in the hydrological cycle, so as to evaluate the health status and restoration potential of the ecological environment within the basin, which is conducive to scientifically protecting and restoring the water ecosystem. At present, most of the water balance calculation methods take lakes and reservoirs as the research objects. Lakes and reservoirs usually have clear boundaries, and the input and output of their water volumes are relatively obvious. In addition, their relatively closed characteristics also make them less affected by precipitation and evaporation. Therefore, the research on their water balance is relatively easy. In contrast, for river systems, the water volume of rivers is affected by various natural factors such as rainfall runoff, groundwater infiltration, and external flows outside the research scope, as well as human activities. As a dynamic, open, and complex water system research object, the transportation and changes of river water volume are more complex; these factors all increase the difficulty of studying the river water balance. However, as the most important part of the surface water system, rivers play an irreplaceable role in aspects such as urban water supply, farmland irrigation, and ecological environment. In-depth research on the water balance of rivers is the basis of hydrological and hydrodynamic research, and also the basis for water environment calculation and evaluation. By mastering the distribution and change laws of water resources through the calculation results of the river water balance, it is of great significance for the rational utilization and protection of river water resources. Therefore, it is urgent to propose a water balance analysis method that takes rivers as the object and conforms to the characteristics of river systems. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method for calculating the water balance of a river. This method takes the river as the calculation object, fully considers the influence of rainfall runoff, groundwater infiltration, external flows outside the research scope, and human activities on the river water volume, and has the advantages of high efficiency, generality, and programmability.

[0004] A method for calculating the water balance of a river disclosed by the present invention includes: determining the research scope, where the research scope includes at least one river, and the river water volume includes at least one of the inflow into the analysis unit, base flow, and external flow outside the scope; dividing the research scope into several analysis units, and at least one analysis unit has water use. The water use of the analysis unit includes industrial water use Q i , rural domestic and commercial water use Q r , urban domestic and commercial water use Q t , and other water use Q o at least one of them;

[0005] The amount of water entering the river in the analysis unit includes the water volume of the sewage treatment plant Q s-t 、the amount of water directly discharged into the river Q st and the amount of rainfall runoff entering the river Q rain at least one of them;

[0006] Among them, the water volume of the sewage treatment plant: Q s-t =(Q i *i i +Q r *i r +Q t *i t +Q o *i o )*i p *i c , where: i i is the pollution production coefficient of industrial water consumption, i r is the pollution production coefficient of rural domestic and commercial water consumption, i t is the pollution production coefficient of urban domestic and commercial water consumption, i o is the pollution production coefficient of other water consumption, i p is the groundwater infiltration coefficient, i c is the sewage collection rate;

[0007] The amount of water directly discharged into the river: Q st =(Q i *i i +Q r *i r +Q t *i t +Q o *i o )*i p *(1 - i c )*i r , where: i r is the coefficient entering the river;

[0008] The calculation formula for the amount of rainfall runoff entering the river Q rain is: Q rain =R * 0.001 * A * 10 6 *α * i e , where: R is the annual rainfall, A is the area of the analysis unit, α is the runoff coefficient, i e is the discharge ratio;

[0009] According to the topological relationship of the river channels within the research scope, the amounts of water entering the river corresponding to each analysis unit are summed and statistically analyzed;

[0010] Calculate the base flow of the river;

[0011] Calculate the external inflow of the river;

[0012] The inflow into the river, base flow, and external inflow are aggregated and calculated, and the result of the aggregation calculation is the water volume of the river.

[0013] The above water balance calculation method for the river fully considers the impacts of rainfall runoff, groundwater infiltration, external inflow within the study area, and human activities on the river water volume. It separately quantifies and calculates the inflow into the analysis unit, base flow, and external inflow, and obtains the water balance calculation data for the target river through summary statistics.

[0014] Furthermore, it also includes comparing the water volume of each river obtained from the aggregation calculation result with the multi-year average flow of the river. When the goodness of fit between the calculation result of one iteration and the multi-year average flow value reaches the set value, the calculation is completed and the iterative calculation stops; otherwise, by adjusting i i 、i r 、i t 、i o 、i p 、i c and i r , continue the iterative calculation until the goodness of fit between the calculated flow and the multi-year average flow value reaches the set value.

[0015] Furthermore, the basis for dividing the study area into several analysis units includes hydrometeorological data, topographic and geomorphic information, and administrative division information; the analysis units include river basins, plots, and administrative units; the administrative units include villages, towns, districts, and counties.

[0016] Furthermore, the industrial water consumption Q i 、the rural domestic and commercial water consumption Q r 、the urban domestic and commercial water consumption Q t and the other water consumption Q o are respectively processed and calculated by selecting one of the water supply data survey method, population quota method, and industrial output value method.

[0017] Furthermore, the pollution production coefficient i i of the industrial water consumption ranges from [0, 1]; the pollution production coefficient i r of the rural domestic and commercial water consumption ranges from [0, 1]; the pollution production coefficient i t of the urban domestic and commercial water consumption ranges from [0, 1]; the pollution production coefficient i o of the other water consumption ranges from [0, 1].

[0018] Furthermore, the groundwater infiltration coefficient i p ≥1.

[0019] Furthermore, the sewage collection rate i cThe value range is [0, 1].

[0020] Further, the river inflow coefficient i r The value range is [0, 1].

[0021] Further, the runoff coefficient α has a value range of [0, 1]; the discharge ratio i e The value range is [0, 1].

[0022] Further, the set value range is set to [-5 m 3 / s, 5 m 3 / s].

[0023] The present invention has the following beneficial effects:

[0024] 1) The water balance calculation method provided by the present invention fully considers the impacts of rainfall runoff, groundwater infiltration, external inflow to the study area, and human activities on river water volume, quantifies and calculates the river inflow, base flow, and external inflow to the analysis unit respectively, and obtains the water balance calculation data of the target river after summary and statistics;

[0025] 2) The water balance calculation method provided by the present invention can optimize the pollution production coefficients i i for industrial water consumption, the pollution production coefficients i r for rural domestic and commercial water consumption, the pollution production coefficients i t for urban domestic and commercial water consumption, the pollution production coefficients i o for other water consumption, the groundwater infiltration coefficient i p the sewage collection rate i c and the river inflow coefficient i r to improve the calculation accuracy of the calculation method. Description of the Drawings

[0026] Figure 1 is a schematic flow chart of the water balance calculation method for a river provided by some embodiments of the present invention,

[0027] Figure 2 is a schematic diagram of the study area and analysis unit division provided by an embodiment of the present invention. Detailed Embodiments

[0028] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present invention can be understood more thoroughly and comprehensively.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0030] The present invention provides a method for calculating the water balance of a river. The calculation method includes the following steps:

[0031] Step 1: To carry out the water balance calculation of the basin, it is necessary to scientifically divide the entire basin according to the actual situation. The basis for the division of the analysis units includes hydrometeorological data, topographic and geomorphic information, and administrative division information. According to the above division basis, the analysis units are divided into different types. Among them, there are analysis units with clear water use characteristics and water supply sources, such as village, township, district, and town divided according to administrative regions, or agricultural and forestry land divided according to usage, such as livestock plots and aquaculture land. It can also include other water bodies entering the river within the research scope, such as river runoff, lakes, or reservoirs. According to water resource utilization and the underlying surface conditions, the research area can also be divided into multiple analysis units, each of which has clear water use characteristics and water supply sources. The above is only an example and does not limit the analysis units, and other division types can also be included. In this embodiment, according to water resource utilization and the underlying surface conditions, the research scope is divided into multiple analysis units, each of which has clear water use characteristics and water supply sources.

[0032] Step 2: Obtain the water consumption data of the analysis units. When the data of the analysis units is relatively detailed, the water supply data survey method is used to calculate the water use data of each analysis unit. Obtain the water use data of various users from relevant departments and institutions, including information such as water consumption, water use type, and water supply source. At the same time, collect environmental factor data such as hydrometeorological data and topographic and geomorphic information within the scope. Divide the water supply data into industrial water use, urban domestic and commercial water use, rural domestic and commercial water use, and other water use according to agriculture, industry, life, and ecology. The number of analysis units is n, and let the current analysis unit serial number be i = 1.

[0033] Step 3: Calculate the water consumption of the analysis units. If relevant information of the domestic sewage outlet is collected, the survey and statistics method is adopted; if population data is collected, the population quota method is used for calculation.

[0034] Step 4: Calculate the amount of water entering the river of the analysis units. The calculation method of the amount of water entering the river specifically includes the following steps:

[0035] Step 41. For each analysis unit i, when relevant departments and institutions have statistical survey data on the specific water consumption of each water user in the analysis unit, the data is classified and summarized according to industrial water use, urban domestic and commercial water use, rural domestic and commercial water use, and other water use, and the industrial water consumption, urban domestic and commercial water consumption, rural domestic and commercial water consumption, and other water consumption are obtained respectively. When relevant departments and institutions do not have detailed water use data, in the case of lack of data in the analysis unit, the water consumption is estimated using water use indicators, and the total water use is obtained after balancing with the water supply. For example, the water use data of each analysis unit is indirectly estimated using the population quota method and the industrial output value method. Specifically, it is estimated by multiplying the indicators such as domestic water use and industrial water use announced or experimentally measured in each region by the population quantity, industrial output value, etc., and balancing with the water supply. Exemplarily: Input the industrial added value and water consumption per 10,000 yuan of industrial added value of analysis unit i, and calculate the industrial water consumption of each analysis unit:

[0036] Industrial water consumption = industrial added value * water consumption per 10,000 yuan of industrial added value;

[0037] In the formula: Industrial water consumption, unit: 10,000 m 3 ; Industrial added value, unit: 10,000 yuan; Water consumption per 10,000 yuan of industrial added value, unit: 10,000 m 3 .

[0038] Input the urban and rural population numbers of analysis unit i, and calculate the urban domestic sewage volume, rural domestic sewage volume, and comprehensive domestic sewage volume Q d :

[0039] Q d =Q a *P / 1000;

[0040] In the formula: Q d is the water consumption, unit: 10,000 m 3 / d; Q a is the per capita water use quota (urban per capita water use quota or rural per capita water use quota), unit: L / (d·person); P is the population quantity, unit: 10,000 people.

[0041] In addition, the statistical plus estimation method can be used to calculate the water consumption of each analysis unit. Agricultural water use is divided into farmland irrigation water use, water use in fish ponds and livestock and poultry. The water consumption of large and medium-sized irrigation areas in farmland irrigation water use is comprehensively counted; the water consumption of small irrigation areas, fish ponds and livestock and poultry is comprehensively calculated by selecting a certain number of typical cases and combining the irrigation area, the water replenishment area of fish ponds and the number of livestock and poultry. The water consumption of key industrial enterprises in industrial water use is comprehensively counted, and the water consumption of non-key water users is estimated through typical investigations and comprehensive calculations. For domestic water use, a sample network of water users is constructed by selecting typical cases to obtain the water consumption indicators of urban and rural residents' living, construction and the tertiary industry. Combining with economic and social indicators such as the population, the completed area of construction projects and the number of employees in the tertiary industry provided by the statistical department, the domestic water consumption is calculated. Other water use such as ecological environment water use includes urban and rural environmental water use, and the urban and rural environmental water use is mainly calculated based on the water use quota and the regional economic and social development situation.

[0042] Step 42: Multiply the various types of water consumption obtained in Step 41 by their corresponding pollution production coefficients to obtain the sewage volume Q of analysis unit i s ;

[0043] Q s = Q i *i i + Q r *i r + Q t *i t + Q o *i o

[0044] In the formula: Q s is the sewage volume of analysis unit i, with the unit of: 10,000 m 3 / d; Q i is the industrial water consumption, Q r is the rural domestic and commercial water consumption, Q t is the urban domestic and commercial water consumption, Q o is the other water consumption, and the units are all: 10,000 m 3 / d; i is the corresponding pollutant generation coefficient, and its value range is 0 - 1. The pollutant generation coefficients of various types of sewage should be determined based on historical water supply and sewage volume data. When the data is lacking, the pollutant generation coefficients of classified urban sewage can be determined according to the urban residential and public facility levels, industrial types, etc., in accordance with the regulations of the classified sewage discharge coefficients in the "Code for Urban Drainage Engineering Planning" (GB 50318 - 2017); The sewage collected by the rural sewage system mainly includes rural residential and commercial sewage, public facility sewage, and infiltrated groundwater. For residential, commercial, and public facility water use, the amount of sewage entering the drainage system depends to a large extent on the purpose of water supply and the completeness of the local sewage collection system. Referring to the "Technical Specification for Drainage Engineering in Towns (Villages)" (CJJ124 - 2008), the "Outdoor Drainage Design Standard" (GB 50014 - 2021), and the local special plan, combined with the economic development status of the research area, determine the rural domestic sewage discharge coefficient. According to different regions and different water use types, the pollutant generation coefficients will vary, and these coefficients may change due to factors such as technological progress, management improvement, and water-saving measures. Therefore, in practical applications, calculations can be adjusted according to the latest data and local specific conditions.

[0045] Step 43: Since there are often varying degrees of damage in the underground pipe network, it will cause groundwater at the damaged locations to infiltrate into the pipe network system. This infiltration here is different from the outward sewage discharge caused by pipe damage. The infiltration of groundwater at the damaged locations into the pipe network system is considered by introducing the infiltration coefficient to obtain the sewage volume Q p , and the permeability is the ratio of the infiltration volume of groundwater to the sewage volume entering the pipe network;

[0046] Q p =Q s *i p

[0047] In the formula: Q p is the sewage volume considering leakage, with the unit of: 10,000 m 3 / d; i p is the groundwater infiltration coefficient, i p ≥1.

[0048] Step 44: The sewage volume considering leakage obtained in Step 43 is multiplied by the sewage collection rate to obtain the water volume Q s-t entering the sewage treatment plant. This water volume is discharged into the corresponding river, and the sewage collection ratio is related to the coverage rate of the urban pipe network;

[0049] Q s-t =Q p *i c

[0050] In the formula: Q s-t is the water volume entering the sewage treatment plant, with the unit of: 10,000 m3 / d; i c is the sewage collection rate. When the analysis unit with water supply does not include a sewage treatment plant, i c = 0. When the analysis unit with water supply includes a sewage treatment plant, its value range is [0, 1].

[0051] Step 45: Calculate the direct discharge volume into the river, and match each analysis unit i with the corresponding river. The calculation formula is as follows:

[0052] Q st = Q p *(1 - i c )*i r

[0053] In the formula: Q st is the direct discharge volume into the river, with the unit of: 10,000 m 3 / d; i c is the sewage collection rate; i r is the river entry coefficient. Considering that not all the sewage that does not enter the sewage treatment plant is directly discharged into the river, after transmission and interception, there is a certain reduction in the direct discharge sewage that finally enters the main river in the corresponding sub - basin. The river entry coefficient i r has a value range of [0, 1]. The specific value of the river entry coefficient i r can be determined by the monitoring data of water quality and water volume. When the data is lacking, it can be determined according to the value - taking method in the "Guiding Opinions on the Total Allocation of Main Water Pollutants", such as determined by the distance (L) from the enterprise discharge outlet and the urban sewage treatment facility discharge outlet to the river sewage discharge outlet: when L < 1 km, the river entry coefficient takes 1.0; when 1 < L < 10 km, the river entry coefficient takes 0.9; when 10 < L < 20 km, the river entry coefficient takes 0.8; when 20 < L < 40 km, the river entry coefficient takes 0.7; when L > 40 km, the river entry coefficient takes 0.6.

[0054] Step 46: Calculate the rainfall - runoff volume into the river by inputting the annual rainfall, runoff coefficient, area, corresponding river, and discharge ratio in the analysis unit area. The runoff coefficient depends on the proportion of each plot in the analysis unit and the runoff generation and concentration coefficients of different plots. The discharge ratio refers to the ratio of the runoff volume generated in the analysis unit area discharged into a certain river. Since the rivers in the analysis unit may be generalized water systems, the sum of the discharge ratios of different rivers in the same analysis unit is less than or equal to 1;

[0055] Q rain = R * 0.001 * A * 10 6 *α * i e

[0056] In the formula: Q rain is the rainfall - runoff volume into the river, with the unit of: 10,000 m 3 ; A is the area of the analysis unit, with the unit of km2 ; α is the runoff coefficient, which characterizes the relationship between rainfall amount and runoff during a rainfall process. The value range of the runoff coefficient α is usually between 0 and 1; i e is the discharge ratio. The discharge ratio i e refers to the ratio of the runoff generated within the analysis unit area that is discharged into a certain river. Since the rivers within the analysis unit may be a generalized water system, the sum of the discharge ratios of different rivers in the same analysis unit is less than or equal to 1.

[0057] Step 47: Sum up the results obtained in Step 43 - 46, which is the water volume flowing into the river of analysis unit i. Determine whether all analysis units have been traversed. If not, let i + 1 enter the next analysis unit, and repeat Steps 41 - 46 until the calculations for all analysis units are completed.

[0058] Step 5: Calculate the rainfall - runoff inflow into the river by inputting the annual rainfall, runoff coefficient, area, corresponding river, and discharge ratio within the analysis unit area. Runoff is one of the most important hydrological elements on land and is a basic element of the water balance. The runoff coefficient depends on the proportion of each plot within the analysis unit and the runoff generation and concentration coefficients of different plots. The discharge ratio refers to the ratio of the runoff generated within the analysis unit area that is discharged into a certain river. Since the rivers within the analysis unit may be a generalized water system, the sum of the discharge ratios of different rivers in the same analysis unit is less than or equal to 1. The calculation formula is as follows:

[0059] Q rain = R * 0.001 * A * 10 6 * α * i e

[0060] In the formula:

[0061] Q rain is the rainfall - runoff inflow into the river, with the unit of: 10,000 m 3 ; A is the area of the analysis unit, with the unit of km 2 ; α is the runoff coefficient; i e is the discharge ratio.

[0062] Step 6: Base flow calculation. A part of the rainfall - runoff flows into the ground to form the base flow. Calculate the total base flow by multiplying the average low - flow of the corresponding river during the dry season and the proportion of the base flow. When calculating the river base flow, the impact of the project on the river hydrological regime, the water demand characteristics of the ecological target, and the ease of obtaining actual data need to be considered. For example, for southern rivers, the ecological base flow should generally not be less than the larger value between the average lowest - flow of the driest month with a 90% guarantee rate and 10% of the average annual natural runoff; for northern rivers, the ecological base flow during the non - flood season should generally not be lower than 20% - 30% of the average annual natural runoff; the proportion of the base flow is also related to the richness of the groundwater system. In areas with rich groundwater systems, it is recommended to take about 10%. The unit of the total base flow: m 3 / s.

[0063] Step 7: Add the external flow into the study area. The external flow into the study area refers to the river that enters the interior of the study area from outside the study area.

[0064] Step 8: Summarize Steps 4 - 7, and based on the correspondence between rivers and analysis units and the river channel topological relationship. The topological relationship of river channels refers to the spatial relationship between the components in the river network, mainly including the flow direction of the river, confluence points, branching conditions, and connectivity. Correlate the river inflow of each analysis unit with the corresponding river or runoff one by one. For runoff, correlate it with the corresponding river, sum up all the inflow discharges of the river, and obtain the corresponding river discharge.

[0065] Step 9: Determine whether all analysis units have been traversed. If i < n, then i = i + 1, and repeat Steps 2 - 8. If i = n, then the calculation for all analysis units is completed.

[0066] Summarize and calculate the river inflow, base flow, and external flow into the study area for each river according to the topological relationship of the river channels within the study area. The result of the summary calculation is the water volume of each river.

[0067] To improve the accuracy of the river water balance calculation method, parameter optimization is carried out for the above process, and the optimization step is Step 10.

[0068] Step 10: Compare the summary calculation result with the multi - year average flow of the river channel. When the fitting degree between the calculated flow in one iteration and the multi - year average flow value reaches the set value range, the calculation is completed, and the iterative calculation stops. Otherwise, enter Step 4, and continue the iteration by adjusting the pollution production coefficient i of industrial water consumption i , the pollution production coefficient i of rural domestic and commercial water consumption r , the pollution production coefficient i of urban domestic and commercial water consumption t , the pollution production coefficient i of other water consumption o , the groundwater infiltration coefficient i p , the sewage collection rate i c and the river inflow coefficient i r .

[0069] For the flow chart of the river water balance calculation method provided by the present invention, please refer to Figure 1 as shown.

[0070] The following describes the specific operation process of the river water balance calculation method provided by the present invention with reference to specific embodiments:

[0071] Embodiment 1

[0072] Taking a certain river basin as an example, calculate the river inflow of the basin based on the water supply data and population data of the basin,

[0073] As Figure 2 shown, there are three rivers A, B, and C within the research scope. According to water resource utilization and the underlying surface conditions, the research scope is divided into multiple analysis units. Each analysis unit has clear water use characteristics and water supply sources. A total of 8 analysis units are divided, and it is defaulted that each analysis unit has a sewage treatment plant, and the sewage treatment plant discharges into the corresponding river of the analysis unit.

[0074] The specific calculation steps are as follows:

[0075] Step 1: Determine the research scope and divide the analysis units;

[0076] Step 2: For the 8 analysis units divided in Step 1, for analysis units 2 and 6, there are relatively detailed data. Use the water supply data survey method to obtain the water use data of each analysis unit, as shown in Table 1;

[0077] Table 1 Water Supply Data Table (unit: 10,000 m 3 / d)

[0078] Analysis unit Industrial water use Commercial water use Urban household water use Rural household water use Other water use 2 13.61 2.46 17.41 5.32 0.116 6 25.32 0.34 9.77 2.15 0.112

[0079] Table 2 Population and Industrial Output Value Data Table

[0080]

[0081] Calculate the data of industrial added value and water consumption per 10,000 yuan of industrial added value of each analysis unit in Table 2 using the population equivalent method:

[0082] Industrial water consumption = industrial added value * water consumption per 10,000 yuan of industrial added value

[0083] In the formula: industrial water consumption, unit: 10,000 m 3 ; industrial added value, unit: 10,000 yuan; water consumption per 10,000 yuan of industrial added value, unit: 10,000 m 3 .

[0084] Input the urban population and rural population of analysis unit i, and calculate the urban domestic sewage volume, rural domestic sewage volume, and comprehensive domestic sewage volume using the quota value:

[0085] Q d = Q a * P / 1000

[0086] In the formula: Q d is the water consumption, unit: 10,000 m 3 / d; Q a is the per capita water use quota (urban per capita water use quota or rural per capita water use quota), unit: L / (d·person); P is the population quantity, unit: 10,000 people.

[0087] The per capita water consumption quota in urban areas is 300 (L / d·person), and the per capita water consumption quota in rural areas is 120 (L / d·person). Substituting the data in Table 2 into the above formula, the calculation results are shown in Table 3 below.

[0088] Table 3 Statistical Analysis Table of Water Consumption (Unit: 10,000 m 3 / d)

[0089] Analysis unit Industrial water use Other water use Urban household water use Rural household water use 1 8.634 0.123 1.09 1.02 3 219.127 0.461 4.95 0.468 4 57.704 0.115 1.25 1.16 5 112.030 0.327 4.52 0.89 7 72.739 0.158 1.39 1.3 8 404.444 0.956 7.62 0.95

[0090] Step 4: Calculate the amount of water entering the river in the analysis unit, including the treated water volume of the sewage treatment plant and the directly discharged sewage volume. The calculation methods for the treated water volume of the sewage treatment plant and the directly discharged sewage volume are as follows:

[0091] Multiply the various water consumption amounts in Table 3 by their corresponding pollutant production coefficients to obtain the sewage volume of analysis unit i:

[0092] Q s = Q i *i i + Q r *i r + Q t *i t + Q o *i o

[0093] In the formula: Q s is the sewage volume of analysis unit i, with the unit of 10,000 m 3 / d; Q i is the industrial water consumption, Q r is the rural domestic and commercial water consumption, Q t is the urban domestic and commercial water consumption, Q o is the other water consumption, and the units are all 10,000 m 3 / d; i is its corresponding pollutant production coefficient, and the value range is 0 - 1. For the convenience of calculation, i i are all set to 0.5, i t are all set to 0.85, i r are all set to 0.5, i o are all set to 0.5. The calculation results are shown in Table 3-1.

[0094] Table 3-1 Statistical Analysis Table of Sewage Volume (Unit: 10,000 m 3 / d)

[0095] Analysis unit Industrial water use Other water use Urban household water use Rural household water use 1 4.317 0.0615 0.9265 0.51 2 6.805 0.058 16.8895 2.66 3 109.5635 0.2305 4.2075 0.234 4 28.852 0.0575 1.0625 0.58 5 56.015 0.1635 3.842 0.445 6 12.66 0.056 8.5935 1.075 7 36.3695 0.079 1.1815 0.65 8 202.222 0.478 6.477 0.475

[0096] Since there are often different degrees of damage in the underground pipe network, it will cause groundwater infiltration into the pipe network system at the damaged parts. By introducing the infiltration coefficient, the sewage volume considering leakage is obtained. The infiltration rate is the ratio of the infiltration amount of groundwater to the sewage volume entering the pipe network;

[0097] Q p = Q s * i p

[0098] Where: Q p is the sewage volume considering leakage, unit: 10,000 m 3 / d; i p is the groundwater infiltration coefficient. The groundwater infiltration coefficient is taken as 1.1, and the calculation results are shown in Table 3-2.

[0099] Table 3-2 Statistical Analysis Table of Sewage Volume Considering Leakage (Unit: 10,000 m 3 / d)

[0100] Analysis unit Industrial water use Other water use Urban household water use Rural household water use 1 4.7487 0.06765 1.01915 0.561 2 7.4855 0.0638 18.57845 2.926 3 120.51985 0.25355 4.62825 0.2574 4 31.7372 0.06325 1.16875 0.638 5 61.6165 0.17985 4.2262 0.4895 6 13.926 0.0616 9.45285 1.1825 7 40.00645 0.0869 1.29965 0.715 8 222.4442 0.5258 7.1247 0.5225

[0101] The sewage volume considering leakage in Table 3-2 multiplied by the sewage collection rate can obtain the water volume entering the sewage treatment plant. This water volume is discharged into the corresponding river. The sewage collection ratio is related to the urban pipe network coverage rate;

[0102] Q s-t = Q p * i c

[0103] Where: Q s-t is the water volume entering the sewage treatment plant, unit: 10,000 m 3 / d; i c is the sewage collection rate.

[0104] The sewage collection rate of industrial sewage is taken as 1, the sewage collection rate of urban sewage is taken as 0.65, the sewage collection rate of rural sewage is taken as 0.35, and the sewage collection rate of other sewage is taken as 0.65. Substituting into the above formula, the calculation results of the water volume entering the sewage treatment plant are shown in Table 4.

[0105] Table 4 Statistical Analysis Table of Water Volume Entering the Sewage Treatment Plant (Unit: 10,000 m 3 / d)

[0106]

[0107]

[0108] Calculate the water volume directly discharged into the river, and match each analysis unit i with the corresponding river. The calculation formula is as follows:

[0109] Q st = Q p *(1 - i c ) * i r

[0110] Where: Q st is the water volume directly discharged into the river, unit: 10,000 m 3 / d; ic is the sewage collection rate; i r is the coefficient of river discharge, with a value range of 0 - 1. The coefficient of river discharge for urban sewage is 0.9, for rural sewage is 0.3, and for other sewage is 0.9. The calculation results of the directly discharged sewage volume are shown in Table 5 below.

[0111] Table 5 Statistical Analysis Table of Directly Discharged Sewage Volume (Unit: 10,000 m 3 / d)

[0112] Analysis unit Corresponding river Industrial water use Other water use Urban household water use Rural household water use 1 B 0 0.02131 0.321032 0.109395 2 B 0 0.020097 5.852212 0.57057 3 A 0 0.079868 1.457899 0.050193 4 A 0 0.019924 0.368156 0.12441 5 C 0 0.056653 1.331253 0.095453 6 A 0 0.019404 2.977648 0.230588 7 C 0 0.027374 0.40939 0.139425 8 A 0 0.165627 2.244281 0.101888

[0113] Step 5: By inputting the annual rainfall, analyze the runoff coefficient, area, corresponding rivers, and discharge ratio within the unit area to calculate the rainfall runoff into the river. The runoff coefficient depends on the proportion of each plot within the analysis unit and the runoff generation and concentration coefficients of different plots. The discharge ratio refers to the proportion of the runoff generated within the analysis unit area that is discharged into a certain river. Since the rivers within the analysis unit may be generalized water systems, the sum of the discharge ratios of different rivers in the same analysis unit is less than or equal to 1.

[0114] Q rain = R * 0.001 * A * 10 6 * α * i e

[0115] In the formula: Q rain is the rainfall runoff into the river, with the unit of 10,000 m 3 ; R is the annual rainfall, with the unit of mm; A is the area of the analysis unit, with the unit of km2; α is the runoff coefficient; i e is the discharge ratio. When the annual rainfall is 1200 mm, the runoff coefficient is taken as 0.55, and the discharge ratio is taken as 0.58, substituting into the above formula for calculation, the results are shown in Table 6 below.

[0116] Table 6 Rainfall Runoff into River Table (Unit: 10,000 m 3 )

[0117] Analysis unit Runoff coefficient <![CDATA[Area (km 2 )]]> Corresponding river Emission ratio <![CDATA[In-river net flow (10,000 m 3 )]]> 1 0.55 192.044 B 0.58 7351.4443 2 0.55 167.475 B 0.58 6410.943 3 0.55 166.63 A 0.58 6378.5964 4 0.55 318.09 A 0.58 12176.4852 5 0.55 201.11 C 0.58 7698.4908 6 0.55 239.82 A 0.58 9180.3096 7 0.55 391.691 C 0.58 14993.9315 8 0.55 266.49 A 0.58 10201.2372

[0118] Step 6: Base flow calculation. Part of the rainfall runoff flows into the ground to form the base flow. Calculate the total base flow by multiplying the average flow rate during the dry season of the corresponding river by the proportion of the base flow. The proportion of the base flow is related to the richness of the groundwater system, and generally, it is recommended to take about 0.1. The unit of the total base flow is m 3 / s.

[0119] Table 7 Total Base Flow Table (Unit: m 3 / s)

[0120] River <![CDATA[Average flow rate during dry season (m 3 / s)]]> Base flow ratio <![CDATA[Total base flow rate (m 3 / s)]]> A 31.2 0.1 3.12 B 6.24 0.1 0.62 C 16.6 0.1 1.66

[0121] Step 7: Add external inflows to the study area. External inflows to the study area refer to the rivers that enter the project area from outside the project area, including upstream inflows and water transfers from outside the study area.

[0122] Table 8 External inflow rates to the study area (unit: m 3 / s)

[0123] River <![CDATA[Flow rate of external flow outside the research scope (m 3 / s)]]> A 16 B 3 C 8

[0124] Step 8: Summarize Steps 4 - 7, and calculate the corresponding river flow rates based on the correspondence between rivers and analysis units and the river channel topology relationship.

[0125] Table 9 Correspondence table between rivers and analysis units

[0126]

[0127] Table 10 Calculated river flow rate table

[0128]

[0129]

[0130] The river channel topology relationship is as Figure 2 shown. Rivers B and C flow into River A. Therefore, the flow rate at the outlet of River A is the sum of the three, i.e., QA total = QA + QB + QC = 120.0578 m 3 / s.

[0131] Step 9: Determine whether all analysis units have been traversed. If i < n, then i = i + 1, and repeat Steps 2 - 8. If i = n, then the calculation for all analysis units is completed.

[0132] Step 10: Compare the summarized calculation results with the multi - year average flow rate of the river channel. When the fitting degree between the calculated flow rate in one iteration and the multi - year average flow rate value reaches the set value range, the set value range is set to [-5 m 3 / s, 5 m 3 / s], the calculation is completed, and the iterative calculation stops. Otherwise, go to Step 4 and continue the iteration by adjusting the pollutant production coefficient, groundwater infiltration coefficient, and the coefficients of urban and rural sewage entering the river.

[0133] There is a measuring station downstream of River A. The location of the measuring station is as Figure 2 shown. The multi - year average flow rate is 116.78 m 3 / s, which meets the set value range with the calculated flow rate of 120.0578 m 3 / s, and the calculation is completed.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. A method for calculating the water balance of a river, characterized in that, Including: Determine the research scope, which includes at least one river, and the water volume of the river includes at least one of the inflow into the analysis unit, base flow, and external inflow into the scope; divide the research scope into several analysis units, at least one of which has water use, and the water use of the analysis unit includes industrial water use Q i , rural domestic and commercial water use Q r , urban domestic and commercial water use Q t and other water use Q o at least one of them; The amount of water entering the river in the analysis unit includes the amount of water from the sewage treatment plant Q s-t , the amount of water directly discharged into the river Q st , and the amount of rainfall runoff entering the river Q rain ; at least one of them Among them, the water volume of the sewage treatment plant: Q s-t =(Q i *i i +Q r *i r +Q t *i t +Q o *i o )*i p *i c , where: i i is the pollution production coefficient of industrial water consumption, i r is the pollution production coefficient of rural domestic and commercial water consumption, i t is the pollution production coefficient of urban domestic and commercial water consumption, i o is the pollution production coefficient of other water consumption, i p is the groundwater infiltration coefficient, i c is the sewage collection rate; Direct discharge into the river: Q st =(Q i *i i +Q r *i r +Q t *i t +Q o *i o )*i p *(1 - i c )*i r , where: i r is the coefficient of discharge into the river; Rainfall runoff into the river quantity Q rain The calculation formula is: Q rain = R * 0.001 * A * 10 6 * α * i e , where: R is the annual rainfall, A is the analysis unit area, α is the runoff coefficient, i e is the discharge ratio; According to the topological relationship of the river channels within the research scope, sum and statistically calculate the inflow into the river corresponding to each analysis unit; Calculate the base flow of the river; Calculate the external inflow of the river; Summarize and calculate the river inflow, base flow, and external inflow of the river, and the result of the summary calculation is the water volume of the river.

2. The method for calculating the water balance of a river according to claim 1, characterized in that It also includes comparing the water volume of each river obtained from the summary calculation result with the average annual flow of the river. When the fitting degree between the calculation result of one iteration operation and the average annual flow value reaches the set value, the calculation is completed and the iterative calculation is stopped; otherwise, by adjusting i i 、i r 、i t 、i o 、i p 、i c and i r , continue the iterative calculation until the fitting degree between the calculated flow and the average annual flow value reaches the set value range.

3. The method for calculating the water balance of a river according to claim 1 or 2, characterized in that, The basis for dividing the research scope into several analysis units includes hydrometeorological data, topographic and geomorphic information, and administrative division information; the analysis units include basins, plots, and administrative units; the administrative units include villages, towns, districts, and counties.

4. The method for calculating the water balance of a river according to claim 1 or 2, characterized in that, The industrial water consumption Q i 、the rural domestic and commercial water consumption Q r 、the urban domestic and commercial water consumption Q t and the other water consumption Q o are respectively processed and calculated by selecting one of the water supply data survey method, the population quota method and the industrial output value method.

5. The method for calculating the water balance of a river according to claim 1 or 2, characterized in that, The pollution production coefficient i of the industrial water consumption i The value range is [0, 1]; The pollution production coefficient i of the rural domestic and commercial water consumption r The value range is [0, 1]; The pollution production coefficient i of the urban domestic and commercial water consumption t The value range is [0, 1]; The pollution production coefficient i of the other water consumption o The value range is [0, 1].

6. The method for calculating the water balance of a river according to claim 1 or 2, characterized in that The groundwater infiltration coefficient i p ≥ 1 7. The method for calculating the water balance of a river according to claim 1 or 2, characterized in that, The sewage collection rate i c has a value range of [0, 1].

8. The method for calculating the water balance of a river according to claim 1 or 2, characterized in that, The river entry coefficient i r has a value range of [0, 1].

9. The method for calculating the water balance of a river according to claim 1 or 2, characterized in that, The value range of the runoff coefficient α is [0, 1]; the discharge ratio i e has a value range of [0, 1].

10. The method for calculating the water balance of a river according to claim 2, characterized in that, The set value range is set to [-5m 3 / s, 5m 3 / s].

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