Optimization method of ecological flow regulation of reservoir coupled with multi-species and multi-reach eco-hydrology

Abstract

The preferred method for coupling multi-species and multi-reach eco-hydrology of reservoir ecological flow regulation, the first step is to determine the downstream multiple target river reaches and multiple target species, coupling analysis obtains the ecological flow threshold range of each target species in each target river reach; the second step is to divide the ecological key stage according to the key life history stage of each target species and set the priority, integrate the priority to generate the comprehensive ecological flow demand of each target river reach in different time periods; the third step is to take the comprehensive ecological flow demand as the benchmark, combined with the natural hydrological regime, to evaluate the ecological flow satisfaction degree and the overall hydrological change degree of each candidate regulation scheme in each target river reach; the fourth step is to build a decision model with the two indexes to comprehensively evaluate each candidate regulation scheme, calculate the comprehensive score of each candidate regulation scheme, and select the scheme with the highest comprehensive score as the final reservoir ecological flow regulation scheme. Therefore, the design can realize the dynamic balance of ecological and hydrological double targets.

Description

Technical Field

[0001] This invention relates to a method for optimizing reservoir ecological flow scheduling, belonging to the field of ecological scheduling of water conservancy and hydropower projects and protection of river ecosystems, and particularly to a method for optimizing reservoir ecological flow scheduling that couples multiple species and multiple river sections' eco-hydrology. Background Technology

[0002] River ecosystems are vital for maintaining global biodiversity and ecosystem services. However, the construction and operation of large-scale water conservancy projects (such as reservoirs), while bringing economic and social benefits, also alter the natural hydrological conditions of rivers, leading to a series of ecological problems such as loss of longitudinal connectivity, homogenization of hydrological rhythms, and degradation of aquatic habitats. To mitigate these adverse ecological impacts, optimizing the reservoir discharge process (i.e., reservoir ecological flow scheduling schemes) can proactively meet downstream ecological needs, thereby balancing engineering benefits with ecological protection.

[0003] However, in actual ecological scheduling decisions, there are usually multiple alternative operating modes, i.e., candidate scheduling schemes, derived from different scheduling objectives, historical experience, or model generation. Some candidate scheduling schemes focus on the one-way optimization of ecological indicators (such as taking the maximization of the habitat suitability index of a specific species as the core objective). Although such schemes may improve the habitat quality in a specific period or local area, they often give rise to highly artificial flow processes that lose natural variability. Natural hydrological variability (such as pulse fluctuations) is an ecological signal that triggers key life processes such as fish migration and spawning. Its loss will weaken the dynamic integrity and long-term resilience of the river ecosystem. Another set of candidate scheduling schemes focuses on minimizing the statistical changes to the natural hydrological situation (such as pursuing the minimum hydrological change degree IHA). However, this mechanical pursuit of statistical characteristic fit may make the scheduling scheme resemble the natural flow pattern in terms of data, but it may not be able to form an actual habitat with suitable hydraulic conditions (such as effective water depth and flow velocity) during the key life stages of the target species, such as reproduction and foraging, sacrificing the ecological function effectiveness of the flow process. As a result, it is impossible to achieve a dynamic balance between ecological and hydrological objectives.

[0004] Chinese patent application number 202411987518.9, filed on December 31, 2024, discloses a method for configuring reservoir ecological flow based on multi-section water diversion and collaborative protection of multiple target fish species: Step S1, determining hydrologically sensitive areas and ecologically sensitive areas based on water diversion impact constraints and fish resource distribution data, constructing a habitat assessment model by overlaying the hydrologically sensitive areas and ecologically sensitive areas, determining key habitats for typical fish species, and then determining target spawning grounds; Step S2, integrating a two-dimensional hydrodynamic model and a fish habitat model to calculate the habitat hydraulic demand and flow pulse demand of different fish species during the spawning period, constructing the ecological water demand process during the spawning period, and simultaneously calculating the ecological baseflow to supplement the basic hydrological demand during the non-spawning period; Step S3, coupling ecological water demand for multiple spawning grounds with overlapping spawning periods to determine a collaborative configuration scheme for reservoir ecological flow. Although this patent can balance multiple spatial sections and multiple species within the same trophic level, it still has the following shortcomings:

[0005] The design, which focuses on optimizing a single ecological indicator, still fails to achieve a dynamic balance between ecological and hydrological objectives.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this patent application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects and problems of existing technologies that cannot achieve a dynamic balance between ecological and hydrological objectives, and to provide a reservoir ecological flow scheduling optimization method that couples multiple species and multiple river sections' ecological and hydrological aspects to achieve a dynamic balance between ecological and hydrological objectives.

[0008] To achieve the above objectives, the technical solution of the present invention is: a method for optimizing reservoir ecological flow scheduling that couples multiple species and multiple river section eco-hydrology, the method comprising:

[0009] Step 1: First, select multiple target river sections downstream of the reservoir and select multiple target species within each target river section; then, through coupled analysis of the hydraulic demand of each target species and the distribution data of hydraulic conditions in each target river section, determine the ecological flow threshold range of each target species in each target river section.

[0010] The second step is to first divide the target species into different ecological critical stages according to the key life history stages of each target species, and set ecological protection priorities for each ecological critical stage; then, based on the ecological protection priorities, coordinate and integrate the ecological flow threshold ranges of each target species in the same ecological critical stage to generate the time-segmented comprehensive ecological flow demand of each target river section.

[0011] Step 3: Based on the above-mentioned time-segmented comprehensive ecological flow demand, the daily flow sequence formed by each candidate scheduling scheme in each target river segment is judged on a daily basis to obtain the ecological flow satisfaction of each candidate scheduling scheme in each target river segment; at the same time, based on the natural hydrological conditions of each target river segment, the change range method is used to evaluate the degree of change of the daily flow sequence formed by each candidate scheduling scheme in each target river segment relative to the natural hydrological conditions, to obtain the overall hydrological change of each candidate scheduling scheme in each target river segment.

[0012] Step 4: First, using the overall hydrological change and ecological flow satisfaction as evaluation indicators, construct a decision model using the analytic hierarchy process (AHP); then, comprehensively evaluate each candidate scheduling scheme through the decision model and calculate the comprehensive score of each candidate scheduling scheme; finally, select the candidate scheduling scheme with the highest comprehensive score as the final reservoir ecological flow scheduling scheme.

[0013] In the first step, the target species include juvenile fish, large invertebrates, and wetland plants.

[0014] In the first step, the water requirements of each target species are the habitat suitability curves of each target species; the habitat suitability curves of each target species are constructed based on the biological distribution data of each target species and the key hydraulic factor data of the corresponding habitat of each target species.

[0015] The key hydraulic factors include water depth and flow velocity.

[0016] In the first step, the coupling analysis refers to:

[0017] First, the habitat suitability curves are spatially overlaid with the hydraulic condition distribution data of each target river section under different reservoir flow rates to calculate the weighted available habitat area of ​​each target species in each target river section under different flow rates.

[0018] Then, based on the correspondence between the weighted available habitat area and the dispatched flow, a change curve is established, and according to the preset ecological protection target, the corresponding flow range is selected from the change curve as the ecological flow threshold range of the corresponding target species in the corresponding target river section.

[0019] In the second step, the process of first dividing different ecological critical stages according to the key life history stages of each target species and setting ecological protection priorities for each ecological critical stage; and then, based on the ecological protection priorities, coordinating and integrating the ecological flow threshold ranges of each target species in the same ecological critical stage to generate the time-segmented comprehensive ecological flow demand for each target river segment includes the following steps:

[0020] First, based on the key life history stages of all target species, several consecutive time periods are divided on a calendar year basis, with each time period corresponding to one or more key ecological stages.

[0021] Next, for each time period, target species that are in a critical life history stage during that time period are identified, and those target species are designated as priority conservation species for that time period.

[0022] Then, for each target river segment, the following operations are performed: For each time period, the ecological flow threshold ranges of all priority protected species within that time period are superimposed and integrated on the target river segment to generate the comprehensive ecological flow demand of the target river segment within that time period.

[0023] Finally, the comprehensive ecological flow demand for all time periods of each target river section is aggregated to form an independent time-segmented comprehensive ecological flow demand sequence for each target river section, covering the whole year.

[0024] The key life history stages include the reproductive period, the rearing period, the foraging period, the dormancy period, and the growth period.

[0025] In the third step, the daily compliance assessment of the daily flow sequence formed by each candidate scheduling scheme in each target river section, based on the aforementioned time-segmented comprehensive ecological flow demand, to obtain the ecological flow satisfaction of each candidate scheduling scheme in each target river section refers to:

[0026] For any candidate scheduling scheme and target river section, using the time-segmented comprehensive ecological flow demand of the target river section as the criterion, calculate the percentage of days with daily flow that fall within the time-segmented comprehensive ecological flow demand range in the daily flow sequence formed by the candidate scheduling scheme in the target river section, relative to the total number of days in a given period, and use this percentage as the ecological flow satisfaction of the candidate scheduling scheme in the target river section.

[0027] Thus, the ecological flow satisfaction of each candidate scheduling scheme in each target river section is obtained.

[0028] In the third step, the step of using the natural hydrological conditions of each target river segment as a benchmark and employing the range of variation method to evaluate the degree of change of the daily flow sequence formed by each candidate scheduling scheme in each target river segment relative to the natural hydrological conditions, and obtaining the overall hydrological change degree of each candidate scheduling scheme in each target river segment, refers to:

[0029] For any candidate scheduling scheme and target river section, using the natural hydrological conditions of the target river section as a benchmark, the variation range method is used to calculate the degree of deviation of the daily flow sequence formed by the candidate scheduling scheme in the target river section from the natural hydrological conditions on multiple sets of hydrological change indicators; by combining the degree of deviation of all hydrological change indicators, a value representing the overall deviation is obtained, which is the overall hydrological change degree of the candidate scheduling scheme in the target river section.

[0030] Thus, the overall hydrological change of each candidate scheduling scheme in each target river section is obtained.

[0031] In the fourth step, the decision-making model includes an objective layer, a criterion layer, a sub-criterion layer, and a scheme layer;

[0032] The target layer corresponds to the decision objective of selecting the optimal reservoir ecological flow scheduling scheme;

[0033] The criteria layer includes a first criterion and a second criterion. The first criterion aims to maximize the ecological flow satisfaction, while the second criterion aims to minimize the overall hydrological change.

[0034] The evaluation unit of the sub-criteria layer is each target river segment;

[0035] The evaluation object of the scheme layer is each of the candidate scheduling schemes.

[0036] In the fourth step, the comprehensive evaluation of each candidate scheduling scheme through the decision model includes the following steps:

[0037] First, at the sub-criteria layer, for each target river segment, based on the ecological flow satisfaction and overall hydrological change of each candidate scheduling scheme in the target river segment, the river segment criterion score of the candidate scheduling scheme in the target river segment is calculated comprehensively.

[0038] Then, at the criterion layer, for each candidate scheduling scheme, the river segment criterion scores of the candidate scheduling scheme in all target river segments are aggregated to calculate the global comprehensive score of the candidate scheduling scheme.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] 1. This invention provides a method for optimizing reservoir ecological flow scheduling that couples multiple species and multiple river sections' eco-hydrology. The method includes: first, identifying multiple downstream target river sections and multiple target species; second, performing coupling analysis to obtain the ecological flow threshold range for each target species in each target river section; third, dividing ecological key stages according to the key life history stages of each target species and setting priorities; fourth, integrating the ecological flow threshold ranges according to priorities to generate comprehensive ecological flow demand for each target river section in different time periods; fifth, using this comprehensive ecological flow demand as a benchmark, combined with natural hydrological conditions, evaluating the ecological flow satisfaction and overall hydrological change of each candidate scheduling scheme in each target river section; and finally, constructing a decision model using these two indicators to comprehensively evaluate each candidate scheduling scheme, calculating the comprehensive score of each candidate scheduling scheme, and selecting the scheme with the highest comprehensive score as the final reservoir ecological flow scheduling scheme. The advantages of this invention also include:

[0041] Firstly, by using ecological flow satisfaction (reflecting the degree to which the scheme meets the ecological needs of species) and overall hydrological change (reflecting the degree to which the scheme deviates from the natural hydrological situation) as evaluation criteria, and by performing weight integration and optimization in a unified model based on the analytic hierarchy process, the limitations of the isolation of ecological and hydrological objectives in existing methods are overcome, thereby achieving the synergistic optimization of ecological suitability and hydrological naturalness.

[0042] Secondly, by dynamically integrating data according to the key life stages of species in different time periods, the comprehensive ecological flow demand of each target river section is generated, enabling the evaluation and selection of scheduling schemes to adapt to the time-varying characteristics of ecological demand, and realizing dynamic response and balance to the needs of different target species and different stages in the time dimension.

[0043] Thirdly, by conducting independent ecological and hydrological response assessments for each target river segment and by spatially aggregating multiple target river segments in decision-making, the spatial limitations of traditional scheduling that ignores the geomorphological and hydraulic heterogeneity of downstream river segments are overcome, and a synergistic balance between ecological benefits and hydrological disturbances at multiple river segment scales is achieved.

[0044] Therefore, this invention can not only optimize the reservoir ecological flow scheduling scheme, but also achieve a dynamic balance between ecological and hydrological objectives.

[0045] 2. In this invention, a reservoir ecological flow scheduling optimization method coupling multiple species and multiple river sections' eco-hydrology, the target species include juvenile fish, large invertebrates, and wetland plants. In application, by selecting target species covering multiple trophic levels and functional groups, including producers (wetland plants), consumers (juvenile fish), and decomposers / key links (large invertebrates), and systematically analyzing the differentiated hydraulic demands of multiple species, this method fundamentally overcomes the limitations of existing technologies that only set protection targets around a single group (such as fish). The ecological flow threshold range generated by this method can synergistically meet the key habitat needs of organisms at different trophic levels, effectively avoiding the stress risks to other groups (such as invertebrate larvae and wetland plants) caused by satisfying the needs of a single group (such as fish spawning pulses), thereby supporting the complete interconnectedness of the river food web and the overall stability of the ecosystem. Therefore, this invention not only achieves a dynamic balance between ecological and hydrological objectives but also enhances river biodiversity.

[0046] 3. In the reservoir ecological flow scheduling optimization method coupled with multi-species and multi-river section eco-hydrology of the present invention, the key life history stages include the breeding period, juvenile period, foraging period, dormancy period, and growth period. In application, differentiated seasonal ecological protection priorities are set for each target species based on the key life history stages, thereby transforming the static and uniform flow target into a dynamic and time-segmented comprehensive ecological flow demand range that matches biological rhythms. This allows the evaluation of candidate scheduling schemes to be based on a time-varying benchmark, effectively overcoming the static limitations of traditional scheduling that relies on fixed rules and is difficult to respond to ecological temporal changes. Therefore, the present invention not only enhances river biodiversity but also solves the problem of static scheduling.

[0047] 4. In the reservoir ecological flow scheduling optimization method coupled with multi-species and multi-segment eco-hydrology of the present invention, firstly, at the sub-criteria level, for each target river segment, based on the ecological flow satisfaction and overall hydrological change of each candidate scheduling scheme in the target river segment, the river segment criterion score of the candidate scheduling scheme in the target river segment is comprehensively calculated. Then, at the criterion level, for each candidate scheduling scheme, the river segment criterion scores of the candidate scheduling scheme in all target river segments are aggregated to calculate the global comprehensive score of the candidate scheduling scheme. In application, by independently evaluating the ecological and hydrological response of each target river segment, the spatial heterogeneity of different river segments in terms of geomorphology, hydraulics, and ecological functions is fully preserved. In the process of aggregating from the river segment score to the global comprehensive score, the scores of each river segment can be differentiated and weighted according to the ecological importance of each river segment, thereby reflecting the priority and contribution of different spatial units in the decision-making process. This not only overcomes the spatial limitations of the traditional method that treats the downstream river as a homogeneous whole for one-size-fits-all evaluation, but also realizes the synergistic optimization and overall balance of ecological flow benefits at the multi-segment scale. Therefore, this invention not only solves the problem of scheduling staticization, but also solves the problem of spatial homogenization. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the workflow of the present invention.

[0049] Figure 2 This is a schematic diagram of the target river section and sampling points in Embodiment 10 of the present invention.

[0050] Figure 3 This is a decision-making flowchart in Embodiment 10 of the present invention.

[0051] Figure 4 This is the seasonal priority decision map of the target species in Embodiment 10 of the present invention.

[0052] Figure 5 This is a structural diagram of the hierarchical analysis method in Embodiment 10 of the present invention.

[0053] Figure 6 This is a spatial distribution map of the comprehensive suitability of each target river section in Embodiment 10 of the present invention.

[0054] Figure 7 This is a graph showing the relationship between flow (Q) and weighted available habitat area (WUA) for each target river section and each target species in Embodiment 10 of the present invention.

[0055] Figure 8 This is a time-segmented integrated ecological flow demand map for each target river section in Embodiment 10 of the present invention.

[0056] Figure 9 This is a graph showing the daily flow process lines and ecological flow demand satisfaction of each target river section in 2005 in Embodiment 10 of the present invention.

[0057] Figure 10 This is a comparison chart of the ecological flow satisfaction (SR) of the four candidate scheduling schemes in Example 10.

[0058] Figure 11 This is a comparison chart of the overall hydrological change (OAD) values ​​of the four candidate scheduling schemes in Example 10.

[0059] Figure 12 This is a comparative analysis chart of the mean ecological flow satisfaction (SR) and overall hydrological change (OAD) of each target river segment in Example 10. Detailed Implementation

[0060] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] See Figures 1-12 A method for optimizing reservoir ecological flow scheduling that couples multiple species and multiple river section eco-hydrology, the method comprising:

[0062] Step 1: First, select multiple target river sections downstream of the reservoir and select multiple target species within each target river section; then, through coupled analysis of the hydraulic demand of each target species and the distribution data of hydraulic conditions in each target river section, determine the ecological flow threshold range of each target species in each target river section.

[0063] The second step is to first divide the target species into different ecological critical stages according to the key life history stages of each target species, and set ecological protection priorities for each ecological critical stage; then, based on the ecological protection priorities, coordinate and integrate the ecological flow threshold ranges of each target species in the same ecological critical stage to generate the time-segmented comprehensive ecological flow demand of each target river section.

[0064] Step 3: Based on the above-mentioned time-segmented comprehensive ecological flow demand, the daily flow sequence formed by each candidate scheduling scheme in each target river segment is judged on a daily basis to obtain the ecological flow satisfaction of each candidate scheduling scheme in each target river segment; at the same time, based on the natural hydrological conditions of each target river segment, the change range method is used to evaluate the degree of change of the daily flow sequence formed by each candidate scheduling scheme in each target river segment relative to the natural hydrological conditions, to obtain the overall hydrological change of each candidate scheduling scheme in each target river segment.

[0065] Step 4: First, using the overall hydrological change and ecological flow satisfaction as evaluation indicators, construct a decision model using the analytic hierarchy process (AHP); then, comprehensively evaluate each candidate scheduling scheme through the decision model and calculate the comprehensive score of each candidate scheduling scheme; finally, select the candidate scheduling scheme with the highest comprehensive score as the final reservoir ecological flow scheduling scheme.

[0066] In the first step, the target species include juvenile fish, large invertebrates, and wetland plants.

[0067] In the first step, the water requirements of each target species are the habitat suitability curves of each target species; the habitat suitability curves of each target species are constructed based on the biological distribution data of each target species and the key hydraulic factor data of the corresponding habitat of each target species.

[0068] The key hydraulic factors include water depth and flow velocity.

[0069] In the first step, the coupling analysis refers to:

[0070] First, the habitat suitability curves are spatially overlaid with the hydraulic condition distribution data of each target river section under different reservoir flow rates to calculate the weighted available habitat area of ​​each target species in each target river section under different flow rates.

[0071] Then, based on the correspondence between the weighted available habitat area and the dispatched flow, a change curve is established, and according to the preset ecological protection target, the corresponding flow range is selected from the change curve as the ecological flow threshold range of the corresponding target species in the corresponding target river section.

[0072] In the second step, the process of first dividing different ecological critical stages according to the key life history stages of each target species and setting ecological protection priorities for each ecological critical stage; and then, based on the ecological protection priorities, coordinating and integrating the ecological flow threshold ranges of each target species in the same ecological critical stage to generate the time-segmented comprehensive ecological flow demand for each target river segment includes the following steps:

[0073] First, based on the key life history stages of all target species, several consecutive time periods are divided on a calendar year basis, with each time period corresponding to one or more key ecological stages.

[0074] Next, for each time period, target species that are in a critical life history stage during that time period are identified, and those target species are designated as priority conservation species for that time period.

[0075] Then, for each target river segment, the following operations are performed: For each time period, the ecological flow threshold ranges of all priority protected species within that time period are superimposed and integrated on the target river segment to generate the comprehensive ecological flow demand of the target river segment within that time period.

[0076] Finally, the comprehensive ecological flow demand for all time periods of each target river section is aggregated to form an independent time-segmented comprehensive ecological flow demand sequence for each target river section, covering the whole year.

[0077] The key life history stages include the reproductive period, the rearing period, the foraging period, the dormancy period, and the growth period.

[0078] In the third step, the daily compliance assessment of the daily flow sequence formed by each candidate scheduling scheme in each target river section, based on the aforementioned time-segmented comprehensive ecological flow demand, to obtain the ecological flow satisfaction of each candidate scheduling scheme in each target river section refers to:

[0079] For any candidate scheduling scheme and target river section, using the time-segmented comprehensive ecological flow demand of the target river section as the criterion, calculate the percentage of days with daily flow that fall within the time-segmented comprehensive ecological flow demand range in the daily flow sequence formed by the candidate scheduling scheme in the target river section, relative to the total number of days in a given period, and use this percentage as the ecological flow satisfaction of the candidate scheduling scheme in the target river section.

[0080] Thus, the ecological flow satisfaction of each candidate scheduling scheme in each target river section is obtained.

[0081] In the third step, the step of using the natural hydrological conditions of each target river segment as a benchmark and employing the range of variation method to evaluate the degree of change of the daily flow sequence formed by each candidate scheduling scheme in each target river segment relative to the natural hydrological conditions, and obtaining the overall hydrological change degree of each candidate scheduling scheme in each target river segment, refers to:

[0082] For any candidate scheduling scheme and target river section, using the natural hydrological conditions of the target river section as a benchmark, the variation range method is used to calculate the degree of deviation of the daily flow sequence formed by the candidate scheduling scheme in the target river section from the natural hydrological conditions on multiple sets of hydrological change indicators; by combining the degree of deviation of all hydrological change indicators, a value representing the overall deviation is obtained, which is the overall hydrological change degree of the candidate scheduling scheme in the target river section.

[0083] Thus, the overall hydrological change of each candidate scheduling scheme in each target river section is obtained.

[0084] In the fourth step, the decision-making model includes an objective layer, a criterion layer, a sub-criterion layer, and a scheme layer;

[0085] The target layer corresponds to the decision objective of selecting the optimal reservoir ecological flow scheduling scheme;

[0086] The criteria layer includes a first criterion and a second criterion. The first criterion aims to maximize the ecological flow satisfaction, while the second criterion aims to minimize the overall hydrological change.

[0087] The evaluation unit of the sub-criteria layer is each target river segment;

[0088] The evaluation object of the scheme layer is each of the candidate scheduling schemes.

[0089] In the fourth step, the comprehensive evaluation of each candidate scheduling scheme through the decision model includes the following steps:

[0090] First, at the sub-criteria layer, for each target river segment, based on the ecological flow satisfaction and overall hydrological change of each candidate scheduling scheme in the target river segment, the river segment criterion score of the candidate scheduling scheme in the target river segment is calculated comprehensively.

[0091] Then, at the criterion layer, for each candidate scheduling scheme, the river segment criterion scores of the candidate scheduling scheme in all target river segments are aggregated to calculate the global comprehensive score of the candidate scheduling scheme.

[0092] The following are supplementary descriptions of the present invention:

[0093] The candidate scheduling schemes described in this invention refer to a set of reservoir scheduling and operation modes that are pre-formulated or generated by a model for comparison before making a final decision.

[0094] The candidate scheduling schemes described in this invention are derived from, but are not limited to: typical operating modes based on historical scheduling procedures or expert experience (empirical models, such as fixed water level scheduling); Pareto optimal solution sets obtained by using multi-objective optimization algorithms (such as NSGA-II) to solve for ecological, power generation, and flood control objectives (optimization generation); different simulated scenarios formed by adjusting key parameters such as starting water level and water storage and release time (scenario simulation); and the selection benchmarks based on the actual operating process of typical historical years or the recommended process under different design specifications (actual comparison).

[0095] In the fourth step of this invention, the decision model constructed using the analytic hierarchy process (AHP) is implemented as follows: First, based on the decision objective of "selecting the optimal reservoir ecological flow scheduling scheme," a four-level hierarchical structure is constructed, including: an objective layer, a criterion layer, a sub-criterion layer, and a scheme layer. The criterion layer includes a first criterion aimed at maximizing ecological flow satisfaction and a second criterion aimed at minimizing overall hydrological change. The sub-criterion layer uses downstream target river sections as evaluation units, and the scheme layer uses each candidate scheduling scheme as the evaluation object. Second, a pairwise comparison method (such as the Saaty scaling method) is used to construct judgment matrices for each level of elements to quantify their relative importance, and a consistency check is performed on all judgment matrices. Then, the local weights of each level of elements are calculated, and the scheme layer weights, sub-criterion layer weights, and criterion layer weights are aggregated sequentially through bottom-up weight synthesis calculations to finally obtain the global comprehensive weight (or comprehensive score) of each candidate scheduling scheme relative to the overall objective. The candidate scheduling scheme with the highest global comprehensive weight is the optimal reservoir ecological flow scheduling scheme selected by the decision model.

[0096] The preferred ecological protection target of this invention is to ensure that the weighted available habitat area is not less than 50% of its peak area.

[0097] In the preferred second step of this invention, the coordinated integration of the ecological flow threshold ranges of each target species at the same ecological critical stage refers to: superimposing the ecological flow threshold ranges of all priority protected species within the time period, taking the intersection, or integrating them according to preset rules.

[0098] Example 1:

[0099] See Figures 1-12 A method for optimizing reservoir ecological flow scheduling that couples multiple species and multiple river section eco-hydrology, the method comprising:

[0100] Step 1: First, select multiple target river sections downstream of the reservoir and select multiple target species within each target river section; then, through coupled analysis of the hydraulic demand of each target species and the distribution data of hydraulic conditions in each target river section, determine the ecological flow threshold range of each target species in each target river section.

[0101] The second step is to first divide the target species into different ecological critical stages according to the key life history stages of each target species, and set ecological protection priorities for each ecological critical stage; then, based on the ecological protection priorities, coordinate and integrate the ecological flow threshold ranges of each target species in the same ecological critical stage to generate the time-segmented comprehensive ecological flow demand of each target river section.

[0102] Step 3: Based on the above-mentioned time-segmented comprehensive ecological flow demand, the daily flow sequence formed by each candidate scheduling scheme in each target river segment is judged on a daily basis to obtain the ecological flow satisfaction of each candidate scheduling scheme in each target river segment; at the same time, based on the natural hydrological conditions of each target river segment, the change range method is used to evaluate the degree of change of the daily flow sequence formed by each candidate scheduling scheme in each target river segment relative to the natural hydrological conditions, to obtain the overall hydrological change of each candidate scheduling scheme in each target river segment.

[0103] Step 4: First, using the overall hydrological change and ecological flow satisfaction as evaluation indicators, construct a decision model using the analytic hierarchy process (AHP); then, comprehensively evaluate each candidate scheduling scheme through the decision model and calculate the comprehensive score of each candidate scheduling scheme; finally, select the candidate scheduling scheme with the highest comprehensive score as the final reservoir ecological flow scheduling scheme.

[0104] Example 2:

[0105] The basic content is the same as in Example 1, except that in the first step, the target species include juvenile fish, large invertebrates and wetland plants.

[0106] In application, juvenile fish, macroinvertebrates, and wetland plants represent advanced consumers, key consumers / decomposers, and primary producers in the aquatic food web, respectively, comprehensively reflecting the integrity of the river's trophic structure. Furthermore, their responses to hydrological changes are complementary: successful juvenile fish replenishment depends on longitudinal hydrological rhythms (such as the pulse flow required for spawning), the community structure of macroinvertebrates is directly controlled by hydrodynamic conditions and substrate stability, and the distribution and abundance of wetland plants are key indicators of the lateral connectivity between the river channel and floodplain. Therefore, simultaneously optimizing ecological flow to meet the needs of these three groups can diagnose and mitigate the impact of dam operation on the downstream ecosystem's structure and function from multiple dimensions, overcoming the limitations of traditional single-species methods.

[0107] Example 3:

[0108] The basic content is the same as in Example 1, except that: in the first step, the hydraulic requirements of each target species are the habitat suitability curves of each target species; the habitat suitability curves of each target species are constructed based on the biological distribution data of each target species and the key hydraulic factors data of the corresponding habitats of each target species; the key hydraulic factors include water depth and flow velocity.

[0109] In application, firstly, field surveys are conducted simultaneously at multiple representative sampling points set up within the target river section; for each target species (such as fish larvae, large invertebrate groups, or wetland plants), standardized sampling methods are used to record its occurrence or quantify its biomass, forming a biological distribution dataset; at the same time, at each sampling point, hydrological measuring instruments are used to measure and record the corresponding key hydraulic factor data, mainly water depth and flow velocity, to ensure that the biological data and physical habitat data are strictly matched in space and time;

[0110] Subsequently, the collected biological data and the corresponding key hydraulic factor data were statistically analyzed. For each target species, the relationship between its distribution or abundance and water depth and flow velocity was analyzed independently. Statistical methods (such as frequency-based habitat suitability models) were used to fit the data, quantifying species preferences into continuous values ​​between 0 and 1, thereby generating two independent mathematical function curves: one describing the relationship between water depth and habitat suitability index, and the other describing the relationship between flow velocity and habitat suitability index. These two curves together constitute the habitat suitability curve set for the target species.

[0111] Example 4:

[0112] The basic content is the same as in Example 1, except that in the first step, the coupling analysis refers to:

[0113] First, the habitat suitability curve is spatially overlaid with the hydraulic condition distribution data of each target river section under different reservoir scheduling flows to calculate the weighted available habitat area of ​​each target species in each target river section under different scheduling flows. Then, a change curve is established based on the correspondence between the weighted available habitat area and the scheduling flow. Based on the preset ecological protection target, the corresponding flow range is selected from the change curve as the ecological flow threshold range of the corresponding target species in the corresponding target river section.

[0114] When applied, for each target river segment, a calibrated and validated two-dimensional hydrodynamic model is used to simulate the water depth and velocity distribution at various spatial locations within the target river segment under different reservoir scheduling modes (or a series of discrete control flow values), generating a spatial dataset of hydraulic conditions corresponding to each flow scenario.

[0115] Subsequently, the habitat suitability curves of each target species are spatially superimposed and gridded with the spatial dataset of hydraulic conditions: For each simulated flow scenario, the simulated values ​​of water depth and flow velocity of each calculation grid are read, and the depth suitability and flow velocity suitability of the grid point for a specific species are obtained by interpolation according to the suitability curve function. The comprehensive habitat suitability index of the point is calculated by using a preset integration rule (such as taking the geometric mean). Then, the comprehensive index values ​​of all grids are multiplied by their representative areas and summed to obtain the weighted available habitat area of ​​the target species in this target river section under the dispatch flow.

[0116] Repeat this process to obtain a series of corresponding data pairs of scheduled flow and weighted available habitat area; based on these data pairs, plot a quantitative change curve reflecting the response relationship of "scheduled flow - weighted available habitat area" of the species in this target river section; finally, according to the ecological protection target preset in management (for example, it is stipulated that the species should be maintained at no less than a certain percentage of its maximum potential weighted available habitat area, such as 50%), identify and extract the range of scheduled flow values ​​that can meet the target from the change curve. This range is the threshold range of the ecological flow demand of the target species in the target river section.

[0117] Example 5:

[0118] The basic content is the same as in Example 1, except that in the second step, the process of first dividing the target species into different ecological critical stages according to their critical life history stages and setting ecological protection priorities for each ecological critical stage, and then coordinating and integrating the ecological flow threshold ranges of each target species in the same ecological critical stage to generate the time-segmented comprehensive ecological flow demand for each target river segment according to the ecological protection priorities, includes the following steps: First, based on the critical life history stages of all target species, several consecutive time periods are divided on a calendar year basis, with each time period corresponding to one or more ecological critical stages; then, for each time period, the target species in the critical life history stage within that time period are identified and set as the priority protection species for that time period; then, for each target river segment, the following operations are performed: for each time period, the ecological flow threshold ranges of all priority protection species within that time period are superimposed and integrated to generate the comprehensive ecological flow demand for that target river segment within that time period; finally, the comprehensive ecological flow demand for all time periods of each target river segment is aggregated to form an independent time-segmented comprehensive ecological flow demand sequence for each target river segment covering the entire year.

[0119] When applying this method, the calendar year is first divided into consecutive ecological critical periods (usually aligned with months or seasons) based on the critical life history stages of all target species. For each period, the target species that are in the critical life history stage within that period are identified and designated as the priority protection species for that period.

[0120] For each target river segment, an integration operation is performed for each ecological critical period: extract the pre-determined ecological flow threshold ranges for all species marked as priority protection within that period; then, based on the established ecological protection priorities, prioritize the needs of high-priority species and find the flow range that can simultaneously meet the needs of all priority species (i.e., the intersection of all threshold ranges); if the threshold ranges do not intersect, determine the flow range with the primary objective of ensuring the needs of the highest priority species; this flow range is the comprehensive ecological flow demand of the target river segment within that specific ecological critical period.

[0121] Then, the comprehensive ecological flow demand generated by each target river section during all ecological critical periods is aggregated in chronological order to form an independent time-segmented comprehensive ecological flow demand sequence for each river section that covers the whole year.

[0122] Example 6:

[0123] The basic content is the same as in Example 1, except that the key life history stages include the breeding period, the rearing period, the foraging period, the dormancy period, and the growth period.

[0124] In application, the division of key life history stages is strictly based on the physiological and ecological periods during which the target species is most sensitive to changes in hydrological conditions. Among them, the reproductive period corresponds to key events such as fish spawning and the emergence and reproduction of large invertebrates, which usually require specific flow pulses or water temperature conditions as ecological signals; the juvenile period refers to the highly vulnerable stage of fish larvae, juveniles, or invertebrate larvae, which has clear requirements for habitat stability, food availability, and refuge conditions; the foraging period is the main growth stage in which species actively feed to accumulate energy, and its habitat suitability is closely related to specific flow velocity and water depth conditions; the dormancy period is a physiological dormancy state that some species enter during unfavorable seasons (such as low temperatures in winter or drought periods), which requires a safe aquatic environment to ensure survival; the growth period specifically refers to the period of vegetative growth and biomass accumulation of primary producers such as wetland plants, whose distribution and abundance are directly controlled by the duration of inundation, water depth, and water flow conditions. The determination of these stages provides a clear biological basis for transforming abstract ecological protection goals into specific and operable seasonal ecological flow priorities, thereby supporting the generation of integrated ecological flow demands in different time periods.

[0125] Example 7:

[0126] The basic content is the same as in Example 1, except that in the third step, the daily compliance judgment of the daily flow sequence formed by each candidate scheduling scheme in each target river section based on the above-mentioned time-segmented comprehensive ecological flow demand means that, for any candidate scheduling scheme and target river section, the percentage of daily flow days falling within the above-mentioned time-segmented comprehensive ecological flow demand range in the daily flow sequence formed by the candidate scheduling scheme in the target river section is calculated based on the time-segmented comprehensive ecological flow demand of the target river section. This percentage is then used as the ecological flow satisfaction of the candidate scheduling scheme in the target river section. Thus, the ecological flow satisfaction of each candidate scheduling scheme in each target river section is obtained.

[0127] When applying the scheme, perform the following operations for each candidate scheduling scheme and each target river segment:

[0128] First, obtain the complete daily flow sequence of the candidate scheduling scheme in the target river section, which is obtained through hydrodynamic model simulation. This sequence usually covers a complete evaluation period (e.g., a hydrological year or calendar year). At the same time, call the time-segmented comprehensive ecological flow demand sequence of the target river section, which clarifies the upper and lower limits of flow in different time periods throughout the year (e.g., each month).

[0129] Then, perform daily judgment: On a daily basis, check whether the daily flow value falls within the comprehensive ecological flow demand range of the corresponding date and time period; for example, for the flow of a certain day in May, determine whether it meets the comprehensive ecological flow range of May.

[0130] Then, the total number of days that meet the above conditions are counted throughout the entire evaluation period, and the percentage of the days that meet the conditions is calculated as the ecological flow satisfaction (SR) of the candidate scheduling scheme in the target river section. The ecological flow satisfaction (SR) directly reflects the proportion of time that the scheduling scheme meets the needs of multiple species and seasonal habitats.

[0131] Example 8:

[0132] The basic content is the same as that of Embodiment 1, except that: in the third step, based on the natural hydrological regime of each target river section, the range of variability approach is adopted to evaluate the degree of change of the daily flow sequence formed by each candidate operation scheme in each target river section relative to the natural hydrological regime. The overall hydrological alteration degree of each candidate operation scheme in each target river section refers to: for any candidate operation scheme and target river section, based on the natural hydrological regime of the target river section, the range of variability approach is used to calculate the degree of deviation of the daily flow sequence formed by the candidate operation scheme in the target river section from the natural hydrological regime on multiple hydrological alteration indices; by synthesizing the degrees of deviation of all hydrological alteration indices, a quantity representing the overall deviation is obtained, which is the overall hydrological alteration degree of the candidate operation scheme in the target river section; thus, the overall hydrological alteration degree of each candidate operation scheme in each target river section is obtained.

[0133] During application, first, long-term daily flow data of the target river section during the natural period (i.e., before reservoir construction or large-scale regulation) is obtained as the benchmark for the natural hydrological regime of the target river section; at the same time, the daily flow sequence of the evaluation period formed by the candidate operation scheme (through model simulation) in the target river section is obtained as the regulated hydrological regime.

[0134] Then, the range of variability approach (RVA) is used for analysis: based on the above two hydrological sequences, a set of hydrological alteration indices (such as 32 IHA indices) is calculated; the hydrological alteration indices include the magnitude, occurrence time, frequency, duration, and rate of change of the flow.

[0135] Then, for each hydrological alteration index, the degree of deviation of the regulated sequence compared with the natural sequence is calculated respectively , and the specific formula is ; where is the number of years in which the index value in the regulated sequence falls within the variation range of the natural sequence (usually defined by the 25th and 75th percentiles), is the expected number of years to fall within.

[0136] Finally, by synthesizing the degrees of deviation of all hydrological alteration indices, the root mean square value is calculated through the formula to obtain a single quantity representing the overall deviation, which is the overall hydrological alteration degree of the candidate operation scheme in the target river section;

[0137] And according to the widely adopted classification criteria in the literature, the OAD results are divided into three categories: low alteration (OAD ≤ 33%), moderate alteration (33% < OAD ≤ 67%), and high alteration (OAD > 67%); thus, the overall hydrological alteration degree of each candidate operation scheme in each target river section is calculated, and the overall hydrological alteration degree reflects the overall degree of change of the operation scheme to the natural flow regime.

[0138] Example 9:

[0139] The basic content is the same as in Example 1, except that in the fourth step, the decision model includes a target layer, a criterion layer, a sub-criterion layer, and a scheme layer; the target layer corresponds to the decision objective of selecting the optimal reservoir ecological flow scheduling scheme; the criterion layer includes a first criterion and a second criterion, the first criterion being optimized to maximize ecological flow satisfaction, and the second criterion being optimized to minimize overall hydrological change; the evaluation unit of the sub-criterion layer is each target river segment; the evaluation object of the scheme layer is each candidate scheduling scheme; in the fourth step, the comprehensive evaluation of each candidate scheduling scheme through the decision model includes the following steps: first, in the sub-criterion layer, for each target river segment, based on the ecological flow satisfaction and overall hydrological change of each candidate scheduling scheme in that target river segment, the river segment criterion score of the candidate scheduling scheme in that target river segment is comprehensively calculated; then, in the criterion layer, for each candidate scheduling scheme, the river segment criterion scores of the candidate scheduling scheme in all target river segments are aggregated to calculate the global comprehensive score of the candidate scheduling scheme.

[0140] When applying this method, first, following the standard procedure of the analytic hierarchy process, construct the judgment matrix hierarchically and calculate the weights:

[0141] At the criteria level, the two criteria, “ecological flow satisfaction (SR)” and “overall hydrological change (OAD)”, are considered to be of equal importance, with a weight ratio of 1:1.

[0142] At the sub-criteria level, pairwise comparisons are made for each target river segment for both the SR criterion and the OAD criterion, an independent judgment matrix is ​​constructed, and the weight of each target river segment under the corresponding criterion is calculated.

[0143] At the scheme level, for each "target river segment - evaluation criterion" combination, pairwise comparisons are made based on the SR or OAD quantification results calculated for each candidate scheduling scheme at that location. A judgment matrix is ​​constructed and the local priority weight of the candidate scheduling scheme relative to the combination is calculated. All constructed judgment matrices must pass the consistency test (consistency ratio CR < 0.1).

[0144] Then, the weights are calculated: the local priority weights of the candidate scheduling schemes calculated at the scheme layer relative to each "river segment-criteria" combination are weighted and synthesized from bottom to top according to the hierarchical structure with the river segment weights corresponding to the sub-criteria layer and the criterion weights corresponding to the criteria layer, respectively, to finally obtain the global comprehensive weight of each candidate scheduling scheme relative to the overall goal; the scheme with the highest global comprehensive weight is determined to be the optimal scheduling scheme.

[0145] Example 10:

[0146] The basic content is the same as in Example 1, except that the ecological scheduling scheme of the Three Gorges Reservoir is optimized based on the protection of multiple species and multiple river sections.

[0147] When applying this method, the first step is to determine the ecological flow threshold range for each target species in each target river segment:

[0148] See Figure 2 First, the study area is the middle reaches of the Yangtze River, which stretches approximately 900 kilometers from the Three Gorges Dam to Hukou. Within this area, three typical river sections with different geomorphological features are further selected as specific targets for ecological protection and assessment: the Yichang section (YC, approximately 50 kilometers downstream of the dam, narrow and deep channel), the Jianli section (JL, approximately 320 kilometers downstream of the dam, wide floodplain), and the Daijiazhou section (DJZ, approximately 750 kilometers downstream of the dam, double-branched channel developed from an island in the river).

[0149] The following data were collected and organized: daily flow and water level data for each river section from 1975 to 2022, divided into two periods: before dam construction (1975-2002) and after dam construction (2003-2022); large-scale digital elevation models (DEMs) and topographic data for each river section; and spatial distribution data of biomass of target species groups (juvenile fish, large invertebrates, and wetland plants) in the three river sections obtained through field sampling.

[0150] Then, two-dimensional hydrodynamic models of three river sections were constructed using the DHI MIKE 21 FM module. The model mesh was an unstructured triangular mesh. The model was calibrated and validated by adjusting the Manning roughness coefficient and eddy viscosity coefficient. Based on field sampling data (corresponding to...),... Figure 2 Using Spearman correlation and frequency distribution histogram analysis at 12 sampling points, habitat suitability curves for key hydraulic factors (flow velocity and water depth) of each species group were determined. For example, the analysis showed that juvenile fish preferred areas with flow velocities of 0-0.30 m / s and water depths of 0.40-1.00 m, and that wetland plant biomass was significantly correlated with flooding depth (expressed as the difference between riverbed elevation and water surface).

[0151] Finally, the velocity and depth fields simulated by the two-dimensional hydrodynamic model under different flow scenarios are spatially superimposed with the suitability curves of each species to obtain the weighted available area (WUA) for each species group under each flow range; the flow (Q)-weighted available area (WUA) relationship curves for each river segment and each species are plotted (e.g., Figure 7 As shown, the horizontal axis represents flow rate Q, and the vertical axis represents normalized flow rate WUA (%). The three curves in the figure represent different species, and the 50% horizontal dashed line is used to determine the threshold range. The flow range that can maintain the WUA of a species group at no less than 50% of its peak value is determined as the ecological flow threshold range of that species in that river section.

[0152] Step 2: Generate the time-segmented comprehensive ecological flow requirements for each target river segment:

[0153] See Figure 4 Based on the key life cycle of the target species, priority protection groups are determined for different seasons; for example, in spring (March-May), priority is given to protecting the germination and growth of wetland plants; in summer (June-August), priority is given to meeting the feeding and growth needs of juvenile fish; for each month, the threshold flow ranges of the priority species groups for that month are superimposed and their intersection is taken to obtain the "comprehensive ecological flow range" for that month (e.g., Figure 4 (As shown); for example, the comprehensive ecological flow range for the Yichang section (YC) in winter is determined to be 3100-7600 m³ / h. 3 / s; Due to the influence of the river island topography, the Daijiazhou section (DJZ) has a range of 6000-14000m. 3 / s and 39000-53000m 3 The bimodal suitable flow range is defined as / s; thus, a comprehensive ecological flow demand sequence covering the whole year is generated for each river segment.

[0154] Step 3: Evaluate the ecological and hydrological performance of candidate scheduling schemes:

[0155] Four representative Three Gorges Reservoir operation modes were designed as candidate schemes:

[0156] Mode M1 (fixed water level scheduling): Based on traditional flood control and power generation needs, a fixed seasonal operating water level is set (e.g., 145 meters during the flood season, 175 meters at the end of the flood season, and 155 meters during the dry season).

[0157] Mode M2 ​​(Multi-objective Fine-grained Scheduling): Based on M1, it further refines the target dates for water level control and attempts to balance multiple objectives such as power generation, shipping, and water supply;

[0158] Mode M3 (Real-time Dispatch Based on Historical Water Levels): Simulates the dynamic determination of the discharge flow based on the real-time water level in the reservoir during actual operation. Its main goal is to create spawning conditions for single species such as the "four major freshwater fish".

[0159] Mode M4 (Real-time scheduling based on historical outflow): Directly uses the actual historical outflow process of the reservoir as the scheduling basis, representing a relatively natural release method that fully responds to changes in upstream water inflow;

[0160] The reservoir outflow process under various modes was simulated using a one-dimensional hydrodynamic model (MIKE 11) (see the model coupling and simulation process for details). Figure 3 For each scheduling mode and each target river segment, the following evaluation is performed:

[0161] See Figures 10-12Based on the time-segmented comprehensive ecological flow demand of this river section, the proportion of days during the simulation period where the daily flow falls within the corresponding monthly demand range was statistically analyzed, serving as the ecological flow satisfaction rate (SR). Simultaneously, using the pre-dam construction natural flow sequence as a benchmark, the range of variation (RVA) method was employed, selecting 32 hydrological change indicators (IHA) for comparison. First, the degree of change for each indicator was calculated, and then the formula was used... By taking the root mean square, we obtain the overall hydrological change (OAD).

[0162] Step 4: Optimize the scheduling scheme based on the analytic hierarchy process (AHP):

[0163] See Figure 5 An AHP decision-making model was constructed, with a hierarchical structure including: the objective layer being "selecting the optimal scheduling mode"; the criterion layer consisting of "ecological flow satisfaction (SR)" (maximized with a weight of 0.50) and "overall hydrological change (OAD)" (minimized with a weight of 0.50); ​​the sub-criterion layer comprising three river segments (Yichang, Jianli, and Daijiazhou), where pairwise comparisons were performed for each objective river segment based on the SR and OAD criteria, constructing independent judgment matrices and calculating the weight of each objective river segment under the corresponding criterion; and the scheme layer comprising four scheduling methods. Modes (M1, M2, M3, M4) were used. For each "target river segment - evaluation criterion" combination, the SR or OAD quantification results calculated for each candidate scheduling scheme at that location were compared pairwise to construct a judgment matrix and calculate the local priority weight of the candidate scheduling scheme relative to the combination. All constructed judgment matrices had to pass a consistency test (consistency ratio CR < 0.1), and the comprehensive weight of each scheduling mode was calculated. The results showed that mode M4 (real-time scheduling based on historical outflow) had the highest comprehensive weight (0.36) and was determined to be the optimal scheme.

[0164] Effect verification: Model M4 achieved a good balance in all three river sections: its ecological flow satisfaction (SR) value remained at a high level of 45%-70%, while the overall hydrological alteration (OAD) value was below 33% (especially in sections YC and JL); this shows that the scheme can effectively meet the habitat needs of multiple species and control the degree of alteration to the natural hydrological situation to a minimum, thus verifying the effectiveness of the optimization method.

[0165] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A method for optimizing reservoir ecological flow scheduling that couples multiple species and multiple river section eco-hydrology, characterized in that: The method includes: Step 1: First, select multiple target river sections downstream of the reservoir and select multiple target species within each target river section; then, through coupled analysis of the hydraulic demand of each target species and the distribution data of hydraulic conditions in each target river section, determine the ecological flow threshold range of each target species in each target river section. The second step is to first divide the target species into different ecological critical stages according to the key life history stages of each target species, and set ecological protection priorities for each ecological critical stage; then, based on the ecological protection priorities, coordinate and integrate the ecological flow threshold ranges of each target species in the same ecological critical stage to generate the time-segmented comprehensive ecological flow demand of each target river section. Step 3: Based on the above-mentioned time-segmented comprehensive ecological flow demand, the daily flow sequence formed by each candidate scheduling scheme in each target river segment is judged on a daily basis to obtain the ecological flow satisfaction of each candidate scheduling scheme in each target river segment; at the same time, based on the natural hydrological conditions of each target river segment, the change range method is used to evaluate the degree of change of the daily flow sequence formed by each candidate scheduling scheme in each target river segment relative to the natural hydrological conditions, to obtain the overall hydrological change of each candidate scheduling scheme in each target river segment. Step 4: First, using the overall hydrological change and ecological flow satisfaction as evaluation indicators, construct a decision model using the analytic hierarchy process (AHP); then, comprehensively evaluate each candidate scheduling scheme through the decision model and calculate the comprehensive score of each candidate scheduling scheme; finally, select the candidate scheduling scheme with the highest comprehensive score as the final reservoir ecological flow scheduling scheme.

2. The optimal method for reservoir ecological flow scheduling coupled with multi-species and multi-river section eco-hydrology as described in claim 1, characterized in that: In the first step, the target species include juvenile fish, large invertebrates, and wetland plants.

3. The optimal method for reservoir ecological flow scheduling coupled with multi-species and multi-river section eco-hydrology as described in claim 1, characterized in that: In the first step, the water requirements of each target species are the habitat suitability curves of each target species; the habitat suitability curves of each target species are constructed based on the biological distribution data of each target species and the key hydraulic factor data of the corresponding habitat of each target species. The key hydraulic factors include water depth and flow velocity.

4. The optimal method for reservoir ecological flow scheduling coupled with multi-species and multi-river section eco-hydrology as described in claim 3, characterized in that: In the first step, the coupling analysis refers to: First, the habitat suitability curves are spatially overlaid with the hydraulic condition distribution data of each target river section under different reservoir flow rates to calculate the weighted available habitat area of ​​each target species in each target river section under different flow rates. Then, based on the correspondence between the weighted available habitat area and the dispatched flow, a change curve is established, and according to the preset ecological protection target, the corresponding flow range is selected from the change curve as the ecological flow threshold range of the corresponding target species in the corresponding target river section.

5. The optimal method for reservoir ecological flow scheduling coupled with multi-species and multi-river section eco-hydrology as described in claim 1, characterized in that: In the second step, the process of first dividing different ecological critical stages according to the key life history stages of each target species and setting ecological protection priorities for each ecological critical stage; and then, based on the ecological protection priorities, coordinating and integrating the ecological flow threshold ranges of each target species in the same ecological critical stage to generate the time-segmented comprehensive ecological flow demand for each target river segment includes the following steps: First, based on the key life history stages of all target species, several consecutive time periods are divided on a calendar year basis, with each time period corresponding to one or more key ecological stages. Next, for each time period, target species that are in a critical life history stage during that time period are identified, and those target species are designated as priority conservation species for that time period. Then, for each target river segment, the following operations are performed: For each time period, the ecological flow threshold ranges of all priority protected species within that time period are superimposed and integrated on the target river segment to generate the comprehensive ecological flow demand of the target river segment within that time period. Finally, the comprehensive ecological flow demand for all time periods of each target river section is aggregated to form an independent time-segmented comprehensive ecological flow demand sequence for each target river section, covering the whole year.

6. The optimal method for reservoir ecological flow scheduling coupled with multi-species and multi-river section eco-hydrology as described in claim 5, characterized in that: The key life history stages include the reproductive period, the rearing period, the foraging period, the dormancy period, and the growth period.

7. The optimal method for reservoir ecological flow scheduling coupled with multi-species and multi-river section eco-hydrology as described in claim 1, characterized in that: In the third step, the daily compliance assessment of the daily flow sequence formed by each candidate scheduling scheme in each target river section, based on the aforementioned time-segmented comprehensive ecological flow demand, to obtain the ecological flow satisfaction of each candidate scheduling scheme in each target river section refers to: For any candidate scheduling scheme and target river section, using the time-segmented comprehensive ecological flow demand of the target river section as the criterion, calculate the percentage of days with daily flow that fall within the time-segmented comprehensive ecological flow demand range in the daily flow sequence formed by the candidate scheduling scheme in the target river section, relative to the total number of days in a given period, and use this percentage as the ecological flow satisfaction of the candidate scheduling scheme in the target river section. Thus, the ecological flow satisfaction of each candidate scheduling scheme in each target river section is obtained.

8. The optimal method for reservoir ecological flow scheduling coupled with multi-species and multi-river section eco-hydrology as described in claim 1, characterized in that: In the third step, the step of using the natural hydrological conditions of each target river segment as a benchmark and employing the range of variation method to evaluate the degree of change of the daily flow sequence formed by each candidate scheduling scheme in each target river segment relative to the natural hydrological conditions, and obtaining the overall hydrological change degree of each candidate scheduling scheme in each target river segment, refers to: For any candidate scheduling scheme and target river section, based on the natural hydrological conditions of the target river section, the variation range method is used to calculate the degree of deviation of the daily flow sequence formed by the candidate scheduling scheme in the target river section from the natural hydrological conditions in multiple sets of hydrological change indicators. By comprehensively considering the degree of deviation of all hydrological change indicators, a value representing the overall deviation is obtained, which is the overall degree of hydrological change of the candidate scheduling scheme in the target river section. Thus, the overall hydrological change of each candidate scheduling scheme in each target river section is obtained.

9. The optimal method for reservoir ecological flow scheduling coupled with multi-species and multi-river section eco-hydrology as described in claim 1, characterized in that: In the fourth step, the decision-making model includes an objective layer, a criterion layer, a sub-criterion layer, and a scheme layer; The target layer corresponds to the decision objective of selecting the optimal reservoir ecological flow scheduling scheme; The criteria layer includes a first criterion and a second criterion. The first criterion aims to maximize the ecological flow satisfaction, while the second criterion aims to minimize the overall hydrological change. The evaluation unit of the sub-criteria layer is each target river segment; The evaluation object of the scheme layer is each of the candidate scheduling schemes.

10. The optimal method for reservoir ecological flow scheduling coupled with multi-species and multi-river section eco-hydrology as described in claim 9, characterized in that: In the fourth step, the comprehensive evaluation of each candidate scheduling scheme through the decision model includes the following steps: First, at the sub-criteria layer, for each target river segment, based on the ecological flow satisfaction and overall hydrological change of each candidate scheduling scheme in the target river segment, the river segment criterion score of the candidate scheduling scheme in the target river segment is calculated comprehensively. Then, at the criterion layer, for each candidate scheduling scheme, the river segment criterion scores of the candidate scheduling scheme in all target river segments are aggregated to calculate the global comprehensive score of the candidate scheduling scheme.

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