Reservoir ecological operation method to meet the needs of fish spawning occurrence and fish egg density

Abstract

The present invention belongs to the ecological field and provides a reservoir ecological regulation method that meets the requirements of fish spawning occurrence and fish egg density, including: obtaining the natural reproduction characteristic information and habitat information of fish species that produce drifting eggs in the regulated target river section, and determining the regulated target fish species; obtaining the first key habitat information required when the spawning occurrence probability of all fish species that produce drifting eggs and the regulated target fish species is not less than a first preset threshold; obtaining the second key habitat information required when the fish egg density of all fish species that produce drifting eggs and the regulated target fish species is not less than a second preset threshold; determining a reservoir ecological regulation plan according to the first key habitat information and the second key habitat information of the river section; and carrying out reservoir ecological regulation according to the reservoir ecological regulation plan. Through the above technical solution, the adverse impact of reservoir regulation operation on the spawning of fish species that produce drifting eggs can be alleviated, which is beneficial to promoting the restoration of fish resources and the protection of biodiversity.

Description

Technical Field

[0001] The present invention belongs to the ecological field, and particularly relates to a reservoir ecological regulation method that meets the requirements of fish spawning occurrence and fish egg density. Background Art

[0002] Fish are an important biological group in river ecosystems, and play a crucial role in maintaining local biodiversity, improving the structure of ecosystems, and realizing their functions. The spawning activities of fish that produce drifting eggs are a key link in the life history of fish, and play a key role in the reproduction and resource maintenance of their species. The spawning activities of fish that produce drifting eggs include the occurrence of spawning activities and the size of the spawning scale, which are closely related to specific water temperatures and hydrological processes. However, the changes in water temperature and hydrological conditions caused by the impoundment operation of cascade reservoirs will affect the spawning activities of fish that produce drifting eggs, and thus affect their diversity and resources. In order to mitigate the impact of reservoir impoundment operation on the survival and reproduction of fish that produce drifting eggs, it is very necessary to use reservoir ecological regulation methods to create a suitable spawning habitat as much as possible for the protection of the resources and diversity of fish that produce drifting eggs.

[0003] The existing reservoir ecological regulation methods only consider the requirements of spawning scale (fish egg density), and cannot well alleviate the adverse effects of reservoir regulation operation on the natural reproduction of fish that produce drifting eggs, which is not conducive to promoting the recovery of the resources of fish that produce drifting eggs and the protection of their diversity. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a reservoir ecological regulation method that meets the requirements of fish spawning occurrence and fish egg density. The method includes:

[0005] Obtaining the natural reproduction characteristic information and habitat information of fish that produce drifting eggs in the regulated target reach, and determining the regulated target fish, where the regulated target fish are some of all fish that produce drifting eggs; obtaining the first key habitat information required when the spawning occurrence probabilities of all fish that produce drifting eggs and the regulated target fish are not less than a first preset threshold; obtaining the second key habitat information required when the fish egg densities of all fish that produce drifting eggs and the regulated target species are not less than a second preset threshold; determining a reservoir ecological regulation plan according to the first key habitat information and the second key habitat information; and performing reservoir ecological regulation according to the reservoir ecological regulation plan.

[0006] In the above method, optionally, the obtaining the natural reproduction characteristic information and habitat information of fish that produce drifting eggs in the regulated target reach includes: obtaining the natural reproduction characteristic information and habitat information during the spawning period of fish that produce drifting eggs in the regulated target reach through on-site supplementary investigation and historical data collection; wherein, the natural reproduction characteristic information includes: reproduction species, reproduction time, and reproduction scale; and the habitat information includes: water temperature information and hydrological information.

[0007] In the above method, optionally, the obtaining of the first key habitat information required when the spawning occurrence probabilities of all fish species that produce drifting eggs and the target fish species for scheduling are not less than the first preset threshold includes:

[0008] Using a frequency distribution diagram, analyze the relationship between the occurrence or non-occurrence of the spawning activities of fish species that produce drifting eggs in the target reach for scheduling and the flow rate of the corresponding sampling section in the target reach for scheduling, and determine the suitable flow rate range when the spawning activity probability of fish species that produce drifting eggs at each sampling section is not less than the first preset threshold through frequency comparison; set multiple water temperature variables and multiple hydrological variables as independent variables, and whether fish eggs are collected at each sampling section each day as the dependent variable, and use a binary distribution model to analyze the relationship with the occurrence or non-occurrence of the spawning activities of the target fish species respectively, and screen and determine the key factors that significantly affect the occurrence of fish spawning activities; calculate the suitable distribution ranges of each key factor when the spawning occurrence probability is not less than the first preset threshold respectively; among them, the flow rate range when the spawning activity probability of all fish species that produce drifting eggs is not less than the first preset threshold, the key factors when the spawning occurrence probability of the target fish species for scheduling is not less than the first preset threshold, and the suitable distribution ranges of the key factors belong to the first key habitat information.

[0009] In the above method, optionally, the obtaining of the second key habitat information required when the egg densities of all fish species that produce drifting eggs and the target fish species for scheduling are not less than the second preset threshold includes:

[0010] Select a scatter plot to analyze the relationship between the change in the egg density of fish species that produce drifting eggs in the target reach for scheduling and the change in the flow rate of different sampling sections in the target reach for scheduling, and determine the flow rate range when the egg density of fish species that produce drifting eggs at different sampling sections is not less than the second preset threshold through appropriate statistical analysis; set multiple water temperature variables and multiple hydrological variables as independent variables, and the egg density as the dependent variable, and use a machine learning algorithm model to analyze the relationship between the change in the egg density of the target fish species in the target reach for scheduling and the water temperature and hydrological variables, and screen and determine the key factors that significantly affect the fish egg density; calculate the suitable distribution ranges of each key factor when the egg density is not less than the second preset threshold respectively;

[0011] Among them, the flow rate range when the egg density of all fish species that produce drifting eggs is not less than the second preset threshold, the key factors when the egg density of the target fish species for scheduling is not less than the second preset threshold, and the suitable distribution ranges of the key factors belong to the first key habitat information.

[0012] In the above method, optionally, the multiple water temperature variables and multiple hydrological variables include: daily average water temperature, daily average transparency, effective consecutive rising water days before spawning, consecutive rising water days before spawning, rising water volume, daily rising rate of flow, rising water level, daily rising rate of water level, water temperature change, daily water temperature change rate, transparency change, daily transparency change rate, accumulated water temperature, accumulated days when water temperature exceeds 15 °C, accumulated days when water temperature exceeds 18 °C.

[0013] In the above method, optionally, there are three sampling sections in the target reach for regulation, which are respectively: a sampling section set upstream of the target reach for regulation, a sampling section set in the middle reaches of the target reach for regulation, and a sampling section set downstream of the target reach for regulation.

[0014] In the above method, optionally, determining the reservoir ecological regulation plan according to the first key habitat information and the second key habitat information includes:

[0015] The reservoir ecological regulation plan includes: regulation timing, regulation flow conditions, regulation flow process parameters; determining the regulation timing according to the water temperature key parameters and the suitable ranges of the water temperature key parameters in the first key habitat information and according to the water temperature key parameters and the suitable ranges of the water temperature key parameters in the second key habitat information, and the regulation timing includes: regulation time, regulation water temperature conditions; obtaining a suitable flow range that simultaneously satisfies the spawning occurrence probability of fish laying drifting eggs at different sampling sections in the target reach for regulation not less than a first preset threshold and a suitable flow range with fish egg density not less than a second threshold according to the flow ranges in the first key habitat information and the second key habitat information to determine the regulation flow conditions; determining the regulation flow process parameters according to the hydrological key parameters and the suitable ranges of the hydrological key parameters in the first key habitat information and the hydrological key parameters and the suitable ranges of the hydrological key parameters in the second key habitat information, and the regulation flow process parameters include: rising water volume, rising water level, consecutive rising water days.

[0016] The beneficial effects brought by this embodiment are as follows:

[0017] By obtaining the natural reproduction characteristic information and habitat information of the fish species that produce drifting eggs in the regulated target river section, and determining the regulated target fish species; obtaining the first key habitat information required when the spawning occurrence probability of all fish species that produce drifting eggs and the regulated target fish species is not less than the first preset threshold; obtaining the second key habitat information required when the egg density of all fish species that produce drifting eggs and the regulated target fish species is not less than the second preset threshold; determining the reservoir ecological regulation plan according to the first key habitat information and the second key habitat information of the river section; and carrying out reservoir ecological regulation according to the reservoir ecological regulation plan, it is possible to alleviate the adverse effects of reservoir regulation operation on the natural reproduction of fish species that produce drifting eggs, and promote the restoration of their fish resources and the protection of biodiversity. In addition, in the implementation of reservoir ecological regulation, comprehensively considering the requirements of fish spawning occurrence and egg density is very important for more scientific and effective reservoir ecological regulation. Description of the Drawings

[0018] Figure 1 It is a schematic flow chart of a reservoir ecological regulation method that meets the requirements of fish spawning occurrence and egg density provided by an embodiment of the present invention;

[0019] Figure 2 It is the earliest date (2019 - 2024) when important fish eggs were collected downstream of a certain dam provided by an embodiment of the present invention;

[0020] Figure 3 It is the inter - annual variation of the annual runoff of fish eggs of fish species that produce drifting eggs downstream of a certain dam provided by an embodiment of the present invention;

[0021] Figure 4 It is the water level change trend of section A during the monitoring period in 2023 provided by an embodiment of the present invention;

[0022] Figure 5 It is the water temperature change trend of section A during the monitoring period in 2023 provided by an embodiment of the present invention;

[0023] Figure 6 It is the transparency change trend of section A during the monitoring period in 2023 provided by an embodiment of the present invention;

[0024] Figure 7 It is the flow distribution when drifting fish eggs were collected at section A downstream of a certain dam provided by an embodiment of the present invention;

[0025] Figure 8 It is the flow distribution when drifting fish eggs were collected at section B downstream of a certain dam provided by an embodiment of the present invention;

[0026] Figure 9 It is the flow distribution when drifting fish eggs were collected at section C downstream of a certain dam provided by an embodiment of the present invention;

[0027] Figure 10 The density distribution of drifting fish eggs at section A under the dam of a certain dam in different flows provided by the embodiment of the present invention;

[0028] Figure 11 The density distribution of drifting fish eggs at section B under the dam of a certain dam in different flows provided by the embodiment of the present invention;

[0029] Figure 12 The density distribution of drifting fish eggs at section C under the dam of a certain dam in different flows provided by the embodiment of the present invention. Specific embodiments

[0030] To make the purpose, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0031] See Figure 1 , the embodiment of the present invention provides a reservoir ecological regulation method that meets the requirements of fish spawning occurrence and fish egg density. The method includes the following steps:

[0032] Step 101, obtain the natural reproduction characteristic information and habitat information of fish species that produce drifting eggs in the regulated target river section, and determine the regulated target fish. The regulated target fish is part of all fish species that produce drifting eggs.

[0033] The implementation manners of this step include but are not limited to: obtaining the natural reproduction characteristic information and habitat information of all fish species that produce drifting eggs in the regulated target river section by obtaining the historical information of the regulated target river section. The natural reproduction characteristic information includes: reproduction species, reproduction time, reproduction scale, etc. The reproduction species refers to: which species of fish produce drifting eggs in the regulated target river section. The habitat information includes: water temperature, transparency, flow rate and water level, etc. The transparency, flow rate and water level information can be called hydrological information. In practical applications, on-site supplementary investigations can also be carried out to further supplement the historical information to improve the detail and comprehensiveness of the information. Then, according to the screening and determination information related to the regulated target fish, determine the composition of the regulated target fish from all fish species that produce drifting eggs in the regulated target river section, that is, part of all fish species that produce drifting eggs constitute the regulated target fish (or called regulated target species). Usually, there are multiple regulated target fish. Five species are given in this embodiment. The screening and determination information includes: life history characteristic information of fish, endemism information, protection level information and current situation information of resource quantity. Among them, the life history characteristic information is used to represent the types of aquatic habitats preferred by fish. The endemism information is used to represent whether the fish is a unique fish in the regulated target river section to be studied. The protection level information is used to represent whether the fish belongs to a national key protected animal and the protection level. The current situation information of resource quantity is used to represent the fish that can be investigated through fish resources and early fish resources, that is, the fish species with a certain resource quantity.

[0034] Step 102: Obtain the first key habitat information required when the spawning occurrence probabilities of all fish species that produce drifting eggs and the target fish species for regulation are not less than the first preset threshold.

[0035] The first preset threshold refers to 75% of the maximum spawning occurrence probability. In other embodiments, it can also be other values, which are not limited in this embodiment. The implementation manners of this step include, but are not limited to: according to the natural reproduction characteristic information and habitat information obtained in Step 101, using a frequency distribution graph to analyze the relationship between the occurrence of spawning activities of fish species that produce drifting eggs in the target river section for regulation and the cross-sectional flow rate, and through frequency comparison, determine the flow rate range when the spawning occurrence probability of fish species that produce drifting eggs is relatively high, that is: exceeding 75% of the maximum spawning occurrence probability. That is to say, relatively high probability means: the probability is not less than 75% of the maximum probability. When the target river section for regulation is relatively long, in order to facilitate ensuring the effectiveness of monitoring, it can be divided into multiple cross-sections for analysis. For example, one sampling cross-section is set at the upstream, middle, and downstream respectively. Correspondingly, analyze the relationship between the occurrence of spawning activities of fish species that produce drifting eggs in the target river section for regulation and the cross-sectional flow rate of the corresponding cross-section, and through frequency comparison, determine the appropriate flow rate range (or flow rate range) when the spawning occurrence probability of fish species that produce drifting eggs in different sampling cross-sections is relatively high, that is: all exceeding 75% of the maximum spawning occurrence probability of each cross-section. The flow rate range when the spawning occurrence probability of fish species that produce drifting eggs is not less than the first preset threshold belongs to the first key habitat information.

[0036] Take 15 water temperature and hydrological variables as independent variables, including: daily average water temperature, daily average transparency, effective continuous rising water days before spawning, continuous rising water days before spawning, flow rate increase, daily flow rate increase rate, water level increase, daily water level increase rate, water temperature change, daily water temperature change rate, transparency change, daily transparency change rate, accumulated water temperature, cumulative days when the water temperature exceeds 15°C, cumulative days when the water temperature exceeds 18°C; whether fish eggs are collected at each cross-section each day is the dependent variable. When fish eggs are collected, the value of the dependent variable is 1, otherwise it is 0.

[0037] Adopt a binary distribution model to respectively analyze the relationship between these variables and the occurrence of spawning activities of the target fish species, and screen and determine the key factors that significantly affect the occurrence of fish spawning activities. It should be noted that for the determination of key factors, according to the statistical significance between this factor and the dependent variable, that is, the significant p-value is less than 0.05 is the key factor.

[0038] Meanwhile, the binary distribution model is used to calculate the suitable distribution ranges of each key factor when the spawning probability is relatively high (reaching 75% or more of the maximum value). That is, with the key factor as the independent variable and the spawning probability as the dependent variable, the suitable distribution ranges of each key factor are calculated according to the binary distribution model. The key factor and its suitable distribution range belong to the first key habitat information, that is, the first key habitat information includes: the flow range when the spawning probability of all fish species laying drifting eggs is not less than the first preset threshold, and the key factor and its suitable distribution range when the spawning probability of the target fish species for regulation is not less than the first preset threshold. The first key habitat information is the information required for fish spawning to occur.

[0039] Step 103: Obtain the second key habitat information required when the fish egg density of all fish species laying drifting eggs and the target fish species for regulation is not less than the second preset threshold.

[0040] The second preset threshold refers to 75% of the maximum value of the fish egg density. The implementation methods of this step include, but are not limited to: according to the information obtained in Step 101, select a scatter plot, analyze the relationship between the change in the fish egg density of fish species laying drifting eggs in the target river section (or the target river reach for regulation) and the change in the flow rate, and through statistical analysis, determine the suitable flow range (or the flow rate range) when the fish egg density of fish species laying drifting eggs is relatively high. A relatively high fish egg density means that the fish egg density is not less than 75% of the maximum value of the fish egg density. When the target river section for regulation is relatively long, it can be divided into multiple sections for analysis. Correspondingly, analyze the relationship between the change in the fish egg density of fish species laying drifting eggs in the target river section for regulation and the change in the flow rate of different sections, and through statistical analysis, determine the flow rate range when the fish egg density of fish species laying drifting eggs is relatively high at different sampling sections. The flow rate range when the occurrence probability of the fish egg density of fish species laying drifting eggs is not less than the second preset threshold belongs to the second key habitat information.

[0041] Take 15 water temperature and hydrological variables as independent variables, including: daily average water temperature, daily average transparency, effective continuous rising water days before spawning, continuous rising water days before spawning, flow rate increase, daily flow rate increase rate, water level increase, daily water level increase rate, water temperature change, daily water temperature change rate, transparency change, daily transparency change rate, accumulated water temperature, cumulative days when the water temperature exceeds 15°C, cumulative days when the water temperature exceeds 18°C; and the fish egg density as the dependent variable.

[0042] Use a machine learning algorithm model to analyze the relationship between the fish egg density changes of the scheduling target river section and water temperature and hydrological variables, and screen and determine the key factors that significantly affect the fish spawning density. It should be noted that for the determination of key factors, according to the statistical significance between this factor and the dependent variable, that is, the significant p-value less than 0.05 is the key factor. The machine learning algorithm models that can be used are: Random Forest Model (RF), Extreme Gradient Boosting Tree Model (Xgboost), etc., and it can also be a combination of the above two models. For example, the two models are used separately and then analyzed. The key factors are determined according to the parameter importance ranking obtained from the analysis of each model.

[0043] At the same time, calculate the suitable distribution range of each key factor when the spawning density is relatively large (reaching 75% or more of the maximum value), that is: taking the key factor as the independent variable and the fish egg density probability as the dependent variable, calculate the suitable distribution range of each key factor according to the binary distribution model. This key factor and its suitable distribution range belong to the second key habitat information, that is, the second key habitat information includes: the flow range when the probability of fish eggs of fish producing drifting eggs is not less than the second preset threshold, the key factor and its suitable distribution range when the probability of fish eggs of the scheduling target fish is not less than the second preset threshold. This second key habitat information is the information required for the fish egg density, and the key parameters are divided into water temperature parameters and water temperature parameters.

[0044] Step 104, determine the reservoir ecological scheduling plan according to the first key habitat information and the second key habitat information. The reservoir ecological scheduling plan includes: scheduling timing, scheduling flow conditions, and scheduling flow process parameters.

[0045] The implementation methods of this step include but are not limited to: First, determine the scheduling timing. Specifically: According to the key water temperature parameters and their suitable ranges with relatively high probabilities of spawning occurrence and relatively high fish egg densities for different scheduling target fish species during spawning, combined with the water temperatures at different times in the scheduling river section, determine the scheduling time and the water temperature conditions for scheduling. The suitable range of water temperature is obtained through the previous model calculation. The scheduling time is determined according to the water temperature conditions at different times in the scheduling target river section. For example, through calculation, the suitable water temperature for fish spawning is 19 - 20. The water temperature display at different times in this river section shows that the water temperature in mid-May is 19 - 20. Then the scheduling time is mid-May, and the water temperature condition is that the scheduling can start only when the water temperature reaches 19 degrees. Then, determine the scheduling flow conditions. Specifically: Synthesize the suitable flow ranges when the spawning activities of fish species producing drifting eggs occur with relatively high probabilities at different sampling sections and the suitable flow ranges when the fish egg densities are relatively high, and obtain the suitable flow range that simultaneously satisfies the relatively high probabilities of spawning occurrence of fish species producing drifting eggs and relatively high fish egg densities in the scheduling target river section through the intersection of the suitable flow ranges. Finally, determine the scheduling flow process parameters, which include synthesizing the key hydrological parameters and their suitable range conditions with relatively high probabilities of spawning occurrence and relatively high fish egg densities for different scheduling target fish species, and determining the flow increase amount, water level increase amount, and continuous rising water days included in the scheduling flow process parameters. That is: The water temperature is determined according to the needs of the scheduling target fish species, the scheduling flow conditions are determined according to the needs of fish species producing drifting eggs, and this flow condition includes the flow requirements of the scheduling target fish species; the flow process parameters are determined according to the scheduling target fish species.

[0046] Step 105: According to the reservoir ecological scheduling plan, conduct reservoir ecological scheduling.

[0047] Obtain the reservoir ecological scheduling plan through Step 104, and then conduct reservoir ecological scheduling based on this reservoir ecological scheduling plan.

[0048] Through such design, it is possible to alleviate the adverse impacts of reservoir scheduling operations on the nature of fish species producing drifting eggs, and promote the restoration of their fish resources and the protection of biodiversity. In addition, in the implementation of reservoir ecological scheduling, comprehensively considering the spawning occurrence and spawning density requirements of fish species is very important for more scientific and effective reservoir ecological scheduling.

[0049] The following takes a certain dam reservoir as the implementation area to detail the process of using this method to determine the reservoir ecological scheduling plan that meets the spawning occurrence and fish egg density requirements of fish species:

[0050] Step 1): Obtain the natural breeding characteristics information and habitat information of fish species producing drifting eggs in the scheduling target river section, and determine the scheduling target fish species.

[0051] From March to July 2023 - 2024, investigations on the natural reproduction status of fish species that produce drifting eggs were carried out at three sections, namely Section A, Section B, and Section C, in the river section downstream of a certain dam, and a total of 22,788 fish eggs were collected. Combining the fish early resource investigation data since 2019, information on the natural reproduction characteristics of fish species that produce drifting eggs in the river section downstream of the dam was obtained. Considering factors such as fish endemism and the current status of resource quantity, Coreius heterodon, Rhinogobio cylindricus, Leptobotia rubrilabris, Leptobotia elongata, and Rhinogobio ventralis were selected as the target fish species for regulation.

[0052] (1)Reproductive species

[0053] A total of 31 species of drifting eggs were collected from 2019 to 2024, as shown in Table 1. The symbol "+" in Table 1 indicates the meaning of "present / there is". Specifically, there are eggs of 9 species of fish that are endemic to the upper reaches, namely Leptobotia rubrilabris, Botia reevesae, Leptobotia microphthalma, Gobiobotia nummifer, Rhinogobio cylindricus, Leptobotia elongata, Rhinogobio ventralis, Jinshaia sinensis, and Jinshaia abbreviata. Among them, Leptobotia rubrilabris, Leptobotia elongata, and Rhinogobio ventralis are second-class protected animals in China.

[0054] Table 1 Species of early fish resources that produce drifting eggs surveyed at each section from 2019 to 2024

[0055] Category Area A Area B Area C Leptobotia + Hemiculter bleekeri + + Ctenopharyngodon idella + + + Squaliobarbus curriculus + + Jinshaia abbreviata + Elopichthys bambusa + Pseudolaubuca engraulis + + + Saurogobio gymnocheilus + Leptobotia rubrilabris + + + Parabotia fasciata + + + Botia reevesae + Lepturichthys fimbriata + + + Hypophthalmichthys molitrix + + Culter alburnus + + Mylopharyngodon piceus + + Saurogobio dabryi + + Belligobio nummifer + Coreius heterodon + + + Rhinogobio typus + + + Leptobotia microphthalma + + + Gobiobotia filifer + + + Gobiobotia boulengeri + + + Squalidus argentatus + + Aristichthys nobilis + + Rhinogobio cylindricus + + + Leptobotia elongata + + + Rhinogobio ventralis + + + Spinibarbus sinensis + Jinshaia sinensis + + + Sinibotia superciliaris + + + Leptobotia taeniops + + Total 16 26 28

[0056] Note: *Fish species endemic to the upper reaches of the Yangtze River

[0057] (2)Reproductive time

[0058] Taking some of the above 31 fish species as examples, from 2019 to 2024, from March to July, the eggs of Rhinogobio spp., Rhinogobio ventralis, and Leptobotia microphthalma were collected earliest, and could be collected in early April; followed by Coreius heterodon eggs, which could be collected after mid-April; the eggs of other fish species, including Rhinogobio cylindricus, Ctenopharyngodon idella, Hypophthalmichthys molitrix, Aristichthys nobilis, etc., could be collected in early May and later. Especially the eggs of Leptobotia elongata could be collected after mid-June, as Figure 2 shown.

[0059] (3)Reproductive scale

[0060] Statistics on the monitoring results of the early resources of fish species that produce drifting eggs from 2019 to 2024 show that along the longitudinal direction of the river, the average annual runoff of fish eggs flowing through Section A, Section B, and the river section of the river presents an upward trend. Among them, the runoff of fish eggs at Section A is the smallest each year, while the runoff of fish eggs at Section C is the largest, as Figure 3 shown. For each year, from left to right are: Section A, Section B, Section C.

[0061] Habitat information is as follows:

[0062] Habitat information is obtained through on-site investigations and collection of information from corresponding hydrological stations, specifically including: water temperature, transparency, flow rate, water level, etc. For example, Figure 4 , Figure 5 and Figure 6 respectively show the trends of water temperature, transparency, and water level changes obtained synchronously during the fish spawning period at the monitoring section at Location A downstream of the dam in 2023. In each figure, the vertical line below indicates the total runoff curve.

[0063] Step 2): Obtain the first key habitat characteristic information required by all fish species that produce drifting eggs and the target fish species for regulation when the probability of spawning is relatively high.

[0064] Based on the information obtained in Step 1, use a frequency distribution diagram to analyze the relationship between the occurrence of spawning activities of fish species that produce drifting eggs in the regulated river section and the flow rate at the corresponding section, and determine the flow rate range when the frequency of spawning activities of fish species that produce drifting eggs at different sampling sections is relatively high through frequency comparison.

[0065] When the flow rate at a certain dam section upstream of Location A is between 1900 m 3 / s and 4200 m 3 / s, when the flow rate upstream of the section at Location B is between 4200 m 3 / s and 8200 m 3 / s, and when the flow rate at the section at Location C is between 3900 m 3 / s and 9000 m 3 / s, the probability of spawning being detected at each section is the highest, all exceeding 75% of the maximum probability of fish eggs occurring at the corresponding flow rates of each section. As Figures 7 - 9 shown, Figure 7 shows the flow rate distribution when drifting fish eggs are collected at the section at Location A downstream of a certain dam, Figure 8 shows the flow rate distribution when drifting fish eggs are collected at the section at Location B downstream of a certain dam, Figure 8 shows the flow rate distribution when drifting fish eggs are collected at the section at Location C downstream of a certain dam.

[0066] Taking 15 water temperature and hydrological variables as independent variables (see Table 2), and whether fish eggs are collected at each section each day as the dependent variable (when fish eggs are collected, the value is 1, otherwise it is 0); using a binary distribution model, analyze the relationship between these variables and the occurrence of spawning activities of the target fish species for regulation respectively, and screen and determine the key factors that significantly affect the occurrence of fish spawning activities; at the same time, calculate the suitable distribution ranges of each key factor when the average probability of spawning occurrence is relatively large (reaching 75% and above) respectively (see Table 3). In Table 3, 5 specific target fish species for regulation are shown, and the blank spaces in the table mean that for a certain fish species, this variable is not a key parameter affecting the occurrence of spawning activities of this fish species. Due to the differences in the hydrological requirements of fish, when determining the key factors, each type of target fish species for regulation is determined separately.

[0067] Table 2 Water temperature, hydrological variables and their codes, meanings and units

[0068] Serial Number Predictor Variable Code Meaning Unit 1 Daily Average Water Temperature WT Average Water Temperature of Each Sampling Day at Each Section ℃ 2 Daily Average Transparency TR Average Water Transparency of Each Sampling Day at Each Section cm 3 Effective Number of Consecutive Rising Water Days before Spawning EDRFD Number of Consecutive Rising Water Days Determined before Any Sampling Day during a Flood Peak Process d 4 Number of Consecutive Rising Water Days before Spawning DCR Number of Consecutive Rising Water Days before Any Sampling Day during a Flood Peak Process d 5 Flow Increase FIQ Daily Average Flow on Any Sampling Day during a Flood Peak Process Minus the Initial Daily Average Flow <![CDATA[m 3 / s]]> 6 Daily Flow Increase Rate DIRF Daily Average Flow on Any Sampling Day during a Flood Peak Process Minus the Initial Daily Average Flow, Divided by the Number of Days Corresponding to the Flow Interval <![CDATA[m 3 / s / d]]> 7 Water Level Increase WRQ Daily Average Water Level on Any Sampling Day during a Flood Peak Process Minus the Initial Daily Average Water Level m 8 Daily Water Level Increase Rate DRRW Daily Average Water Level on Any Sampling Day during a Flood Peak Process Minus the Initial Daily Average Water Level, Divided by the Number of Days Corresponding to the Water Level Interval m / d 9 Water Temperature Change WTVQ Daily Average Water Temperature on Any Sampling Day during a Flood Peak Process Minus the Initial Daily Average Water Temperature ℃ 10 Daily Water Temperature Change Rate DVRW Daily Average Water Temperature on Any Sampling Day during a Flood Peak Process Minus the Initial Daily Average Water Temperature, Divided by the Number of Days Corresponding to the Water Temperature Interval ℃ / d 11 Transparency Change TVQ Daily Average Transparency on Any Sampling Day during a Flood Peak Process Minus the Initial Daily Average Transparency cm 12 Daily Transparency Change Rate DVRQ Daily Average Transparency on Any Sampling Day during a Flood Peak Process Minus the Initial Daily Average Transparency, Divided by the Number of Days Corresponding to the Transparency Interval cm / d 13 Accumulated Water Temperature AWT Accumulated Water Temperature from the Day when the Water Temperature Began to Rise Rapidly (First Temperature Increase Exceeding 0.3 °C) before Any Sampling Day to the Day before Spawning ℃·d 14 Accumulated Number of Days with Water Temperature over 15 °C DWT15 Number of Days with Daily Average Water Temperature Exceeding 15 °C during the Period from the Day with the Lowest Water Temperature before Spawning to the Day before Any Sampling Day d 15 Accumulated Number of Days with Water Temperature over 18 °C DWT18 Number of Days with Daily Average Water Temperature Exceeding 18 °C during the Period from the Day with the Lowest Water Temperature before Spawning to the Day before Any Sampling Day d

[0069] Table 3 Key parameters for the occurrence of spawning activities and their suitable ranges (75% and above)

[0070] Variable Coreius heterodon Rhinogobio ventralis Rhinogobio cylindricus Leptobotia elongata Leptobotia rubrilabris WT (°C) 20.0~27.0 19.0~27.2 22.0~27.5 WRQ (m) 0.72~3.0 0.61~1.30 AWT (°C·d) >882.9 >839.92 DRRW (m / d) 0.20~0.80 0.28~0.92 EDRFD (d) 1~7 4~7

[0071] Step 3), Obtain the key water temperature, hydrological parameters and their suitable ranges required when the fish egg densities of all fish species producing drifting eggs and the main target fish species for regulation are relatively large.

[0072] According to the information obtained in Step 1, select a scatter plot, analyze the relationship between the change in the fish egg density of fish species producing drifting eggs in the target river section for regulation and the change in the flow rate at different sections, and through statistical analysis, determine the flow rate range when the fish egg density of fish species producing drifting eggs is relatively large at different sampling sections.

[0073] Integrating the fish egg density and its corresponding flow distribution probability, it can be known that when the flow rate at a certain dam section upstream of the section in Area A is between 1700 m 3 / s and 3800 m 3 / s, the frequency of the fish eggs flowing through the section in Area A with a density greater than 5 ind. / 1000 m 3 is high; when the flow rate upstream of the section in Area B is between 7000 m 3 / s and 11000 m 3 / s, the frequency of the fish eggs flowing through the section in Area B with a density greater than 20 ind. / 1000 m 3 is high; when the flow rate upstream of the section in Area C is between 6000 m 3 / s and 14000 m 3 / s, the frequency of its density greater than 80 ind. / 1000 m 3 is high, as Figures 10 - 12As shown Figure 10 It shows the density distribution of drifting fish eggs at different flow rates in the cross-section of Area A Figure 11 It shows the density distribution of drifting fish eggs at different flow rates in the cross-section of Area B Figure 12 It shows the density distribution of drifting fish eggs at different flow rates in the cross-section of Area C

[0074] Taking 15 water temperature and hydrological variables as independent variables and fish egg density as the dependent variable, a machine learning algorithm model is used to analyze the relationship between the density changes of the main target species of fish eggs in the regulated river section and water temperature and hydrological variables, and to screen and determine the key factors that significantly affect the spawning density of fish; at the same time, the suitable distribution ranges of each key factor when the spawning density is relatively large (reaching 75% or more of the maximum value) are calculated respectively (Table 4). In Table 4, 5 specific regulated target fish species are shown, and the blanks in the table mean that for a certain fish species, this variable is not a key parameter affecting the spawning activity of this fish species

[0075] Table 4 Key parameters for fish egg density changes and their suitable distribution ranges (75% or more of the density maximum value)

[0076] Variable Coreius heterodon Rhinogobio ventralis Rhinogobio cylindricus Leptobotia elongata Leptobotia rubrilabris TR (cm) 5~20 175~280 5~35 WT (°C) 18.5~23.0 20.0~26.5 DWT15 (d) 20~115 8~20 15~90 DWT18 (d) 3~18 30~75 WRQ (m) 1.5~3.0 WTVQ (°C) 1.25~2.0 1.6~4.0 1.5~3.0 2.0~4.0 2.0~4.0 <![CDATA[FIQ (m 3 / s)]]> ≥1800 800~1500 ≥1800 ≥3000 ≥3000 TVQ (cm) -100~-80 -190~-75 or 50~100 -190~-85 10~70 -25~-12 AWT (°C·d) 345.7~757.6 397.1~1994.3 DRRW (m / d) 0.1~0.4 0.75~2.00 DVRW (℃ / d) 0.25~1.0 CRD (d) 2~7 1~7 2~8 4~7 3~5 DVRQ (cm / d) -50~-25

[0077] Note: The variables in bold black are the most critical variables affecting the spawning and reproduction of fish biological groups or different fish species, and the others are variables of secondary importance

[0078] Step 4): Based on the water temperature and hydrological parameters and their suitable ranges for fish spawning occurrence and fish egg density requirements, determine the reservoir ecological regulation plan, including: regulation timing, regulation flow conditions, and regulation flow process parameters

[0079] First, determine the regulation timing, including determining the regulation time and regulation water temperature conditions according to the key water temperature parameters and their suitable ranges with a relatively high probability of spawning occurrence and a relatively large fish egg density for different regulated target fish species

[0080] Based on the results of breeding time, water temperature, etc. obtained in Step 1, and combining with the water temperature requirements for fish spawning occurrence and spawning density obtained in Step 2, it is proposed that the ecological regulation to promote the natural reproduction of fish species laying drifting eggs downstream of a certain dam be implemented in 3 times, and its regulation timing is as follows

[0081] The first time is between mid-late April and early May. When the number of days with the water temperature reaching 15°C is more than 8 days and the water temperature reaches 19°C, carry out ecological regulation tests for fish species with early spawning occurrence such as Rhinogobio ventralis

[0082] The second time is between late May and mid-June. When the water temperature reaches above 20°C, carry out ecological regulation tests for fish species such as Coreius heterodon and Rhinogobio cylindricus whose spawning activities occur between late spring and early summer

[0083] The third time is in mid-June and later. When the water temperature reaches above 22°C, ecological regulation experiments are carried out for fish such as Leptobotia elongata and Leptobotia rubrilabris that require large-flow flood processes for stimulation and have a late spawning time.

[0084] Then, determine the regulation flow conditions. According to the results of Step 2 and Step 3, through the intersection of the flow ranges, a suitable flow range that simultaneously satisfies the high spawning probability and high fish egg density of fish that produce drifting eggs in different river sections is obtained. The results are shown in Table 5.

[0085] Table 5 Suitable flows that satisfy the high spawning probability and high fish egg density of fish that produce drifting eggs in each river section

[0086] Parameter A certain dam (Location A) Location B Location C Suitable flow rate for spawning occurrence 1900-4200 4200-8200 3900-9000 Suitable flow rate for fish egg density 1700-3800 7000-11000 6000-14000 Obtain the suitable flow rate range through intersection solution 1900-3800 7000-8200 6000-9000

[0087] Finally, determine the process parameters of the regulation flow, including the key hydrological parameters and their suitable range conditions that comprehensively consider the relatively high spawning probability and relatively high fish egg density of fish with different regulation objectives, and determine the flow increase amount, water level increase amount, and continuous rising water days.

[0088] According to the results of Step 2 and Step 3, the process parameters of the three ecological regulation flows are determined as follows.

[0089] For the first ecological regulation experiment, keep the water rising for at least 1 day and at most no more than 7 days. During this period, the flow increase amount is between 800 and 1500 m 3 / s;

[0090] For the second ecological regulation experiment, keep the water rising for at least 4 days. During this period, the flow increase amount is above 1800 m 3 / s, and the water level increase amount is 1.5 - 3 m;

[0091] For the third regulation, keep the water rising for at least 4 days. During this period, the flow increase amount is above 3000 m 3 / s.

[0092] Step 5): According to the reservoir ecological regulation plan obtained in Step 4), carry out reservoir ecological regulation.

[0093] As is known by common technical knowledge, the present invention can be implemented by other embodiments that do not depart from its spiritual essence or essential features. Therefore, the above-disclosed embodiments are illustrative in all aspects and are not the only ones. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims

1. A reservoir ecological operation method that meets the requirements of fish spawning occurrence and fish egg density, characterized in that, The method includes: Obtaining the natural reproduction characteristic information and habitat information of the fish species that produce drifting eggs in the target river section for regulation, and determining the target fish species for regulation, where the target fish species for regulation are some of all the fish species that produce drifting eggs; Obtaining the first key habitat information required when the spawning occurrence probabilities of all the fish species that produce drifting eggs and the target fish species for regulation are not less than a first preset threshold; Obtaining the second key habitat information required when the egg densities of all the fish species that produce drifting eggs and the target fish species for regulation are not less than a second preset threshold; Determining a reservoir ecological regulation plan according to the first key habitat information and the second key habitat information; Carrying out reservoir ecological regulation according to the reservoir ecological regulation plan; Among them, the obtaining of the first key habitat information required when the spawning occurrence probabilities of all the fish species that produce drifting eggs and the target fish species for regulation are not less than a first preset threshold includes: Using a frequency distribution diagram to analyze the relationship between the occurrence or non-occurrence of the spawning activities of the fish species that produce drifting eggs in the target river section for regulation and the flow magnitude of the corresponding sampling sections in the target river section for regulation, and determining the suitable flow range when the spawning activity probabilities of the fish species that produce drifting eggs at each sampling section are not less than a first preset threshold through frequency comparison; Setting multiple water temperature variables and multiple hydrological variables as independent variables, and whether the fish eggs at each sampling section are collected each day as the dependent variable, and using a binary distribution model to analyze the relationship with the occurrence or non-occurrence of the spawning activities of the target fish species for regulation respectively, and screening and determining the key factors that significantly affect the occurrence of the fish spawning activities; Respectively calculating the suitable distribution ranges of each key factor when the spawning occurrence probability is not less than a first preset threshold; Among them, the flow range when the spawning activity probabilities of all the fish species that produce drifting eggs are not less than a first preset threshold, the key factors when the spawning occurrence probabilities of the target fish species for regulation are not less than a first preset threshold, and the suitable distribution ranges of the key factors belong to the first key habitat information; The obtaining of the second key habitat information required when the egg densities of all the fish species that produce drifting eggs and the target fish species for regulation are not less than a second preset threshold includes: Selecting a scatter diagram to analyze the relationship between the change in the egg density of the fish species that produce drifting eggs in the target river section for regulation and the change in the flow at different sampling sections in the target river section for regulation, and determining the flow range when the egg densities of the fish species that produce drifting eggs at different sampling sections are not less than a second preset threshold through appropriate statistical analysis; Setting multiple water temperature variables and multiple hydrological variables as independent variables, and the egg density as the dependent variable, and using a machine learning algorithm model to analyze the relationship between the change in the egg density of the target fish species for regulation in the target river section for regulation and the water temperature and hydrological variables, and screening and determining the key factors that significantly affect the fish spawning density; Respectively calculating the suitable distribution ranges of each key factor when the spawning density is not less than a second preset threshold; Among them, the flow range when the egg densities of all the fish species that produce drifting eggs are not less than a second preset threshold, the key factors when the egg densities of the target fish species for regulation are not less than a second preset threshold, and the suitable distribution ranges of the key factors belong to the first key habitat information.

2. The method according to claim 1, characterized in that, The obtaining of the natural reproduction characteristic information and habitat information of the fish species that produce drifting eggs in the target river section for regulation includes: Through on-site supplementary investigation and collection of historical data, obtain the natural reproduction characteristic information and habitat information of fish species that produce drifting eggs during the spawning period in the target reach of the regulation; Among them, the natural reproduction characteristic information includes: reproductive species, reproductive time, and reproductive scale; The habitat information includes: water temperature information and hydrological information.

3. The method according to claim 1, characterized in that, The multiple water temperature variables and multiple hydrological variables include: daily average water temperature, daily average transparency, effective continuous rising water days before spawning, continuous rising water days before spawning, flow increase, daily flow increase rate, water level increase, daily water level increase rate, water temperature change, daily water temperature change rate, transparency change, daily transparency change rate, cumulative water temperature, cumulative days with water temperature over 15°C, and cumulative days with water temperature over 18°C.

4. The method according to claim 1, characterized in that, There are three sampling sections in the target reach of the regulation, namely: the sampling section set upstream of the target reach of the regulation, the sampling section set in the middle reaches of the target reach of the regulation, and the sampling section set downstream of the target reach of the regulation.

5. The reservoir ecological operation method for meeting the requirements of fish spawning occurrence and fish egg density according to claim 1, characterized in that, Determining the reservoir ecological regulation plan according to the first key habitat information and the second key habitat information includes: The reservoir ecological regulation plan includes: regulation timing, regulation flow conditions, and regulation flow process parameters; Determine the regulation timing according to the water temperature key parameters in the first key habitat information and the suitable range of the water temperature key parameters and according to the water temperature key parameters in the second key habitat information and the suitable range of the water temperature key parameters. The regulation timing includes: regulation time and regulation water temperature conditions; According to the flow range in the first key habitat information and the flow range in the second key habitat information, obtain the suitable flow range that simultaneously satisfies the spawning occurrence probability of fish species that produce drifting eggs at different sampling sections in the target reach of the regulation not less than the first preset threshold and the suitable flow range with fish egg density not less than the second threshold to determine the regulation flow conditions; Determine the regulation flow process parameters according to the hydrological key parameters in the first key habitat information and the suitable range of the hydrological key parameters and the hydrological key parameters in the second key habitat information and the suitable range of the hydrological key parameters. The regulation flow process parameters include: flow increase, water level increase, and continuous rising water days.

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