A reservoir ecological flow allocation method based on multi-section water diversion and multi-target fish collaborative protection

Abstract

The application discloses a reservoir ecological flow allocation method based on multi-section water diversion and multi-target fish collaborative protection, which comprises the following steps: S1, determining a hydrological sensitive area and an ecological sensitive area based on water diversion influence constraints and fish resource distribution data, superimposing the hydrological sensitive area and the ecological sensitive area to construct a habitat evaluation model, determining a key habitat of a typical fish, and further determining a target spawning ground; S2, integrating a two-dimensional hydrodynamic model and a fish habitat model, calculating habitat hydraulic requirements and flow pulse requirements of different fishes in a spawning period, constructing an ecological water demand process in the spawning period, and simultaneously calculating an ecological base flow to supplement basic hydrological requirements in a non-spawning period; and S3, coupling ecological water demand for multiple spawning grounds overlapping in the spawning period, and determining a reservoir ecological flow collaborative allocation scheme. The method is based on the particularity of multi-section water diversion disturbance and multi-target collaborative protection of the west line project water source area, studies ecological water demand of typical fishes, and determines a reservoir ecological flow allocation scheme.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reservoir management, and in particular to a reservoir ecological flow configuration method based on multi-section water regulation and multi-target fish collaborative protection. BACKGROUND

[0002] The ecological water demand in a river channel generally refers to the water amount that the river channel needs to maintain in order to exert the normal function of the river channel ecological system and maintain the biodiversity in the river channel. The ecological flow in the river channel generally refers to the minimum water demand for maintaining the survival of aquatic organisms and riparian organisms. In order to maintain the stability of the river ecological system and achieve the goal of river water ecological protection, it is crucial to determine a scientific and reasonable ecological water demand process and formulate a suitable water resource management strategy. There are more than one hundred methods and calculation models for ecological water demand research so far, which are mainly divided into hydrology method, hydraulics method, habitat simulation method and overall method.

[0003] The adverse effects of water conservancy construction on fish are reflected in the aspects of weakening of river longitudinal connectivity, river fragmentation, change of topography and geomorphology and change of hydrological regime. With the increasing requirement for fish habitat protection, the ecological response of fish habitat to the change of hydrological regime has become a hot spot. Many scholars have conducted in-depth research on the ecological water demand of a single fish in a certain spawning ground, but there are few studies on the response relationship of habitat quality between multiple sensitive habitats. Therefore, the connection between the hydrological characteristics and ecological characteristics of typical fish in multiple target spawning grounds still needs to be discussed, and the coupling method system of the ecological water demand process of multiple target fish key habitats also needs to be discussed.

[0004] Meeting the hydrological process required for the spawning and reproduction of key protected fish and promoting river ecological protection in the water source area are the primary goals of ecological flow regulation. Under the current climate, hydrological boundary conditions and engineering scheme changes, it is necessary to comprehensively analyze the ecological water demand in combination with the particularity of the multi-section water regulation disturbance and multi-target collaborative protection in the source area of the Dadu River. By scientifically identifying the key habitats of fish within the influence range of the project, reasonably quantifying the connection between multiple habitats of fish and formulating the ecological flow process at the reservoir dam site, a scientific basis can be provided for the ecological flow management of the reservoir. SUMMARY

[0005] In order to solve the ecological water demand problem of typical fish, protect the hydrological process required for the spawning and reproduction of fish and promote river ecological protection in the water source area, the present application provides a reservoir ecological flow configuration method based on multi-section water regulation and multi-target fish collaborative protection.

[0006] The reservoir ecological flow configuration method based on multi-section water regulation and multi-target fish collaborative protection provided by the present application has the following steps:

[0007] S1, determine a hydrological sensitive area based on water diversion influence constraints, determine an ecological sensitive area based on fish resource distribution data, superimpose the hydrological sensitive area and the ecological sensitive area to construct a habitat evaluation model, determine a typical fish key habitat through habitat evaluation, and determine a target spawning ground.

[0008] The purpose of step S1 is to evaluate the flow recovery condition downstream of the dam site after water diversion through quantitative calculation and analysis, and to identify the region sensitive to hydrological condition change, i.e., the hydrological sensitive area, based on the flow recovery constraint. Meanwhile, according to the distribution characteristics of fish resources, representative typical fish are selected as research objects, and the spatial distribution of spawning grounds of these typical fish is analyzed in detail to clarify the ecological sensitive area. Finally, the hydrological sensitive area and the ecological sensitive area are superimposed, the fish key habitat is screened, the target spawning ground is determined, scientific support and basis are provided for subsequent fish ecological water demand research. Specifically, the following two steps are included:

[0009] S11, determine the hydrological sensitive area: in order to clarify the influence of water diversion on the river channel downstream of the dam, the annual water diversion of the reservoir is evenly distributed to each month, the flow before and after water diversion is calculated and compared. The flow recovery degree after water diversion downstream of the reservoir is expressed by percentage, and the flow recovery degree Q' after water diversion is calculated according to the following formula:

[0010]

[0011] In the formula, Q i调水后 is the flow at each section downstream of the dam after the monthly average allocation of water diversion; Q i调水前 is the flow at each section downstream of the dam under natural conditions.

[0012] When a larger tributary flows into the main stream, the flow in the river channel will be adequately recovered. The hydrological sensitive area can be determined by using the flow recovery degree Q' after water diversion. In the present application, the river section with a flow recovery degree Q' ≤ 70% is defined as the hydrological sensitive area.

[0013] S12, determination method of the ecological sensitive area: according to the distribution characteristics of fish resources, representative typical fish are selected as research objects, the distribution of spawning grounds of typical fish is investigated, and the spatial distribution of spawning grounds of these typical fish is analyzed in detail to clarify the ecological sensitive area.

[0014] S13, superimpose the hydrological sensitive area and the ecological sensitive area, construct a habitat evaluation model according to the principle of "upstream priority, comprehensive evaluation", and the specific method is as follows:

[0015] (1) Construct an index system, according to the influence of water conservancy project and the distribution of spawning ground, from the project response degree and the spawning ground characteristics, an index system for measuring the priority protection order of spawning ground is constructed:

[0016]

[0017] In the formula, x' is the result of each index after normalization; min(x) is the minimum value of each index; max(x) is the maximum value of each index;

[0018] (2) The index weight is determined by using the entropy weight method, and the calculation formula is as follows:

[0019]

[0020] d j =1-E j

[0021]

[0022] In the formula: p(x ij ) is the standardized value of each index; E j is the information entropy of the jth item; d j is the difference coefficient of the jth index, w j is the index weight.

[0023] (3) The index values and weights determined by steps (1) and (2) are used to obtain the priority protection comprehensive evaluation value V 综 of each spawning site by the weighted summation method, and the calculation formula is as follows:

[0024] V 综 =∑C i ω i , i=1,2,…,n

[0025] In the formula: C i is the normalized result of each index; ω i is the index weight, and n is the number of indexes.

[0026] S2, divide the different life cycles of fish, integrate the two-dimensional hydrodynamic model and the fish habitat model, calculate the habitat hydraulic demand and flow pulse demand of different fish in the spawning period by using the IFIM method, construct the ecological water demand process of fish in the spawning period, and calculate the ecological base flow to supplement the basic hydrological demand in the non-spawning period; The specific steps are as follows:

[0027] S21, the hydrodynamic model of the determined typical fish key habitat is established for numerical simulation to obtain the hydrodynamic parameters under different flow conditions, and the WUA is calculated by combining the fish habitat model and the flow velocity and depth suitability curve; WUA is defined as the product of the unit habitat suitability index and the area of the unit; The calculation formula of WUA is as follows:

[0028]

[0029] In the formula: n is the number of units; A im is the area of the calculation unit 2 ; HSI i SI is the comprehensive habitat suitability index of the calculation unit vi SI is the flow rate suitability index, ranging from 0 to 1 di SI is the water depth suitability index, ranging from 0 to 1 ci SI is the river suitability index (including bottom and cover conditions), ranging from 0 to 1.

[0030] The flow rate and water depth suitability curve is obtained by collecting the characteristics of the selected typical fish.

[0031] A HEC-RAS one-dimensional hydrodynamic model is established from the upper boundary of the spawning ground to the downstream hydrological station. First, the one-dimensional hydrodynamic model is calibrated and verified to ensure the accuracy and reliability of the model, and then the one-dimensional hydrodynamic data of the spawning ground location is extracted and used for the calibration and verification of the two-dimensional hydrodynamic model.

[0032] S22, obtain the flow-WUA relationship of different fish in the spawning ground, determine the optimal flow, optimal interval and suitable interval of ecological water demand of fish in the spawning period, and introduce the ecological hydrological index to construct the ecological water demand process of fish in the spawning period. Preferably, the flow corresponding to 80% and 60% of the WUA peak value is set as the optimal interval and the suitable interval, respectively.

[0033] Fish have different requirements for hydraulic conditions in different life cycles. For the spawning period, in addition to ensuring the flow required for suitable spawning habitat, a flow pulse process that stimulates fish spawning is also needed to provide a signal for fish spawning and stimulate fish gonadal development. The flow pulse is defined as a fluctuation process in which the flow rises from a minimum value to a maximum value and then falls to the next local minimum value, with a total duration of not less than three days. Since parent fish need about 2 days of stimulation to perform spawning behavior, the flow pulse process is further set as a flow pulse process with a rising water duration of more than 2 days.

[0034] S23, for fish in the non-spawning period, the hydrological method is used to calculate the ecological base flow to supplement the basic hydrological demand in the non-spawning period; to ensure that in the non-reproductive stage of fish, their habitat can still maintain the necessary ecological water quantity, thereby ensuring the survival and reproduction of fish. The hydrological method used can be one of Tennant method, 7Q10 method, Qp method and Texas method.

[0035] S3, for multiple spawning grounds downstream of multiple reservoirs with hydrological connection and overlapping spawning periods, the ecological water demand is coupled to determine the collaborative configuration scheme of reservoir ecological flow.

[0036] The purpose of step S3: The ecological flow process of the reservoir based on the single fish demand may cause potential conflicts in actual operation due to the difference in the flow demand of different fish, thereby affecting the scientific management and effective allocation of ecological flow. There is a hydrological connection between the spawning grounds in the downstream river reach of the reservoir. This hydrological connection causes the correlation of WUA between different spawning grounds. If the spawning periods are independent of each other, the ecological water demand of different spawning grounds in the spawning period does not affect each other; on the contrary, when the spawning periods overlap, it is extremely likely that the ecological water demand of the upstream and downstream spawning grounds cannot be met at the same time. At this time, the ecological water demand of these spawning grounds needs to be coupled to reasonably allocate the ecological flow of the reservoir.

[0037] According to the ecological water demand process of the single-target fish spawning period and the ecological base flow at the dam site in the non-spawning period, the reservoir discharge process is formulated. The ecological water demand in the spawning period is given priority to, and the discharge in the non-spawning period is supplemented by using the hydrological method.

[0038] In order to maximize the use of fish habitat, the ecological water demand of different fish spawning periods in the upstream and downstream is coupled, the single fish water demand is converted into multi-target water demand, so that different fish and different river reaches of the spawning grounds with hydrological linkage can maximize the ecological function, and the optimal allocation of the reservoir flow is realized.

[0039] The method for coupling the ecological water demand of multiple spawning grounds is as follows:

[0040] According to the flow-WUA relationship of each spawning ground calculated by the ecological water demand in the spawning period, the interval flow Q 区 between the upstream and downstream spawning grounds is the link that connects multiple spawning grounds, and the hydrological relationship between the upstream and downstream spawning grounds is Q 上 +Q 区 =Q 下 , the hydrological relationship is used to establish the relationship between WUA 上 and WUA 下 ; the relationship Q 上 ~WUA 上 , Q 下 ~WUA 下 and Q 上 +Q 区 =Q 下 is established, and the relationship WUA 上 ~WUA 下 is established, and the optimal ecological flow combination mode of multiple spawning grounds is sought in the relationship WUA 上 ~WUA 下 .

[0041] Among them, in order to compare the fish WUA of multiple spawning grounds with hydrological connection under different flow combinations, the normalization processing is performed on each spawning ground, and the formula is as follows:

[0042]

[0043] In the formula, WUA i is the normalized WUA, ranging from 0 to 1; WUA i is the fish WUA under different flow of spawning ground, unit: m 2 ; Max(WUA i ) is the maximum value, unit: m 2 ; ω i is the weight of each spawning ground, determined according to different target requirements; C WUA is the normalized comprehensive result of WUA of multiple spawning grounds, ranging from 0 to 1.

[0044] Strictly speaking, due to the importance of spawning ground and the difference of hydrological response, different weights should be given to different spawning grounds, but due to insufficient information, it is considered that the weights of each factor are the same in the present research.

[0045] The evaluation method of coupling results is as follows:

[0046] (1) for a single spawning ground, when WUA is 80% and above the peak value, the habitat quality is considered to be excellent; when WUA is between 60%-80% of the peak value, the habitat quality is considered to be good; when WUA is less than 60% of the peak value, the habitat quality is considered to be poor;

[0047] (2) for n spawning grounds, when the habitat quality of all spawning grounds is excellent, the comprehensive evaluation result is considered to be excellent; when the habitat quality of all spawning grounds is good and above, and no less than n / 2 is excellent, the comprehensive evaluation result is considered to be good; when the habitat quality of all spawning grounds is good and above, and the number of excellent ones is less than n / 2, the comprehensive evaluation result is considered to be medium; the rest is poor.

[0048] Finally, according to the optimal flow combination mode of ecological water demand, the optimized annual flow process of the reservoir is constructed.

[0049] Compared with the prior art, the present application has the advantages of:

[0050] The present application is based on the particularity of "multi-section water diversion disturbance and multi-target collaborative protection" of the water source area of the west line project, and the ecological water demand of typical fish is deeply studied to determine the reservoir ecological flow allocation scheme, which can provide scientific basis for the reservoir ecological flow management work.

[0051] Other advantages, objects and characteristics of the present application will be embodied in part through the following description, and will be understood by those skilled in the art through research and practice of the present application. DETAILED DESCRIPTION

[0052] Figure 1 Flow chart of the reservoir ecological flow configuration method of the present application.

[0053] Figure 2 The target spawning ground position identified by constructing the key habitat model in the embodiment of the present application.

[0054] Figure 3 The relationship curve between the flow-WUA of the spawning ground of the Amur pike researched in the embodiment of the present application.

[0055] Figure 4 The flow process line of the spawning period of the Amur pike calculated in the embodiment of the present application.

[0056] Figure 5 The annual flow process of the Huona dam site reservoir before the embodiment of the present application is implemented.

[0057] Figure 6 The annual flow process of the Keke dam site reservoir before the embodiment of the present application is implemented.

[0058] Figure 7 The position relationship diagram of the spawning ground in the embodiment of the present application.

[0059] Figure 8 The coupling mode schematic diagram of the ecological water demand of the spawning ground in the embodiment of the present application.

[0060] Figure 9 The coupling process of the ecological water demand of the three spawning grounds in the embodiment of the present application.

[0061] Figure 10 The optimized ecological flow configuration scheme of the Huona reservoir in the embodiment of the present application.

[0062] Figure 11 The optimized ecological flow configuration scheme of the Keke reservoir in the embodiment of the present application. DETAILED DESCRIPTION

[0063] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0064] As shown in the figure, the reservoir ecological flow configuration method based on multi-section water diversion and multi-target fish collaborative protection provided by the present application includes the following steps: Figure 1 Step S1, determine the hydrological sensitive area based on the water diversion influence constraint, determine the ecological sensitive area based on the fish resource distribution data, superimpose the hydrological sensitive area and the ecological sensitive area to construct a habitat evaluation model, determine the key habitat of the typical fish through habitat evaluation, and determine the target spawning ground.

[0065]

[0066] ​In this embodiment, the daily flow data of the source area of the Dadu River in the past 50 years are collected, analyzed and calculated for frequency, and the typical years of wet year, normal year and dry year are scientifically selected. The influence of water diversion on the source area of the Dadu River is systematically analyzed under different hydrological conditions of the West Line Project, and the recovery of the flow downstream of the dam site in the driest month of the dry year is focused on. The typical fish species and their key habitats are screened.

[0067] Determination of hydrological sensitive area: According to the change of flow at the hydrological station in each month of the wet year, normal year and dry year after water diversion of the West Line Project, it is known that the influence of water diversion is the largest in February of the dry year, which is also the driest month of the dry year. The change of flow downstream of the dam site is analyzed by selecting the driest month of the dry year as the typical working condition, and the water diversion amount is allocated to each month. The flow of the Makok River and the Ake River is restored to 66% of the natural condition after the confluence of the Zhumuzi River and the Chuesijia River, and the flow of the Shuangjiangkou is restored to 77% of the natural condition after the confluence of the Zhumuzi River and the Chuesijia River. The flow of the Dadu River is restored to 78% at the Dadujing hydrological station. The river section with a flow recovery lower than 70% is set as the hydrological sensitive area. The hydrological sensitive area ranges from about 181 km of the river section below the Zhuandan Reservoir, about 182 km of the river section of the Makok River downstream of the Huona Reservoir, about 124 km of the river section of the Ake River downstream of the Keke Reservoir, and 55 km of the river section below the confluence of the Makok River and the Ake River.

[0068] Determination of ecological sensitive area: According to the distribution of fish resources in the investigation area, combined with the change of fish resources and the importance of fish, typical fish are selected from the 12 fish species in the source area of the Dadu River of the West Line Project. In this embodiment, the Sichuan-Shaanxi Oncorhynchus is a national Class I protected fish and is listed in the Red List of Chinese Endangered Species. Historically, the Sichuan-Shaanxi Oncorhynchus was distributed in the entire Dadu River, but it is now in an extremely endangered state and is only distributed above the confluence of the Chabu River in the upper reaches of the Dadu River. The Schizothorax Biddulphi is a national Class II protected fish and a Sichuan provincial protected fish. The Onychostoma lini is a Chinese endemic species and a Yangtze River upstream endemic fish. The dominant fish population in the upper reaches of the Dadu River is composed of the Onychostoma lini and the Schizothorax Biddulphi, so the above three fish species are selected as typical fish, and the distribution of spawning grounds of the typical fish is investigated to determine the ecological sensitive area where the spawning grounds are located.

[0069] The hydrological sensitive area and the ecological sensitive area are superimposed, and a habitat evaluation model is constructed according to the principle of "upstream priority and comprehensive evaluation". In this embodiment, the evaluation results of the spawning ground are shown in Table 1, and the basic conditions of the key habitats selected according to the principle of "upstream priority and comprehensive evaluation" are shown in Table 2.

[0070] Table 1 Evaluation of Spawning Ground

[0071]

[0072] Table 2 Basic conditions of key habitats selected according to the principle of "upstream priority and comprehensive evaluation"

[0073]

[0074] Based on the above method, four typical key habitats were determined, namely, the spawning ground of Amur trout in Dagniang (spawning ground A) and Donganzheng (spawning ground B), the spawning ground of Schizothorax in Lianghexuoxiao (spawning ground C) and Ribo Balang (spawning ground D). Among them, spawning grounds A and B are located in the tributaries of Zhumuzi River, namely, Ma'ekou River and A'ekou River, with upstream water sources of reservoirs Huona and Ke'ekou. Spawning ground D is located in the main stream of Zhumuzi River, which is spatially located upstream and downstream and has hydrological connection. The key habitats of specific typical fish species are shown in Table 2. Figure 2

[0075] In step S2, different life cycles of fish are divided, two-dimensional hydrodynamic model and fish habitat model are integrated, IFIM method is used to calculate the habitat hydraulic demand and flow pulse demand of different fish in the spawning period, and the ecological water demand process line in the spawning period is constructed. At the same time, the ecological base flow is calculated to supplement the basic hydrological demand in the non-spawning period.

[0076] In this embodiment, the living habits of typical fish species are investigated, mainly the flow velocity and water depth suitability curve, which provides support for subsequent ecological water demand calculation in the spawning period. The spawning period of Schizothorax grahami is from August to September, the spawning period of Schizothorax chongmi is from March to June, and the spawning period of Amur trout is from March to April. The research on Schizothorax is relatively mature, while the research on Amur trout is relatively less. By analyzing and summarizing the research on Amur trout in the past 30 years, the flow velocity and water depth suitability curve of Amur trout is obtained. The suitable flow velocity for reproduction is 0.38-0.9 m / s, and the water depth is 0.15-1 m.

[0077] According to the IFIM method, the relationship between different flow fields and the WUA of target fish is established by integrating the hydrodynamic model and the fish habitat suitability model. WUA is defined as the product of unit habitat suitability index and the area of the unit, which is the most widely used habitat quality evaluation index. The habitat suitability of fish spawning ground can be determined by evaluating the response of habitat suitability to hydrological regime under reservoir regulation. The calculation formula is as follows:

[0078]

[0079] In the formula, n is the number of units; A i is the area of the calculation unit, m 2 ; HSI i is the comprehensive habitat suitability index of the calculation unit; SI vi is the flow velocity suitability index, with a value range of 0-1; SI di is the water depth suitability index, with a value range of 0-1; SI ci ​The river channel suitability index (including the substrate and cover conditions) ranges from 0 to 1. The river channel substrate of the study area is gravel, which meets the spawning requirements of the three typical fish species, so the river channel suitability index SI is calculated ci is set to 1.

[0080] Further, a HEC-RAS one-dimensional hydrodynamic model is established from the upper boundary of the spawning ground to the downstream hydrological station. First, the one-dimensional hydrodynamic model is calibrated and verified to ensure the accuracy and reliability of the model. Then, the one-dimensional hydrodynamic data of the spawning ground location are extracted and used for the calibration and verification of the two-dimensional hydrodynamic model.

[0081] The flow corresponding to 80% and 60% of the WUA peak value is set as the optimal interval and the suitable interval.

[0082] In this embodiment, the optimal flow of the ecological water demand of the Schizothorax davidi in the A and B spawning grounds is 70 m 3 / s and 21 m 3 / s, respectively; the optimal flow of the ecological water demand of the Schizothorax grahami in the C and D spawning grounds is 170 m 3 / s and 150 m 3 / s, respectively; and the optimal flow of the ecological water demand of the Schizothorax qianguo in the C and D spawning grounds is 140 m 3 / s and 150 m 3 / s, respectively.

[0083] Then, the ecological water demand of the spawning ground is calculated:

[0084] The flow corresponding to the maximum WUA is generally considered to be the ecological flow most suitable for fish reproduction. However, in actual processes, it is often not possible to guarantee the long-term existence of this flow. The flow higher than 80% of the WUA peak value is defined as the optimal habitat, and the flow higher than 60% of the WUA peak value is defined as the suitable habitat. The flow range corresponding to the optimal habitat is the optimal interval of the ecological water demand. When the flow of the spawning ground is within the optimal interval of the ecological water demand, it indicates that the WUA of the spawning ground can reach more than 80% of the WUA peak value, and the habitat at this time is very beneficial to fish reproduction. The flow range corresponding to the suitable habitat is the suitable interval of the ecological water demand. When the actual flow of the spawning ground is within the suitable interval of the ecological water demand, the WUA of the spawning ground can reach more than 60% of the peak value, which guarantees the reproduction requirements of fish. Conversely, when the flow of the spawning ground is not within the suitable interval of the ecological water demand, the suitable habitat of the spawning ground will be lost by 60% or more, which is extremely unfavorable to the growth and reproduction of fish. Therefore, the flow of the fish spawning ground should be ensured to be within the suitable interval of the ecological water demand during the spawning period. Figure 3 The flow-WUA relationship curve of the Schizothorax davidi spawning ground in this embodiment is shown in FIG. 6. According to the analysis of the ecological hydrological indicators of the spawning ground, the flow pulse process is established, and the process line of the ecological water demand flow during the spawning period is obtained. Table 3 shows the ecological water demand scheme of the Schizothorax davidi during the spawning period.Figure 4 The flow process line of the spawning period of the Amur pike.

[0085] Table 3 Ecological water demand scheme of the spawning period of the Amur pike

[0086]

[0087] Supplement the ecological torrent in the non-spawning period: According to the collected hydrological data, combined with the maximum value of the monthly results calculated by the Tennant method, the 7Q10 method, the Qp method and the Texas method, and the specification requirements, determine the ecological base flow of Zhuanda, Hona and Keke in the non-spawning period.

[0088] Step S3, for multiple spawning grounds downstream of multiple reservoirs with hydrological connection and overlapping spawning period, ecological water demand coupling research is carried out, and a collaborative configuration scheme of reservoir ecological flow is put forward, which provides a scientific basis and reference for reservoir ecological flow management.

[0089] According to the ecological water demand process of single-target fish in the spawning period and the ecological base flow at the dam site in the non-spawning period, the reservoir discharge process is developed, which gives priority to the ecological water demand in the spawning period, and the discharge in the non-spawning period is supplemented by the results of hydrological method.

[0090] Figure 5 and Figure 6 are the annual flow processes of Hona and Keke dam sites, respectively.

[0091] According to Figure 7 The location relationship of reservoir-spawning ground shows that the Amur pike spawning grounds A and B are on the tributaries of the Mako River and the Ako River of the Zhumuzi River, and the upstream Hona Reservoir and Keke Reservoir serve different fish species with the Schizothorax fish D spawning ground on the main stream of the Zhumuzi River. The Amur pike spawning grounds A and B are the habitats of the Amur pike, and the spawning period is from March to April; the Schizothorax fish D spawning ground is the habitat of the Schizothorax grahami and the Schizothorax chongmi, and their spawning periods are from August to September and from March to June, respectively. It can be seen that the spawning periods of the Amur pike and the Schizothorax chongmi overlap (from March to April). The ecological water demand flow of the Amur pike in the spawning period is small, and the flow corresponding to the maximum WUA of the spawning ground A is 70m 3 / s, and the flow corresponding to the maximum WUA of the spawning ground B is 21m 3 / s, while the ecological water demand flow of the Schizothorax chongmi in the spawning period is large, and the flow corresponding to the maximum WUA of the spawning ground D is 150m 3 / s.

[0092] From Figure 5 and Figure 6It can be seen that for March and April when the spawning period overlaps, there are differences in the flow processes at the two dam sites. The flow process based on the spawning needs of Sichuan-Shaanxi Taimen is smaller, while the flow process based on the spawning needs of Qikou Schizothorax is larger. When there are multiple ecological flow results, the usual practice is to use the outer envelope method to take the maximum value. Assuming that the maximum value of the optimal flow during the spawning period of different fish species is used at the Huona and Keke dam sites, the discharge flow process based on the spawning needs of Qikou Schizothorax, the peak flows in March and April are 28m 3 / s and 17m 3 / s. Based on the catchment area, the flow rates of Sichuan-Shaanxi Taimen spawning grounds A and B are 63m 3 / s and 55m 3 / s. By Figure 3 It can be seen that the WUA corresponding to spawning site A and spawning site B is 1100m 2 and 827m 2 , the WUA normalized results were 0.97 and 0.5, respectively. Combined with the WUA of the spawning ground of Schizothorax chinensis D i ′ is 1, indicating a comprehensive result of 0.79. Table 4 shows that the maximum discharge rate for the optimal flow rate during the spawning period of different fish species can still maintain a high WUA for spawning sites A and D. However, for spawning site B, it cannot achieve a suitable spawning habitat for Sichuan-Shaanxi Taimen (WUA is less than 60% of the peak value), so the discharge process cannot be directly based on the maximum discharge rate.

[0093] Table 4 Spawning ground conditions of Huona and Keke reservoirs according to the maximum spawning demand of different fish species during the discharge process

[0094] Spawning ground Spawning ground A of Huai Sze Chub Spawning ground B of Huai Sze Chub Spawning ground D of Qipu Fish Flow (m 3 / s) 63 55 150 WUA(m 2 )]]> 1100 827 21376 WUA ′ ]]> 0.97 0.5 1

[0095] When the discharge flow at the dam site is small, it is conducive to the reproduction of Sichuan-Shaanxi Taimen that prefers slow-flow habitats upstream, but it will lead to insufficient ecological water flow for the Qikou Schizothorax that prefers rapid-flow habitats downstream, which is not enough to stimulate its spawning and reproduction; on the contrary, if the discharge flow at the dam site is large, although it is conducive to the spawning of Qikou Schizothorax in the downstream spawning grounds, it is not suitable for the spawning and reproduction of Sichuan-Shaanxi Taimen upstream.

[0096] In order to maximize the utilization of fish habitats, the ecological water demands of different fish species during the overlapping spawning periods upstream and downstream are coupled, and the single fish water demand is converted into multi-target water demand, so that the spawning grounds of different fish species and different river sections with hydrological linkage can maximize their ecological functions and achieve optimal configuration of reservoir flow.

[0097] The coupling method for key habitats is:

[0098] For multiple spawning grounds distributed in the cross-river network and with hydrological connections, a study on the ecological water demand coupling of multiple spawning grounds was conducted based on the principle of multi-field collaborative optimization. According to the flow-WUA relationship of each spawning ground calculated based on the ecological water demand during the spawning period, the interval confluence Q between the upstream and downstream spawning grounds was calculated. 区 As a link, connecting multiple spawning grounds, the hydrological relationship between the upstream and downstream spawning grounds is Q 上 +Q 区 =Q 下 , using hydrological relationships to establish WUA 上 with WUA 下 The relationship between Figure 8 As shown. Joint Q 上 ~WUA 上 , Q 下 ~WUA 下 and Q 上 +Q 区 =Q 下 Establishment of WUA 上 ~WUA 下 relationship, and in WUA 上 ~WUA 下 The optimal ecological flow combination pattern for the coordination of multiple spawning grounds is sought in the relationship between the two.

[0099] In order to more clearly and conveniently compare the WUA of fish in multiple spawning grounds with hydrological connections under different flow combinations, each spawning ground was normalized.

[0100] In this example, the ecological water demand of three spawning grounds, namely, the spawning grounds A and B of Sichuan-Shaanxi Taimen and the spawning ground of Qikou Schizothorax, D, was coupled to study the flow-WUA relationship of the three spawning grounds and the hydrological relationship Q. A +Q B +Q 区 =Q D The WUA relationship between the three spawning grounds can be obtained to determine the impact of the flow of the two upstream Sichuan-Shaanxi Taimen spawning grounds A and B on the WUA of the downstream schizothorax D spawning ground. The WUA relationship results between the three spawning grounds are shown in Figure 9 .

[0101] Figure 9The heat map represents the WUA of the spawning ground D of the Fluvial Carps, which is determined by the flow through the spawning grounds A and B and the interval confluence (interval confluence is calculated according to the catchment area). The two broken lines represent the flow-WUA relationship of the spawning grounds A and B respectively. The darker the color of the heat map, the larger the WUA of the Fluvial Carps in the spawning ground D, and vice versa. It can be seen that when the flow combination (including interval flow) of the spawning grounds A and B is within a certain flow range, the WUA of the Fluvial Carps in the spawning ground D is relatively large. When the flow of the spawning ground A decreases, the flow of the spawning ground B needs to increase to maintain a relatively high WUA of the Fluvial Carps in the spawning ground D. When the flow of the spawning ground B decreases, the flow of the spawning ground A needs to increase to maintain a relatively large WUA of the Fluvial Carps.

[0102] Figure 9 The middle red box represents the optimal interval of ecological water requirement of the spawning ground A, which is 48-119 m 3 / s, and the green box represents the optimal interval of ecological water requirement of the Rong'an County, which is 10-31 m 3 / s. The black diagonal part represents that the WUA of the two spawning grounds reaches 80% of the peak value. The flow combination in the dark color area of the heat map can maintain a relatively high WUA of the three spawning grounds.

[0103] The evaluation method of the coupling results is shown in Table 5, which is as follows:

[0104] a. According to the habitat suitable interval and the habitat optimal interval in the foregoing, the rules are set to evaluate the coupling results. For a single spawning ground, when the WUA is 80% or more of the peak value, the habitat quality is considered to be excellent; when the WUA is 60% or more of the peak value, the habitat quality is considered to be good; and when the WUA is less than 60% of the peak value, the habitat quality is considered to be poor.

[0105] b. For n spawning grounds, when the habitat quality of all the spawning grounds is excellent, the comprehensive evaluation result is considered to be excellent; when the habitat quality of all the spawning grounds is good or above, and at least n / 2 of them are excellent, the comprehensive evaluation result is considered to be good; when the habitat quality of all the spawning grounds is good or above, the comprehensive evaluation result is considered to be medium; and the rest is poor.

[0106] Table 5 Evaluation rules of coupling results

[0107]

[0108] The normalized comprehensive results of the WUA of the spawning grounds A and B of the Sichuan-Shaanxi Chum Salmon and the spawning ground D of the Fluvial Carps are shown in Figure 9 . The flow combination corresponding to the highest value is the optimal flow combination mode. The optimal flow combination mode and the habitat quality of the spawning grounds are shown in Table 6. When the flow of the spawning ground A is 107 m 3 / s, the flow of spawning ground B is 21m 3 / s, the WUA comprehensive result C WUA is 0.97. At this time, the WUA of spawning grounds A, B and D is 1048m 2 , 1654m 2 and 20867m 2 , respectively. The corresponding normalized results are 0.93, 1.00 and 0.98, respectively, that is, the WUA of the three spawning grounds is all above 80% of the WUA peak value, and the WUA of the three spawning grounds is all at a high level.

[0109] Table 6 coupling effect comparison

[0110]

[0111] Finally, according to the optimal flow combination mode of ecological water demand, the optimized annual flow process of the reservoir is constructed.

[0112] According to the WUA comprehensive result C WUA , the optimal flow combination mode corresponding to the maximum is that the flow of spawning ground A is 107m 3 / s, the flow of spawning ground B is 21m 3 / s, at this time C WUA is 0.97. Based on the optimal flow combination mode to optimize the annual flow process configuration of the reservoir, the Huona Reservoir shapes a flow pulse process with a peak flow of 47.0m 3 / s for 3 times in March-April, a flow pulse process with a peak flow of 37.3m 3 / s for 5 times in May-June, and a flow pulse process with a peak flow of 37.3m 3 / s for 3 times in August-September, and the ecological base flow is discharged according to the calculation results of hydrology in the real period. The Keke Reservoir shapes a flow pulse process with a peak flow of 6.4m 3 / s for 3 times in March-April, a flow pulse process with a peak flow of 14.2m 3 / s for 5 times in May-June, and a flow pulse process with a peak flow of 14.2m 3 / s for 3 times in August-September, and the ecological base flow is discharged according to the calculation results of hydrology in the remaining period.

[0113] According to the optimal flow combination mode, the annual flow process optimization configuration results of the Huona Reservoir and the Keke Reservoir are shown in Figure 10 and Figure 11 .

[0114] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art, without departing from the technical solution of the present application, can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, as long as it does not deviate from the technical solution of the present application, shall still fall within the scope of the technical solution of the present application.

Claims

1. A reservoir ecological flow configuration method based on multi-section water diversion and multi-target fish coordinated protection, characterized in that: The following steps are involved: S1. Determine hydrologically sensitive areas based on water diversion impact constraints and ecologically sensitive areas based on fish resource distribution data. Construct a habitat assessment model by superimposing hydrologically sensitive and ecologically sensitive areas. Determine typical key fish habitats and target spawning grounds through habitat assessment. Among them, river sections where the degree of flow recovery after water diversion, Q′, is less than or equal to 70%, are identified as hydrologically sensitive areas. The calculation formula for the degree of flow recovery after water diversion, Q′, is as follows: Where: Q i调水后 Q is the flow rate of each section below the dam after the monthly water diversion volume is allocated; i调水前 is the flow rate of each section below the dam under natural conditions; S2. Construct the ecological water demand process during the fish spawning period and calculate the ecological base flow to supplement the basic hydrological demand during the non-spawning period. The specific steps are as follows: S21. Build a hydrodynamic model for identified typical key fish habitats and conduct numerical simulations to obtain hydrodynamic parameters under different flow conditions. Combined with the fish habitat model and the velocity and depth suitability curves, calculate the WUA. WUA is defined as the product of the unit habitat suitability index and the unit area. S22. Obtain the flow-WUA relationship of different fish species in the spawning grounds, determine the optimal flow, optimal interval, and suitable interval of ecological water demand during the spawning period, and introduce eco-hydrological indicators to construct the ecological water demand process during the spawning period; S23. For fish species in the non-spawning period, calculate the ecological base flow to supplement the basic hydrological demand in the non-spawning period; S3. Coupling ecological water demands for multiple spawning sites downstream of multiple reservoirs, with hydrological connections and overlapping spawning periods, is conducted to determine a coordinated allocation plan for reservoir ecological flows. The method for coupling ecological water demands for multiple spawning sites is as follows: Based on the flow-WUA relationship of each spawning ground calculated based on the ecological water demand during the spawning period, the interval confluence Q between the upstream and downstream spawning grounds 区 As a link, connecting multiple spawning grounds, the hydrological relationship between the upstream and downstream spawning grounds is Q 上 +Q 区 =Q 下 , using the above hydrological relationship to establish WUA 上 with WUA 下 relationship; Joint Q 上 ~WUA 上 , Q 下 ~WUA 下 and Q 上 +Q 区 =Q 下 Establishment of WUA 上 ~WUA 下 relationship, and in WUA 上 ~WUA 下 The optimal ecological flow combination pattern for the coordination of multiple spawning grounds is sought in the relationship between the two.

2. The reservoir ecological flow configuration method based on multi-section water diversion and multi-target fish coordinated protection according to claim 1 is characterized in that: In step S1, the method for determining ecologically sensitive areas is: based on the distribution characteristics of fish resources, representative typical fish are selected as research objects, and the spatial distribution of the spawning grounds of these typical fish are carefully analyzed to clarify their ecologically sensitive areas.

3. The reservoir ecological flow configuration method based on multi-section water diversion and multi-target fish coordinated protection according to claim 1 is characterized in that: In step S1, the hydrologically sensitive areas and ecologically sensitive areas are superimposed to construct a habitat assessment model. The specific method is as follows: (1) Construct an indicator system to measure the priority order of spawning ground protection from two aspects: the degree of engineering response and the characteristics of the spawning grounds. In the formula, x′ is the normalized result of each indicator; min(x) is the minimum value of each indicator; max(x) is the maximum value of each indicator; (2) The entropy weight method is used to determine the indicator weights. The calculation formula is as follows: d j =1-E j Where: p(x ij ) is the standardized value of each indicator; E j is the information entropy of the jth item; d j is the difference coefficient of the j-th indicator, w j is the indicator weight; (3) Using the values ​​and weights of the indicators determined in steps (1) and (2), the priority protection comprehensive assessment value V of each spawning ground is obtained by weighted summation method. 综 , the calculation formula is as follows: V 综 =∑C i ω i ,i=1,2,…,n Where: C i is the normalized result of each indicator; ω i is the indicator weight, and n is the number of indicators.

4. The reservoir ecological flow configuration method based on multi-section water diversion and multi-target fish coordinated protection according to claim 1 is characterized in that: In step S21, the WUA calculation formula is as follows: Where: n is the number of units; A i is the area of ​​the calculation unit, m 2 ; HSI i is the comprehensive habitat suitability index of the calculation unit; SI vi SI is the flow rate suitability index, ranging from 0 to 1; di SI is the water depth suitability index, ranging from 0 to 1; ci It is the river suitability index, ranging from 0 to 1.

5. The reservoir ecological flow configuration method based on multi-section water diversion and multi-target fish coordinated protection according to claim 1 is characterized in that: In step S22, the flow rates corresponding to 80% and 60% of the WUA peak are set as the optimal interval and the appropriate interval, respectively.

6. The reservoir ecological flow configuration method based on multi-section water diversion and multi-target fish coordinated protection according to claim 1 is characterized in that: In step S3, in the ecological water demand coupling method for multiple spawning grounds, in order to facilitate the comparison of the fish WUA of multiple spawning grounds with hydrological connections under different flow combinations, each spawning ground is normalized using the following formula: Where WUA i ′ is the normalized WUA, ranging from 0 to 1; WUA i is the WUA of fish at different flow rates in the spawning grounds, in m 2 ;Max(WUA i ) is the maximum value, unit is m 2 ; ω i is the weight of each spawning ground, determined according to different target requirements; C WUA It is the comprehensive result of the normalized WUA of multiple spawning grounds, ranging from 0 to 1.

7. The reservoir ecological flow configuration method based on multi-section water diversion and multi-target fish coordinated protection according to claim 1 is characterized in that: In step S3, the evaluation method for the ecological water demand coupling results of multiple spawning sites is as follows: (1) For a single spawning site, when WUA is 80% or above of the peak value, the habitat quality is considered excellent; when WUA is between 60% and 80% of the peak value, the habitat quality is considered good; when WUA is less than 60% of the peak value, the habitat quality is considered poor; (2) For n spawning grounds, when the habitat quality of all spawning grounds is excellent, the comprehensive evaluation result is considered excellent; when the habitat quality of all spawning grounds is good or above, and no less than n / 2 of them are excellent, the comprehensive evaluation result is considered good; when the habitat quality of all spawning grounds is good or above, and the number of excellent ones is less than n / 2, the comprehensive evaluation result is considered fair; The rest of the cases are poor.

8. The reservoir ecological flow configuration method based on multi-section water diversion and multi-target fish coordinated protection according to claim 7 is characterized in that: Based on the optimal flow combination model of ecological water demand, the optimized reservoir annual flow process is constructed.

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