Eco-environmental quality evaluation of water source area

4.3. 1 ecological environment evaluation standard

When evaluating the ecological environment, an appropriate standard is needed. Ecological environment is a complex system composed of many factors interacting and restricting each other, including the changes of internal essence (ecological structure) and external appearance (environmental function), as well as the development and change law from quantitative change to qualitative change. Therefore, the standard system of evaluation is not only complex, but also varies from place to place. At present, China lacks eco-environmental standards, mainly due to the lack of research on eco-environmental benchmarks. The standard of ecological environment assessment is mainly based on:

(1) National, industrial and local standards: environmental quality standards promulgated by the state, such as water quality standards for farmland irrigation, maximum allowable concentration of air pollutants for crop protection, standards for safe use of pesticides, food hygiene standards, etc. Industry standards refer to the environmental assessment norms, regulations and design requirements issued by the industry. Standards issued by local governments, planning area objectives, water system protection requirements and protection requirements of special areas (such as greening rate requirements and soil erosion prevention requirements) are all optional evaluation criteria.

(2) Background and background standard: the background value and background value of the regional ecological environment are used as evaluation standards, such as regional vegetation coverage, regional soil erosion background value, biological yield, biodiversity, etc.

(3) Analogy standard: take the similar ecological environment that has not been seriously disturbed by human beings or the primitive natural ecosystem under similar natural conditions as analogy standard; The ecological factors and functions of similar conditions are used as analogy standards, such as biodiversity, vegetation coverage, water storage function, windbreak and sand fixation ability of similar habitats. The analogy standard should be scientifically selected according to the evaluation content and requirements.

(4) Scientific research has judged the ecological effect. Through scientific research under local or similar conditions, the requirements of greening rate, the maximum allowable amount of pollutants in organisms and the environmental quality requirements of particularly sensitive organisms can be used as evaluation standards or reference standards.

The evaluation criteria of this book are mainly based on the special research results of comprehensive evaluation of ecological environment in Henan Province and the results of other related researchers.

4.3.2 Introduction of main methods of ecological environment assessment

In the work of ecological environment evaluation, evaluation method is an indispensable means of ecological environment evaluation. At present, the ecological environment assessment methods used at home and abroad mainly include the following:

(1) Analogy analysis method: It is a commonly used qualitative and semi-quantitative method, which generally includes analogy of ecological environment as a whole, analogy of ecological factors and analogy of ecological environment problems. Analogy analysis is a common method in eco-environmental impact assessment. According to the impact of existing development and construction activities on the ecological environment, this method analyzes or predicts the possible ecological environment impact of development and construction activities. Choosing a good analogy object is the basis of analogy analysis or prediction evaluation, and it is also the key to the success or failure of this method.

(2) List method: It is a qualitative analysis method proposed by Little et al. in 197 1. It lists the impacts of the planned development and construction activities and various eco-environmental factors that may be affected in the same table, analyzes them point by point, and indicates the nature and intensity of the impacts with positive and negative symbols, numbers and other symbols, so as to analyze the eco-environmental impacts of the development and construction activities.

(3) Ecological map method: that is, graphic superposition method, that is, more than two pieces of ecological environment information are superimposed on a map to form a composite map to indicate the direction and degree of ecological environment change. This method is intuitive, vivid, simple and clear, and cannot be used for accurate quantitative evaluation. Ecological map method is mainly used in regional environmental impact assessment, or evaluation of super-large construction projects with regional influence, as well as land use planning and agricultural development planning.

(4) Comprehensive evaluation method of ecosystem: Ecosystem is a multi-level complex system and an open system composed of many factors (biological factors and abiotic factors). It is the most commonly used evaluation method to recognize and evaluate such a complex system by combining qualitative and quantitative methods. The specific application of this method is analytic hierarchy process, which systematizes, models and quantifies the decision-making thinking process of complex phenomena, and is also called multi-level weight analysis decision. Analytic Hierarchy Process has many applications. Yao Jian (1998) applied analytic hierarchy process (AHP) to various eco-environmental quality assessments.

(5) Index and comprehensive index evaluation method: In environmental impact assessment, index method is the prescribed evaluation method. Index method and comprehensive index method are suitable for single factor evaluation and multi-factor comprehensive evaluation of ecological environment quality. The method is relatively simple, which highlights the comprehensiveness, hierarchy, objectivity and comparability of eco-environmental quality assessment, and is one of the commonly used evaluation methods at present. But before using this method, an appropriate index system and evaluation standard must be established, and the selected indexes must be comparable. Through the evaluation, the regional eco-environmental quality can be graded, so as to compare the eco-environmental quality in different regions and different periods vertically and horizontally. The disadvantage of this method in practical application is that it is difficult to weight and quantify accurately.

(6) Fuzzy evaluation method: There are often some uncertain factors in the process of ecological environment evaluation, which leads to the uncertainty and distortion of the evaluation results. Fuzzy set theory can improve the reliability of evaluation results, so fuzzy evaluation method is introduced into ecological environment evaluation. The key of this method is to find a fuzzy evaluation matrix. Its biggest feature is to define the boundary of eco-environmental quality classification with membership degree, which can be used to classify eco-environmental quality, divide the advantages and disadvantages of eco-environmental quality, and highlight the areas with poor eco-environmental quality as key areas. Commonly used fuzzy evaluation methods include fuzzy comprehensive evaluation method and fuzzy clustering evaluation method. Xu Fuliu (200 1) and Yao Jian (1998) combined fuzzy clustering and analytic hierarchy process to evaluate urban environmental quality and watershed ecological environmental quality respectively.

(7) Evaluation method of artificial neural network: Artificial neural network is composed of a large number of simple neurons, which rely on computers to obtain superb computing power. By simulating the complex network system of human brain thinking mode, it uses accumulated knowledge to obtain recognition and association abilities similar to those of human beings. Therefore, the artificial neural network is used to learn the known environmental samples, acquire prior knowledge, and learn to identify and evaluate new samples. Li Zuoyong et al. (1999) and Tang Lini et al. (2003) developed the application of artificial neural network B-P model in ecological environment assessment. When B-P network model is applied to environmental quality assessment, it is not necessary to specify the weight of each evaluation index artificially, and it will be adjusted adaptively during the learning process, so the evaluation result is objective. In addition, the B-P network can select any number of evaluation parameters according to different needs to establish an ecological environment quality evaluation model, and this method has strong adaptability.

(8) Landscape ecological method: Landscape pattern and its changes are the comprehensive reflection of a certain regional ecological environment system caused by the interaction of various natural and human factors. The type, shape, size, quantity and spatial combination of landscape blocks are the result of the interaction of various interference factors, which also affect the regional ecological process and edge effect. Therefore, the study of landscape spatial pattern in a certain region is an effective means to reveal the ecological situation and spatial variation characteristics of the region. Different ecological structures in the study basin are divided into landscape unit patches, and the regional ecological environment status is given from a macro perspective through quantitative analysis of landscape spatial pattern and landscape heterogeneity characteristic index. This method evaluates the ecological environment from two aspects: one is the analysis of spatial structure; The second is function and stability analysis. This evaluation method can reflect the basic principle that the structure and function of ecosystem are consistent.

(9) Other methods:

1) Multi-factor quantitative analysis: the change of ecological environment in a certain time and range is determined by the change and state of various ecological factors. Therefore, by measuring the changing trend of various ecological factors, we can carry out correlation analysis and principal component analysis of ecological factors, and then analyze the changing trend of ecological environment.

2) Regression analysis: it is a statistical analysis method to study the relationship between two or more variables. One variable in regression analysis is a dependent variable, and the rest are independent variables. We can find the statistical relationship between independent variables and dependent variables by monitoring or observing data.

3) System analysis method: For multi-objective dynamic problems, system analysis method can be used for evaluation.

4.3.3 Ecological environment evaluation index system

Eco-environmental quality evaluation is based on the selected index system and quality standards, using appropriate methods to evaluate the quality of a regional eco-environment and its impact. If it is the ecosystem information based on the current situation of the system, it is the evaluation of the current situation of ecological environment quality; If the prediction information of ecological environment change is applied to the evaluation, it is the prediction and evaluation of ecological environment quality; If the goal is to evaluate the relationship between the change of ecosystem quality and the influence of engineering objects, it can be called eco-environmental impact assessment. Comprehensive evaluation of eco-environmental quality is a systematic research work, involving many fields of nature and humanities, among which the theories and methods of ecology, environmental science and resource science are of great significance to guide eco-environmental quality evaluation.

The speed and degree of ecological environment deterioration depend on the interference intensity of human activities and the fragility of the ecological environment itself, while the quality of the ecological environment is affected by many environmental factors, and the fragility of the ecological environment is formed by the interaction or superposition of many factors. On different time and space scales, the degree of ecological fragility caused by the same reason is different. Whether the eco-environmental evaluation index system is reasonable or not directly affects the accuracy and reliability of the evaluation results. When constructing the eco-environmental evaluation index system of a specific region, we should choose the environmental factors that can best reflect the local eco-environmental quality and its changes.

4.3.3. 1 Selection principle of evaluation index

(1) scientific principle: the selection of evaluation indicators should be based on scientific accuracy, and indicators that can reflect the essential characteristics and changes of ecological environment quality in the evaluation area should be selected. At the same time, in order to compare with neighboring areas, the selected indicators should be unified and quantified as much as possible.

(2) Principle of comprehensiveness: To comprehensively measure many environmental factors considered, the index system should comprehensively reflect all aspects of the ecological environment and conduct comprehensive analysis and evaluation.

(3) Dominant principle: There are many factors that restrict the quality of ecological environment. It is impossible to scientifically evaluate the quality and change of ecological environment with a single factor, but it is neither possible nor realistic to generalize. Therefore, we should choose the leading indicators that are representative and can directly reflect the main characteristics of regional ecological environment quality. For example, among the factors of eco-environmental quality evaluation in the Loess Plateau, soil erosion is the main limiting factor, and the indicators related to soil erosion should be considered in the selection of indicators, such as precipitation, rainfall intensity, soil texture, vegetation status, erosion modulus, farming methods, etc.

(4) the principle of operability: the selection of indicators should consider the availability and collectability of data as much as possible. Although some indicators can well reflect the present situation and changes of ecological environment quality, they are not available in the process of ecological environment quality evaluation.

Therefore, when selecting indicators, the principles of conciseness, convenience, effectiveness and practicality should be followed, that is, by summarizing the theories of related disciplines, the observation data that have great influence on the quality of ecological environment and are easy to obtain are obtained, which is conducive to the production and management departments to master and operate, and to closely combine theory with practice.

Establishment of Evaluation Index System in 4.3.3.2

Based on the evaluation index system of eco-environmental quality established by scholars at home and abroad, combined with the actual situation of the study area, according to the above-mentioned principles of selecting evaluation indexes, through the comprehensive and systematic analysis and research of natural environment and human factors in the study area, the restrictive factors or leading factors of eco-environmental quality evaluation are identified, and the specific indicators that best represent and reflect the essential characteristics of eco-environmental quality in this area are screened out, and finally the comprehensive evaluation index system of water source eco-environment is formulated. Considering the problems existing in the local natural, social, economic and ecological environment in the evaluation area and the factors affecting the quality of the ecological environment, the established index system is constantly adjusted and improved in the work. In this study, 8 first-class indicators and 23 second-class indicators closely related to ecological environment quality were selected (Table 4. 13).

4.3.4 Ecological Environment Assessment Based on Analytic Hierarchy Process

The terrain of the water source area is complex, and the terrain inclines from northwest to southeast. Laojieshan, the main vein of Funiu Mountain, is a northern barrier, with the highest elevation of 22 12.5m, and the terrain in the southeast drops, with the lowest elevation of 120m. Laojieshan, the main vein of Funiu Mountain, crosses the northern boundary of the water source from west to east. The water source area belongs to agricultural planting area, and its economic development is relatively backward. The per capita arable land is 0.07hm2, which is lower than the average level of Nanyang and Henan. The contradiction between man and land is very prominent. At present, due to the scarcity of forest vegetation, poor quality, low water storage and soil consolidation capacity, unreasonable farming methods, the deterioration of ecological environment, serious soil erosion, soil pollution caused the decline of cultivated land fertility, wetlands and biodiversity, surface water quality and groundwater level and other ecological and environmental problems. As the water source area of the Middle Route of South-to-North Water Transfer Project, the ecological situation in this area has attracted much attention. A comprehensive evaluation of the present situation of the ecological environment in this region and an early warning study of the ecological environment in the water source area can provide countermeasures and suggestions for the protection of the ecological environment in the water source area and provide scientific guidance for ensuring the water quality safety of the Middle Route Project of South-to-North Water Transfer. In this study, analytic hierarchy process (AHP) was used to evaluate the ecological environment of water source area.

Table 4. 13 comprehensive evaluation index system of ecological environment in water source area of South-to-North Water Transfer Project

4.3.4. 1 analytic hierarchy process

Analytic Hierarchy Process (AHP) was put forward by T.L.Saaty, a famous American expert in operational research, in 1970s. Its basic idea is to establish an orderly hierarchical system according to the nature of the problem and the required overall goal, and then compare and judge all related problems in the system. Through the comprehensive calculation and processing of the comparative evaluation results, the system analysis is attributed to the determination of the relative importance weight of the lowest layer relative to the highest layer or the ranking of the relative advantages and disadvantages. Analytic Hierarchy Process (AHP) has been widely used in the analysis and decision-making of complex systems at home and abroad. The technical means are relatively mature, thus ensuring the rationality and effectiveness of the research method.

The analytic hierarchy process (AHP) is used to comprehensively evaluate the ecological environment of water source area. Firstly, the AHP model of eco-environmental factors is established. Its basic principle is: decompose all the elements of the related schemes of the evaluation system into several levels, judge and compare all the elements of the same level according to the previous level, calculate the weight of each element, and determine the optimal scheme according to the principle of comprehensive weight and maximum weight. The analytic hierarchy process can be roughly divided into five steps, namely: ① establishing a hierarchical structure model; (2) constructing a judgment matrix; ③ Hierarchical single sorting and its consistency test; (4) hierarchical general sorting; ⑤ Consistency test of hierarchical total sorting. The detailed description of the above steps will be explained in the following ecological environment assessment.

Establishment of Hierarchical Structure Model of Ecological Environment Assessment in 4.3.4.2

Combined with the actual ecological environment in the study area, the factors that have obvious influence on the ecological environment in this area are selected (Table 4. 13), and the ecological environment index system of water source area is divided into three layers (Figure 4.8).

4.3.4.3 constructs judgment matrix.

Any systematic analysis must have certain information, and the information of analytic hierarchy process is mainly people's judgment on the relative importance of each factor at each level. These judgments are quantized by introducing appropriate scales to form a judgment matrix. The judgment matrix indicates the comparison of the relative importance between a certain factor at the higher level and the related factors at the same level. In the comprehensive evaluation of the ecological environment in the water source area, A is the target layer, indicating the purpose of solving the problem, that is, the overall goal to be achieved by the level. B is the middle layer, indicating the intermediate link involved in achieving the predetermined overall goal by adopting a certain scheme. As the main basic element involved in the highest level, let B={B 1, B2, B3, B4, B5, B6, B7, B8}, where B 1 is climate condition, B2 is water resource condition, B3 is landform condition and B4 is vegetation condition. C is the lowest layer, indicating the specific index factors to realize the evaluation, and it is C={C 1, C2, C3, C4, C5, C6, C7, C8, C9, C 10, c1.

Figure 4.8 Analytic Hierarchy Process Model for Comprehensive Evaluation of Ecological Environment

According to the established AHP model, the judgment matrices of A-B and B-C are constructed, as shown in Table 4. 14. Each element {Cij} in the judgment matrix indicates the relative importance of the i-th factor to the Bk factor compared with the j-th factor among the factors related to the superior factor Bk. In order to quantify the judgment, T.L.Saaty is generally quoted.

According to the proposed 1 ~ 9 scale method, determine the values of Bij and Cij according to the proposed 1 ~ 9 scale (Table 4. 15). On the basis of table 4. 15, according to the data, the researchers' understanding of the actual situation and the opinions of consulting experts, the judgment matrix value of ecological environment evaluation in the study area is given by Delphi method.

Table 4. 14 A-B-C judgment matrix

Table 4. Values of15 Judgment Matrix and Its Significance

A. Hierarchical single sorting and consistency checking

According to the judgment matrix of some factors in a certain level to some factors in the previous level, the maximum eigenvalue and eigenvector of the judgment matrix can be calculated, so as to calculate the relative importance of some factors in a certain level relative to some factors in the previous level. These ranking calculations are called hierarchical ranking. The maximum eigenvalue of the judgment matrix and its corresponding eigenvector can be obtained by cholesky decomposition, and the calculation steps are as follows:

1) calculate the product Mi of the elements in each row of the judgment matrix a.

Theory, Method and Practice of Ecological Security of Land Resources in Henan Province

2) Calculate the nth root Wi of Mi.

Theory, Method and Practice of Ecological Security of Land Resources in Henan Province

3) Normalized vector W=(W 1, W2, …, Wn)T, namely

Theory, Method and Practice of Ecological Security of Land Resources in Henan Province

Then W=(W 1, W2, …, Wn)T is the desired feature vector.

4) Calculate the maximum characteristic root λmax of the judgment matrix.

Theory, Method and Practice of Ecological Security of Land Resources in Henan Province

Where: (AW)i represents I elements of vector AW.

Because of the complexity of objective things or the one-sidedness of understanding things, it is necessary to test the consistency and randomness of the judgment matrix to determine whether the feature vectors (weights) obtained from the constructed judgment matrix are reasonable. The formula is:

CR=CI/RI

CI is the consistency index of the judgment matrix, which is calculated by the following formula:

Theory, Method and Practice of Ecological Security of Land Resources in Henan Province

Where: λmax is the largest characteristic root; N is the order of the judgment matrix.

For different judgment matrices, their CI values are different. Generally speaking, the greater the order n, the greater the CI value. In order to measure whether the judgment matrices of different orders have satisfactory consistency, it is necessary to introduce the average random consistency index RI value of the judgment matrix. The RI value is obtained by randomly constructing 500 sample matrices for each order with n 1 ~ 9, calculating the CI value of its consistency index, and then taking the average value. RI value can be selected according to Table 4. 16.

Table 4. Average random consistency index value of16 analytic hierarchy process

For 1, the second-order judgment matrix always has complete consistency. When the order is greater than 2, the ratio of the consistency index CI of the judgment matrix to the average random consistency index ri of the same order, that is, the random consistency ratio CR is less than 0. 10, then the judgment matrix is considered to have satisfactory consistency, indicating that the weight distribution is reasonable; Otherwise, the judgment matrix needs to be adjusted until satisfactory consistency is achieved.

According to the above calculation method and test method, the numerical judgment matrices of A-B, B 1-C, B2-C, B3-C, B4-C, B5-C, B6-C, B7-C and B8-C are calculated in single order at all levels and checked for consistency. The results are shown in Table 4. 17 to Table 4.

B. Overall ranking of grades and consistency test

Hierarchical total ranking is a process of calculating the weight value of all elements at the same level to the overall goal by using the ranking results of all levels in the same level and the weight of all elements at the previous level. That is, the weight of each index relative to the total target layer = the weight of each index relative to the reference layer × the weight of the reference layer relative to the target layer.

Table 4. 17 A-B numerical judgment matrix (ranking weight value of relative importance of basic elements relative to ecological environment)

λmax=8.392，RI= 1.4 1，CI=0.056，CR = CI/RI = 0.04 & lt； 0. 1, which satisfies the consistency.

Table 4. 18 B 1-C numerical judgment matrix (ranking weight of relative importance of each evaluation index relative to meteorological factors)

λmax=3.004，RI=0.58，CI=0.00 18，CR = CI/RI = 0.003 & lt； 0. 1, which satisfies the consistency.

Table 4. 19 B2-C numerical judgment matrix (ranking weight of relative importance of each evaluation index relative to water resources factors)

λmax=3.000，RI=0.58，CI=0.000，CR = CI/RI = 0.000 & lt； 0. 1, which satisfies the consistency.

Table 4.20 B3-C Numerical Judgment Matrix (ranking weight values of relative importance of each evaluation index relative to topographic factors)

λmax=2, which is a second-order matrix and satisfies absolute consistency.

Table 4.2 1 B4-C numerical judgment matrix (ranking weight of relative importance of each evaluation index relative to vegetation factors)

λmax=2, which is a second-order matrix and satisfies absolute consistency.

Table 4.22 B5-C Numerical Judgment Matrix (ranking weight values of relative importance of each evaluation index relative to soil factors)

λmax=2, which is a second-order matrix and satisfies absolute consistency.

Table 4.23 B6-C Numerical Judgment Matrix (ranking weight values of relative importance of each evaluation index relative to population and land factors)

λmax=3.0 18，RI=0.58，CI=0.009，CR = CI/RI = 0.0 16 & lt； 0. 1, which satisfies the consistency.

Table 4.24 B7-C numerical judgment matrix (ranking weight values of relative importance of each evaluation index relative to disaster factors)

λmax=5.004，RI= 1. 12，CI=0.00 1，CR = CI/RI = 0.00 1 & lt； 0. 1, which satisfies the consistency.

Table 4.25 B8-C Numerical Judgment Matrix (the relative importance of each evaluation index relative to environmental pollution factors ranks the weights)

λmax=3.065，RI=0.58，CI=0.032，CR = CI/RI = 0.056 & lt； 0. 1, which satisfies the consistency.

When Cr, the overall ranking consistency rate of the hierarchy is

According to the above method, the relative importance of evaluation elements at all levels in the ecological environment evaluation of the study area is ranked and tested (Table 4.26, Figure 4.9).

Theory, Method and Practice of Ecological Security of Land Resources in Henan Province

Table 4.26 Comprehensive ranking of relative importance of various factors in ecological environment assessment

Figure 4.9 Histogram of relative importance of each factor in ecological environment assessment

Theory, Method and Practice of Ecological Security of Land Resources in Henan Province

CR = CI/RI = 0.0034/0.5362 = 0.006 & lt； 0. 1, which satisfies the consistency.

4.3.5 Analysis of ecological environment quality evaluation results

4.3.5. 1 ecological factor value standard

In order to evaluate the quality of ecological environment in the study area, it is necessary to evaluate and grade the influencing factors of ecological environment, give the scores of environmental influencing factors, then multiply their weighted values to get the total score, and determine the grade of ecological environment according to the total score.

After the evaluation index is determined, collect the status data of each index. These data with different units of measurement cannot be directly used for evaluation. There is no comparability because the dimensions between the data are not uniform. Even the same parameter can be judged according to the measured value, but due to the lack of a comparable environmental standard, it can not accurately reflect its impact on the environment. Therefore, it is necessary to quantify the participating factors and solve the problem of incomparable parameters by standardized methods. There are many methods of quantitative treatment. A simple and practical method is to quantify and grade from low to high to reflect the change of environmental conditions from poor to excellent. Only in this way can we finally make a comparison. You can use hierarchical allocation:

A. Scope standardization method

The standardized quantification formula of ecological factors is: assignment = (Xi-xmin)/(xmax-xmin) ×10, where xi is the measured value; Xmax is the maximum value measured; Xmin is the minimum value of measurement.

If the conceptual meaning of the environmental quality of the quantified grading value of a factor is contrary to the expression of the above formula (for example, the greater the soil erosion, the worse the environmental quality), then the standardized quantitative formula of the participating factors is:

Assignment =10-(Xi-Xmin)/(Xmax-xmin) ×10, where xi is the measured value, xmax is the measured maximum value and xmin is the measured minimum value.

B. Standardized method of expert scoring method

This method mainly adopts the opinions of experts and directly assigns and scores the index factors according to the experience of experts.

This book adopts expert grading laws and regulations to model assignments. The collected raw data of these indicators with different dimensions are normalized to eliminate the influence of different dimensions of the raw data. Combined with the actual situation of the study area and referring to a series of grading standards in ecological environment assessment, the evaluation standards of each specific evaluation factor are given, and the index values are basically 1 ~ 10. See Table 4.27 for the values of ecological factors.

Comprehensive evaluation results of ecological quality of 4.3.5.2 water source area

To quantitatively evaluate the eco-environmental quality of water sources, it is necessary to give specific standards to characterize the eco-environmental quality. By referring to and studying the grading standards of ecological environment evaluation of relevant scholars and experts, the ecological environment quality is graded, and the score is 1 ~ 10: it is divided into five grades, I-V, and the score range of each grade is given. See Table 4.28 for the index characteristics of each grade.

Investigate and collect the statistical data of the study area, get the actual value of each index, get its score according to the value standard of each ecological factor, and calculate its total score by using the comprehensive index model. Specifically, the final score is calculated by the formula (Table 4.29). Where Pi is the score of each ecological factor; Wi is the weight of each ecological factor. The greater the score, the better the ecological environment, and the less the score, the worse the ecological environment.

Table 4.27 Criteria for Selecting Ecological Factors

Table 4.28 Characteristics of Comprehensive Standards for Eco-environmental Quality

Table 4.29 Comprehensive Score of Ecological Factors in Water Source Area

sequential

From this, it can be calculated that the final score of each ecological factor in this area is 5.2085, and the results show that the ecological environment quality of the water source area is in a general state. At present, the ecological environment in this area has been destroyed to a certain extent, and the ecosystem structure has changed, but it can still maintain its basic functions, and it is easy to deteriorate after being disturbed, resulting in ecological problems. The comprehensive study on the ecological environment of the water source area shows that human activities are the main reason for the deterioration of the ecological environment in this area. The implementation of the Middle Route of South-to-North Water Transfer Project will lead to a large number of cultivated land inundation and a large number of immigrants need to be resettled, and the contradiction between people and land will become more acute. The natural growth of population will lead to the continuous increase of population density, and the ecological environment in this area will continue to deteriorate in the near future. Another feature of this area is excessive use of pesticides and fertilizers, and serious non-point source pollution; Soil erosion has not been effectively controlled, and the loss area continues to expand; There are many kinds of minerals in the water source area, mostly small and medium-sized mines. The mining method of marble and vanadium ore with large reserves is open-pit mining, which occupies land, blocks rivers and destroys landscapes, resulting in continuous geological disasters. If we continue to develop and utilize resources without restriction, the relative balance of the ecological environment will be broken and the carrying capacity of the ecological environment will be greatly reduced.

In order to ensure that Danjiangkou water source area can meet the water quality requirements of the Middle Route of South-to-North Water Transfer Project for a long time, realize "continuous enhancement of sustainable development ability, improvement of ecological environment, remarkable improvement of resource utilization efficiency, harmonious coexistence between man and nature, and promote the whole society to embark on the civilized development road of production development, affluent life and good ecology", it is necessary to strengthen the ecological environment construction in this area and do a good job in returning farmland to forests and grasslands; Increase and improve forest vegetation and enhance the function of forest water storage and conservation; Reduce soil erosion, build a multi-variety and multi-functional shelter forest system focusing on water conservation forest and water and soil conservation forest, fundamentally control soil erosion and improve the ecological environment of water sources; Rational use of pesticides and fertilizers, development of organic agriculture and ecological agriculture; Stop soil erosion caused by human activities, focus on harnessing the surrounding areas, shallow hills and areas with serious soil erosion in Danjiangkou reservoir area, and do a good job in harnessing small watersheds. Rectify the mining order, reduce the occurrence of geological disasters, and control and gradually improve the ecological environment in this area.