Method for calculating and evaluating water quality of water body based on multi-medium action

Abstract

The invention belongs to the technical field of basin water environment simulation and prediction, and particularly relates to a water quality calculation and evaluation method based on multi-medium action. By comprehensively considering the influence of the interaction among multiple media on the water body, the accuracy and systematicness of simulation are improved, and the method has high flexibility and expandability, can be applied to various water environment management scenes, and provides powerful support for scientific decision making.

Description

Technical Field

[0001] The present invention belongs to the technical field of watershed water environment simulation and prediction, and particularly relates to a method for calculating and evaluating water quality of water bodies based on multi-medium interaction. Background Art

[0002] At present, the numerical simulation technology of water environment mainly relies on water quality models. These models generally use numerical calculation methods, and their core lies in the discretization of mathematical equations. However, traditional water quality models often ignore the complex mechanism of water quality pollution during construction, especially the pollutant transport process between different media (such as atmosphere, water body, sediment), and the interaction between these media and aquatic plants and microbial communities. This simplified treatment makes it difficult to accurately describe and simulate the pollutant transport mechanism in the comprehensive ecosystem of air-water-sediment-aquatic plant-microorganism through existing mathematical methods. Therefore, the existing water quality models have certain limitations in terms of refined simulation and prediction capabilities, and it is difficult to comprehensively reflect the dynamic changes of pollutants and their ecological effects in the real water environment. In order to improve the accuracy and practicality of simulation, future research needs to further integrate multidisciplinary knowledge, deeply explore the cross-media transport mechanism of pollutants and their ecological impacts, so as to develop more complex and refined water quality models.

[0003] The work of water ecological environment protection has entered a new stage, and the research focus is not only limited to the water environment itself, but gradually focuses on the comprehensive consideration of the health and balance of the water ecological environment system. In actual work, we not only need to consider water quality, but also pay attention to the cycling process of nutrients in aquatic organisms, sediments and water bodies. The water ecological system includes media such as water, mud, and organisms, involves nutrient exchange at interfaces such as water-air, water-sediment, and water-organism, and also includes the impact of aquatic organism growth and decomposition on the water body and the self-purification effect of microorganisms on the water body. The refined simulation of the water ecological environment based on physical mechanisms can reproduce and predict the migration and transformation of nutrients in different media, which is of great significance for studying the evolution mechanism of lake and wetland water ecology and continuously improving the quality of the water ecological environment.

[0004] The exchange of matter and energy at the water-air interface has a significant impact on the water ecology. Water temperature and dissolved oxygen are important factors affecting the water ecological system of lakes, reservoirs and wetlands. With global climate change and human activity interference, abnormal change trends of surface water dissolved oxygen and water temperature frequently appear. Therefore, exploring the temperature conduction and reoxygenation mechanism at the water-air interface is beneficial to optimizing the water ecological system simulation model and more deeply predicting the changes of the water ecological system.

[0005] The migration and transformation of nutrients at the water-sediment interface is an important means for the study of endogenous sources in natural water bodies. In natural water bodies, sediments are reservoirs for pollutants. After pollutants enter the water body, they will enter the sediments and gradually accumulate. Sediments are a type of solid-phase medium with the widest contact with the water body in lake wetlands. The interface between the sediments covering the largest area of the entire lake bottom and the overlying water body constitutes the water-sediment interface in a macroscopic sense. Most of the pollutants in the surface sediments are in an active or incompletely degraded state and are extremely likely to participate in the material exchange within the sediments and at the sediment-water interface. Therefore, it is of great significance to explore the principles of particulate nutrient deposition in the water body and the diffusion of dissolved nutrients in the sediments, which can quantitatively evaluate the migration and transformation of nutrients at the water-sediment interface, predict and manage the eutrophication risk of the water body, and thus provide a basis for water environmental protection strategies.

[0006] The nutrient transfer at the water-aquatic plant interface is an important path for studying the water purification effect of aquatic organisms. Biological characteristics such as the plant species of aquatic plants, plant planting density, plant growth rate, plant biomass, nutrient absorption, spatial distribution layout, nutrient release rate, and seasonal cycle mortality will all have positive or negative impacts on the water environment of lake and wetland water bodies. Numerical simulation of the growth and decay of aquatic plants is beneficial to the reasonable allocation of the growth coverage area of aquatic plants and the scientific management of the biomass during the plant life cycle, providing an additional tool for the improvement and management of the water quality of lake and wetland water bodies.

[0007] The nutrient transfer at the water-aquatic animal interface is also an important path for studying the water purification effect of aquatic organisms. Biological characteristics such as the distribution of aquatic animals, animal types, animal growth rate, animal nutrient absorption, animal natural mortality, animal body decomposition rate, animal body decomposition products and proportions, and animal fishing rate will all have positive or negative impacts on the water environment of lake and wetland water bodies. Quantifying the nutrient transfer between water and aquatic animals provides an additional tool for the improvement and management of the water quality of lake and wetland water bodies.

[0008] Microbial growth plays a very important role in the self-purification process of water bodies. Through the measurement of oxygen microprofiles, denitrification rates, sediment nitrogen content, and microbial community composition, it is concluded that microorganisms are of great significance for the treatment of nitrogen pollution in eutrophic water bodies. Increasing the environmental temperature can promote microbial activity and the influence of sediments on phosphorus adsorption. However, the current domestic research on the microbial community structure and functional characteristics is still relatively limited. Therefore, in-depth exploration of the potential of microorganisms to remove pollutants such as nitrogen and phosphorus in water bodies and their key limiting factors helps to effectively optimize microbial treatment strategies and improve the self-purification efficiency of water bodies. Summary of the Invention

[0009] Based on the above analysis, the technical solution of this application discloses a method for calculating and evaluating the water quality of water bodies based on multi-media left communication, including the following steps:

[0010] S1. Medium division: Divide the water body into media according to time sequence, space and properties, and divide the water body into water, atmosphere, sediment, aquatic plants, aquatic animals and microbial media;

[0011] S2. Characteristic evaluation of the divided medium states:

[0012] S3. Evaluation of the exchange characteristics at the water-medium interface:

[0013] S4. Evaluation of the impact of the convection-diffusion mechanism under the hydrodynamic action of natural water bodies on water quality;

[0014] S5. Evaluation of the impact of multi-medium coupling on water body water quality.

[0015] Furthermore, the medium states described in S2 are respectively:

[0016] (1) Atmospheric state parameters: temperature, oxygen content, atmospheric pressure, nutrient content;

[0017] (2) Sediment state parameters: sediment thickness, porosity, nutrient (carbon, nitrogen, phosphorus, etc.) components, organic matter mineralization rate, sediment diagenesis rate;

[0018] (3) Aquatic plant state parameters: plant distribution, plant type, plant growth rate, plant nutrient uptake, plant decomposition rate, plant decomposition products and proportions, plant management methods;

[0019] (4) Aquatic animal state parameters: animal distribution, animal type, animal growth rate, animal nutrient uptake, animal natural mortality rate, animal body decomposition rate, animal body decomposition products and proportions, animal fishing rate;

[0020] (5) Microbial state parameters: microbial distribution, microbial type, microbial growth rate, microbial nutrient uptake, microbial natural mortality rate, microbial body decomposition rate, microbial body decomposition products and proportions;

[0021] (6) Water body state parameters: flow rate, water depth, flow velocity, water temperature, particulate nutrient concentration (carbon, nitrogen, phosphorus), dissolved nutrient concentration (carbon, nitrogen, phosphorus).

[0022] Furthermore, the evaluation of the medium interface exchange characteristics described in S3 includes:

[0023] (1) Water-air interface exchange flux: light intensity, temperature exchange, dissolved oxygen reaeration, dry deposition, wet deposition;

[0024] Flux1 = f1(I, T, DO, w1, w2)

[0025] Among them: Flux1 is the nutrient flux at the water-air interface, g / m2 ·d; I is the light intensity, ××; DO is the dissolved oxygen in water, mg / l; w1 and w2 are atmospheric deposition, g / m 2 ·d.

[0026] (2) Water-sediment interface exchange flux: particulate nutrient deposition, dissolved nutrient diffusion;

[0027] Flux2 = f2(pwm, dwm, dsm, wpm, codif)

[0028] Where: Flux2 is the nutrient flux at the water-sediment interface, g / m 2 ·d; pwm is the concentration of particulate nutrients in water, mg / l; dwm is the concentration of dissolved nutrients in water, mg / l; dsm is the concentration of dissolved nutrients in sediment, mg / l; wpm is the deposition rate of particulate nutrients in water, g / m 2 ·d; codif is the diffusion coefficient of dissolved nutrients at the water-sediment interface, m 2 / s.

[0029] (3) Water-plant interface exchange flux: nutrient uptake by plant growth, nutrient release by plant decomposition, harvest rate;

[0030] Flux3 = f3(con3, gr, met, pr)

[0031] Where: Flux3 is the nutrient flux at the water-aquatic plant interface, g / m 2 ·d; con3 is the plant density, g / m 2 ; gr is the nutrient uptake rate by aquatic plant growth, g / m 2 ·d; met is the nutrient release rate by aquatic plant decomposition, g / m 2 ·d; pr is the harvest rate of aquatic plants, dimensionless.

[0032] (4) Water-animal interface exchange flux: nutrient release by animal decomposition;

[0033] Flux4 = f4(con4, bmet, cob)

[0034] Where: Flux4 is the nutrient flux at the water-aquatic animal interface, g / m 2 ·d; con4 is the density of aquatic animals, g / m 2 ; bmet is the death rate of aquatic animals, g / m 2 ·d; cob is the proportion of nutrient release from the death of aquatic animals, dimensionless.

[0035] (5) Water-microorganism interface exchange: nutrient uptake by microorganism growth, nutrient release by microorganism decomposition;

[0036] Flux5 = f5(con5, mgr, mmet, mpr)

[0037] Where: Flux5 is the nutrient flux at the water-microbe interface, g / m 2 ·d; con5 is the microbe density, g / m 2 ; mgr is the nutrient absorption rate for microbe growth, g / m 2 ·d; mmer is the nutrient release rate from microbe decomposition, g / m 2 ·d; mpr is the microbe removal rate, dimensionless.

[0038] Furthermore, the impact assessment of the advection-diffusion mechanism on water quality described in S4 is as follows: Using a hydrodynamic water quality model, calculate the advection-diffusion coefficient of the water body under hydrodynamic action,

[0039] Flux6 i,j = f6(wcon i , wcon j , cohw i,j )

[0040] Where: Flux6 i,j is the nutrient flux from region j to region i under dynamic action, g / d; wcon i , wcon j are the nutrient concentrations in the water bodies of regions i and j respectively, mg / l; cohw i,j is the dynamic action coefficient from region j to region i under dynamic action, dimensionless.

[0041] Furthermore, the impact assessment of the multi-media coupling effect on the water quality of the water body described in S5 is as follows:

[0042] con i = con1 i + Flux6 i,j ·86400 / V i

[0043] Where: con i , con1 i are the nutrient concentrations before and after the calculation period in region i respectively, mg / l; V i is the volume of the water body in region i, m 3 .

[0044] The beneficial effects of the present invention lie in comprehensively considering the influence of the interaction between multi-media on the water body, improving the accuracy and systematicness of the simulation, having high flexibility and scalability, and being able to be applied to various water environment management scenarios, providing strong support for scientific decision-making. Detailed implementation manners

[0045] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0046] Unless otherwise specifically stated, the relative arrangements, numerical expressions and values of the components and steps set forth in these embodiments do not limit the scope of the present application. Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0047] Embodiment 1 A method for calculating and evaluating the water quality of water bodies based on the action of multiple media

[0048] Step 1. Divide the media: Divide the water body of the target water quality to be evaluated into six media: water, atmosphere, sediment, aquatic plants, aquatic animals, and microorganisms.

[0049] Step 2. Evaluate the state characteristics of the media respectively, where

[0050] (1) The analysis indexes of the water body state characteristics include flow rate, water depth, flow velocity, water temperature, particulate nutrient concentration (carbon, nitrogen, phosphorus), and dissolved nutrient concentration (carbon, nitrogen, phosphorus);

[0051] (2) The analysis indexes of the atmosphere state characteristics include air temperature, oxygen content, atmospheric pressure, and nutrient content;

[0052] (3) The analysis indexes of the sediment state characteristics include sediment thickness, porosity, nutrient (carbon, nitrogen, phosphorus, etc.) components, organic matter mineralization rate, and sediment diagenesis rate;

[0053] (4) The analysis indexes of the aquatic plant state characteristics include plant distribution, plant type, plant growth rate, plant nutrient uptake, plant decomposition rate, plant decomposition products and proportions, and plant management methods;

[0054] (5) The analysis indexes of the aquatic animal state characteristics include animal distribution, animal type, animal growth rate, animal nutrient uptake, animal natural mortality rate, animal decomposition rate, animal decomposition products and proportions, and animal fishing rate;

[0055] (6) The analysis indicators of microbial state characteristics include microbial distribution, microbial type, microbial growth rate, microbial nutrient uptake, microbial natural mortality rate, microbial body decomposition rate, microbial body decomposition products and their proportions.

[0056] Step 3. Evaluate the characteristics of medium interface exchange

[0057] (1) Water-air interface exchange flux: light intensity, temperature exchange, dissolved oxygen reaeration, dry deposition, wet deposition;

[0058] Flux1 = f1(I, T, DO, w1, w2)

[0059] Where: Flux1 is the nutrient flux at the water-air interface, g / m 2 ·d; I is the light intensity, lx; T is the temperature, °C; DO is the dissolved oxygen in water, mg / l; w1, w2 are the atmospheric depositions, g / m 2 ·d.

[0060] (2) Water-sediment interface exchange flux: particulate nutrient deposition, dissolved nutrient diffusion;

[0061] Flux2 = f2(pwm, dwm, dsm, wpm, codif)

[0062] Where: Flux2 is the nutrient flux at the water-sediment interface, g / m 2 ·d; pwm is the concentration of particulate nutrients in water, mg / l; dwm is the concentration of dissolved nutrients in water, mg / l; dsm is the concentration of dissolved nutrients in sediment, mg / l; wpm is the deposition rate of particulate nutrients in water, g / m 2 ·d; codif is the diffusion coefficient of dissolved nutrients at the water-sediment interface, m 2 / s.

[0063] (3) Water-plant interface exchange flux: nutrient uptake by plant growth, nutrient release by plant decomposition, harvesting rate;

[0064] Flux3 = f3(con3, gr, met, pr)

[0065] Where: Flux3 is the nutrient flux at the water-aquatic plant interface, g / m 2 ·d; con3 is the plant density, g / m 2 ; gr is the nutrient uptake rate by aquatic plant growth, g / m 2 ·d; met is the nutrient release rate by aquatic plant decomposition, g / m 2 ·d; pr is the harvesting rate of aquatic plants, dimensionless.

[0066] (4) Water - animal interface exchange flux: Nutrients are released during the decomposition of animals;

[0067] Flux4 = f4(con4, bmet, cob)

[0068] Where: Flux4 is the nutrient flux at the water - aquatic animal interface, g / m 2 ·d; con4 is the density of aquatic animals, g / m 2 ; bmet is the death rate of aquatic animals, g / m 2 ·d; cob is the proportion of nutrient release during the death of aquatic animals, dimensionless.

[0069] (5) Water - microorganism interface exchange: Microorganisms grow and absorb nutrients, and microorganisms decompose and release nutrients;

[0070] Flux5 = f5(con5, mgr, mmet, mpr)

[0071] Where: Flux5 is the nutrient flux at the water - microorganism interface, g / m 2 ·d; con5 is the density of microorganisms, g / m 2 ; mgr is the nutrient absorption rate during the growth of microorganisms, g / m 2 ·d; mmet is the nutrient release rate during the decomposition of microorganisms, g / m 2 ·d; mpr is the removal rate of microorganisms, dimensionless.

[0072] Step 4. Evaluation of the impact of the convection - diffusion mechanism on water quality under the hydrodynamic action of natural water bodies: Use the hydrodynamic water quality model to calculate the convection - diffusion coefficient of the water body under hydrodynamic action,

[0073] Flux6 i,j = f6(wcon i , wcon j , cohw i,j )

[0074] Where: Flux6 i,j is the nutrient flux from region j to region i under dynamic action, g / d; wcon i , wcon j are the nutrient concentrations of the water bodies in regions i and j respectively, mg / l; cohw i,j is the dynamic action coefficient from region j to region i under dynamic action, dimensionless.

[0075] Step 5. Evaluation of the impact of multi - medium coupling on water quality.

[0076] con i = con1 i + Flux6i,j ·86400 / V i

[0077] Wherein: con i and con1 i are the nutrient concentrations before and after the calculation period in area i, respectively, in mg / l; V i is the water volume of area i, in m 3 .

[0078] Although the content of the present invention has been described in detail through the above embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A water quality calculation and evaluation method based on multi-media left-flow, characterized in that: The steps include: S1. Divide media: Divide water bodies into water, atmosphere, sediment, aquatic plants, aquatic animals and microorganisms according to time sequence, space and attributes; S2. Characteristic evaluation of the divided medium state: S3. Evaluate the exchange characteristics between water and medium interface: S4. Assessment of the impact of convection-diffusion mechanisms on water quality under the hydrodynamic effects of natural water bodies; S5. Assessment of the impact of multi-media coupling on water quality.

2. The evaluation method according to claim 1, characterized in that: The medium states described in S2 are: (1) Atmospheric state parameters: temperature, oxygen content, atmospheric pressure, and nutrient salt content; (2) Sediment state parameters: sediment thickness, porosity, nutrient (carbon, nitrogen, phosphorus, etc.) composition, organic matter mineralization rate, sedimentary diagenesis rate; (3) Aquatic plant status parameters: plant distribution, plant type, plant growth rate, plant nutrient absorption, plant decomposition rate, plant decomposition products and proportions, and plant management methods; (4) Aquatic animal status parameters: animal distribution, animal type, animal growth rate, animal nutrient absorption, animal natural mortality rate, animal body decomposition rate, animal body decomposition products and proportions, animal capture rate; (5) Microbial status parameters: microbial distribution, microbial type, microbial growth rate, microbial nutrient absorption, microbial natural mortality rate, microbial decomposition rate, microbial decomposition products and proportions; (6) Water state parameters: flow rate, water depth, flow velocity, water temperature, concentration of particulate nutrients (carbon, nitrogen, phosphorus), and concentration of dissolved nutrients (carbon, nitrogen, phosphorus).

3. The evaluation method according to claim 1, characterized in that: S3 The medium interface exchange characteristic evaluation includes: (1) Water-air interface exchange flux: light intensity, temperature exchange, dissolved oxygen reoxygenation, dry deposition, and wet deposition; Flux1=f1(I,T,DO,w1,w2) Where: Flux1 is the nutrient flux at the water-air interface, g / m 2 ·d; I is light intensity, ××; DO is dissolved oxygen in water, mg / l; w1 and w2 are atmospheric deposition, g / m 2 ·d. (2) Water-sediment interface exchange flux: deposition of particulate nutrients and diffusion of dissolved nutrients; Flux2=f2(pwm,dwm,dsm,wpm,codif) Where: Flux2 is the nutrient flux at the water-sediment interface, g / m 2 ·d; pwm is the concentration of particulate nutrients in the water, mg / l; dwm is the concentration of dissolved nutrients in the water, mg / l; dsm is the concentration of dissolved nutrients in the sediment, mh / l; wpm is the deposition rate of particulate nutrients in the water, g / m 2 ·d; codif is the diffusion coefficient of dissolved nutrients at the water-sediment interface, m 2 / s. (3) Water-plant interface exchange flux: plant growth absorption of nutrients, plant decomposition release of nutrients, and harvest rate; Flux3=f3(con3,gr,met,pr) Where: Flux3 is the nutrient flux at the water-aquatic plant interface, g / m 2 d;con3 is plant density, g / m 2 gr is the nutrient absorption rate of aquatic plants, g / m 2 ·d; met is the nutrient release rate of aquatic plants during decomposition, g / m 2 ·d; pr is the aquatic plant harvest rate, dimensionless. (4) Water-animal interface exchange flux: animal decomposition releases nutrients; Flux4=f4(con4,bmet,cob) Where: Flux4 is the nutrient flux at the water-aquatic animal interface, g / m 2 d;con4 is the density of aquatic animals, g / m 2 ; bmet aquatic animal mortality rate, g / m 2 ·d; cob is the ratio of nutrients released by dead aquatic animals, dimensionless. (5) Water-microorganism interface exchange: microbial growth absorbs nutrients, and microbial decomposition releases nutrients; Flux5=f5(con5,mgr,mmet,mpr) Where: Flux5 is the nutrient flux at the water-microorganism interface, g / m 2 ·d;con5 is the density of microorganisms, g / m 2 ; mgr is the nutrient absorption rate of microbial growth, g / m 2 ·d; mmet is the nutrient release rate of microbial decomposition, g / m 2 ·d; mpr is microbial removal rate, dimensionless.

4. The evaluation method according to claim 1, characterized in that: The impact of the convection-diffusion mechanism on water quality described in S4 is assessed by using a hydrodynamic water quality model to calculate the convection-diffusion coefficient of the water body under the action of hydrodynamic forces. Flux6 i,j =f6(wcon i ,wcon j ,cohw i,j ) Among them: Flux6 i,j is the nutrient flux from region j to region i under dynamic action, g / d; wcon i 、wcon j are the nutrient concentrations in the water bodies of regions i and j, mg / l; cohw i,j is the dynamic action coefficient of region j on region i under dynamic action, dimensionless.

5. The evaluation method according to claim 1, characterized in that: The impact of multi-media coupling on water quality described in S5 is evaluated as follows: con i =con1 i +Flux6 i,j ·86400 / V i Among them: con i 、con1 i are the nutrient concentrations in region i before and after the calculation period, mg / l; V i is the volume of water in region i, m 3 .