Method for Selecting and Constructing Reference Points in Inundated River Aquatic Ecosystems Affected by Interference

Abstract

To have a high nature imitation effect of reference point micro inhabitation environment, hold water ecological space heterogeneity of a target water body at the maximum without changing a microorganism / organic feature in a natural water ecological system in the whole construction process, and realize a natural water ecological environmental status.SOLUTION: A selection and construction method of a reference point in interfered submergence type river water ecology includes steps of: dividing a basin basic space unit S1; analyzing an influence on an ecological environment stress of human activity in the basin basic space unit and extracting a water ecological feature S2; selecting a reference candidate point S3; evaluating an aquatic organism status of the reference candidate point S4; constructing a nature imitation reference point S5; and evaluating the aquatic organism status of the nature imitation reference point S6.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention belongs to the field of watershed ecology technology. Specifically, the present invention relates to a method for selecting and constructing a reference point in an interfered crown water type river aquatic ecosystem.

Background Art

[0002] During the "14th Five-Year Plan" period, China's aquatic ecological environment protection has gradually changed from simple water environment quality management to a management mode that comprehensively manages water from three aspects: "water environment, water resources, and aquatic ecology". A reasonable evaluation of aquatic ecological measures will be the basic requirement for future long-term aquatic ecological environment protection work. Aquatic ecological monitoring and evaluation are the basis and premise of aquatic ecological protection and measures. Even for the US aquatic ecological monitoring and evaluation system, which was implemented earliest for aquatic ecological monitoring and evaluation, and the European Union aquatic ecological monitoring and evaluation system, which has the widest application range, they both relate to the establishment and determination of the reference state in the aquatic ecosystem. Regarding the establishment method of the reference state, currently, there are mainly four types: the point reference method, the historical data method, the best available state method, and the expert experience judgment method. The latter three methods have the following deficiencies.

[0003] (1) Regarding the historical data method, the data is insufficient and the data quality cannot be guaranteed. Historical data obtained from different channels have different derivation routes and observation purposes, so the synchronous consistency of data such as water quality, hydrology, and aquatic organisms obtained is low, the availability of set data is insufficient, and due to the interference of the regional external environment, the hydrological rhythm changes greatly, the aquatic biological community changes, and the reference state based on historical data does not reflect the response expression of species changes, making it difficult to guarantee the quality of historical reference state data.

[0004] (2) For the expert judgment method, its subjectivity and locality are significant. Expert consultation is also judged based on historical data according to the experience of experts, and to a certain extent, it is subjective. Although there is a certain degree of similarity between the aquatic ecosystem integrity similar to the water environment conditions, due to the changes in elements such as hydrology, topography, climate, and microbial environment in different regions, there are differences in the aquatic ecosystem functions and aquatic ecosystem environments. As a result, the value of using different forms of reference state samples in different regions is small, and the limitations of expert consultation are significant.

[0005] (3) For the optimal available state method, based on the desired state or damage state, the reference state is predicted by the model method, which has uncertainty and needs to be actually verified. The main process is to investigate the damage degree or desired state by investigating parameter indicators such as biological indicators and physicochemical indicators of the damage point, and then use some mature mathematical model methods to perform simulation selection of the reference point or simulation of the ideal reference state. In principle, this method can predict the aquatic ecosystem information of the river, but the prediction results have a certain degree of uncertainty and may need to be actually verified.

[0006] Regarding the reference point method, it can be represented by monitoring and evaluating that there is no (or little) interference in the water area, and exploring comparable biological state points and biological parameter indicators obtained from these points to determine the reference state. As can be seen from this, the reference point method is the most direct and reliable way to determine the reference state.

[0007] For China with scarce water resources, due to the impacts of industrialization, urbanization, and agricultural intensification, most rivers are affected by human activities such as water conservancy development, pollution source discharge, and agricultural non-point sources. What is defined as the reference point is a reference point that has no (or little) human interference and has an optimal biological state. Currently, it is not clearly defined how to select and construct a reasonable and acceptable reference point in the aquatic ecosystem for rivers affected by interference.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The technical problem to be solved by the present invention is to analyze the spatial heterogeneity of hydrological morphology, the differences in physical and chemical characteristics of the water environment under different interferences, and the aquatic biological situation against the background that most rivers are interfered. For rivers with floodable water, to provide a method for selecting and constructing reference points in the river aquatic ecosystem under interference, and to solve the problem of obtaining reference points in the aquatic ecosystem after the river is artificially interfered.

Means for Solving the Problems

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows.

[0010] A method for selecting and constructing reference points in a flooded river aquatic ecosystem under interference, comprising: In the division of the basic spatial unit of the basin, based on the natural flooding characteristics and DEM data of the target basin, using a certain threshold method or a suitability index method to determine a reasonable catchment area threshold, and inputting the DEM data and the determined catchment area threshold into the SWAT model to perform the division of the basic spatial unit of the basin, step S1; In the analysis of the impact of human activities on the ecological environment stress and the extraction of aquatic ecological characteristics within the basic spatial unit of the basin, based on the analysis of the impact of human activities on the ecological environment stress within each basic spatial unit of the basin, determining the external environmental stress received, and then classifying the basic spatial unit of the basin in step S1, and extracting the shore substrate type, maximum water depth value, average water depth value, long-term average water depth value, shore average flow velocity value, shore maximum flow velocity value and average altitude value for the basic spatial unit of the basin affected by the same kind of stress, and extracting the shore average water flow value, average water depth value, average altitude value and shore substrate type of the basic spatial unit of the same cluster affected by the same kind of stress as the aquatic ecological characteristics of the basic spatial unit of the same cluster, step S2; In the selection of reference candidate points, step S3 of selecting at least one reference candidate point from within the river basin basic spatial units of the same type of aquatic ecological characteristics in step S2; In the evaluation of the aquatic biological situation of the reference candidate points, four biological indicators, namely the Shannon-Wiener diversity index, the biomass percentage of pollution-tolerant species, the abundance (presence) percentage of pollution-tolerant species, and the abundance (presence) percentage of sensitive species, are selected, and the aquatic biological situation of the reference candidate points in step S3 is evaluated and scored, and it is determined whether each reference candidate point meets the specified criteria. If it meets the specified criteria, the reference point is selected as the point with the highest score, and the selection of the reference point is completed. If it does not meet the specified criteria, step S5 is executed to construct a natural mimic reference point in step S4; In the construction of the natural mimic reference point, the point with the highest biological score in the reference candidate point is selected, and three stepped units, namely the upper riffle unit, the middle depression unit, and the lower riffle unit, which are sequentially connected using stones of different sizes, are constructed. The three stepped units form a water stop belt by fitting each other with boulders, crushed stones, cobblestones, and small crushed stones on one side away from the riverbank. The water stop belts of the three stepped units are sequentially connected to form a wavy water stop wall. The riverbed of the middle depression unit forms a concave depression (pit). The height difference between the riverbed of the middle depression unit and the riverbed of the upper riffle unit / the lower riffle unit is equal to the difference between the maximum water depth value and the average water depth value extracted in step S2. An upper water stop wall is provided between the middle depression unit and the upper riffle unit, and a lower water stop wall is provided between the middle depression unit and the lower riffle unit. Both ends of the upper water stop wall and the lower water stop wall are respectively connected to the water stop belt of the middle depression unit and the riverbank, and overflow openings are provided on both the upper water stop wall and the lower water stop wall. A small habitat environment composed of boulders and cobblestones is laid on the riverbeds of the three stepped units in step S5; In the evaluation of the aquatic biological situation of the natural imitation reference point, within the specified time after construction in step S5, sampling and identification of benthic animals are carried out for the natural imitation reference point, and the evaluation and scoring of the aquatic biological situation are carried out with reference to the method in step S4 to determine whether the natural imitation reference point reaches the specified standard. If it does not reach the specified standard, after adjusting the two physical element conditions of the water depth and flow velocity of the microhabitat environment, the benthic animal survey and the evaluation of the aquatic biological situation are repeated within the specified time until the evaluation of the aquatic biological situation is above the specified standard, and step S6 of completing the construction of the natural imitation reference point is included.

[0011] In addition to the above solutions, in another improved solution, the microhabitat environment in the upper shallows unit / the lower shallows unit includes one central boulder and a plurality of jade stones stacked around the central boulder. The plurality of microhabitat environments in the upper shallows unit / the lower shallows unit are arranged in a shape similar to the Chinese character 'zhi'. The microhabitat environment in the middle depression unit is arranged at the deepest position of the middle depression unit and includes two adjacent central boulders and a plurality of jade stones stacked around the two central boulders.

[0012] In addition to the above solutions, in another improved solution, the stacked height of the water stop belt in the upper shallows unit / the lower shallows unit is higher than the average water depth value extracted in step S2, or 3 - 5 cm higher than the long-term average water level of the target basin. The stacked height of the water stop belt in the depression unit is higher than the maximum water depth value extracted in step S2, or 7 - 15 cm higher than the long-term average water level of the target basin. The heights of the upper water stop wall and the lower water stop wall are equal to the height of the water stop belt in the middle depression unit. At least one overflow port with a diameter of 5 cm is provided on the upper water stop wall, and at least one overflow port with a diameter of 10 cm is provided on the lower water stop wall.

[0013] In addition to the above solutions, in another improved solution, the width of the wavy water stop wall that is concave toward the riverbank side in the middle section is 15° ± 2°, the straight length of the wavy water stop wall is 200 cm, both ends of the wavy water stop wall are 75 cm away from the riverbank, the shortest distance between the middle section of the wavy water stop wall and the riverbank is 50 cm, the straight lengths of the water stop zones of the upper shallow shoal unit and the lower shallow shoal unit are both 75 cm, and the length of the water stop zone of the middle concave unit is 50 cm.

[0014] In addition to the above solutions, in another improved solution, the substrate type of the natural imitation reference point is the same as the riverside substrate type extracted in step S2. In principle, the substrate types within the three stepped units are kept consistent. If the three stepped units have a mixed substrate type, they are laid according to the substrate type with the smallest particle size.

[0015] In addition to the above solutions, in another improved solution, in the step of constructing the natural imitation reference point in step S5, first, a wavy water stop wall is constructed at a position 50 - 70 cm away from the riverbank using stones of different sizes. Subsequently, upper and lower water stop walls are constructed between the wavy water stop wall and the riverbank using stones of different sizes to form three stepped units. Further, a depression is dug in the riverbed between the upper and lower water stop walls to form a middle concave unit. Finally, a small habitat environment is constructed in the riverbed of each stepped unit.

[0016] In addition to the above solutions, in another improved solution, when constructing the natural imitation reference point in step S5, the particle size of the rubble used is 10 - 20 cm, the particle size of the gravel is 5 - 10 cm, the particle size of the cobblestone is 1 - 5 cm, and the particle size of the small crushed stone is < 1 cm.

[0017] In addition to the above solutions, in another improved solution, in step S1, the fixed threshold method is the catchment area threshold determined according to experience or by repeated comparison with an accurate water system map, and the suitability index formula is

Number

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Number

[0018] Scoring Criteria for Biological Evaluation Indicators

Table 1

[0019] Rank the scoring of the aquatic biological situation. 12 - 20 points are excellent, 9 - 12 points are good, 5 - 10 points are medium, and 0 - 5 points are poor. In the judgment of whether each reference candidate point in step S3 reaches the specified standard, the specified standard refers to the reference candidate points that are evaluated as good or above in the above scoring criteria, that is, the reference candidate points with a good aquatic biological situation are selected as reference points.

[0020] In addition to the above solution, in another improved solution, the specific steps for extracting the aquatic ecological characteristics of the same type of river basin basic space unit in step S2 are as follows.

[0021] S21. In the determination of the shore substrate type of the river basin basic space unit, the substrate type is determined by the particle size of the shore riverbed within a range of 1 meter from the riverbank. If the river channel width is less than 1 meter, the range from the river center line to the riverbank is taken. S22. Perform pre-clustering based on the riverbank sediment type of the watershed spatial basic unit. That is, distinguish the riverbank sediment types of the basic spatial units affected by the same type of main stress, use the riverbank sediment type as the clustering factor, and perform clustering. S23. In the classification measurement of the basic requirements characteristics of the aquatic ecosystem of the watershed basic spatial unit, the water flow is the flow velocity measured in the mid-water period of the riverbank water body, the water depth is the water depth measured in the mid-water period of the riverbank water body, and the altitude is the average altitude within the watershed basic spatial unit. S24. In performing clustering analysis using the hierarchical clustering method, use all the watershed basic spatial units affected by the same type of stress as samples, use the sediment type as the pre-clustering variable factor to perform clustering on the watershed spatial basic units affected by the same type of stress, and further use the water flow velocity, water depth, and altitude as the post-clustering variables. After performing normalization processing, use the shortest distance method of clustering to perform clustering again to obtain the final result. S25. In extracting the aquatic ecosystem environment characteristics of the same type of watershed basic spatial unit, use the average water flow value, average water depth value, average altitude value, and sediment type of the watershed basic spatial units in the same cluster affected by the same type of stress as the aquatic ecosystem characteristics of the watershed of this type.

[0022] In addition to the above solutions, in another improved solution, in step S3, the reference candidate points should simultaneously meet the following six requirements: (1) The concentration of pollutants generated non-artificially whose water quality is maintained or measured at level III or above within a range of 1 km upstream and downstream on both sides of the coast should be kept within the background level range. (2) There are no sewage outfalls within a range of 1 km upstream and downstream on both sides of the coast. (3) There is no agricultural cultivation with a wide area of more than 100 mu (about 666.7 square meters) within a range of 1 km upstream and downstream on both sides of the coast. (4) There is no known aquaculture within a range of 1 km upstream and downstream on both sides of the coast. (5) There are no main roads, urban arterial roads, or highway routes within a range of 1 km upstream and downstream on both sides of the coast. (6) The resident population within a range of 1 km upstream and downstream on both sides of the coast is less than 100 people.

Advantages of the Invention

[0023] The technical solution of the present invention has at least the following beneficial technical effects.

[0024] (1) The present invention provides a method for selecting and constructing a reference point in a river aquatic ecosystem that can be surely operated and withstand acceptable interference. Humans cannot survive without water resources, and human activities will more or less generate certain interference to the aquatic environment. Then, a reference point with an optimal biological state that is not subject to artificial interference defined in the quality monitoring and evaluation of the aquatic environment cannot be found in a natural river basin. In accordance with the concept of sustainable harmonious development between humans and nature, the present invention provides a method for selecting and constructing a reference point for a river aquatic ecosystem that withstands acceptable interference through a series of steps such as stress analysis on human activity interference, extraction of aquatic environment characteristics affected by stress, selection of reference candidate points, evaluation of the aquatic biological situation of candidate points, and construction of a natural imitation reference point. In particular, it provides a method for constructing a reference point in the aquatic ecosystem of a river that has received severe interference by constructing a natural imitation reference microhabitat environment, and can be widely applied to obtain a reference point for a flooded river aquatic ecosystem that has received interference, and has practical operability.

[0025] (2) The reference point selected by the method of the present invention has significant representativeness. The present invention fully considers the spatial heterogeneity of aquatic environment characteristics and the difference in the impact of different human interferences on the aquatic environment, analyzes the spatio-temporal variability of hydrological conditions and the spatial heterogeneity of the aquatic environment by dividing the basic spatial unit of the river basin, analyzes different types of physical and chemical interferences received by the aquatic environment due to the impact of human activity stress on the aquatic environment, extracts the physical characteristics of water bodies affected by the same type of stress for the aquatic characteristics of the basic spatial unit of the river basin affected by the same type of stress, determines the biological integrity of the reference point selected by evaluating the aquatic biological situation. As can be seen from this, the reference point selected based on the present invention represents to a certain extent the spatial heterogeneity, physicochemical characteristics and aquatic biological integrity of the aquatic environment, and well matches the meaning and characteristics represented by the reference point.

[0026] (3) The effect of the natural imitation reference point constructed using the method of the present invention is high. In a river that has suffered severe interference and whose aquatic ecosystem integrity has been greatly damaged, from the perspective of the three physical elements of substrate, water depth, and flow velocity that most directly affect the presence of aquatic organisms, in the present invention, sampling uses different types of substrates to fit into each other and stack up three stepped units: the upper riffle, the middle depression, and the lower riffle, creating micro-scale water depth diversity and flow velocity diversity, creating habitat diversity for macroinvertebrates, constructing an acceptable aquatic environment situation on-site, and thereby realizing the construction of a natural imitation reference point. Throughout the construction process, the microorganisms and organic matter characteristics in the natural aquatic ecosystem are not changed, the substrate heterogeneity of the target water body is maximally retained, and a natural aquatic environment situation can be embodied.

Brief Description of the Drawings

[0027] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to interpret the present invention and do not unduly limit the present invention.

Figure 1

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Figure 11

Embodiments for Carrying out the Invention

[0028] Hereinafter, the present invention will be described in detail with reference to the drawings. The description of this part is only schematic and interpretive, and has no restrictive effect on the protection scope of the present invention. Also, those skilled in the art can perform corresponding combinations for the examples and features in different examples in this specification based on the description of this specification.

[0029] Referring to the schematic of FIG. 1, the method for selecting and constructing reference points in the interference-affected flooded river aquatic ecosystem of the present invention is as follows: In the division of the basic watershed spatial unit, based on the natural flooding characteristics of the target watershed and DEM (Digital Elevation Model) data, a reasonable catchment area threshold is determined using a certain threshold method or a suitability index method, and the DEM data and the determined catchment area threshold are input into the SWAT model (Soil and Water Assessment Tool) to perform the step S1 of dividing the basic watershed spatial unit. The certain threshold method is a catchment area threshold determined according to experience or by repeated comparison with an accurate river system map, and the suitability index formula (References: Hydro Process, 2006(20):289 - 306, WEN-TZUL et al.).

Number

[0030] The stress of human activities on the aquatic ecological environment is limited to the disturbance extending within a range of 1 kilometer from the land side based on the shoreline, and the degree of influence is determined based on the ratio of the interference area to the area of the basic spatial unit of the basin. The one with the largest occupied ratio is the main stress impact. Among them, the interference area of non-point sources such as riverbank agricultural cultivation, mining, shore deposits, shore mountain debris flows or landslides is the direct impact area within 1 kilometer along the shore. The interference area of hydropower development is the basin area of the river reach with reduced water flow within the basic unit of this basin. The interference area of point source disturbances such as domestic sewage discharge and industrial sewage discharge is the basin area of the mixing process segment after direct discharge. If there are the same type of disturbance activities on both the left and right banks, the degree of influence on the stress is the superposition of the disturbance areas on the left and right banks.

[0031] Referring to the schematic of Figure 2, the specific steps for extracting the aquatic ecological characteristics of the same type of basic spatial units of the basin in step S2 are as follows.

[0032] S21. In the determination of the shore sediment type of the basic spatial unit of the basin, the sediment type is determined by the particle size of the shore riverbed within 1 meter from the riverbank. If the river channel width is less than 1 meter, the range from the center line of the river to the riverbank is taken. The specific determination of the shore sediment type is shown in Table 1 below. If it meets Table 2 below and the ratio difference between different sediment types is 10% or more, the sediment type with the largest ratio is selected as the sediment type of the basic spatial unit of the basin. If the ratio difference between different substrate types is less than 10%, the two main sediment types are selected as the mixed sediment.

[0033] Shore sediment type

Table 2

[0034] S22. Perform pre-clustering based on the basic spatial unit of the basin space of the shore sediment type. That is, distinguish the shore sediment types of the basic spatial units affected by the same type of main stress, use the shore sediment type as the clustering factor, and perform clustering. S23. In the classification measurement of the basic requirements characteristics of the aquatic ecosystem of the basic spatial unit of the basin, the basic requirements characteristics are obtained by on-site measurement during the medium water period (March - May or September - November). Within the range of 1 meter from the shore of the upper, middle, and lower river segments in the basic spatial unit of the basin, use a portable ultrasonic flowmeter to measure the flow velocity, and take the average flow velocity of the upper, middle, and lower river segments as the water flow velocity of the water body unit. Within the range of 1 meter from the shore of the upper, middle, and lower river segments in the basic spatial unit of the basin, use a hand-held depth gauge to measure the water depth of the shore water body, and take the average flow velocity of the upper, middle, and lower river segments as the average water depth of the water body unit. According to the division boundary of the basic spatial unit of the basin, based on the DEM data, obtain the average altitude value of the basic spatial unit of the basin as the average altitude. S24. When performing clustering analysis using a step-by-step clustering method, all the basin basic spatial units affected by the same type of stress are used as samples. The main stress impact type and substrate type are used as pre-cluster variable factors to perform clustering on the basin spatial basic units affected by the same type of stress. Furthermore, water flow velocity, water depth, and altitude are used as post-cluster variables. After normalization processing, clustering is performed again using the clustering shortest distance method (Reference: Chen Jiangli et al., 2014, v.31; No.142(12):29 - 33) to obtain the final result. S25. In extracting the aquatic ecological environment characteristics of the same type of basin basic spatial units, the average water flow value, average water depth value, average altitude value, and substrate type of the basin basic spatial units in the same cluster affected by the same type of stress are used as the aquatic ecological characteristics of the basins of this type.

[0035] S3. In selecting reference candidate points, at least one reference candidate point is selected from within the basin basic spatial units with the same type of aquatic ecological characteristics in step S2. The reference candidate points should simultaneously meet the following six requirements: (1) The water quality should be maintained at level III or above or the concentration of non-artificially generated pollutants measured within a 1 km range upstream and downstream on both sides of the coast should be maintained within the background level range; (2) There should be no sewage outfalls within a 1 km range upstream and downstream on both sides of the coast; (3) There should be no agricultural cultivation with a wide area of more than 100 mu (about 666.7 square meters) within a 1 km range upstream and downstream on both sides of the coast; (4) There should be no known aquaculture within a 1 km range upstream and downstream on both sides of the coast; (5) There should be no main roads, urban arterial roads, or highway routes within a 1 km range upstream and downstream on both sides of the coast; (6) The resident population within a 1 km range upstream and downstream on both sides of the coast should be less than 100 people.

[0036] S4. In the evaluation of the aquatic biological status of the reference candidate points, four biological indicators, namely the Shannon-Wiener diversity index, the percentage of the biomass of pollution-tolerant species, the percentage of the abundance of pollution-tolerant species, and the percentage of the abundance of sensitive species, are selected. The aquatic biological status of the reference candidate points in step S3 is evaluated and scored, and it is determined whether each reference candidate point reaches the specified standard. If it reaches the specified standard, the point with the highest score is selected as the reference point, and the selection of the reference point is completed. If it does not reach the specified standard, step S5 is executed to construct a natural mimic reference point. In the evaluation of the aquatic biological status of the reference candidate points, the calculation formula of the Shannon-Wiener diversity index is [Number] where in (Equation 2), H: Shannon-Wiener diversity index, n: The total number of benthic animals at the candidate point, s: The number of benthic animal species at the candidate point, n i : The number of individuals of the i-th benthic animal species at the candidate point, and Pollution-tolerant species and sensitive species are discriminated based on the level of the pollution tolerance value (TV, Tolerance value) of benthic animals. If TV ≤ 3, it is a sensitive species; if TV ≥ 7, it is a pollution-tolerant species. The pollution tolerance value of benthic animals is obtained by referring to the list of pollution tolerance values of benthic animals in Appendix K of the "Technical Guide for Monitoring and Evaluating the Quality of River Aquatic Ecosystems". The calculation formula of the percentage of the abundance of pollution-tolerant species is [Number] where in (Equation 3), B w : The percentage value of the abundance of pollution-tolerant species, n w : The number of pollution-tolerant benthic animal species, s: The number of benthic animal species at the candidate point, and The calculation formula of the percentage of the abundance of sensitive species is [Number] where in (Equation 4), B m: Percentage value of sensitive species abundance, n m : Number of pollution-tolerant benthic species, s: Number of benthic species at the candidate point, where The calculation formula for the percentage of the biomass of pollution-tolerant species is

Number

[0037] After calculating the biological index of the reference candidate point based on the above calculation formula, score it with reference to the scoring criteria of the biological evaluation index in Table 1 listed in the content of the above-mentioned invention.

[0038] The lowest score for the aquatic biological status scoring is 0 points, and the highest score is 20 points. Rank the scores of the aquatic biological status. 12 - 20 points is excellent, 9 - 12 points is good, 5 - 10 points is medium, and 0 - 5 points is poor. In the judgment of whether each reference candidate point in step S3 reaches the specified standard, the specified standard is to select the reference candidate point evaluated as good or above in the above scoring criteria, that is, the aquatic biological status is good or above, as the reference point.

[0039] S5. In constructing the natural imitation reference point, select the point with the highest biological score among the reference candidate points, and use stones of different sizes to construct the natural imitation reference point. The natural imitation reference point includes three stepped units: an upper shallow shoal unit, a middle depression unit, and a lower shallow shoal unit that are sequentially connected. The three stepped units are embedded with each other using rubble stones, crushed stones, jade stones, and small crushed stones (a combination of 2, 3, or 4 of the 4 types of rubble stones, crushed stones, jade stones, and small crushed stones) on one side away from the riverbank to form a water stop belt. The water stop belts of the three stepped units are sequentially connected to form a wavy water stop wall. The riverbed of the middle depression unit forms a concave depression. The height difference between the riverbed of the middle depression unit and the riverbed of the upper shallow shoal unit / lower shallow shoal unit is equal to the difference between the maximum water depth value and the average water depth value extracted in step S2. An upper water stop wall is provided between the middle depression unit and the upper shallow shoal unit, and a lower water stop wall is provided between the middle depression unit and the lower shallow shoal unit. Both ends of the upper water stop wall and the lower water stop wall are respectively connected to the water stop belt of the middle depression unit and the riverbank, and overflow openings are provided on both the upper water stop wall and the lower water stop wall. A small habitat environment composed of rubble stones and jade stones is laid on the riverbeds of the three stepped units. Based on the living habit that benthic animals prefer to attach to the surface of jade stones or hide in the gaps between jade stones, a small habitat environment is arranged in each unit to provide living space for benthic animals. Use bottom sediments of different sizes to construct a small habitat environment suitable for the survival of the benthic animal group at the reference candidate point, and obtain the corresponding aquatic biological situation information by collecting benthic animals on the surface, gaps, etc. of the small habitat environment in the three stepped units.

[0040] S6. In the evaluation of the aquatic biological situation of the natural imitation reference point, within the specified time after construction in step S5, sampling and identification of benthic animals are carried out for the natural imitation reference point, and the evaluation and scoring of the aquatic biological situation are carried out with reference to the method in step S4 to determine whether the natural imitation reference point reaches the specified standard. If it does not reach the specified standard, two ecological element characteristics, namely the water depth and flow velocity of the microhabitat environment, are adjusted to reach the relevant index conditions. The specific method is to adjust the water depth of the microhabitat environment by adjusting the height of the overflow opening from the riverbed, and directly achieve the purpose of adjusting the flow velocity of the microhabitat environment by adjusting the arranged overflow opening, increase the number of overflow openings, and achieve the purpose of improving the flow velocity of the microhabitat environment. Repeat the benthic animal survey and the evaluation of the aquatic biological situation within the specified time until the evaluation of the aquatic biological situation reaches or exceeds the specified standard, and complete the construction of the natural imitation reference point.

[0041] Referring to the schematics from FIG. 3 to FIG. 11, in the present invention, the microhabitat environment in the upper riffle unit / lower riffle unit includes one central boulder and a plurality of jade stones stacked around the central boulder. The plurality of microhabitat environments in the upper riffle unit / lower riffle unit are arranged in a shape similar to the Chinese character 'zhi'. The interval between each microhabitat environment is 20 cm. The microhabitat environment in the middle depression unit is arranged at the deepest position of the middle depression unit and includes two adjacent central boulders and a plurality of jade stones stacked around the two central boulders. The particle size of the used boulders is 10 - 20 cm, the particle size of the crushed stones is 5 - 10 cm, the particle size of the jade stones is 1 - 5 cm, and the particle size of the small crushed stones is < 1 cm.

[0042] Referring to the schematics of FIG. 5 and FIG. 6, the stacked height of the water stop belts in the upper riffle unit / lower riffle unit is higher than the average water depth value extracted in step S2, or 3 - 5 cm higher than the long - term average water level of the target watershed. The stacked height of the water stop belts in the depression unit is higher than the maximum water depth value extracted in step S2, or 7 - 15 cm higher than the long - term average water level of the target watershed. The heights of the upper water stop wall and the lower water stop wall are equal to the height of the water stop belt in the middle depression unit.

[0043] Referring to the schematic diagram of FIG. 3, the width that is concave toward the riverbank side in the middle section of the wavy water-stop wall is 15° ± 2°, the straight-line length of the wavy water-stop wall is 200 cm, both ends of the wavy water-stop wall are 75 cm away from the riverbank, the shortest distance between the middle section of the wavy water-stop wall and the riverbank is 50 cm, the straight-line lengths of the water-stop zones of the upper shallow-trough unit and the lower shallow-trough unit are both 75 cm, and the length of the water-stop zone of the middle concave unit is 50 cm. The concave shape of the wavy water-stop wall toward the riverbank side can reduce the lateral impact of the outer water body to a certain extent and improve the stability of the natural imitation reference point.

[0044] Referring to the schematics of FIGS. 3 and 10, the substrate types of the three stepped units at the natural imitation reference point are the same as the riverside substrate types extracted in step S2. In principle, the substrate types within the three stepped units are kept consistent. If the three stepped units are of a mixed substrate type, they are laid according to the substrate type with the smallest particle size. For example, sand is filled in the voids of the jade stones and laid in a sandy manner. When different substrate types are distributed in different regions, differences occur in the substrate types of each unit. For example, jade stones are mainly distributed in the shallow water area of the riverbed, and sludge is distributed in the deep pool area at the bottom of the riverbed. Then, jade stone substrates are laid in the corresponding shallow-trough units, and sludge substrates are laid in the concave units.

[0045] Referring to the schematics of FIGS. 4, 7, and 8, by providing overflow openings, the hydraulic connection between the upper shallow-trough unit / lower shallow-trough unit and the middle concave unit is realized. The water flow and water depth of the natural imitation reference point are determined by the position and quantity of the overflow openings on the water-stop wall of the concave unit. Generally, two overflow openings with a diameter of 5 cm are provided on the upper water-stop wall, and the two overflow openings are horizontally separated by 10 cm to ensure that the river water in the upper shallow-trough unit flows into the middle concave unit. An overflow opening with a diameter of 10 cm is provided on the lower water-stop wall to allow the river water in the middle concave unit to flow into the lower shallow-trough unit through the overflow opening. The height and quantity of the overflow openings can be adjusted as needed, and an overflow opening with a diameter of 10 cm is provided on the lower water-stop wall at the river bottom.

[0046] In the step of constructing the natural imitation reference point in step S5, first, a wavy water stop wall is constructed at a position 50 - 70 cm away from the shore using stones of different sizes. Subsequently, the upper and lower water stop walls are constructed using stones of different sizes to form three staircase units, and finally, a small habitat environment is constructed for each staircase unit.

[0047] (Example 1) For the Baoxing River Basin in Ya'an City, the method of the present invention is used to select and construct reference points in the aquatic ecosystem. The Baoxing River is the main source of the Qingyi River, flowing through 9 towns in Baoxing County, Ya'an City, and converging into the Minjiang River waterway along the Qingyi River. The valleys crisscross, with rich water resources and marble deposits. There are currently 47 small hydropower plants in operation and 12 mines. As a result, the aquatic ecological environment of the Baoxing River Basin is greatly affected by human activity interferences such as hydropower development and mining development. The method steps are as follows as shown in Figure 1.

[0048] S1. In the division of the basin basic spatial unit, based on the suitability index analysis, a catchment area threshold of 7500 m 2 is determined and input into the SWAT model to divide the Baoxing River Basin into 13 basin basic spatial units.

[0049] S2. In the analysis of the impact of human activities on the stress of the aquatic ecological environment and the extraction of the aquatic ecological characteristics of the basin basic spatial unit, mainly taking the disturbances extending within a range of 1 kilometer from the land side with the shoreline as the reference, the degree of influence is determined based on the ratio of the interference area to the area of the basin basic spatial unit. Four basic spatial units are mainly affected by geological disaster stress, three basic spatial units are mainly affected by domestic pollution stress, four basic spatial units are mainly affected by hydropower development stress, one basic spatial unit is mainly affected by industrial pollution stress, and one basic spatial unit is mainly affected by mining stress.

[0050] During the medium water period (March - May or September - November), measure the shore sediment type, maximum water depth, average water depth, annual average water depth, average shore flow velocity, maximum shore flow velocity, and average altitude of the basic spatial units of geological disasters, domestic pollution, hydropower, and industrial pollution basins respectively. Through measurement, the aquatic ecological characteristics of each basic spatial unit are shown in Table 3.

[0051] Aquatic ecological characteristics during the medium water period of each basic spatial unit in the Baoxing River Basin

Table 3

[0052] Perform pre - cluster analysis with the shore sediment type as the cluster factor, and then perform post - cluster analysis using the clustering shortest distance method with water flow velocity, water depth, and altitude as the cluster factors. Cluster the 13 basic basin units into 6 aquatic ecological types, namely high - altitude good ecological units, medium - altitude good ecological units, hydropower development - interfering ecological units, mining - interfering ecological units, domestic pollution - interfering ecological units, and industrial - interfering ecological units.

[0053] Extract the average shore flow velocity value, average shore water depth value, average altitude value, and shore sediment type of the same kind of basic spatial units as the aquatic ecological characteristics of this type. Details are shown in Table 4.

[0054] Aquatic ecological characteristic values of each aquatic ecological type

Table 4

[0055] S3. In the selection of reference candidate points, the selection criteria for reference candidate points are as follows: (1) within the range of 1 km upstream and downstream on both sides of the coast, the concentration of pollutants generated non-artificially whose water quality is maintained or measured at level III or above should be kept within the background level range; (2) there should be no sewage outfalls within the range of 1 km upstream and downstream on both sides of the coast; (3) there should be no agricultural cultivation with a wide area of more than 100 mu (about 666.7 square meters) within the range of 1 km upstream and downstream on both sides of the coast; (4) there should be no known aquaculture within the range of 1 km upstream and downstream on both sides of the coast; (5) there should be no main roads, urban arterial roads, or highway routes within the range of 1 km upstream and downstream on both sides of the coast; (6) the resident population within the range of 1 km upstream and downstream on both sides of the coast should be less than 100 people. Based on these criteria, 10 reference candidate points are selected. Among them, for the high-altitude ecologically good unit, 2 reference candidate points are selected; for the medium-altitude ecologically good unit, 2 reference candidate points are selected; for the out-of-life disturbance ecological unit, 2 reference candidate points are selected; for the out-of-mine disturbance ecological unit, 1 reference candidate point is selected; for the out-of-industry disturbance ecological unit, 1 reference candidate point is selected; for the out-of-hydroelectric development disturbance ecological unit, 2 reference candidate points are selected, completely covering each ecological feature unit.

[0056] S4. In the evaluation of the aquatic ecological status of reference candidate points, during the medium water period (March - May or September - November), investigation sampling is carried out on the benthic animals of 10 reference candidate points. Four biological indicators, namely the Shannon-Wiener diversity index, the percentage of biomass of pollution-tolerant species, the percentage of abundance of pollution-tolerant species, and the percentage of abundance of sensitive species, are selected, and the evaluation of the aquatic ecological status of the reference candidate points described in the invention content is carried out based on the evaluation method (the evaluation results are shown in Table 5). The evaluation of the six aquatic biological statuses at 10 reference candidate points is good or above, corresponding to the high-altitude ecologically good unit, the medium-altitude ecologically good unit, the water conservancy disturbance ecological unit, and the out-of-mine disturbance ecological unit respectively. Among them, in the high-altitude ecologically good unit, the aquatic ecological status score of point 2# is higher than that of point 1#; in the hydroelectric development interference ecological unit, point 5# is higher than point 3#. Therefore, 4 reference candidate points, namely 2#, 5#, 7#, and 4#, are selected as reference points.

[0057] Reference candidate point information and aquatic ecological status scoring results

Table 5

[0058] S5. In the construction of the natural imitation reference point, at the reference candidate points of the living interference ecological unit and the industrial interference ecological unit, select No. 9 and No. 10 with high aquatic ecological status scores to construct the natural imitation reference point. The specific construction method refers to step S5 of the above-mentioned content of the present invention. Among them, the stacked height of the water stop belt of the No. 9 natural imitation reference point is 5 cm higher than the long-term average water level, that is, the stacked height is 20 cm. The water depth difference between the depression unit and the shoal unit is 10 cm. One overflow port with a diameter of 5 cm is provided on the upper water stop wall, and one overflow port with a diameter of 10 cm is provided on the lower water stop wall. The stacked height of the water stop belt of the No. 10 natural imitation reference point is the maximum water depth height at the shore, that is, 45 cm. The water depth difference between the depression unit and the shoal unit is 7 cm. Two overflow ports with a diameter of 5 cm are provided on the upper water stop wall, and one overflow port with a diameter of 10 cm is provided on the lower water stop wall.

[0059] S6. In the evaluation of the aquatic ecological status of the natural imitation reference point, 20 days after the microhabitat environment is constructed, benthic animals are measured and four biological indicators, namely, the Shannon-Wiener diversity index, the biomass percentage of pollution-tolerant species, the abundance percentage of pollution-tolerant species, and the abundance percentage of sensitive species, are calculated. Based on the method of S4 in the above-mentioned content of the present invention, the ecological status of the natural imitation reference point is evaluated. The results are shown in Table 6.

[0060] Evaluation of the Aquatic Ecological Status of the Natural Imitation Reference Point

Table 6

[0061] As can be seen hereinafter, if the evaluation of the aquatic biological status of the constructed natural imitation reference points of 9# and 10# is "good" or above, the construction of the river reference points affected by interference can be realized, and after the construction, biological parameters such as biotope composition, aquatic biodiversity, aquatic biological sensitivity, and functional traits including ecological type units can be obtained for the reference points, thereby determining the reference state of the aquatic environment and effectively solving the problem that the river ecological unit after being affected by interference cannot find the reference standard, and providing support for the aquatic ecological restoration or treatment of subsequent interference river segments.

[0062] The above embodiments are preferred embodiments of the present invention. However, the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention are all equivalent substitution forms and are all included within the protection scope of the present invention.

Explanation of Signs

[0063] 1-Upper riffle unit 2-Middle depression unit 3-Lower riffle unit 4-Wavy water stop wall 5-Upper water stop wall 6-Lower water stop wall 7-Small habitat 8-River bank 9-Block stone 10-Crushed stone 11-Jade stone 12-Overflow 13-Natural substrate 14-Water stop belt

Claims

1. A step of dividing a basic spatial unit of a basin, which includes determining a reasonable catchment area threshold using a fixed threshold method or a suitability index method based on the natural inundation characteristics and DEM data of the target basin, inputting the DEM data and the determined catchment area threshold into a SWAT model to perform the division of the basic spatial unit of the basin, namely step S1; A step of analyzing the impact of human activities on the ecological environment stress and extracting the hydro-ecological characteristics within the basic spatial unit of the basin, which includes determining the type of external environmental stress received based on the analysis of the impact of human activities on the ecological environment stress within each basic spatial unit of the basin, then classifying the basic spatial units of step S1, extracting the shore substrate type, maximum water depth value, average water depth value, long-term average water depth value, average shore flow velocity value, maximum shore flow velocity value and average altitude value for the basic spatial units of the basin affected by the same type of stress, and extracting the average shore water flow value, average water depth value, average altitude value and shore substrate type of the basic spatial units of the same cluster of the basin affected by the same type of stress as the hydro-ecological characteristics of the basic spatial units of the same cluster, namely step S2; A step of selecting reference candidate points, which is to select at least one reference candidate point from within the basic spatial units of the basin with the same type of hydro-ecological characteristics in step S2, namely step S3; A step of evaluating the aquatic biological situation of the reference candidate points, which is to select four biological indicators: Shannon-Wiener diversity index, percentage of biomass of pollution-tolerant species, percentage of abundance of pollution-tolerant species, and percentage of abundance of sensitive species, evaluate and score the aquatic biological situation of the reference candidate points in step S3, determine whether each reference candidate point meets the specified criteria, if it meets the specified criteria, select the reference point with the highest score, complete the selection of the reference point, if it does not meet the specified criteria, execute step S5 to construct a natural imitation reference point, namely step S4; A step of constructing a natural imitation reference point, which includes selecting the point with the highest biological score among the reference candidate points, and constructing three stepped units, namely an upper riffle unit, a middle depression unit, and a lower riffle unit, which are sequentially connected using stones of different sizes. The three stepped units form a water stop belt by fitting each other with rubble stones, crushed stones, jade stones, and small crushed stones on one side away from the river bank. The water stop belts of the three stepped units are sequentially connected to form a wavy water stop wall. The river bed of the middle depression unit forms a concave depression. The height difference between the river bed of the middle depression unit and the river bed of the upper riffle unit / the lower riffle unit is equal to the difference between the maximum water depth value and the average water depth value extracted in step S2. An upper water stop wall is provided between the middle depression unit and the upper riffle unit, and a lower water stop wall is provided between the middle depression unit and the lower riffle unit. Both ends of the upper water stop wall and the lower water stop wall are respectively connected to the water stop belt of the middle depression unit and the river bank, and overflow openings are provided on both the upper water stop wall and the lower water stop wall. A small habitat environment composed of rubble stones and jade stones is laid on the river beds of the three stepped units in step S5, A step of evaluating the aquatic biological situation of the natural imitation reference point, which includes sampling and identifying benthic animals for the natural imitation reference point within a specified time after construction in step S5, and evaluating and scoring the aquatic biological situation with reference to the method of step S4 to determine whether the natural imitation reference point reaches the specified standard. If it does not reach the specified standard, after adjusting the two physical element conditions of the water depth and flow velocity of the micro-habitat environment, sampling and identifying benthic animals, evaluating and scoring the aquatic biological situation are repeated within the specified time until the aquatic biological situation evaluation is above the specified standard, and then completing the construction of the natural imitation reference point in step S6. A method for selecting and constructing a reference point in a flooded river aquatic ecosystem affected by interference, characterized by the above.

2. The small habitat environment within the upper riffle unit / the lower riffle unit includes one central boulder and a plurality of jade stones stacked around the central boulder. The plurality of small habitat environments within the upper riffle unit / the lower riffle unit are arranged in a shape similar to the Chinese character 'zhi'. The small habitat environment within the middle depression unit is arranged at the deepest position of the middle depression unit and includes two adjacent central boulders and a plurality of jade stones stacked around the two central boulders. The method for selecting and constructing a reference point in a flooded river aquatic ecosystem affected by interference according to claim 1, characterized in that.

3. The stacked height of the water stop belts of the upper riffle unit / lower riffle unit is higher than the average water depth value extracted in step S2, or 3 - 5 cm higher than the long-term average water level of the target river basin. The stacked height of the water stop belt of the depression unit is higher than the maximum water depth value extracted in step S2, or 7 - 15 cm higher than the long-term average water level of the target river basin. The heights of the upper water stop wall and the lower water stop wall are equal to the height of the water stop belt of the middle depression unit. At least one overflow opening with a diameter of 5 cm is provided on the upper water stop wall, and at least one overflow opening with a diameter of 10 cm is provided on the lower water stop wall. The method for selecting and constructing a reference point in a flooded river aquatic ecosystem affected by interference according to claim 2, characterized in that.

4. The width of the wave-shaped water stop wall that is concave towards the river bank side in the middle section is 15° ± 2°. The straight-line length of the wave-shaped water stop wall is 200 cm. Both ends of the wave-shaped water stop wall are 75 cm away from the river bank. The shortest distance between the middle section of the wave-shaped water stop wall and the river bank is 50 cm. The straight-line lengths of the water stop belts of the upper riffle unit and the lower riffle unit are both 75 cm. The length of the water stop belt of the middle depression unit is 50 cm. The method for selecting and constructing a reference point in a flooded river aquatic ecosystem affected by interference according to claim 3, characterized in that.

5. The substrate type of the natural imitation reference point is the same as the shore substrate type extracted in step S2. In principle, the substrate types within the three stepped units are kept consistent. If the three stepped units have a mixed substrate type, they are laid according to the substrate type with the smallest particle size. The method for selecting and constructing a reference point in a flooded river aquatic ecosystem affected by interference according to claim 4, characterized in that.

6. The step of constructing the natural imitation reference point in step S5 is as follows: First, construct a wavy water stop wall at a position 50-70 cm away from the riverbank using stones of different sizes. Subsequently, construct the upper water stop wall and the lower water stop wall between the wavy water stop wall and the riverbank using stones of different sizes to form three stepped units. Furthermore, dig a depression in the riverbed between the upper water stop wall and the lower water stop wall to form a middle depression unit. Finally, construct a small habitat environment in the riverbed of each stepped unit. The method for selecting and constructing a reference point in a flooded river aquatic ecosystem affected by interference as claimed in claim 5, characterized in that it is as described above.

7. In the case of constructing the natural imitation reference point in step S5, the particle size of the rubble stones used is 10-20 cm, the particle size of the gravel is 5-10 cm, the particle size of the cobblestones is 1-5 cm, and the particle size of the small crushed stones is <1 cm. The method for selecting and constructing a reference point in a flooded river aquatic ecosystem affected by interference as claimed in any one of claims 1-6, characterized in that it is as described above.

8. In step S1, the fixed threshold method is a catchment area threshold determined according to experience or by repeated comparison with an accurate water system map. The suitability index formula is 【Number 1】 where, in formula (1), L ｉ : Insufficient water flow length, L ｒ : Excessive water flow length L Ｔ : Total length of river system, Z: River section with extra or insufficient water flow length, n: Total number of river sections with extra or insufficient water flow length, and In the evaluation of the aquatic biological situation of the reference candidate points in step S4, the calculation formula of the Shannon-Wiener diversity index is 【Number 2】 where, in formula (2), H: Shannon-Wiener diversity index, n: Total number of benthic animals at the candidate point, s: Number of benthic animal species at the candidate point, n ｉ : The number of individuals of the i-th benthic animal of the candidate points, and The pollution-tolerant species and sensitive species are discriminated based on the high or low pollution tolerance value (TV, Tolerance value) of the benthic animals. If TV ≤ 3, it is a sensitive species; if TV ≥ 7, it is a pollution-tolerant species. The pollution tolerance value of the benthic animals is obtained by referring to the list of pollution tolerance values of benthic animals in Appendix K of the "Technical Guide for Monitoring and Evaluating the Quality of River Aquatic Environments". The calculation formula of the pollution-tolerant species abundance percentage is [Number 3] where, in formula (3), B ｗ : Pollutant resistance species abundance percentage value, n ｗ : The number of species of benthic animals resistant to pollution s: Number of benthic animal species at the candidate point, and The calculation formula of the sensitive species abundance percentage is 【Number 4】 where, in formula (4), B ｍ : Percentage value of sensitive species abundance n ｍ : The number of species of benthic animals resistant to pollution s: Number of benthic animal species at the candidate point, and The calculation formula of the percentage of the biomass of pollution-tolerant species is 【Number 5】 where, in formula (5), M ｗ : Percentage value of the biomass of pollution-tolerant species, m ｗ : Biomass of pollution-tolerant species of benthic animals, m: Total biomass of benthic animals at the candidate point, and After calculating the biological indicators of the reference candidate points based on the above calculation formula, score them by referring to the scoring criteria of the preset biological evaluation indicators, rank the scores, where 12 - 20 points are excellent, 9 - 12 points are good, 5 - 10 points are medium, and 0 - 5 points are poor. In the determination of whether each reference candidate point in step S3 reaches the specified standard, the specified standard is to select, as the reference point, the reference candidate points that are evaluated as good or above in the above scoring criteria, that is, the aquatic biological situation is good. The method for selecting and constructing reference points in the flooded river aquatic ecosystem affected by interference according to claim 7, characterized in that.

9. The specific steps for extracting the aquatic ecological characteristics of the same type of watershed basic space unit in step S2 are as follows: S21: In the determination of the substrate type of the watershed basic space unit, the substrate type is determined by the particle size of the riverside riverbed within a range of 1 meter from the riverbank. If the river channel width is less than 1 meter, the range from the river center line to the riverbank is taken. S22: Perform pre-clustering based on the watershed spatial basic unit of the riverside substrate type, that is, distinguish the riverside substrate types of the basic space units affected by the same main stress, and use the stress-affected type and the riverside substrate type as clustering factors to perform clustering. S23: In the classification and measurement of the basic requirements characteristics of the aquatic ecosystem of the watershed basic space unit, the water flow is the flow velocity measured in the middle water period of the riverside water body, the water depth is the water depth measured in the middle water period of the riverside water body, and the altitude is the average altitude within the watershed basic space unit. S24: In performing clustering analysis using the step-by-step clustering method, all watershed basic space units affected by the same type of stress are used as samples, the substrate type is used as the pre-clustering variable factor to perform clustering on the watershed spatial basic units affected by the same type of stress, and then the water flow velocity, water depth, and altitude are used as post-clustering variables. After normalization processing, perform clustering again using the clustering shortest distance method to obtain the final result. S25: In the extraction of the aquatic ecological environment characteristics of the same type of watershed basic space unit, including taking the average water flow value, average water depth value, average altitude value, and substrate type of the watershed basic space units in the same cluster affected by the same type of stress as the aquatic ecological characteristics of the watershed of this type. The method for selecting and constructing reference points in the flooded river aquatic ecosystem affected by interference according to claim 7, characterized in that.

10. In the step S3, the reference candidate points should simultaneously satisfy six requirements: (1) the concentration of pollutants generated non-artificially whose water quality is maintained or measured at level III or above within a range of 1 km upstream and downstream on both sides of the coast should be kept within the background level range; (2) there should be no sewage outfall within a range of 1 km upstream and downstream on both sides of the coast; (3) there should be no agricultural cultivation with a wide area of 100 mu (about 666.7 square meters) or more within a range of 1 km upstream and downstream on both sides of the coast; (4) there should be no known aquaculture within a range of 1 km upstream and downstream on both sides of the coast; (5) there should be no main roads, urban arterial roads, or highway routes within a range of 1 km upstream and downstream on both sides of the coast; (6) the resident population within a range of 1 km upstream and downstream on both sides of the coast should be less than 100. The method for selecting and constructing reference points in the flooded river aquatic ecosystem affected by interference according to claim 7 is characterized in that it should satisfy the above six requirements simultaneously.

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