Grouping ecological scheduling method capable of meeting requirements of different fishes to maximum extent

Abstract

The invention discloses a grouping ecological scheduling method capable of meeting different fish requirements to the maximum extent, and relates to the technical field of reservoir ecological scheduling, and the method comprises the steps: clearly researching the existing fish species of a river reach through environment DNA investigation; determining an overall framework and scheduling opportunity of ecological scheduling of the reservoir according to the spawning water temperature and spawning type grouping of each species; improving spawning habitat suitability evaluation, and defining an ex-warehouse flow range capable of maximally covering spawning of indigenous fishes in each regulation and control period; key indexes such as spawning stimulation and natural hydrological process recovery are comprehensively considered, and daily variation of ex-warehouse flow is optimized; and finally, coordinating ex-warehouse flow and water level change constraints of fishes of different spawning types to form a grouping and classifying ecological scheduling optimization scheme giving consideration to fish differentiation demands in different time periods.

Description

Technical Field

[0001] The invention relates to the technical field of reservoir ecological dispatching, and in particular to a group ecological dispatching method for maximally meeting the needs of different fish species. Background Art

[0002] The construction of reservoirs creates a barrier to river continuity, which changes the hydrological processes upstream and downstream, leading to changes in aquatic habitat conditions including water temperature, water depth, and flow rate, affecting the spawning of fish living in the river. For this reason, reservoir ecological regulation is a measure to reduce the impact of reservoir construction and operation on river ecosystems.

[0003] At present, the idea of ​​ecological regulation of reservoirs in the existing technology is mainly to protect the spawning needs of key fish such as the "four major fishes", which has significantly promoted the reproduction scale of some fish. However, the ecological regulation method used in the existing technology has not been effective in restoring fish species diversity.

[0004] To this end, the present invention aims to provide a grouping ecological scheduling method that maximizes the satisfaction of different fish needs. From the perspective of promoting more fish spawning, the fish are grouped according to their spawning time and type, and grouping and classification ecological scheduling that maximizes the satisfaction of the spawning needs of indigenous fish is carried out to solve the problems existing in the prior art. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned problems and provide a group ecological scheduling method that maximizes the satisfaction of different fish needs. Based on the existing reservoir ecological scheduling technology, the method of the present invention proposes a group classification ecological scheduling optimization idea that takes into account the differentiated needs of fish; through environmental DNA investigation, the existing fish species in the river section are clearly studied; according to the spawning water temperature and spawning type of each species, the ecological scheduling period and the fish covered by each scheduling period are divided; based on the correlation analysis between spawning scale and hydrological factors, the scheduling timing of each ecological scheduling period is determined; and the weighted average method is used to improve the spawning habitat suitability evaluation, and define the outflow flow range that can maximize the coverage of the spawning of indigenous fish in each regulation period; comprehensively consider spawning stimulation and natural hydrological process recovery, and optimize key indicators such as the daily fluctuation range of the outflow flow; finally, coordinate the outflow flow and water level change constraints of fish of different spawning types to form an ecological scheduling method for different fish needs in different time periods.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] The present invention provides a grouping ecological scheduling method for maximally meeting the needs of different fish species, the method comprising the following steps:

[0008] S1. Obtain the existing fish species in the target river section through environmental DNA survey;

[0009] S2. Group the fish in the study area according to their spawning time, type and water temperature requirements, and determine the overall framework of reservoir ecological regulation. The spawning types are mainly divided into sticky eggs and drifting eggs, and the fish of the same spawning type are divided into 2-3 groups according to the spawning water temperature;

[0010] S3. Organize the monitoring data of fish spawning and hydrological data such as water temperature and flow, use the stepwise multivariate regression model to analyze the correlation between spawning scale and hydrological data, identify the key hydrological factors and thresholds that affect fish spawning, and determine the timing of ecological scheduling for each group based on the thresholds;

[0011] S4. Analyze the preferences of indigenous fish for spawning habitat elements (including flow rate, water depth, and bottom quality) during each ecological regulation period, construct a two-dimensional hydrodynamic model, and use an improved habitat simulation method to determine the reservoir outflow range that maximizes fish spawning stimulation during each regulation period;

[0012] S5. Couple habitat simulation method with natural hydrological situation analysis to analyze the fluctuation of water level and flow under natural conditions during each regulation period, and determine indicators such as daily water level fluctuation and daily average flow fluctuation;

[0013] S6. For each group, coordinate the outflow flow and water level change constraints of fish laying sticky eggs and drifting eggs, define key indicators such as outflow flow, daily flow variation, etc. that can maximize the spawning needs of each group of fish, and form an ecological scheduling plan that takes into account the differentiated needs of fish in different time periods.

[0014] Furthermore, in the process of collecting environmental DNA samples, no less than 3 sections are collected in each river section, no less than 3 sampling points are collected in each section, and samples are collected at each point no less than four times in different seasons; in the process of comprehensive species identification, the species finally determined is collected in at least one-third of the points, and the same section is collected no less than twice.

[0015] Furthermore, in step S3, the hydrological parameters of the stepwise multiple regression analysis include: water temperature, flow on the spawning day, flow one day before spawning, flow two days before spawning, flow increase on the spawning day, flow increase one day before spawning, flow increase two days before spawning, spawning flow water level increase, water level increase one day before spawning, and water level increase two days before spawning.

[0016] Furthermore, in step S4, the improved habitat simulation method specifically includes: in order to maximize the habitat preferences of more fish in each group, the weighted average method is used to calculate the optimal value of the habitat elements that stimulate the spawning of different indigenous fish; the weighted standard deviation is used to calculate the suitable interval of each habitat element, and the t-test is used to verify the difference between the optimal value and the average value; the calculation formulas are formula (1) and formula (2) respectively:

[0017] S W =∑ ij (ni x j / ∑n i ) (Formula 1)

[0018]

[0019] Where: S W is the optimum value of habitat elements, where S represents habitat elements such as water depth and flow velocity; x i is the habitat suitability value of species i; S SD is the weighted standard deviation of habitat elements, that is, the suitable interval of habitat elements; n i is the number of individuals of species i in the environmental DNA survey.

[0020] Furthermore, in step S4, the improved habitat simulation method is used to determine the outflow range of the hydropower station during the ecological dispatch of different types of fish. Taking the fish with sticky eggs as an example, the calculation formula is as follows:

[0021] WUA=f[Q] (Formula 3)

[0022]

[0023]

[0024]

[0025] Where: WUA is the effective habitat area, m 2 ; Q is the outbound flow, m 3 / s; f[] is the functional relationship between WUA and traffic flow; is the flow corresponding to the maximum effective habitat area; is the lower limit of the outflow flow suitable for spawning of fish with sticky eggs. is the upper limit of the outflow flow suitable for spawning of fish with sticky eggs, m 3 / s.

[0026] Furthermore, in step S5, during the ecological scheduling of drifting egg fish, the focus is on creating a continuous water rise process to stimulate spawning and a gentle water retreat process to support the drifting hatching of fish eggs. The key indicator analysis of the rise-recession process specifically includes: based on the daily measured data of spawning volume and flow, screening the pulse flow process that effectively stimulates spawning; analyzing the water rise index of the pulse flow process, and defining the total water level increase standard ΔW that can stimulate spawning according to the 90% guarantee rate requirement. std , Standard of continuous flooding time t std Based on the above-mentioned flood process standards, the long-sequence natural daily flow data of the sections of the hydrological stations adjacent to the spawning grounds were analyzed to screen out the water that meets the requirements of ΔW. std and Δt stdFor all the rising water processes, according to the 75% guarantee rate requirement, the daily increase ΔQ of the outflow flow during the ecological dispatch period is finally determined. 漂 , duration of flooding t 漂 .

[0027] Furthermore, in step S5, during the ecological dispatch of fish with sluggish eggs, the outflow of the reservoir and the daily fluctuation of the water level are controlled to stimulate fish spawning and ensure that the fish eggs are not exposed and die due to the sudden drop in water level; wherein, the daily fluctuation of the water level ΔW 粘 It is determined based on the maximum water level difference within N consecutive days during the spawning period (April-July) under natural flow conditions, where N is the hatching time of fish eggs. The principle is to assume that water level fluctuations within N consecutive days for more than half of the days under natural conditions will not affect the development of sticky eggs; then the daily fluctuation range of the outflow flow of the hydropower station ΔQ is determined based on the water level-flow relationship. 粘 ;

[0028]

[0029] ΔW 粘 =QUARTLLE(ΔW j ,3) (Formula 8)

[0030] ΔQ 粘 =g[ΔW 粘 ] (Formula 9)

[0031] Where: W i is the daily average water level on the i-th day, m; ΔW j is the maximum water level difference during N consecutive days of spawning under natural conditions, m; j ranges from 1 to the maximum number of days during spawning, and the value of N is determined according to the hatching time of fish eggs; ΔW 粘 is the maximum water level fluctuation during the ecological regulation period of fish with roe-sinking eggs, m; ΔQ 粘 is the maximum flow variation during the ecological regulation period of sticky and sinking egg fish, m 3 / s; g[] is the water level-flow relationship curve of the control section.

[0032] Furthermore, in step S6, the ecological scheduling scheme that takes into account the differentiated needs of fish specifically includes: the outflow flow is the union of the suitable flow ranges for different spawning types of fish, and a flooding process is created to stimulate the spawning of drifting eggs, but the flooding-recession process considers the constraint of the maximum intraday water level fluctuation to meet the spawning habitat of sticky and sinking eggs; the key control indicators of the scheduling scheme include the initial outflow flow Q 初 , Daily average traffic increase ΔQ 涨 , duration of flooding t 涨 , daily average traffic decrease ΔQ 退 , water withdrawal duration t 退 , Maximum intraday water level variation ΔW max; The calculation process of each indicator is as follows:

[0033] Initial value of outbound flow Q 初 Not less than the lower limit of suitable flow rate for sticky and sedimentary eggs Q 粘 and the lower limit of suitable flow rate for drifting eggs Q 漂 ; Peak outbound flow Q 峰 Determined by the initial value and the total increase in traffic; the formula is as follows:

[0034]

[0035] Q 峰 ≥Q 初 +ΔQ 漂 ×t 漂 (Formula 11)

[0036] Where: Q 初 The starting value of the outflow rate for ecological dispatching of both sinking and drifting eggs is m 3 / s;Q 峰 is the maximum outflow flow, m 3 / s;

[0037] During the flooding process, priority is given to the stability of the water level for fish with sluggish eggs, and the maximum daily fluctuation of the outflow flow is required to be ΔQ 涨 In principle, it should not exceed ΔQ 粘 , then the daily increase formula of the outflow flow rate that takes into account both sticky and drifting eggs is:

[0038]

[0039] When the water level rise requirement for drifting eggs exceeds the water level change requirement for sticky eggs, in order to ensure both the total water level rise and the daily water level change, the duration of the water rise needs to be increased.

[0040] t 涨 ≥ROUNDUP[(Q 峰 -Q 初 ) / ΔQ 涨 ,0] (Formula 13)

[0041] During the water withdrawal process, the daily decline in outflow flow is based on the water level stability control index of sticky egg fish, that is, ΔQ 退 =ΔQ 粘 , then the duration of flooding is

[0042] t 退 ≥ROUNDUP[(Q 峰 -Q 初 ) / ΔQ 退 ,0] (Formula 14).

[0043] The difficulty and significance of the technical problem solved by the present invention are:

[0044] At present, the idea of ​​ecological scheduling in the existing technology is to protect the spawning needs of key fish such as the "four major carps". Although it has significantly promoted the reproduction scale of some fish, it has not had a significant effect on the restoration of fish species diversity. To this end, the scheme of the present invention promotes more fish spawning, and groups fish according to their spawning time and type, to maximize the group classification ecological scheduling that meets the spawning needs of indigenous fish. The scheme of the present invention uses four group scheduling to achieve a coverage rate of more than 90% for indigenous fish in the upper reaches of the Yangtze River.

[0045] In summary, compared with the prior art, the solution of the present invention has the following beneficial effects:

[0046] 1. The ecological scheduling of drifting eggs in the prior art focuses on the habitat needs of the "four major carps". During the scheduling period, the fish species stimulated to spawn are less than half of the existing species, especially the rare and endemic fish such as the round-mouthed copper fish and the long thin loach, which have poor spawning effects. The scheme of the present invention adopts a grouping and classification control method, in which the grouping basis is the spawning water temperature and the classification basis is the spawning type, and the habitat suitability evaluation method is improved accordingly, so as to maximize the coordination of the differentiated spawning needs of different fish. Through 4 group scheduling, the coverage rate of native fish in the upper reaches of the Yangtze River reaches more than 90%.

[0047] 2. In the prior art, the "base load power generation scheduling" for fish with sticky eggs and the "artificial flood peak scheduling" for fish with drifting eggs are carried out separately, but the fish egg monitoring results show that the "base load power generation scheduling" period can also promote the spawning of fish with drifting eggs, and vice versa; the scheme of the present invention combines the ecological scheduling of the two spawning types in some time periods, on the premise that the water temperature can stimulate some fish with sticky eggs and drifting eggs at the same time. The main way is to create a rising water process to stimulate the spawning of drifting eggs, but the outflow flow and the daily water level fluctuation during the rising and receding water process take into account the constraints of sticky eggs. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is the location of the environmental DNA sampling point in the lower reaches of the Jinsha River in the embodiment of the present invention;

[0049] Figure 2 The fish species composition of the lower reaches of the Jinsha River in the embodiment of the present invention;

[0050] Figure 3 It is the monitoring result of the fish egg runoff and the actual water temperature during the scheduling period from 2020 to 2023 in the embodiment of the present invention;

[0051] Figure 4 is the contribution rate of the hydrological factors to the egg-laying amount in the embodiment of the present invention;

[0052] Figure 5 is the habitat suitability curve of fish species that lay sticky and sinking eggs in the embodiment of the present invention;

[0053] Figure 6 is the habitat suitability curve of fish species laying drifting eggs in March and April in the embodiment of the present invention;

[0054] Figure 7 is the habitat suitability curve of fish species that lay drifting eggs in May and June in the embodiment of the present invention;

[0055] Figure 8 The suitable habitat for fish in the lower reaches of the Jinsha River varies with the downstream flow rate in the embodiment of the present invention;

[0056] Fig. 9 It is an analysis of the natural flooding process in the lower reaches of the Jinsha River in an embodiment of the present invention;

[0057] Fig.10 is the main fish egg hatching time in the lower reaches of the Jinsha River in the embodiment of the present invention;

[0058] Fig.11 is a flow chart of a method in an embodiment of the present invention. DETAILED DESCRIPTION

[0059] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0060] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0061] Example:

[0062] The embodiment of the present invention provides a group ecological scheduling method for maximally meeting the needs of different fish species, and the method comprises the following steps:

[0063] S1. Obtain the existing fish species in the target river section through environmental DNA survey;

[0064] S2. Group the fish in the study area according to their spawning time, type and water temperature requirements, and determine the overall framework of reservoir ecological regulation. The spawning types are mainly divided into sticky eggs and drifting eggs, and the fish of the same spawning type are divided into 2-3 groups according to the spawning water temperature;

[0065] S3. Organize the monitoring data of fish spawning and hydrological data such as water temperature and flow, use the stepwise multivariate regression model to analyze the correlation between spawning scale and hydrological data, identify the key hydrological factors and thresholds that affect fish spawning, and determine the timing of ecological scheduling for each group based on the thresholds;

[0066] S4. Analyze the preferences of indigenous fish for spawning habitat elements (including flow rate, water depth, and bottom quality) during each ecological regulation period, construct a two-dimensional hydrodynamic model, and use an improved habitat simulation method to determine the reservoir outflow range that maximizes fish spawning stimulation during each regulation period;

[0067] S5. Couple habitat simulation method with natural hydrological situation analysis to analyze the fluctuation of water level and flow under natural conditions during each regulation period, and determine indicators such as daily water level fluctuation and daily average flow fluctuation;

[0068] S6. For each group, coordinate the outflow flow and water level change constraints of fish laying sticky eggs and drifting eggs, define key indicators such as outflow flow, daily flow variation, etc. that can maximize the spawning needs of each group of fish, and form an ecological scheduling plan that takes into account the differentiated needs of fish in different time periods.

[0069] Among them, in the process of collecting environmental DNA samples, no less than 3 sections were collected in each river section, no less than 3 sampling points were collected in each section, and samples were collected at each point no less than four times in different seasons; in the process of comprehensive species identification, the species finally determined was collected in at least one-third of the points, and the same section was collected no less than twice.

[0070] In this embodiment, in step S3, the hydrological parameters of the stepwise multiple regression analysis include: water temperature, flow on the spawning day, flow one day before spawning, flow two days before spawning, flow increase on the spawning day, flow increase one day before spawning, flow increase two days before spawning, spawning flow water level increase, water level increase one day before spawning, and water level increase two days before spawning.

[0071] In this embodiment, in step S4, the improved habitat simulation method specifically includes: in order to maximize the habitat preferences of more fish in each group, the weighted average method is used to calculate the optimal value of the habitat elements that stimulate the spawning of different indigenous fish; the weighted standard deviation is used to calculate the suitable interval of each habitat element, and the t-test is used to verify the difference between the optimal value and the average value; the calculation formulas are the following formula (1) and formula (2):

[0072] S W =∑ ij (n i x j / ∑ni) (Formula 1)

[0073]

[0074] Where: S W is the optimum value of habitat elements, where S represents habitat elements such as water depth and flow velocity; x i is the habitat suitability value of species i; S SD is the weighted standard deviation of habitat elements, that is, the suitable interval of habitat elements; n i is the number of individuals of species i in the environmental DNA survey.

[0075] In this embodiment, in step S4, the improved habitat simulation method is used to determine the outflow range of the hydropower station during the ecological dispatch of different types of fish. Taking the fish with sticky eggs as an example, the calculation formula is as follows:

[0076] WUA=f[Q] (Formula 3)

[0077]

[0078]

[0079]

[0080] Where: WUA is the effective habitat area, m 2 ; Q is the outbound flow, m 3 / s; f[] is the functional relationship between WUA and traffic flow; is the flow corresponding to the maximum effective habitat area; is the lower limit of the outflow flow suitable for spawning of fish with sticky eggs. is the upper limit of the outflow flow suitable for spawning of fish with sticky eggs, m 3 / s.

[0081] In this embodiment, in step S5, during the ecological scheduling of drifting egg fish, the focus is on creating a continuous water rise process to stimulate spawning and creating a gentle water retreat process to support the drifting hatching of fish eggs. The key indicator analysis of the rise-recession process specifically includes: based on the daily measured data of spawning volume and flow, screening the pulse flow process that effectively stimulates spawning; analyzing the water rise index of the pulse flow process, and defining the total water level increase standard ΔW that can stimulate spawning according to the 90% guarantee rate requirement. std , Standard of continuous flooding time t std Based on the above-mentioned flood process standards, the long-sequence natural daily flow data of the sections of the hydrological stations adjacent to the spawning grounds were analyzed to screen out the water that meets the requirements of ΔW. std and Δt std For all the rising water processes, according to the 75% guarantee rate requirement, the daily increase ΔQ of the outflow flow during the ecological dispatch period is finally determined. 漂 , duration of flooding t 漂 .

[0082] In this embodiment, in step S5, during the ecological dispatch of fish with sticky eggs, the outflow of the reservoir and the daily fluctuation of the water level are mainly controlled to stimulate fish spawning and ensure that the fish eggs are not exposed and die due to the sudden drop in water level; wherein, the daily fluctuation of the water level ΔW 粘 It is determined based on the maximum water level difference within N consecutive days during the spawning period (April-July) under natural flow conditions, where N is the hatching time of fish eggs. The principle is to assume that water level fluctuations within N consecutive days for more than half of the days under natural conditions will not affect the development of sticky eggs; then the daily fluctuation range of the outflow flow of the hydropower station ΔQ is determined based on the water level-flow relationship. 粘 ;

[0083]

[0084] ΔW 粘 =QUARTLLE(ΔW j ,3) (Formula 8)

[0085] ΔQ 粘 =g[ΔW 粘 ] (Formula 9)

[0086] Where: W i is the daily average water level on the i-th day, m; ΔW j is the maximum water level difference during N consecutive days of spawning under natural conditions, m; j ranges from 1 to the maximum number of days during spawning, and the value of N is determined according to the hatching time of fish eggs; ΔW 粘 is the maximum water level fluctuation during the ecological regulation period of fish with roe-sinking eggs, m; ΔQ 粘 is the maximum flow variation during the ecological regulation period of sticky and sinking egg fish, m 3 / s; g[] is the water level-flow relationship curve of the control section.

[0087] In this embodiment, in step S6, the ecological scheduling scheme that takes into account the differentiated needs of fish specifically includes: the outflow flow is the union of the suitable flow ranges of different spawning types of fish, and a flooding process is created to stimulate the spawning of drifting eggs, but the flooding-recession process considers the constraint of the maximum intraday water level fluctuation to meet the spawning habitat of sticky and sinking eggs; the key control indicators of the scheduling scheme include the initial outflow flow Q 初 , Daily average traffic increase ΔQ 涨 , duration of flooding t 涨 , daily average traffic decrease ΔQ 退 , water withdrawal duration t 退 , Maximum intraday water level variation ΔW max ; The calculation process of each indicator is as follows:

[0088] Initial value of outbound flow Q 初 Not less than the lower limit of suitable flow rate for sticky and sedimentary eggs Q 粘 and the lower limit of suitable flow rate for drifting eggs Q漂 ; Peak outbound flow Q 峰 Determined by the initial value and the total increase in traffic; the formula is as follows:

[0089]

[0090] Q 峰 ≥Q 初 +ΔQ 漂 ×t 漂 (Formula 11)

[0091] Where: Q 初 The starting value of the outflow rate for ecological dispatching of both sinking and drifting eggs is m 3 / s;Q 峰 is the maximum outflow flow, m 3 / s;

[0092] During the flooding process, priority is given to the stability of the water level for fish with sluggish eggs, and the maximum daily fluctuation of the outflow flow is required to be ΔQ 涨 In principle, it should not exceed ΔQ 粘 , then the daily increase formula of the outflow flow rate that takes into account both sticky and drifting eggs is:

[0093]

[0094] When the water level rise requirement for drifting eggs exceeds the water level change requirement for sticky eggs, in order to ensure both the total water level rise and the daily water level change, the duration of the water rise needs to be increased.

[0095] t 涨 ≥ROUNDUP[(Q 峰 -Q 初 ) / ΔQ 涨 ,0] (Formula 13)

[0096] During the water withdrawal process, the daily decline in outflow flow is based on the water level stability control index of sticky egg fish, that is, ΔQ 退 =ΔQ 粘 , then the duration of flooding is

[0097] t 退 ≥ROUNDUP[(Q 峰 -Q 初 ) / ΔQ 退 ,0] (Formula 14).

[0098] The following are application examples of the embodiments of the present invention:

[0099] 1. Fish sampling survey in the lower reaches of the Jinsha River

[0100] In order to clarify the fish species composition in the lower reaches of the Jinsha River, 12 river sections of the lower reaches of the Jinsha River and its main tributaries were selected for field sampling (see Figure 1 ). Environmental DNA detection technology was used to conduct four samplings in June and October 2021, and January and April 2022. During the sampling process, in order to ensure the reliability of species information, no less than 3 sections were collected in each river section, no less than 3 sampling points were collected in each section, and no less than four samples were collected at each point in different seasons. The species finally determined were collected in at least one-third of the points, and the same section was collected at least twice.

[0101] According to the sampling results, there are 86 main fish species in the dispatching area, including 46 species of fish with sinking eggs, 35 species of fish with drifting eggs, and 5 species of fish with floating eggs. Representative fish include rare and endemic fish in the upper reaches of the Yangtze River, such as the round-mouthed copper fish, the long thin loach, the long-finned goby, the cylindrical goby, and the schizothorax fish.

[0102] 2. Fish grouping and ecological regulation period division in the lower reaches of the Jinsha River

[0103] The suitable water temperature requirements for spawning of major fish species in the lower reaches of the Jinsha River are analyzed, as shown in Table 1 below. Among them, the critical water temperature for spawning of 11 species of fish is lower than 15°C, accounting for 16% of the total, and the critical water temperature for spawning of about 40% of fish is lower than 18°C. According to the daily measured water temperature data of the Xiangjiaba Hydrological Station and the Yibin Hydrological Station, the peak spawning period of representative fish species in the lower reaches of the Jinsha River is concentrated in April-June, and the spawning period of some fish species is March-April.

[0104] According to the monitoring results of the fish egg runoff and the actual water temperature during the dispatching period from 2020 to 2023, it is recommended to subdivide the critical water temperature for fish that lay sticky eggs from "15℃" into 13℃ and 16℃; the critical water temperature for fish that lay drifting eggs from "18℃" into 16℃, 20℃, and 22℃, further expand the coverage of the dispatching period, and stimulate the spawning of fish with different spawning water temperature requirements. According to the suitable spawning water temperature for different fish, four batches of ecological dispatching experiments are carried out throughout the year. The first batch is mainly for fish that lay sticky eggs, the second batch takes into account both sticky and drifting eggs, and the third and fourth batches are mainly for fish that lay drifting eggs. The critical water temperatures for starting are 13℃, 16℃, 20℃, and 22℃, respectively. Through four dispatches, the spawning and reproduction needs of 144 of the 158 fish species in the dispatching area can be covered, accounting for 91%.

[0105] Table 1 Major fish groups and suitable water temperature range for spawning in the lower reaches of the Jinsha River

[0106]

[0107]

[0108] 3. Determine the timing of scheduling

[0109] Statistical methods were used to analyze the daily spawning amount and measured flow of the corresponding sections in the sections downstream of Wudongde Dam, Baihetan Dam and Yibin during the ecological scheduling of drift-eating fish by the cascade power stations in the lower reaches of the Jinsha River from 2022 to 2023, so as to identify the key hydrological factors affecting the spawning of drift-eating fish.

[0110] Based on the monitoring spawning data and the corresponding change trends of flow and water level data, 10 relevant hydrological factor indicators were proposed, and the indicator settings are shown in Table 2 below.

[0111] Table 2 Hydrological factor indicators

[0112]

[0113] The single factor linear regression method was used to conduct regression analysis on the 10 hydrological factors of the three sections and the spawning amount. At the same time, the absolute flow was used as a constraint condition and the flow threshold was set. The flow threshold of Wudongde and Baihetan dams was 2050m 3 / s, the flow threshold of Yibin River section is 4250m 3 / s, regression analysis was performed on the spawning data exceeding the flow threshold, and the significant P values ​​of the results are shown in Table 3.

[0114] Table 3 Single factor linear regression results and significance before and after setting flow threshold

[0115]

[0116]

[0117] Note: If the P value is less than 0.1, the 90% significance test is passed, and the effect is weakly significant; if the P value is less than 0.05, the 95% significance test is passed, and the effect is significant.

[0118] From the results of single factor linear regression, when the flow threshold is not set, all single factors under Wudongde Dam have no significant effect on the spawning amount; the flow rate 2 days before spawning, the flow rate increase 2 days before spawning and the water level increase 1 day before spawning under Baihetan Dam are strongly significant, and the flow rate 1 day before spawning and the water level increase 2 days before spawning are weakly significant; the daily flow increase and daily water level increase in Yibin section are weakly significant. After setting the flow threshold, the P value of the single factor regression test of each factor generally shows a downward trend, and the significance of the influence is enhanced. For example, the daily average flow rate under Wudongde Dam, the flow rate 1 day before spawning and the flow rate 2 days before spawning have strong significant effects on the spawning amount; the daily average flow rate at Baihetan is weakly significant, and the flow rate 1 day before spawning changes from weak significance to strong significance; the effect of the water level increase in Yibin section on the spawning amount changes from weak significance to strong significance. Overall, above the absolute flow threshold, the effect of flow and water level (increase) on the spawning of drifting egg-laying fish is relatively more significant.

[0119] Based on the spawning monitoring data of the three sections, the set hydrological indicators were used as dependent variables. Stepwise multiple regression analysis was performed to eliminate collinear factors and screen significantly correlated environmental factors. The results are shown in Tables 4 and 5.

[0120] Table 4 Results of stepwise multiple regression model

[0121]

[0122] Table 5 Significance results of hydrological factors

[0123]

[0124] Based on the above results, the flow rate one day before spawning, the flow rate two days before spawning, the flow rate increase two days before spawning, the water level, the water level increase one day before spawning, and the water level increase two days before spawning have a linear effect on the amount of eggs laid, especially the flow rate one day before spawning and the flow rate two days before spawning factors, which show a very significant effect. Furthermore, relative importance analysis was used to quantitatively explore the contribution rate of the above environmental factors to the amount of eggs laid. The results are as follows: Figure 4 The results show that the flow rate one day before spawning and the flow rate two days before spawning have the greatest impact on the spawning amount of fish eggs, with contribution rates of 40.6% and 33.5% respectively, followed by the flow rate increase two days before spawning, indicating that the spawning process usually occurs two days after the water level rises.

[0125] Strengthen the monitoring of early fish resources during the entire spawning period, pay attention to the time interval between the scheduling period and the last concentrated spawning period, and use the start of spawning of fish and water temperature as the starting condition for scheduling. It is recommended that the timing of starting ecological scheduling should take into account the natural laws of water temperature and fish spawning, and pay attention to the time interval between the scheduling period and the last peak spawning period. According to the early fish egg resource monitoring data from 2020 to 2023, the best effect of scheduling experiments is to conduct scheduling experiments about 5 days after the last peak spawning period. At the same time, further strengthen the continuous monitoring of early fish resources, observe the laws of fish spawning, and clarify the time interval between the two peak spawning periods.

[0126] In addition to water temperature, it is recommended to carry out ecological scheduling during the natural flood season, synergizing artificial flood peaks with natural flooding to be more conducive to fish spawning. According to the changes in fish egg runoff and flow in important monitoring sections from 2022 to 2023, Jinxia and Three Gorges Reservoirs conducted a total of 10 ecological scheduling experiments on fish that lay drifting eggs, 4 of which were in a natural flood state. The maximum daily spawning amount during the scheduling period was significantly higher than the ecological scheduling during the non-natural flood period, and the peak spawning amount increased by more than 20%.

[0127] In summary, it is recommended that in addition to requiring the water temperature to meet the standard, the scheduling period should be at least 5 days after the last spawning peak, or after the first monitoring of fish spawning. For the "artificial flood peak" scheduling test, the scheduling period should be as far as possible after 2 days of natural water rise.

[0128] 4. Fish spawning velocity and water depth preferences in each scheduling period

[0129] The recommended value of the outflow flow of the hydropower station is obtained by simulating the suitable habitat of representative fish. The habitat demand analysis of 68 representative fish species for spawning is combined to construct the habitat suitability curves of different stages and types of fish, such as Figures 5 to 7 As shown, the habitat preferences of fishes that lay sticky eggs in different periods are basically similar, while the habitat preferences of fishes that lay drifting eggs in different periods are quite different.

[0130] 5. Outbound flow range in each dispatch period

[0131] Mike 21 two-dimensional hydrodynamic models were constructed for each river section, and the habitat simulation method was used to analyze the changes in spawning habitat suitability under different reservoir discharge flows. Figure 8 As shown. According to the habitat simulation method, the suitable habitat area under different flow rates is calculated to determine the suitable flow range for the spawning needs of drifting fish eggs. Taking the flow corresponding to 80% of the maximum habitat area as the starting flow of the flooding process, the starting discharge flow of Wudongde and Baihetan Hydropower Stations in March and April is not less than 1800m 3 / s, the initial discharge flow of Xiangjiaba Hydropower Station is not less than 2400m 3 / s; from May to June, the initial discharge flow of Wudongde and Baihetan hydropower stations shall not be less than 2400m 3 / s, the initial discharge flow of Xiangjiaba Hydropower Station is not less than 3400m 3 / s.

[0132] 6. Daily changes in outbound flow during each dispatch period

[0133] The threshold parameters of ecological scheduling should be based on natural hydrological processes as an important reference. Although it is impossible to completely restore the natural flow process, the formulation of parameters such as the magnitude of water rise, duration of water rise, and intraday variation can refer to natural hydrological processes.

[0134] Analyze the natural flooding process in the key sections of the Yangtze River mainstream during the period when human activities are less disturbed, and determine the flooding amplitude and duration. According to the test results, the spawning process mostly occurs 2 days after the river water rises. By counting the flooding processes with a duration (T≥2) days, the flooding process standard is set as "the daily increase is at least 5% of the multi-year average flow and lasts for 3 days", or "the daily increase is less than 5% of the multi-year average flow for no more than 1 day and lasts for 4 days". Based on the measured daily flow at Huadan Station, Pingshan Station, Lizhuang Station, and Zhutuo Station from 1956 to 2000, the average daily increase in flow, the average daily increase in water level, and the total increase in flow during each flooding process from March to June are analyzed. Fig. 9 The results show that the continuous rise in water lasts for no less than 4 days, the total increase in flow is no less than 60% of the multi-year average flow, the daily average increase in flow is no less than 12% of the multi-year average, and the daily average increase in water level is no less than 0.8m. The ecological regulation target plan is determined by combining habitat evaluation with the natural rise in water process. The total increase in the discharge flow of Wudongde and Baihetan during the scheduling period is no less than 2200m 3 / s, the average daily increase is about 450m 3 / s, the total increase of Xiangjiaba discharge is no less than 2800m 3 / s, the average daily increase is about 550m 3 / s.

[0135] In addition, it is recommended to include the water withdrawal period in the ecological regulation period and put forward relevant control requirements. The fish egg hatching time is used as an important basis for determining the ecological regulation water withdrawal process. The fish egg hatching time and spawning water temperature requirements of various species are analyzed, and the fitting relationship between the fish egg hatching time and the minimum spawning water temperature is constructed. According to the centroid and confidence ellipse, the overall fish egg hatching time in the study area is about 60h. Further analysis of the fish egg hatching time of fish in different spawning periods and different spawning types, such as Fig.10 As shown in the figure, the hatching time of fish eggs that lay drifting eggs is mostly around 40-70 hours, and the hatching time of fish eggs in different periods is relatively consistent, while the hatching time of sticky eggs varies greatly. Therefore, it is recommended that the overall water withdrawal process should be no less than 3 days.

[0136] 7. Ecological scheduling proposal

[0137] On the basis of the current ecological scheduling test plan, the scheduling coverage will be further expanded to stimulate the spawning of fish with different habitat needs. According to the suitable water temperature for spawning of different fish, it is recommended to carry out four batches of ecological scheduling tests throughout the year, of which the first batch is mainly for fish that lay sticky eggs, the second batch takes into account both sticky and drifting eggs, and the third and fourth batches are mainly for fish that lay drifting eggs. According to the suitable water temperature during the peak spawning period of representative fish, the critical water temperature for starting the ecological scheduling test is set at 13.5℃, 16℃, 20℃, and 22℃ respectively. Through four scheduling, the spawning and reproduction needs of 144 of the 158 fish species in the scheduling area can be covered, accounting for 91%.

[0138] Table 6 Division of ecological dispatching periods and covered fish species for the Three Gorges and Jinxia cascade hydropower stations

[0139]

[0140]

[0141] (1) The first ecological regulation

[0142] The first ecological dispatch focuses on fish that lay sticky eggs, such as schizothorax, which prefer low-temperature spawning. The dispatch timing is determined according to the water temperature range of the spawning peak of schizothorax, requiring the water temperature to be no less than 13.5°C during the dispatch period. In addition, in addition to requiring the water temperature to meet the standard, the dispatch timing should also be at least 5 days after the last spawning peak, or after the first monitoring of fish spawning.

[0143] During the dispatching process, in order to create suitable habitat conditions for spawning of fish with sticky eggs, the focus is on controlling the fluctuation range of the discharge flow of the cascade reservoirs and reducing the daily drop in the water level in the river section below the dam. The important parameters of the first ecological dispatching period are shown in Table 7, where the daily fluctuation range of the outflow flow is calculated based on the fluctuation range of the natural water level in the river section below the dam, and the water level fluctuation control target is determined based on the natural flow conditions; the duration is determined based on the hatching time of eggs of representative fish.

[0144] Table 7 Key points and main control parameters of the first ecological scheduling period

[0145]

[0146] * In addition to requiring the water temperature to meet the standard, the scheduling time should also be at least 5 days after the last spawning peak, or after the first monitoring of fish spawning.

[0147] Key points of the Wudongde Hydropower Station dispatch during the first ecological dispatch period: From March to April, the water temperature in the downstream section of the Wudongde Dam reached 13.5℃. An ecological dispatch test for fish that lay sticky eggs was carried out at an appropriate time to ensure that the daily fluctuation of the water level in the spawning waters of the downstream section of the dam did not exceed 1.0m, and the daily maximum flow fluctuation was controlled to not exceed 750m3 / s, the maximum downstream flow should not exceed 2600m 3 / s, lasting about 10 days. The specific implementation time and flow control process are combined with real-time hydrological forecasts, early fish resource monitoring and dynamic adjustment of hydropower station operation conditions. Note that the scheduling period is more than 5 days apart from the last spawning peak, or after the first monitoring of fish spawning.

[0148] Key points of the first ecological dispatching period of Baihetan Hydropower Station: From March to April, the water temperature of the downstream section of Baihetan Dam reached 13.5℃. The ecological dispatching test for fishes laying sticky eggs was carried out at an appropriate time to ensure that the daily fluctuation of the water level in the spawning waters of the downstream section of the dam did not exceed 1.0m, and the daily maximum flow fluctuation was controlled to be no more than 750m 3 / s, the maximum downstream flow should not exceed 2600m 3 / s, lasting about 10 days. The specific implementation time and flow control process are combined with real-time hydrological forecasts, early fish resource monitoring and dynamic adjustment of hydropower station operation conditions. Note that the scheduling period is more than 5 days apart from the last spawning peak, or after the first monitoring of fish spawning.

[0149] Key points of the first ecological dispatch period for Xiangjiaba Hydropower Station: From March to April, the water temperature of the Yibin River reached 13.5℃. The ecological dispatch test for sticky egg-laying fish was carried out at an appropriate time to ensure that the daily fluctuation of the water level in the Yibin River did not exceed 1.5m, and the daily maximum flow fluctuation was controlled to not exceed 1000m 3 / s, the maximum downstream flow should not exceed 3400m 3 / s, lasting about 10 days. The specific implementation time and flow control process are combined with real-time hydrological forecasts, early fish resource monitoring and dynamic adjustment of hydropower station operation conditions. Note that the scheduling period is more than 5 days apart from the last spawning peak, or after the first monitoring of fish spawning.

[0150] Key points of the Three Gorges Hydropower Station dispatch during the first ecological dispatch period: From April to June, combined with the drawdown of the Three Gorges Reservoir, when the water temperature in the Three Gorges Reservoir exceeds 17°C, 1-2 ecological dispatch tests for fish that lay sticky eggs in the reservoir area will be carried out at an appropriate time. During the dispatch period, the daily drop in the reservoir water level will be controlled to be no more than 0.2m, and the duration will be no less than 4 days. The specific implementation time and flow control process will be combined with real-time hydrological forecasts, early fish resource monitoring and dynamic adjustment of the operating conditions of the hydropower station.

[0151] (2) Second ecological regulation

[0152] The second ecological dispatch focuses on the cascade power stations in the lower reaches of the Jinsha River, taking into account both sticky and drifting egg-laying fish. Among them, the key protection targets of drifting egg-laying fish are species that prefer low temperature spawning, such as the long-finned goby and the heterocyst. The dispatch timing is determined based on the peak spawning water temperature range of spawning fish from April to May, requiring the water temperature to be no less than 16°C during the dispatch period. In addition to requiring the water temperature to meet the standard, the dispatch timing should be at least 5 days apart from the last spawning peak period. In addition, based on the correlation analysis of the previous fish egg volume and flow process, the dispatch period should be as far as possible after 2 days of natural water rise.

[0153] During the dispatching process, in order to meet the spawning ground needs of fish with sticky eggs, it is necessary to control the daily stability of the water level, while taking into account the stimulation needs of fish with drifting eggs. It is required to gradually increase the discharge flow of the reservoir, create a rising water process, and finally achieve a slow retreat. During the retreat process, the water level should be avoided from dropping rapidly. Therefore, during the second ecological dispatching period, it is necessary to focus on controlling the starting flow, daily water level fluctuation, daily average flow increase, rising water duration, retreat time and daily flow drop. The important parameters of the second ecological dispatching period are shown in Table 8, where the starting flow is determined by analyzing the suitable flow range for laying drifting eggs according to the habitat simulation method; the daily water level control target is determined according to the natural flow conditions; the daily flow increase and duration are determined according to the natural rising water process, and the daily water level fluctuation constraint is taken into account; in addition, combined with the early fish resource monitoring data in the past four years, the spawning peak occurs 3-6 days after the start of the rising water, so the rising water duration is set to be no less than 5-6 days, and the total duration is no less than 10 days; the daily flow drop during the retreat period is set according to the daily flow change during the first ecological dispatching period, and the retreat duration is no less than 4 days.

[0154] Table 8 Key points and main control parameters of the second ecological scheduling period

[0155]

[0156] * In addition to requiring the water temperature to meet the standard, the scheduling time should also be at least 5 days after the last spawning peak and 2 days after the natural rise in water.

[0157] The key points of the Wudongde Hydropower Station dispatch during the second ecological dispatch period: From April to May, the water temperature in the downstream section of the Wudongde Dam reached 16°C, and an ecological dispatch test was carried out at an appropriate time to take into account both sticky and drifting egg-laying fish. During the flooding process, the initial discharge flow of the reservoir was controlled to be no less than 1800m 3 / s, the average daily increase is 300-450m 3 / s, and ensure that the daily fluctuation of water level in the spawning waters of the downstream section of the dam does not exceed 1.0m; the daily average flow drop during the water withdrawal process does not exceed 750m 3 / s, and ensure that the daily fluctuation of the water level in the spawning waters of the downstream section of the dam does not exceed 1.0m; the total duration is about 10 days, of which the flooding lasts for 5-6 days and the water retreat lasts for 4-5 days. The specific implementation time and flow control process are combined with real-time hydrological forecasts, early fish resource monitoring and dynamic adjustment of hydropower station operation conditions. Note that the scheduling period is more than 5 days apart from the last spawning peak period and 2 days after the natural flooding.

[0158] Key points of the second ecological dispatching period for Baihetan Hydropower Station: From April to May, the water temperature in the downstream section of Baihetan Dam reached 16°C, and an ecological dispatching experiment was carried out at an appropriate time to take into account both fish that lay sticky eggs and fish that lay drifting eggs. During the flooding process, the initial discharge flow of the reservoir was controlled to be no less than 1800m 3 / s, the average daily increase is 300-450m 3 / s, and ensure that the daily fluctuation of the water level in the spawning waters of the lower reaches of Baihetan Dam does not exceed 1.0m; the average daily flow drop during the water withdrawal process does not exceed 750m 3 / s, and ensure that the daily fluctuation of the water level in the spawning waters of the downstream section of Baihetan Dam does not exceed 1.0m; the total duration is about 10 days, of which the flooding lasts for 5-6 days and the water retreat lasts for 4-5 days. The specific implementation time and flow control process are combined with real-time hydrological forecasts, early fish resource monitoring and dynamic adjustment of hydropower station operation conditions. Note that the scheduling period is more than 5 days apart from the last spawning peak period and 2 days after the natural flooding.

[0159] Key points of the second ecological dispatch period for Xiangjiaba Hydropower Station: From April to May, the water temperature of the Yibin River section reached 16°C, and an ecological dispatch experiment was carried out at an appropriate time to take into account both sticky and drifting egg-laying fish. During the flooding process, the initial discharge flow of the reservoir was controlled to be no less than 2400m 3 / s, the average daily increase is 400-550m 3 / s, and ensure that the daily fluctuation of water level in the spawning waters of the Yibin River does not exceed 1.5m; the daily average flow drop during the water withdrawal process does not exceed 1000m 3 / s, and ensure that the daily fluctuation of the water level in the spawning waters of the Yibin River section does not exceed 1.5m; the total duration is about 10 days, of which the flooding lasts for 5-6 days and the water retreat lasts for 4-5 days. The specific implementation time and flow control process are combined with real-time hydrological forecasts, early fish resource monitoring and dynamic adjustment of hydropower station operation conditions. Note that the scheduling period is more than 5 days apart from the last spawning peak period and 2 days after the natural flooding.

[0160] (3) The third and fourth ecological adjustments

[0161] The third and fourth ecological dispatches were conducted for drifting egg-laying fishes that like to spawn at high temperatures, such as the "four major carps" and loaches, and the Wudongde-Baihetan joint dispatch and Xiluodu-Xiangjiaba-Three Gorges joint dispatch experiments were carried out respectively. The dispatch timing was determined based on the water temperature range of the peak spawning period of spawning fishes from May to June. The water temperature during the third dispatch was required to be no less than 20°C and the water temperature during the fourth dispatch was required to be no less than 23°C. In addition to requiring the water temperature to meet the standard, the dispatch timing should be at least 5 days apart from the last spawning peak period, and the dispatch period should be as far as possible after 2 days of natural water rise.

[0162] During the dispatching period, the focus was on creating a continuous water rise process. Compared with the second dispatching, due to the changes in the background flow conditions and the different requirements of key protected fish for water rise stimulation, the third and fourth ecological dispatching had a larger water rise, a larger absolute flow, and a shorter duration. The important control parameters during the third and fourth ecological dispatching periods are shown in Table 9. According to the spawning needs of drifting egg-laying fish, the focus was on controlling the starting flow, daily flow increase and duration, and the flow decline during the water retreat process.

[0163] Table 9 The key points and main control parameters of the third and fourth ecological scheduling periods

[0164]

[0165] * In addition to requiring the water temperature to meet the standard, the scheduling time should also be at least 5 days after the last spawning peak and 2 days after the natural rise in water.

[0166] Key points of the joint dispatch of Wudongde-Baihetan Hydropower Station during the third and fourth ecological dispatch periods: From May to June, the water temperature in the downstream section of Wudongde Dam reached 20℃ and 23℃, and an "artificial flood peak" Wudongde-Baihetan joint ecological dispatch test was carried out at an appropriate time for fish that lay drifting eggs, creating a simulated natural flood-recession process suitable for fish spawning and reproduction. During the dispatch period, the initial discharge flow of Wudongde and Baihetan Hydropower Stations was not less than 2400m 3 / s, the daily increase in traffic is no less than 570m 3 / s / d, the duration of flooding is not less than 4 days, and the daily flow reduction during the receding stage is not more than 750m 3 / s / d, and the number of days for water withdrawal is about 3 to 4 days. The specific implementation time and flow control process are combined with real-time hydrological forecasts, early fish resource monitoring and dynamic adjustment of hydropower station operation conditions. Note that the scheduling period is more than 5 days apart from the last spawning peak period and 2 days after the natural rise.

[0167] Key points of the joint dispatch of Wudongde-Baihetan Hydropower Station during the third and fourth ecological dispatch periods: From May to July, when the water temperature of the Yibin River reaches 20℃ and 23℃, a joint ecological dispatch test of "artificial flood peak" targeting fish with drifting eggs will be carried out at an appropriate time to create a simulated natural flooding-recession process suitable for fish spawning and reproduction. During the dispatch period, the initial discharge flow of Xiangjiaba Hydropower Station shall not be less than 3400m 3 / s, the daily increase in traffic is no less than 680m 3 / s / d, the initial discharge flow of the Three Gorges Hydropower Station is not less than 10000m 3 / s, the daily increase in traffic volume is between 1000 and 2000m 3 / s / d, the duration of flooding shall not be less than 4 days, and the daily reduction of discharge from Xiangjiaba Hydropower Station shall not exceed 750m during the water withdrawal stage. 3 / s / d, the daily reduction of the discharge flow of the Three Gorges Hydropower Station is no more than 2000m 3 / s / d, and the duration of water withdrawal is no less than 3-4 days. The specific implementation time and flow control process are combined with real-time hydrological forecasts, early fish resource monitoring and dynamic adjustment of hydropower station operation conditions. Note that the scheduling period is more than 5 days apart from the last spawning peak period and 2 days after the natural rise.

[0168] The above specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, such modifications are protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A grouping ecological scheduling method that maximizes the needs of different fish species is characterized by: The method comprises the following steps: S1. Obtain the existing fish species in the target river section through environmental DNA survey; S2. Group the fish in the study area according to their spawning time, type and water temperature requirements, and determine the overall framework of reservoir ecological regulation. The spawning types are mainly divided into sticky eggs and drifting eggs, and the fish of the same spawning type are divided into 2-3 groups according to the spawning water temperature; S3. Organize the monitoring data of fish spawning and hydrological data such as water temperature and flow, use the stepwise multivariate regression model to analyze the correlation between spawning scale and hydrological data, identify the key hydrological factors and thresholds that affect fish spawning, and determine the timing of ecological scheduling for each group based on the thresholds; S4. Analyze the preferences of indigenous fish for spawning habitat elements in each ecological regulation period, construct a two-dimensional hydrodynamic model, and use the improved habitat simulation method to determine the reservoir outflow range that maximizes the stimulation of fish spawning in each regulation period; S5. Couple habitat simulation method with natural hydrological situation analysis to analyze the fluctuation of water level and flow under natural conditions during each regulation period, and determine indicators such as daily water level fluctuation and daily average flow fluctuation; S6. For each group, coordinate the outflow flow and water level change constraints of fish laying sticky eggs and drifting eggs, define key indicators such as outflow flow, daily flow variation, etc. that can maximize the spawning needs of each group of fish, and form an ecological scheduling plan that takes into account the differentiated needs of fish in different time periods.

2. The grouping ecological scheduling method for maximizing the needs of different fish species as claimed in claim 1 is characterized by: In the process of collecting environmental DNA samples, no less than 3 sections are collected in each river section, no less than 3 sampling points are collected in each section, and samples are collected at each point no less than four times in different seasons; in the process of comprehensive species identification, the species finally determined are collected in at least one-third of the points, and the same section is collected no less than twice.

3. The grouping ecological scheduling method for maximizing the needs of different fish species as claimed in claim 1 is characterized by: In step S3, the hydrological parameters of the stepwise multiple regression analysis include: water temperature, flow on the spawning day, flow one day before spawning, flow two days before spawning, flow increase on the spawning day, flow increase one day before spawning, flow increase two days before spawning, spawning flow water level increase, water level increase one day before spawning, and water level increase two days before spawning.

4. The grouping ecological scheduling method for maximizing the satisfaction of different fish needs as claimed in claim 1 is characterized by: Step S4 The improved habitat simulation method specifically includes: in order to maximize the habitat preferences of more fish in each group, the weighted average method is used to calculate the optimal values ​​of habitat elements that stimulate spawning of different indigenous fish; the weighted standard deviation is used to calculate the suitable interval of each habitat element, and the t-test is used to verify the difference between the optimal value and the average value; the calculation formulas are formula (1) and formula (2): S W =∑ ij (n i x j / ∑n i ) (Formula 1) Where: S W is the optimum value of habitat elements, where S represents habitat elements such as water depth and flow velocity; x i is the habitat suitability value of species i; S SD is the weighted standard deviation of habitat elements, that is, the suitable interval of habitat elements; n i is the number of individuals of species i in the environmental DNA survey.

5. The grouping ecological scheduling method for maximizing the satisfaction of different fish needs as claimed in claim 1 is characterized by: In step S4, the improved habitat simulation method is used to determine the outflow range of the hydropower station during the ecological dispatch of different types of fish. Taking the fish with sticky eggs as an example, the calculation formula is as follows: WUA=f[Q] (Formula 3) Where: WUA is the effective habitat area, m 2 ; Q is the outbound flow, m 3 / s; f[] is the functional relationship between WUA and traffic flow; is the flow corresponding to the maximum effective habitat area; is the lower limit of the outflow flow suitable for spawning of fish with sticky eggs. is the upper limit of the outflow flow suitable for spawning of fish with sticky eggs, m 3 / s.

6. The grouping ecological scheduling method for maximizing the satisfaction of different fish needs as claimed in claim 1 is characterized by: In step S5, during the ecological scheduling of drifting egg fish, the focus is on creating a continuous water rise process to stimulate spawning and a gentle water retreat process to support the drifting hatching of fish eggs. The key indicator analysis of the rise-recession process specifically includes: based on the daily measured data of spawning volume and flow, screening the pulse flow process that effectively stimulates spawning; analyzing the water rise index of the pulse flow process, and defining the total water level increase standard ΔW that can stimulate spawning according to the 90% guarantee rate requirement. std , Standard of continuous flooding time t std Based on the above-mentioned flood process standards, the long-sequence natural daily flow data of the sections of the hydrological stations adjacent to the spawning grounds were analyzed to screen out the water that meets the requirements of ΔW. std and Δt std For all the rising water processes, according to the 75% guarantee rate requirement, the daily increase ΔQ of the outflow flow during the ecological dispatch period is finally determined. 漂 , duration of flooding t 漂 .

7. The grouping ecological scheduling method for maximizing the satisfaction of different fish needs as claimed in claim 1 is characterized by: In step S5, during the ecological dispatch of fish with sticky eggs, the focus is on controlling the outflow of the reservoir and the daily fluctuation of the water level to stimulate fish spawning and ensure that the fish eggs are not exposed and die due to the sudden drop in water level; among them, the daily fluctuation of the water level ΔW 粘 It is determined based on the maximum water level difference within N consecutive days during the spawning period under natural flow conditions, where N is the hatching time of fish eggs. The principle is to assume that water level fluctuations within N consecutive days for more than half of the days under natural conditions will not affect the development of sticky eggs; then the daily fluctuation range of the outflow flow of the hydropower station ΔQ is determined based on the water level-flow relationship. 粘 ; ΔW 粘 =QUARTLLE(ΔW j , 3) (Formula 8) ΔQ 粘 =g[ΔW 粘 ] (Formula 9) Where: W i is the daily average water level on the i-th day, m; ΔW j is the maximum water level difference during N consecutive days of spawning under natural conditions, m; j ranges from 1 to the maximum number of days during spawning, and the value of N is determined according to the hatching time of fish eggs; ΔW 粘 is the maximum water level fluctuation during the ecological regulation period of fish with roe-sinking eggs, m; ΔQ 粘 is the maximum flow variation during the ecological regulation period of sticky and sinking egg fish, m 3 / s; g[ ] is the water level-flow relationship curve of the control section.

8. The method for grouping ecological scheduling to maximize the satisfaction of different fish needs as claimed in claim 1, characterized in that: step S6 The ecological scheduling scheme that takes into account the differentiated needs of fish specifically includes: the outflow flow is the union of the suitable flow ranges of different spawning types of fish, and the rising water process is created to stimulate the spawning of drifting eggs. However, the rising and falling water process takes into account the constraints of the maximum daily water level fluctuation to meet the spawning habitat of sticky and sinking eggs. The key control indicators of the scheduling scheme include the initial outflow flow Q 初 , Daily average traffic increase ΔQ 涨 , duration of flooding t 涨 , daily average traffic decrease ΔQ 退 , water withdrawal duration t 退 , Maximum daily water level variation ΔW max ; The calculation process of each indicator is as follows: Initial value of outbound flow Q 初 Not less than the lower limit of suitable flow rate for sticky and drifting eggs Q 漂 ; Peak outbound flow Q 峰 Determined by the initial value and the total increase in traffic; the formula is as follows: Q 峰 ≥Q 初 +ΔQ 漂 ×t 漂 (Formula 11) Where: Q 初 The starting value of the outflow rate for ecological dispatching of both sinking and drifting eggs is m 3 / s;Q 峰 is the maximum outflow flow, m 3 / s; During the flooding process, priority is given to the stability of the water level for fish with sluggish eggs, and the maximum daily fluctuation of the outflow flow is required to be ΔQ 涨 In principle, it should not exceed ΔQ 粘 , then the daily increase formula of the outflow flow rate that takes into account both sticky and drifting eggs is: When the water level rise requirement for drifting eggs exceeds the water level change requirement for sticky eggs, in order to ensure both the total water level rise and the daily water level change, the duration of the water rise needs to be increased. t 涨 ≥ROUNDUP[(Q 峰 -Q 初 ) / ΔQ 涨 ,0] (Formula 13) During the water withdrawal process, the daily decline in outflow flow is based on the water level stability control index of sticky egg fish, that is, ΔQ 退 =ΔQ 粘 , then the duration of flooding is t 退 ≥ROUNDUP[(Q 峰 -Q 初 ) / ΔQ 退 ,0] (Formula 14).

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