Urban water body health measurement method driven by composite indexes

Abstract

The invention discloses a composite index-driven urban water body health measurement method, which belongs to the field of environmental sciences, and constructs a new index system comprising 12 composite indexes such as algae apparent turbidity, water body algae primary productivity, oxygen dynamic equilibrium index, multi-element spectrum blotting and the like; aiming at the complexity of the urban water body, the invention provides the urban water body health measurement method driven by the composite indexes by taking the composite indexes and the key water quality indexes as elements, taking the water body nutrition level, the water body cleanliness degree and the ecosystem elasticity as key dimensions and taking self-adaption and quick response as cores. According to the method, the limitations of water quality and biological index separation, evaluation and early warning separation, lack of pertinence of an index system, incapability of feeding back internal optimization, neglect of an advanced monitoring technology and the like of a traditional urban water environment evaluation method are broken through, and a theoretical foundation is laid for water ecology monitoring and evaluation system research; the method is applied to urban water to realize rapid grading quantitative evaluation of the water ecological health state.

Description

Technical Field

[0001] The invention belongs to the field of environmental science, and in particular relates to a composite indicator-driven urban water health measurement method. Background Art

[0002] The current water environment assessment methods are still insufficient in the face of complex and dynamically changing environments. In particular, the current comprehensive assessment of water ecological health often focuses on health in a narrow sense and fails to fully consider the monitoring and assessment of water ecological risks. At the same time, the research limitations of water quality-biological composite indicators and driving factors make it difficult for traditional evaluation systems to quickly respond to potential risks and water environment deterioration trends when faced with extreme situations and the fuzzy space of multi-indicator cross-evaluation. Therefore, there is an urgent need for a comprehensive and systematic water ecological health dynamic assessment method and a new monitoring system to match it. It is necessary to break through the development and application of new composite indicators, build a systematic water ecological health dynamic measurement model and algorithm, develop a multi-level dynamic adaptive urban water health measurement framework that can provide real-time warnings, accurately grasp the water ecological health status and rapid warning of water ecological safety, so as to meet the key requirements of water quality assurance and ecological safety of the aquatic ecosystem. Summary of the invention

[0003] In response to the technical problems raised in the background technology, the present invention innovatively proposes that the evaluation of the water ecological health system is like conducting a comprehensive physical examination of the human body and generating comprehensive evaluation results. Among them, the nutrient level of the water body is analogous to the human health index value. The human body needs appropriate nutrition to maintain health. Similarly, the appropriate amount of nutrients in the water body is also crucial to biological growth and ecological balance. If the nutrients are too low, productivity will be reduced, and if they are too high, it may cause excessive reproduction of algae and destroy the balance; the cleanliness of the water body can be compared to the appearance of a person, which directly reflects the overall health of the water body. High transparency indicates that the water body is healthy, and turbidity or odor may indicate pollution; the resilience of the ecosystem can be compared to the human immune level. Strong resilience indicates that the system can effectively respond to pollution and maintain its metabolic capacity and carrying capacity, just like a person with a healthy physique can effectively resist disease. Further, the present invention determines corresponding evaluation indicators for the three key dimensions of aquatic ecological health. These indicators include single indicators and composite indicators to ensure a comprehensive evaluation of each dimension.

[0004] The technical solution of the present invention is as follows:

[0005] A composite indicator-driven urban water health measurement method includes the following steps:

[0006] Step 1: Obtain indicators

[0007] The index acquisition includes single index and composite index. The composite index is obtained by fitting and calculating after the single index is acquired. The number of composite indexes is 12, which are divided into four categories of composite indexes, including algae composite index, organic matter composite index, dissolved oxygen composite index and water quality composite index.

[0008] The algae composite index includes algae nutrient ratio NP=TN / TP, algae production per unit equivalent nutrient ETP=Chla / TP, ETN= Chla / TN, apparent turbidity per unit mass of algae AT=Tur / Chla, and primary productivity level of algae in water body GPP;

[0009] The organic compound index includes multivariate spectral imprint MT;

[0010] The dissolved oxygen composite index includes dissolved oxygen saturation DO%, dissolved oxygen flux DO flux and oxygen dynamics balance index ODEI;

[0011] The water quality composite index includes the internal pollution index CPI, the water quality health index WQHI and the comprehensive water toxicity ATA based on the photosynthesis inhibition effect of algae.

[0012] Step 2: Obtain the water body nutrient level grade based on the water body nutrient level identification path

[0013] First, a preliminary judgment is made based on TP to determine the level of nutrients and judge it as lacking, limited or sufficient; secondly, TN, chla and algae composite indicators NP, ETP, ETN are supplemented in a targeted manner to preliminarily determine the threshold and water nutrient level; then oxygen composite indicators are supplemented to assist in identification in the critical interval; finally, GPP is supplemented to the fuzzy interval to obtain the water nutrient level grade;

[0014] Step 3: Obtain the water cleanliness level based on the water cleanliness identification path

[0015] First, a preliminary judgment is made based on the apparent turbidity Tur of the water body to determine the two extremes of cleanliness and turbidity, and at the same time, the fuzzy interval of the water body cleanliness is judged. Then, the internal pollution level and the algae apparent turbidity are supplemented to obtain the water body cleanliness level.

[0016] Step 4: Obtain ecosystem resilience level based on ecosystem resilience identification pathway

[0017] First, during the N days of continuous monitoring, the system stage and water quality health status within N days were divided according to the WQHI and its changing trend. (1) The system stage can be divided into the recovery stage and the interference deterioration stage; (2) The water quality health status can be divided into excellent, fuzzy and poor.

[0018] For the analysis of monitoring data on recovery capacity in the recovery phase, the water quality recovery degree RD is considered first, including the recovery rate RR and the recovery speed RS; secondly, the water body self-purification capacity (dissolved oxygen composite index analysis) is supplemented for the fuzzy interval that cannot be judged. The water body self-purification capacity is mainly judged based on DO% and ODEI;

[0019] For the monitoring data analysis of the stabilization ability during the disturbance stage, first, if the WQHI changes within a certain range, it can be considered that the fluctuation is acceptable and the stabilization ability is strong. If the water quality volatility is unacceptable, the stabilization ability is weak. If it is in the fuzzy interval, the functional stability index GPP (ecosystem metabolic capacity) is supplemented. If the metabolic capacity is acceptable in the disturbance stage, the stability is strong. If the metabolic capacity is unacceptable in the disturbance stage, the stability is weak. If it is in the fuzzy interval, the biological stability index (biodiversity) is also needed for auxiliary judgment, mainly to judge the Shannon-Winner index of algae during the disturbance stage.

[0020] For the analysis of monitoring data on adaptive capacity, firstly, the changes in the disturbance-recovery WQHI are comprehensively considered to reflect the stability and recovery of water quality in the whole cycle. Secondly, the biological adaptive capacity is supplemented for the fuzzy interval that cannot be judged. The biological adaptive capacity is mainly judged based on the plankton integrity index (P-IBI, alternative for zooplankton);

[0021] Finally, the ecosystem resilience rating is obtained.

[0022] Step 5: Multi-dimensional dynamic weighting calculation

[0023] If two or more of the three dimensions have a score of <20, it means that the water ecological health level is poor. If one of the three dimensions has a score of <20, it means that the water ecological health level is poor; if two or more of the three dimensions have a score of >80, it means that the water ecological health level is excellent; if one of the three dimensions has a score of >80, it means that the water ecological health level is good. The rest are defined as fuzzy intervals, and the comprehensive index TCR is calculated:

[0024] ,

[0025] Among them, TCR represents the comprehensive index of water ecological health, s represents the score corresponding to a single dimension, and w represents the weight corresponding to a single dimension;

[0026] (1) If the nutrient level of the water body is oligotrophic at this time, it means that the N and P concentrations are low, which usually corresponds to clean or relatively clean water. However, the ecosystem may be very sensitive to external disturbances at this time, and special attention should be paid to ecological resilience. Oligotrophic: The weights of water nutrient level, water cleanliness level and ecosystem resilience level are 0.15, 0.15 and 0.7 respectively.

[0027] (2) If the nutrient level of the water body is at a mild or moderate eutrophication, it means that algae are multiplying in large numbers and it is easy to transition to a more severe eutrophication. The cleanliness of the water body may fluctuate significantly, but the metabolic capacity of the ecosystem is often strong. Therefore, elasticity is not the most important limiting factor. Consider giving the two dimensions of the water body a higher weight, especially in the case of moderate eutrophication. The weights of the water nutrient level, water cleanliness and ecosystem resilience are 0.3, 0.3 and 0.4 respectively.

[0028] Step 6: Obtain the comprehensive index of urban water ecological health

[0029] The comprehensive index of urban water ecological health is obtained according to the weighted calculation in step 5. On the one hand, it is judged according to the extreme value of a single dimension. For the fuzzy interval, the comprehensive index of urban water ecological health TCR is calculated according to the formula, and the urban water ecological health level in the fuzzy interval is classified into three levels: good (>80), medium (40~80), and poor (<40).

[0030] Step 7: Ecosystem safety level identification path

[0031] The present invention determines a multi-level rapid warning indicator system, including first-level warning indicators MT and DO%, second-level warning indicators AT, GPP and ODEI, and comprehensive water quality toxicity indicators for extreme situations.

[0032] DO% is selected as the first-level water ecological early warning indicator. When DO% shows an abnormality, the system can combine MT to further clarify the dominant pollution type of the abnormality, whether it is algal pollution caused by algal growth or decomposition, or exogenous pollution caused by natural processes and human activities. For algal pollution, algal composite indicators such as AT and GPP should be supplemented. For exogenous input pollution, focus should be placed on ODEI, which is closely related to the self-purification capacity of water bodies and organic matter. At the same time, GPP is supplemented as an auxiliary judgment. Finally, to ensure that the system can fully respond to various situations in urban water scenarios, toxicity indicators are supplemented to identify potential water ecological risks under extreme conditions.

[0033] Beneficial effects:

[0034] (1) Systematically integrating water quality indicators and biological indicators, the present invention constructs a new indicator system including 12 composite indicators such as algae apparent turbidity, primary productivity of algae in water bodies, oxygen dynamics balance index, and multivariate spectral imprinting;

[0035] (2) In view of the complexity of urban water bodies, this paper proposes a composite indicator-driven urban water health measurement method based on composite indicators and key water quality indicators as elements, water nutrient level, water cleanliness and ecosystem resilience as key dimensions, and self-adaptation and rapid response as the core. This method breaks through the limitations of traditional urban water environment evaluation methods, such as the separation of water quality and biological indicators, the separation of evaluation and early warning, the lack of pertinence of the indicator system, the inability to feedback internal optimization, and the neglect of advanced monitoring technology. It lays a theoretical foundation for the research of water ecological monitoring and evaluation system, and can be applied to urban water to achieve rapid hierarchical and quantitative evaluation of water ecological health status. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the composition of the urban water ecological health measurement indicator system;

[0037] Figure 2 A flowchart of a composite indicator-driven urban water health measurement method;

[0038] Figure 3 This is a flowchart of the progressive evaluation path. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0040] Example

[0041] like Figure 1 , Figure 2 and Figure 3 As shown in the figure, a composite indicator-driven urban water health measurement method is described as follows:

[0042] 1. Water nutrient level

[0043] For the nutrient level of water bodies, a preliminary judgment is made based on TP to determine the level of algal nutrients. Subsequently, TN, Chla, NP, ETP, and ETN are supplemented to determine the limiting factors and eutrophication response thresholds. For the fuzzy space of eutrophication, GPP is further used for auxiliary identification to improve the accuracy of identification and evaluation.

[0044] 2. Water cleanliness

[0045] In the evaluation of water cleanliness, a preliminary judgment is first made based on Tur to determine the two extremes of cleanliness and turbidity, while also judging the fuzzy space of water cleanliness. Second, the internal pollution and algae apparent turbidity are supplemented for fine identification.

[0046] 3. Ecosystem Resilience

[0047] For ecosystem resilience, the system is first divided into different stages and water quality health status based on WQHI and its changing trends, and then the stabilization capacity, recovery capacity and adaptability are evaluated respectively. The stabilization capacity assessment starts with the acceptability of water quality fluctuations based on WQHI. If there are ambiguous results, the functional stability is checked, first of all, the dissolved oxygen in the water body (DO% and DO flux). If this step fails to clearly identify, the WQHI is used to further evaluate the carbon and nutrient cycling capacity, and GPP data is added when needed to calculate the acceptability of fluctuations in the metabolic capacity of the ecosystem. If the identification is still ambiguous, the Shannon-Winner index is further used to measure and grade biological stability; for recovery capacity, the water quality recovery rate RR and recovery speed RS are first considered based on WQHI; secondly, DO% and ODEI are supplemented to the fuzzy space to measure the self-purification capacity of the water body; the adaptability assessment is based on the full-cycle environmental capacity deviation, and P-IBI is supplemented to the fuzzy space to assist in identification. Finally, the assessment results of ecosystem resilience are calculated based on the VOR framework.

[0048] IV. Ecosystem Security Early Warning

[0049] In addition, in order to enhance the early warning function of the new evaluation system, the present invention specially designs a reverse water ecological safety early warning path. Compared with the periodic positive evaluation identification, although this path shares monitoring equipment, there are significant differences between data collection and path analysis modes. Specifically, the reverse early warning path will use real-time or near real-time data for rapid screening, focusing on key composite indicators, and quickly judging the state of the water body in a short time step. Abnormal screening results will trigger the correction of the forward identification path and the optimization of the detection frequency of indicators such as TN, TP, COD, and supplement toxicity assessment when high risks are detected.

[0050] 5. Multi-dimensional accounting and quantitative grading

[0051] For multi-dimensional accounting, the results of single-dimensional calculations are first quantitatively graded, and the classification results reflect the nutrient level, cleanliness and resilience of the water body. After determining the extreme cases, a comprehensive accounting is performed for the fuzzy space, and the weight setting is dynamically adjusted according to the state of the water body. For example, in an environment with poor nutrients, nutrient level and cleanliness are less important, while resilience is more critical.

[0052] On the contrary, in an environment with large algae growth, the importance of nutrition level and cleanliness will increase, while the importance of resilience will decrease accordingly. Finally, the evaluation results are divided into five levels in combination with the grading standards of the evaluation system. So far, the present invention has established a calculation method for the comprehensive index of water ecological health, and at the same time proposed a systematic water ecological health status evaluation method based on a new indicator system, a new identification path and a new calculation model.

[0053] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A composite indicator-driven urban water health measurement method, characterized in that: The steps include: Step 1: Obtain indicators; Step 2, obtaining the water body nutrient level grade according to the water body nutrient level identification path; Step 3, obtaining the water cleanliness level according to the water cleanliness identification path; Step 4: Obtain the ecosystem resilience level based on the ecosystem resilience identification path; Step 5: Multi-dimensional dynamic weighted accounting; Step 6: Obtain the comprehensive index and health level of urban water ecological health.

2. The method for measuring urban water health driven by composite indicators according to claim 1 is characterized by: In step 1, the index acquisition includes a single index and a composite index. The composite index is obtained by fitting and calculating after the single index is acquired. The number of the composite indexes is 12, which are divided into four categories of composite indexes, including algae composite index, organic matter composite index, dissolved oxygen composite index and water quality composite index; The algae composite index includes algae nutrient ratio NP=TN / TP, algae production per unit equivalent nutrient ETP=Chla / TP, ETN= Chla / TN, algae apparent turbidity per unit mass AT=Tur / Chla, and algae primary productivity level GPP in water bodies; The organic compound index includes multivariate spectral imprint MT; The dissolved oxygen composite index includes dissolved oxygen saturation DO%, dissolved oxygen flux DO flux and oxygen dynamic balance index ODEI=Rr / Or; The water quality composite index includes the internal pollution index CPI, the water quality health index WQHI and the comprehensive water toxicity ATA based on the photosynthesis inhibition effect of algae.

3. The method for measuring urban water health driven by composite indicators according to claim 1 is characterized by: In step 2, firstly, a preliminary judgment is made based on TP to determine the level of nutrients and judge it as lacking, limiting or sufficient; secondly, TN, chla and algae composite indicators NP, ETP, ETN are supplemented in a targeted manner to preliminarily judge the threshold and water nutrient level; then, oxygen composite indicators are supplemented to the critical interval to assist in identification; finally, GPP is supplemented to the fuzzy interval to obtain the water nutrient level grade.

4. The method for measuring urban water health driven by composite indicators according to claim 1 is characterized by: In step 3, first, a preliminary judgment is made based on the apparent turbidity Tur of the water body to determine the two extremes of cleanliness and turbidity, and at the same time, the fuzzy interval of the water body cleanliness is judged. Then, the internal pollution level and the algae apparent turbidity are finely identified to obtain the water body cleanliness level.

5. The method for measuring urban water health driven by composite indicators according to claim 1 is characterized by: In step 4, first, within N days of continuous monitoring, the system stage and water quality health status within N days are divided according to the WQHI and its change trend. (1) The system stage can be divided into the recovery stage and the interference deterioration stage; (2) The water quality health status can be divided into excellent, fuzzy and poor; For the analysis of monitoring data of recovery capacity in the recovery stage, the water quality recovery degree RD is considered first, including the recovery rate RR and the recovery speed RS; secondly, the water body self-purification capacity is supplemented for the fuzzy interval that cannot be judged. The water body self-purification capacity is mainly judged based on DO% and ODEI; For the monitoring data analysis of the stabilization ability during the disturbance stage, first, if the WQHI changes within a certain range, it can be considered that the fluctuation is acceptable and the stabilization ability is strong. If the water quality volatility is unacceptable, the stabilization ability is weak. If it is in the fuzzy interval, the functional stability index GPP is supplemented. If the metabolic capacity is acceptable in the disturbance stage, the stability is strong. If the metabolic capacity is unacceptable in the disturbance stage, the stability is weak. If the fuzzy interval needs to be supplemented with biological stability indicators for auxiliary judgment, it is mainly to judge the Shannon-Winner index of algae in the disturbance stage. For the analysis of monitoring data on adaptive capacity, firstly, the changes of disturbance-recovery WQHI are comprehensively considered to reflect the stability and recovery degree of water quality in the whole cycle. Secondly, the biological adaptive capacity is supplemented for the fuzzy interval that cannot be judged. The biological adaptive capacity is mainly judged based on the plankton integrity index. Finally, the ecosystem resilience rating is obtained.

6. The method for measuring urban water health driven by composite indicators according to claim 1 is characterized by: In step 5, if two or more of the three dimensions have a score of <20, it means that the water ecological health level is poor; if one of the three dimensions has a score of <20, it means that the water ecological health level is poor; if two or more of the three dimensions have a score of >80, it means that the water ecological health level is excellent; if one of the three dimensions has a score of >80, it means that the water ecological health level is good; the rest are defined as fuzzy intervals, and the comprehensive index TCR is calculated: ， Among them, TCR represents the comprehensive index of water ecological health, s represents the score corresponding to a single dimension, and w represents the weight corresponding to a single dimension; (1) If the water nutrient level is oligotrophic, the weights of the water nutrient level, water cleanliness level, and ecosystem resilience level are 0.15, 0.15, and 0.7, respectively; (2) If the water nutrient level is at a mild or moderate eutrophication level, the weights of the water nutrient level, water cleanliness level and ecosystem resilience level are 0.3, 0.3 and 0.4 respectively.

7. The method for measuring the health of urban water bodies driven by composite indicators according to claim 1 is characterized by: In step 6, the comprehensive index of urban water ecological health is obtained according to the weighted calculation in step 5. On the one hand, it is judged according to the extreme value of a single dimension. For the fuzzy interval, the comprehensive index of urban water ecological health TCR is calculated according to the formula, and the urban water ecological health level in the fuzzy interval is classified into three levels: good (>80), medium (40~80), and poor (<40).

8. The method for measuring the health of urban water bodies driven by composite indicators according to claim 1 is characterized by: The method also includes step 7, identification of ecosystem safety level. In step 7, the multi-level rapid warning indicator system includes the first-level warning indicators MT and DO%, the second-level warning indicators AT, GPP and ODEI, and the comprehensive water quality toxicity indicator for extreme situations; DO% is selected as the first-level water ecological warning indicator; when DO% shows an abnormality, the system combines MT to clarify the dominant pollution type of the abnormality, whether it is algae pollution caused by algae growth or decomposition, or exogenous pollution caused by natural processes and human activities; for algae pollution, the algae composite indicator is supplemented, and for exogenous input pollution, the focus is on ODEI, which is closely related to the self-purification capacity of the water body and organic matter, and GPP is supplemented as an auxiliary judgment; finally, the toxicity indicator is supplemented to identify potential water ecological risks in extreme situations.

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