A method for regulating water distribution in the landscape environment of reclaimed water rivers based on algae risk control

Abstract

The present invention discloses a method for regulating water distribution of a reclaimed water river landscape environment based on algae risk control, including: controlling algae risk based on the water source characteristics and hydraulic characteristics of the river water body of seasonal river landscape environment water use, based on the algae growth curve of the indicator algae species, using the nitrogen-phosphorus ratio and the water body replacement rate as control indicators; constructing a joint regulation model for water quantity and water quality of a river included in reclaimed water based on the nitrogen-phosphorus ratio and the water body replacement rate; optimizing the nitrogen-phosphorus ratio under the water body environment of the indicator algae species river based on the joint regulation model for water quantity and water quality of the river included in reclaimed water; optimizing the joint regulation model for water quantity and water quality of a river included in reclaimed water based on the optimized nitrogen-phosphorus ratio; and performing joint regulation of water quantity and water quality using the optimized joint regulation model for water quantity and water quality of a river included in reclaimed water. The rational allocation and precise regulation of multiple water sources in seasonal rivers are realized.

Description

Technical Field

[0001] The present application relates to the technical field of water resources and water ecological environment, and in particular to a method for regulating water distribution in a reclaimed water river landscape environment based on algae risk control. Background Art

[0002] Recycled water is used to replenish the landscape environment of urban rivers. It not only solves the problem of insufficient water supply for seasonal river landscape environment, but also alleviates the pressure on the ecological environment of rivers and lakes caused by the tailwater discharge of sewage treatment plants. It is a key point of recycled water utilization. The water volume and water quality of seasonal rivers vary greatly within the year and from year to year. In addition, the water quality standard of recycled water for landscape environment water is not high. The risk of algae outbreak caused by eutrophication after recycled water is used for river landscape environment water distribution deserves attention. Studies have shown that there are many factors affecting algae reproduction during the eutrophication of landscape water bodies, among which: the influence of nitrogen and phosphorus nutrients on algae growth ranks first; the ratio of total nitrogen (TN) and total phosphorus (TP) (nitrogen-phosphorus ratio) is the main parameter controlling algae growth.

[0003] Regarding the use of recycled water for landscape water distribution, application numbers CN202410143623.8, 202311068310.2, 202222719485.2, 202210647108.4, 202122296722.4, 201811214451.X, etc. respectively disclose a number of recycled water treatment technologies and devices, application numbers 202210132749.6, 20 2110448592.3, 202010681227.2, 201610475813.5, 202210198200.7, 202110317690.3, 201210120358.9, 201910274823.6, 202310918375.5 disclose a number of optimization technologies, scheduling and control methods for landscape environmental water replenishment. These achievements do not consider the algae risk control problem of recycled water utilization, and do not involve the regulation technology and methods after the seasonal river water quantity and water quality change characteristics are coupled with recycled water, resulting in different degrees of river water quality decline and abnormal algae reproduction in some areas after the use of recycled water for water distribution. Summary of the invention

[0004] In order to solve the above-mentioned technical problems, the embodiment of the present application provides a method for regulating water distribution in a landscape environment of a recycled water river channel based on algae risk control, so as to solve the algae risk control problem existing in the related technology that does not consider the utilization of recycled water and the regulation technology problem that does not involve the seasonal river water quantity and water quality change characteristics and the coupling with recycled water.

[0005] According to an embodiment of the present application, a method for regulating water distribution in a reclaimed water river landscape environment based on algae risk control is provided, comprising:

[0006] According to the water source characteristics of seasonal river landscape water and the hydraulic characteristics of river water bodies, based on the algae growth curve of indicator algae species, the algae risk is controlled using the nitrogen-phosphorus ratio and water body replacement rate as control indicators. The nitrogen-phosphorus ratio is used as a control indicator for free-flowing river sections, and the water body replacement rate is used as a control indicator for backwater sections with water storage and weirs in the river;

[0007] Based on the nitrogen-phosphorus ratio and the water body replacement rate, a joint regulation model of water quantity and water quality in a river channel that incorporates recycled water is constructed. The joint regulation model of water quantity and water quality in a river channel that incorporates recycled water is composed of an objective function and constraints. The objective function includes an algae risk control target and a river flow or water quantity target. The constraints include constraints on the available amount of surface water resources in the basin and constraints on the available amount of recycled water.

[0008] Based on the river water quantity and quality joint control model that incorporates recycled water, the nitrogen-phosphorus ratio in the water environment of the indicative algae species river is optimized;

[0009] Based on the optimized nitrogen-phosphorus ratio, the joint regulation model of water quantity and quality of rivers that incorporate recycled water is optimized;

[0010] The optimized model for joint regulation of river water quantity and quality that incorporates recycled water is used to carry out joint regulation of water quantity and quality.

[0011] Optionally, the algae risk control target is:

[0012] ;

[0013] ;

[0014] Where: is the nitrogen-to-phosphorus ratio in the water of the river section; They are the total nitrogen concentration and total phosphorus concentration in the water of the river section respectively; It is divided into the lower limit and upper limit of the reasonable range of nitrogen-phosphorus ratio for controlling algae growth; The water exchange cycle of the return water section; is the water storage capacity of the water body in the return water section; They are the replenishment volume per unit time of surface water and recycled water in the water body of the return water section; They are respectively the lower limit and upper limit of the reasonable range of water exchange cycle in the return water section.

[0015] Optionally, the river flow or water volume target is:

[0016] ;

[0017] ;

[0018] Where: is the water flow of the river section; is the target flow in the water body of the river section; They are the landscape flow and environmental flow of the water body in the river section respectively; is the water level of the return water section; is the target water level in the water body of the return section; They are the landscape water level and environmental water level of the backwater section respectively.

[0019] Optionally, the available amount constraint of surface water resources and the available amount constraint of recycled water in the basin are respectively:

[0020] Constraints on the available amount of surface water resources in this basin: ;

[0021] Constraints on the availability of recycled water: ;

[0022] Where: for The surface water replenishment flow and recycled water replenishment flow of the basin during this period; They are The upper limit of the available surface water and recycled water in this basin during this period.

[0023] Optionally, when solving the objective function, it is necessary to use a watershed water resources and non-point source pollution load calculation model, a river water quality and ecological coupling model, and a water balance model, and these three models are subject to constraints. The watershed water resources and non-point source pollution load calculation model is constructed using SWMM software, and the river water quality and ecological coupling model and water balance model are constructed using WASP5.

[0024] The SWMM software was used to calibrate the parameters of the established water resources and non-point source pollution load model using monitoring data;

[0025] The WASP5 software was used to calibrate the parameters of the established river water quality and ecological coupling model using monitoring data until the difference between the model simulation value and the monitoring value was less than the first threshold.

[0026] Optionally, the monitoring data is used to adopt an optimized joint control model of river water quantity and quality that incorporates recycled water to simulate the scheduling and operation of the river landscape environment system, and the simulation operation results are compared with the monitoring data. When the deviation is less than the second threshold, the model is feasible, otherwise it returns for parameter verification.

[0027] Optionally, based on the river water quantity and quality joint control model incorporating recycled water, the nitrogen-phosphorus ratio in the indicative algae species river water environment is optimized, including:

[0028] Collecting water from natural rivers and recycling water sources;

[0029] Conducting total nitrogen concentration and total phosphorus concentration testing on the natural river water source and the collected recycled water source;

[0030] According to the results of total nitrogen concentration and total phosphorus concentration detection, algae were cultured in single water source and mixed water source to obtain the algae growth curve, and the effect of absorbance on algae growth was analyzed;

[0031] Based on the algae growth curve and the effect of absorbance on algae growth, combined with the actual situation of the river channel using recycled water as the water supply source, based on the hydrodynamics and water quality calculation formula, with the goal of inhibiting algae growth and meeting the water supply volume of the river channel, the nitrogen-phosphorus ratio of river water and recycled water with different water volume ratios was calculated;

[0032] Taking nitrogen-phosphorus ratios N:P of 0:1, 5:1, 10:1, 16:1, and 40:1 as standard theoretical interval values, and N:P = 16:1 and N:P = 40:1 as lower and upper critical values ​​for judging that algal cell growth is inhibited, the above steps are repeated until each target in the objective function is achieved.

[0033] Optionally, during the single water source culture and mixed water source culture processes, the culture conditions are set to a temperature of 30°C, a light of 2000 LUX, and a light-dark ratio of 12h:12h.

[0034] The technical solution provided by the embodiments of the present application may have the following beneficial effects:

[0035] It can be seen from the above embodiments that the present application, while utilizing recycled water to supplement seasonal river landscape environment water, overcomes technical problems such as river water quality degradation and abnormal algae reproduction that may occur after recycled water is used for river landscape environment water distribution, thereby achieving the technical effect of reasonable allocation and precise regulation of multiple water sources in seasonal rivers, thereby achieving the goals of simultaneous regulation of algae risk control and river water volume, and further achieving the optimal allocation of the available amount of surface water resources in the basin and the available amount of recycled water.

[0036] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0038] Figure 1 It is a schematic diagram of an implementation object according to an exemplary embodiment.

[0039] Figure 2It is a flow chart showing a method for regulating water distribution in a reclaimed water river landscape environment based on algae risk control according to an exemplary embodiment.

[0040] Figure 3 The figure is a diagram showing the influence of different proportions of mixed water on different algae growth densities according to an exemplary embodiment.

[0041] Figure 4 The figure is a diagram showing the influence of different proportions of mixed water on the growth states of different algae according to an exemplary embodiment.

[0042] Figure 5 It is a generalized diagram of a watershed runoff generation and confluence system based on SWMM software according to an exemplary embodiment.

[0043] Figure 6 is a comparison diagram of a model parameter verification process according to an exemplary embodiment.

[0044] Figure 7 The ecological model chlorophyll a verification process is shown according to an exemplary embodiment. DETAILED DESCRIPTION

[0045] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0046] The embodiment of the present application provides a method for regulating water distribution of a reclaimed water river landscape environment based on algae risk control, which relies on an engineering system for water distribution of seasonal river landscape environment with reclaimed water. The engineering system for water distribution of seasonal river landscape environment with reclaimed water includes a reclaimed water plant, a reclaimed water supply network, and a river channel backwater dam; the river channel backwater dam regulates and stores multiple water sources to form a certain flooding range to meet landscape requirements. The water quantity and quality perception in the regulation can be collected through the following facilities, including but not limited to water quantity and quality monitoring facilities of reclaimed water plants, water quantity detection facilities of reclaimed water supply networks, precipitation monitoring facilities in the basin where seasonal rivers are located, and water quantity and quality monitoring facilities in rivers.

[0047] Figure 1This is a schematic diagram of an implementation object according to an exemplary embodiment. Using nitrogen-phosphorus ratio and water body replacement rate as control indicators, the river with water storage by weirs and dams is used to distribute recycled water to the river landscape environment based on algae risk control. This embodiment takes the seasonal urban river in a county in central Zhejiang as an example. The river suffers from insufficient water in the dry season all year round, and there is a serious shortage of water for the landscape environment, which leads to the water environment quality not meeting expectations, which is far from the overall goal of urban construction. The catchment area of ​​a seasonal urban river is 24km 2 , located in the central urban area of ​​the city, the water shortage for the landscape environment in this basin is solved through the precise allocation of recycled water.

[0048] Figure 2 is a flow chart of a method for regulating water distribution in a reclaimed water river landscape environment based on algae risk control according to an exemplary embodiment. Figure 2 As shown, the method may include the following steps:

[0049] S1: Based on the water source characteristics of seasonal river landscape water and the hydraulic characteristics of river water bodies, and based on the algae growth curve of indicator algae species, the algae risk is controlled using the nitrogen-phosphorus ratio and water body replacement rate as control indicators. The nitrogen-phosphorus ratio is used as a control indicator for free-flowing river sections, and the water body replacement rate is used as a control indicator for backwater sections with water storage and weirs in the river;

[0050] Specifically, based on the water source characteristics of seasonal river landscape environment water use and the hydraulic characteristics of river water bodies, Microcystis aeruginosa and Chlorella vulgaris are used as indicator algae species, and the algae growth curves of the indicator algae species are determined.

[0051] According to the growth curve of the indicative algae species, when phosphorus nutrients are sufficient, the nitrogen-phosphorus ratio of 45:1 is the best condition for the growth of Microcystis; when the phosphorus concentration of recycled water is lower than 0.1 mg / L, water can be distributed as much as possible to avoid eutrophication of the river; when the phosphorus concentration of recycled water is higher than 0.1 mg / L, it is necessary to combine the actual nitrogen and phosphorus conditions of river water and recycled water to decide whether to distribute water. The test results are consistent with the results of relevant literature.

[0052] Figure 3 , Figure 4 The effects of different water source ratios on the density of Microcystis and Chlorella are given. Microcystis aeruginosa and Chlorella grow best and fastest when the ratio of river water to recycled water is 1:1 and 2:1. And through the analysis of the average growth rate, it can be found that the ratio of 1:2 and 0:1 is the least suitable for the growth of Microcystis aeruginosa and Chlorella. In order to control harmful cyanobacteria blooms such as Microcystis, it is recommended that as much water as possible should be supplied to the river when conditions permit.

[0053] The maximum specific growth rate of Microcystis aeruginosa appeared around the 3rd day, and the maximum specific growth rate of Chlorella appeared around the 5th to 7th day. In order to effectively inhibit the occurrence of blue-green algae blooms in the Chengxi River, when there is no rainfall runoff for a long time, the water distribution cycle should not exceed 3 to 6 days, and the 3-day water exchange rate should not be less than 75%.

[0054] S2: Based on the nitrogen-phosphorus ratio and the water body replacement rate, a joint regulation model of water quantity and water quality in the river channel that incorporates recycled water is constructed, wherein the joint regulation model of water quantity and water quality in the river channel that incorporates recycled water is composed of an objective function and constraints, wherein the objective function includes an algae risk control target and a river channel flow or water quantity target, and the constraints include a constraint on the available amount of surface water resources in the basin and a constraint on the available amount of recycled water;

[0055] Specifically, the joint regulation model of river water quantity and quality that incorporates recycled water is composed of an objective function and constraints.

[0056] 1) Objective function:

[0057] 1.1) Algae risk control objectives: When the reclaimed water quality meets the water quality for landscape environment, the ratio of total nitrogen concentration to total phosphorus concentration in the river section water body is controlled within a reasonable range; the replacement rate (or water exchange cycle) ratio in the return water section water body is controlled within a reasonable range.

[0058] The algae risk control objectives are:

[0059] ;

[0060] ;

[0061] Where: is the nitrogen-to-phosphorus ratio in the water of the river section; They are the total nitrogen concentration and total phosphorus concentration in the water of the river section (mg / L); It is divided into the lower limit and upper limit of the reasonable range of nitrogen-phosphorus ratio for controlling algae growth; is the water exchange cycle of the return water body (d); is the water storage capacity of the water body in the return section (m 3 ); are the surface water and recycled water replenishment per unit time of the water body in the backwater section (m 3 / d); They are respectively the lower and upper limits of the reasonable range of water exchange cycle in the return water section (d).

[0062] 1.2) River flow or water volume target: The flow rate target for the river section water body is taken as no less than the larger value between the landscape flow and the environmental flow; the water level target for the backwater section water body is taken as no less than the larger value between the landscape water level and the ecological water level.

[0063] The river flow or water volume targets are:

[0064] ;

[0065] ;

[0066] Where: is the water flow rate of the river section (m 3 / s); is the target flow rate in the river section water body (m 3 / s); are the landscape flow and environmental flow of the river section water body (m 3 / s); is the water level of the return water section (m); is the target water level in the water body of the return section (m); They are the landscape water level and environmental water level of the backwater section water body (m) respectively.

[0067] 1.3) Economic objectives can also be considered: when the water quantity and quality meet the requirements, the operating cost of the recycled water system is minimized.

[0068]

[0069] Where: is the operating cost of the recycled water system (Yuan); is the operating cost of recycled water per cubic meter (Yuan / m 3 ); is the total amount of recycled water used (m 3 ).

[0070] 2) Constraints:

[0071] The available amount constraints of surface water resources and recycled water in this basin are:

[0072] Constraints on the available amount of surface water resources in this basin: ;

[0073] Constraints on the availability of recycled water: ;

[0074] Where: for Surface water replenishment flow and recycled water replenishment flow in this basin during this period (m 3 / s); They are The upper limit of available surface water and recycled water in this basin during this period (m 3 / s).

[0075] When solving the objective function, it is necessary to use the basin water resources and non-point source pollution load calculation model, the river water quality and ecological coupling model and the water balance model. These three models are subject to constraints. Among them, the basin water resources and non-point source pollution load calculation model is constructed using SWMM software, and the river water quality and ecological coupling model and water balance model are constructed using WASP5.

[0076] The SWMM software is used to calibrate the parameters of the established water resources and non-point source pollution load model using monitoring data. The WASP5 software is used to calibrate the parameters of the established river water quality and ecological coupling model using monitoring data until the difference between the model simulation calculation value and the monitoring value is less than the first threshold (for example, 15%).

[0077] Among them, the calculation model of water resources in the basin and non-point source pollution load is:

[0078] The water resources model of the watershed characterizes the inflow process of each sub-basin flow into the rainwater inlet. The nonlinear reservoir model is used to describe the surface runoff process. Each sub-catchment area is generalized as a nonlinear reservoir with a shallow depth. Rainfall is the input, and soil infiltration and surface runoff are the outflow. The continuity equation and Manning's formula are solved together:

[0079]

[0080]

[0081] Where: V is the total water volume of the subcatchment (m 3 ), d is the surface water depth of the subcatchment (m), A is the area of ​​the subcatchment (m 2 ), t is rainfall time (s), i' is net rainfall intensity (mm), Q0 is runoff flow (m 3 / s); W is the characteristic width of the subcatchment (m); n is the Manning coefficient; S is the slope of the subcatchment.

[0082] The non-point source pollution load model represents the non-point source pollution caused by rainfall runoff in the basin, and is solved by the following equation:

[0083]

[0084] Where: M0 is the total amount of non-point source pollution in a certain pollutant area (t); C0 is the non-point source pollution concentration in a certain pollutant area (mg / L).

[0085] Among them, the river water quality and ecological coupling model:

[0086] The river water quality and ecological model uses the following equations to solve the main indicators separately:

[0087] ①Carbonization oxygen demand

[0088]

[0089] Where: C is the concentration of the specific indicator (mg / L), t is the time (s), k is the mineralization rate of the specific indicator, and K is the diffusion coefficient of the specific indicator (m 2 / s), θ is the specific index temperature coefficient ( o C / s), f is the specific index dissolution rate (mol / L), BOD is the biochemical oxygen demand (mg / L), and in addition, the terms in the above formula represent the death of phytoplankton, carbon oxidation, particle sedimentation, denitrification, organic matter sedimentation, suspension, and diffusion.

[0090] ②Dissolved oxygen

[0091]

[0092] The units of the parameters in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent reoxygenation, carbon oxidation, nitrification, sediment oxygen demand, growth, and respiration. The calculation method for saturated dissolved oxygen concentration is:

[0093] ③Circulation equation of ammonia nitrogen

[0094]

[0095] The units of each parameter in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent phytoplankton death, mineralization, phytoplankton growth, and nitrification, respectively.

[0096] ④ Nitrate nitrogen cycle equation

[0097]

[0098] The units of the parameters are the same as those in the above formulas. In addition, the terms in the above formula represent nitrification, phytoplankton growth, and denitrification, respectively.

[0099] ⑤Circulation equation of organic nitrogen

[0100]

[0101] The units of each parameter in the formula are the same as those in the previous formulas. In addition, each term in the above formula represents phytoplankton death, mineralization, and organic matter deposition, respectively.

[0102] ⑥Inorganic phosphorus (PO4) cycle

[0103]

[0104] The units of each parameter in the formula are the same as those in the previous formulas. In addition, each term in the above formula represents phytoplankton death, mineralization, and phytoplankton growth, respectively.

[0105] ⑦Organic phosphorus (OP) cycle

[0106]

[0107] The units of each parameter in the formula are the same as those in the previous formulas. In addition, each term in the above formula represents phytoplankton death, mineralization, and sedimentation, respectively.

[0108] ⑧ Phytoplankton nitrogen cycle

[0109]

[0110] The units of the parameters in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent growth, death, and particle sedimentation respectively.

[0111]

[0112]

[0113] ⑨Phytoplankton phosphorus cycle

[0114]

[0115] The units of the parameters are the same as those in the previous formulas. In addition, the terms in the above formula represent growth, death, and particle sedimentation, respectively.

[0116] Among them, the water balance model:

[0117] Water balance model of river section water body:

[0118] Water balance model of the return water section:

[0119] Where: They are The water flow of the river section during the period, the surface water replenishment flow of the basin and the recycled water replenishment flow (m 3 / s); They are Water storage capacity of the return water section at the beginning and end of the time period (m 3 ); They are The amount of surface water replenishment, recycled water replenishment and evaporation and leakage loss in the water body of the return water section of the basin during the period (m 3 / s).

[0120] The SWMM software was used to construct a calculation model for water resources and non-point source pollution load in this basin. The basin system is summarized in Figure 5 , the model parameter verification process is shown in Figure 6In this embodiment, SWMM software is used to establish a watershed model of the river where the embodiment is located and to perform grid division for water resource calculation, as shown in FIG. Figure 5 The established model was calibrated and verified using the on-site monitoring data of the river where the embodiment is located. The verification results are shown in Figure 6 shown.

[0121] The reaction kinetic relationship between various water quality indicators in WASP5 is used to simulate the spatiotemporal dynamic changes of major water quality indicators such as nitrogen, phosphorus, and chlorophyll. Figure 7 Under different water source and water volume ratios, the verification results of the spatiotemporal dynamic changes of major water quality indicators such as nitrogen, phosphorus, and chlorophyll are good, meeting the model accuracy control requirements.

[0122] S3: Based on the river water quantity and quality joint control model that incorporates recycled water, the nitrogen-phosphorus ratio in the water environment of the indicative algae species river is optimized;

[0123] Specifically, natural river water sources and recycled water sources are collected; the total nitrogen concentration and total phosphorus concentration of the natural river water sources and the collected recycled water sources are detected; according to the results of the total nitrogen concentration and total phosphorus concentration detection, algae are cultured in single water source and mixed water source to obtain algae growth curves, and the effect of absorbance on algae growth is analyzed; based on the algae growth curve and the effect of absorbance on algae growth, combined with the actual situation of the river channel with recycled water as the water supply source, based on the hydrodynamics and water quality calculation formulas, with the goal of inhibiting algae growth and meeting the water supply volume of the river channel, the nitrogen-phosphorus ratio of river water and recycled water with different water volume ratios is calculated; with nitrogen-phosphorus ratios N:P of 0:1, 5:1, 10:1, 16:1, and 40:1 as standard theoretical interval values, N:P = 16:1 and N:P = 40:1 as the lower critical value and upper critical value for judging the inhibition of algae cell growth, the above steps are repeated until each target in the objective function is achieved.

[0124] In the single water source culture and mixed water source culture processes, the culture conditions were set as a temperature of 30°C, a light of 2000LUX (luminance), and a light-dark ratio of 12h:12h.

[0125] S4: Based on the optimized nitrogen-phosphorus ratio, optimize the joint regulation model of water quantity and quality of rivers that incorporate recycled water;

[0126] Specifically, after the model is verified, the algae risk control target, river flow or water volume, the available amount constraints of surface water resources in this basin and the available amount constraints of recycled water are used as control conditions to carry out joint regulation and optimization of the water volume and water quality of the river in the embodiment that incorporates recycled water.

[0127] S5: Use the optimized model for joint regulation of water quantity and quality in rivers that incorporate recycled water to conduct joint regulation of water quantity and quality.

[0128] Specifically, the monitoring data is used to adopt an optimized joint control model of river water quantity and quality that incorporates recycled water to simulate the scheduling and operation of the river landscape environment system. The simulation operation results are compared with the monitoring data. When the deviation is less than the second threshold (for example, 10%), the model is feasible, otherwise it returns for parameter verification.

[0129] Under the conditions of this embodiment, the response relationship of chlorophyll a at different water distribution flow rates of the target river reclaimed water is shown in Table 1.

[0130] Table 1 Chlorophyll a concentration and response time of monitoring section under different water distribution flow rates of reclaimed water;

[0131]

[0132] Joint control strategy of water quantity and quality:

[0133] Main influencing factors: precipitation conditions and recycled water quality conditions. On the one hand, precipitation brings short-term input of non-point source pollution, resulting in short-term deterioration of river water quality; on the other hand, the influx of rainwater causes an increase in river water volume and water level, which supplements the shortage of water for river landscape environment. Recycled water quantity and quality conditions: Due to treatment technology reasons, the water quality of recycled water plants fluctuates to a certain extent from season to season.

[0134] Control strategy: A multi-objective and multi-scenario control strategy that takes water quantity and quality dual control as the goal, is based on full-process perception data, and uses precipitation-based recycled water control as the means.

[0135] The medium- and long-term regulation plan for this basin: When the water level at the river monitoring control point is lower than 57.77m, the recycled water distribution will be started. When the water level at the control point reaches 57.77 or above, if the water quality at the factory is worse than the benchmark value, the water diversion will be stopped on the same day; water distribution will be started again after the water quality at the outlet is better than the benchmark value. Under rainfall conditions, when the water level at the river monitoring control point exceeds 58.23m, water distribution will be stopped; after the rainfall stops and the water level drops below 57.8m, water distribution will be started again.

[0136] It can be seen from the above embodiments that the present application, while utilizing recycled water to supplement seasonal river landscape environment water, overcomes technical problems such as river water quality degradation and abnormal algae reproduction that may occur after recycled water is used for river landscape environment water distribution, thereby achieving the technical effect of reasonable allocation and precise regulation of multiple water sources in seasonal rivers.

[0137] Those skilled in the art will readily appreciate other embodiments of the present application after considering the description and practicing the contents disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The description and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the claims.

[0138] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for regulating water distribution in a reclaimed water river landscape environment based on algae risk control, characterized in that: include: According to the water source characteristics of seasonal river landscape water and the hydraulic characteristics of river water bodies, based on the algae growth curve of indicator algae species, the algae risk is controlled using the nitrogen-phosphorus ratio and water body replacement rate as control indicators. The nitrogen-phosphorus ratio is used as a control indicator for free-flowing river sections, and the water body replacement rate is used as a control indicator for backwater sections with water storage and weirs in the river; Based on the nitrogen-phosphorus ratio and the water body replacement rate, a joint regulation model of water quantity and water quality in a river channel that incorporates recycled water is constructed. The joint regulation model of water quantity and water quality in a river channel that incorporates recycled water consists of an objective function and constraints. The objective function includes an algae risk control target and a river flow or water quantity target. The constraints include constraints on the available amount of surface water resources in the basin and the available amount of recycled water. Based on the river water quantity and quality joint control model that incorporates recycled water, the nitrogen-phosphorus ratio in the water environment of the indicative algae species river is optimized; Based on the optimized nitrogen-phosphorus ratio, the joint regulation model of water quantity and quality of rivers that incorporate recycled water is optimized; Use the optimized river water quantity and quality joint control model that incorporates recycled water to conduct joint control of water quantity and quality; Among them, the algae risk control objectives are: ； ； Where: is the nitrogen-to-phosphorus ratio in the water of the river section; They are the total nitrogen concentration and total phosphorus concentration in the water of the river section respectively; It is divided into the lower limit and upper limit of the reasonable range of nitrogen-phosphorus ratio for controlling algae growth; The water exchange cycle of the return water section; is the water storage capacity of the water body in the return water section; They are the replenishment volume per unit time of surface water and recycled water in the water body of the return water section; They are the lower and upper limits of the reasonable interval of water exchange cycle in the return water section; The river flow or water volume targets are: ； ； Where: is the water flow of the river section; is the target flow in the water body of the river section; They are the landscape flow and environmental flow of the water body in the river section respectively; is the water level of the return water section; is the target water level in the water body of the return section; They are the landscape water level and environmental water level of the backwater section water body respectively; The available amount constraints of surface water resources and recycled water in this basin are: Constraints on the available amount of surface water resources in this basin: ; Constraints on the availability of recycled water: ; Where: for The surface water replenishment flow and recycled water replenishment flow of the basin during this period; They are The upper limit of the available surface water volume and recycled water volume in the basin during the period; When solving the objective function, it is necessary to use the basin water resources and non-point source pollution load calculation model, the river water quality and ecological coupling model and the water balance model. These three models are subject to constraints. Among them, the basin water resources and non-point source pollution load calculation model is constructed using SWMM software, and the river water quality and ecological coupling model and water balance model are constructed using WASP5. The SWMM software was used to calibrate the parameters of the established water resources and non-point source pollution load model using monitoring data; The WASP5 software was used to calibrate the parameters of the established river water quality and ecological coupling model using monitoring data until the difference between the model simulation value and the monitoring value was less than the first threshold; Among them, the calculation model of water resources in the basin and non-point source pollution load is: The water resources model of the watershed characterizes the inflow process of each sub-basin flow into the rainwater inlet. The nonlinear reservoir model is used to describe the surface runoff process. Each sub-catchment area is generalized as a nonlinear reservoir with a shallow depth. Rainfall is the input, and soil infiltration and surface runoff are the outflow. The continuity equation and Manning's formula are solved together: Where: V is the total water volume of the subcatchment (m 3 ), d is the surface water depth of the subcatchment (m), A is the area of ​​the subcatchment (m 2 ), t is rainfall time (s), i' is net rainfall intensity (mm), Q0 is runoff flow (m 3 / s); W is the characteristic width of the subcatchment (m); n is the Manning coefficient; S is the slope of the subcatchment; The non-point source pollution load model represents the non-point source pollution caused by rainfall runoff in the basin, and is solved by the following equation: ； Where: M0 is the total amount of non-point source pollution in a certain pollutant area (t); C0 is the concentration of non-point source pollution in a certain pollutant area (mg / L); Among them, the river water quality and ecological coupling model: The river water quality and ecological model uses the following equations to solve the main indicators separately: ①Carbonization oxygen demand: ； Where: C is the concentration of the specific indicator (mg / L), t is the time (s), k is the mineralization rate of the specific indicator, and K is the diffusion coefficient of the specific indicator (m 2 / s), θ is the specific index temperature coefficient ( o C / s), f is the specific index dissolution rate (mol / L), BOD is the biochemical oxygen demand (mg / L), and in addition, the terms in the above formula represent the death of phytoplankton, carbon oxidation, particle sedimentation, denitrification, organic matter sedimentation, suspension, and diffusion respectively; ②Dissolved oxygen: ； The units of the parameters in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent reoxygenation, carbon oxidation, nitrification, sediment oxygen demand, growth, and respiration. The calculation method for saturated dissolved oxygen concentration is: ③Circulation equation of ammonia nitrogen: ； The units of the parameters in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent phytoplankton death, mineralization, phytoplankton growth, and nitrification respectively; ④Circulation equation of nitrate nitrogen: ； The units of the parameters in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent nitrification, phytoplankton growth, and denitrification, respectively; ⑤Circulation equation of organic nitrogen: ； The units of the parameters in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent phytoplankton death, mineralization, and organic matter deposition respectively; ⑥Inorganic phosphorus (PO4) cycle: ； The units of the parameters in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent phytoplankton death, mineralization, and phytoplankton growth respectively; ⑦Organic phosphorus (OP) cycle: ； The units of the parameters in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent phytoplankton death, mineralization, and sedimentation respectively; ⑧Phytoplankton nitrogen cycle: ； The units of the parameters are the same as those in the above formulas. In addition, the terms in the above formula represent growth, death, and particle sedimentation respectively; where: ； ； ⑨Phytoplankton phosphorus cycle: ； The units of the parameters in the formula are the same as those in the previous formulas. In addition, the terms in the above formula represent growth, death, and particle sedimentation respectively; Among them, the water balance model: Water balance model of river section water body: ; Water balance model of the return water section: ; Where: They are The water flow of the river section during the period, the surface water replenishment flow of the basin and the recycled water replenishment flow (m 3 / s); They are Water storage capacity of the return water section at the beginning and end of the time period (m 3 ); They are The amount of surface water replenishment, recycled water replenishment and evaporation and leakage loss in the water body of the return water section of the basin during the period (m 3 / s).

2. The method for regulating water distribution in a reclaimed water river landscape environment based on algae risk control according to claim 1, characterized in that: The optimized river water quantity and quality joint control model incorporating recycled water is used based on the monitoring data to simulate the scheduling and operation of the river landscape environment system. The simulation results are compared with the monitoring data. When the deviation is less than the second threshold, the model is feasible, otherwise it is returned for parameter verification.

3. The method for regulating water distribution in a reclaimed water river landscape environment based on algae risk control according to claim 1, characterized in that: Based on the joint regulation model of river water quantity and quality incorporating recycled water, the nitrogen-phosphorus ratio in the water environment of the indicative algae species river is optimized, including: Collecting water from natural rivers and recycling water sources; Conducting total nitrogen concentration and total phosphorus concentration testing on the natural river water source and the collected recycled water source; According to the results of total nitrogen concentration and total phosphorus concentration detection, algae were cultured in single water source and mixed water source to obtain the algae growth curve, and the effect of absorbance on algae growth was analyzed; Based on the algae growth curve and the effect of absorbance on algae growth, combined with the actual situation of the river channel using recycled water as the water supply source, based on the hydrodynamics and water quality calculation formula, with the goal of inhibiting algae growth and meeting the water supply volume of the river channel, the nitrogen-phosphorus ratio of river water and recycled water with different water volume ratios was calculated; Taking nitrogen-phosphorus ratios N:P of 0:1, 5:1, 10:1, 16:1, and 40:1 as standard theoretical interval values, and N:P = 16:1 and N:P = 40:1 as lower and upper critical values ​​for judging that algal cell growth is inhibited, the above steps are repeated until each target in the objective function is achieved.

4. The method for regulating water distribution in a reclaimed water river landscape environment based on algae risk control according to claim 1, characterized in that: During the single water source culture and mixed water source culture processes, the culture conditions were set as a temperature of 30°C, a light of 2000 LUX, and a light-dark ratio of 12h:12h.

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