Method and system for deducing suitable ecological flow of fish fattening farm

Abstract

The invention discloses a method and system for deducing suitable ecological flow of a fish fattening farm, and the method comprises the following steps: constructing a fattening farm hydraulic habitat index system for quantifying the spatial heterogeneity of habitat plaques, and carrying out the analysis and calculation of the hydraulic habitat index values of the fattening farm under different flow conditions for a research water area through a two-dimensional hydrodynamic model, and selecting the flow corresponding to the waterpower habitat index value which is most suitable for the inhabitation of the researched fish as the suitable ecological flow of the fattening field. The method not only considers the target organisms, but also considers other organisms in the river, is more beneficial to creating water flow conditions suitable for coexistence of multiple species, and has certain scientific significance and reference value for fish fattening field protection and ecological restoration.

Description

Technical Field

[0001] The invention belongs to the technical field of ecological restoration of river habitats, and in particular relates to a method and system for deriving suitable ecological flow of a fish fattening farm. Background Art

[0002] The aquatic environment necessary for fish to complete their life cycle is called fish habitat (habitat), including spawning grounds, fattening grounds, wintering grounds and migration channels, etc., which are crucial for the survival and reproduction of fish. Research on river fish habitats has always been a hot topic in the protection and restoration of water ecology. In theoretical research, the suitability of fish habitats and the ecological significance of various indicators are mostly qualitatively analyzed. Most studies on the ecological flow of fish habitats focus on the spawning period of fish. Considering the different conditions required for different stages of the fish life cycle, the ecological flow of other life cycles such as the fattening period should also be taken seriously. Regarding fish fattening grounds, water flow not only affects the survival of fish, but also has a significant impact on the food resources of fish. Currently, there are few studies that analyze the ecological water demand of fish and the biomass of food they need.

[0003] At present, the research on ecological flow of river fish habitats is mainly focused on fish spawning grounds, and the most commonly used method is habitat simulation. This method combines hydraulic models with the life stages of target organisms in rivers to quantitatively quantify the relationship between river flow and corresponding habitat area, thereby determining the ecological water demand of specific life stages of target organisms. Yi Yujun established a habitat fitness model for Chinese sturgeon and simulated the spawning habitat of Chinese sturgeon below Gezhouba Dam to obtain the ecological flow suitable for spawning of Chinese sturgeon. Cai Yupeng determined the preferred water depth, flow rate and bottom quality of Chinese sturgeon during the spawning period through a survey of the spawning river section of Chinese sturgeon during natural reproduction, and quantified the relationship between flow and suitable area during the spawning period of Chinese sturgeon, and obtained the suitable ecological flow during the spawning period of Chinese sturgeon. Guo Wenxian, Li Jian and others used PHABSIM model and Delft3D combined with habitat simulation model to quantify the relationship between flow and suitable area of ​​spawning grounds of the four major carps. Hou Jun et al. established a habitat suitability model for the spawning period of the naked-tailed fish (Young husbandi) in Lhasa through numerical simulation and statistics, and obtained the environmental flow of the naked-tailed fish in Lhasa during the spawning period using the habitat simulation method. Li Youguang et al. used crucian carp and aquatic insects as indicator species, constructed a multi-species habitat suitability model based on the fuzzy logic method, and conducted habitat simulation. Based on the quantitative response relationship between habitat quality and flow, they determined the suitable ecological flow range for crucian carp and aquatic insects in the Shihe River.

[0004] However, most of the existing studies on ecological flow in fish habitats only consider the spawning period, which is more sensitive to fish, and do not consider the impact of fattening period in other life stages on fish; in addition, regarding fish fattening grounds, water flow not only affects fish survival, but also has a significant impact on fish food resources. There is a lack of relevant research on ecological water demand that combines fish with the biomass of food they need. Finally, current research focuses on a certain point or a certain section in the river, combining fish specific behaviors (such as spawning behavior) and hydraulic factors (flow velocity, water depth, etc.) to construct a suitability curve, and then deduce the suitable ecological flow. However, the life activity requirements of fish are closely related to the spatial heterogeneity of water flow. Studying the response process between the life activity requirements of fish and the spatial heterogeneity of water flow from the perspective of the spatial characteristics of habitat water flow is of great significance for studying the functional characteristics of fish fattening grounds. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies in the prior art and provide a method for deriving suitable ecological flow for fish fattening farms. The method not only takes into account the target organisms but also other organisms in the river, and is more conducive to creating water flow conditions suitable for the coexistence of multiple species. It has certain scientific significance and reference value for the protection of fish fattening farms and ecological restoration.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for deriving an appropriate ecological flow for a fish fattening farm, characterized in that it includes the following steps: constructing a fattening farm hydraulic habitat index system for quantifying the spatial heterogeneity of habitat patches, using a two-dimensional hydrodynamic model to analyze and calculate the hydraulic habitat index values ​​of the fattening farm under different flow conditions for the study water area, and selecting the flow corresponding to the hydraulic habitat index value most suitable for the fish under study as the appropriate ecological flow for the fattening farm.

[0008] Furthermore, a hydraulic habitat indicator system for fattening farms is established, including a hydraulic indicator layer, a habitat patch layer, and a patch landscape ecological indicator layer. The patch types of the habitat patch layer are divided according to the hydraulic indicators of the hydraulic indicator layer, and the indicator values ​​of the patch landscape ecological indicator layer are calculated according to the patch types.

[0009] Furthermore, the hydraulic indicator layer includes water depth and flow velocity, and the patch types include deep pools, rapids, shallows, and slow currents along the shore.

[0010] Furthermore, the methods for classifying plaque types include:

[0011] Establish the membership function of water depth and flow velocity;

[0012] According to the membership function of water depth and flow velocity, the water depth is divided into three levels: shallow, medium and deep, and the flow velocity is divided into two levels: slow and fast.

[0013] According to the results of water depth and flow velocity classification, the four types of patches, namely deep pools, shallows, rapids and slow currents along the shore, were judged and classified through if-and-then rules.

[0014] Furthermore, the water depth membership calculation method is:

[0015]

[0016] y is the degree of membership, h is the water depth, m i is the parameter of the membership function, k i The water depth endpoint value of the division.

[0017] Furthermore, the velocity membership calculation method is:

[0018]

[0019] y is the degree of membership, v is the flow rate, n i is the parameter of the membership function, p i is the flow velocity endpoint value of the division.

[0020] Furthermore, the patch landscape ecological indicator layer includes patch area ratio and diversity index, among which the patch area ratio PALND refers to the ratio of a certain type of patch area to the water area, and the formula is:

[0021]

[0022] a ij is the area of ​​a certain type of patch ij, and A is the water area;

[0023] The diversity index SHDI is used to describe the uniformity and quantity of patch type distribution. The calculation formula is:

[0024]

[0025] N is the number of habitat patches, p i is the proportion of area occupied by habitat patches.

[0026] Another object of the present invention is to provide a system for realizing the above-mentioned method for deriving the suitable ecological flow of the fish fattening farm, comprising:

[0027] The hydraulic habitat indicator system construction module establishes a hydraulic habitat indicator system for fattening farms to quantify the spatial heterogeneity of habitat patches;

[0028] The calculation module of the hydraulic index system of the research area is used to analyze and calculate the hydraulic index values ​​of the fattening farm under different flow conditions using a two-dimensional hydrodynamic model for the research waters;

[0029] The suitable flow calculation module is used to select the flow corresponding to the hydraulic habitat index value that is most suitable for the fish species under study from the hydraulic habitat index system calculation module of the study area as the suitable ecological flow for the fattening farm.

[0030] An electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0031] A computer-readable storage medium stores a computer program, which implements the steps of the above method when executed by a processor.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention takes into account the water flow conditions required for fish fattening and the survival of bait organisms, combines the relationship between the function of the fattening field and the spatial heterogeneity of the water flow, divides a variety of river patch types based on hydraulic factors, combines the suitable patches required for the survival of fish and fattening bait organisms during the fattening period, and takes the ecological flow corresponding to the largest proportion of patches suitable for studying fish habitats and the highest patch diversity index as the suitable ecological flow for fish fattening. Compared with the previous method, hydraulic factors are mostly used to describe the situation of a single point or cross-section scale in the river. The method uses habitat patches as the local mesoscale, which is more convenient for practical operation. In addition, the method classifies river habitat patches (the ecological significance of habitat patches for fattening is shown in Table 1), and takes the highest "diversity index" as one of the judgment conditions for suitable fattening ecological flow, which not only considers the target organisms but also other organisms in the river, and is more conducive to creating water flow conditions suitable for the coexistence of multiple species. The method of the present invention has certain scientific significance and reference value for the protection of fish fattening fields and ecological restoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of a method for deriving an appropriate ecological flow rate for a fish fattening farm according to an embodiment of the present invention;

[0034] Figure 2 It is a two-dimensional hydrodynamic model of a river section for fattening sweetfish in an embodiment of the present invention, wherein (a) is a topographic map, and (b) is a grid map;

[0035] Figure 3 Calculation results of the two-dimensional hydrodynamic model of the sweetfish fattening river section in an embodiment of the present invention, (a) water depth map, (b) flow velocity map;

[0036] Figure 4 1 is a diagram of water depth and flow velocity membership function according to an embodiment of the present invention, (a) water depth membership function diagram, (b) flow velocity membership function diagram;

[0037] Figure 5 The distribution diagram of different types of habitat patches under three flow rates in the embodiment of the present invention, (a) Q = 6.28m3 / s, (b) Q = 89.09 m 3 / s, (c) Q = 239.60 m 3 / s;

[0038] Figure 6 is a graph showing the variation of the diversity index with flow rate according to an embodiment of the present invention;

[0039] Figure 7 is a graph showing the change in the ratio of the patch area of ​​each type of habitat with flow rate according to an embodiment of the present invention;

[0040] Figure 8 1 is a graph showing the change in the ratio of the patch area of ​​the shallows and deep pools with flow rate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0043] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0044] like Figure 1 As shown, the embodiment of the present invention discloses a method for deriving an appropriate ecological flow rate for a fish fattening farm, comprising the following steps:

[0045] Step 1: Construct a feedlot hydraulic habitat indicator system for quantifying spatial heterogeneity of habitat patches;

[0046] The hydraulic habitat index system of the fattening farm uses water depth and flow velocity as the hydraulic index layer, four types of fattening habitat patches, deep pools (resting and sheltering areas), rapids (material transport areas), shallows (feeding and fattening areas), and slow streams along the shore (food sources) as the habitat patch layer, and patch area ratio and diversity index as the patch landscape ecological index layer. The ecological significance of the hydraulic habitat index system of the fattening farm for fish fattening is as follows, as shown in Table 1.

[0047] Table 1 Hydraulic habitat indicators and their ecological significance in fattening farms

[0048]

[0049] The patch types of the habitat patch layer are divided according to the water depth and flow velocity of the hydraulic index layer, and then the patch area ratio and diversity index of the patch landscape ecological index layer are calculated according to the patch type. When dividing the patch type, the membership function of water depth and flow velocity is first established as shown in the following formula:

[0050] Water depth membership function

[0051]

[0052] y is the degree of membership, h is the water depth, m i is the parameter of the membership function, k i The water depth endpoint value of the division.

[0053] The flow velocity membership calculation method is:

[0054]

[0055] y is the degree of membership, v is the flow rate, n i is the parameter of the membership function, p i is the flow velocity endpoint value of the division.

[0056] The water depth is divided into three levels: shallow, medium, and deep according to the water depth membership function, and the flow velocity is divided into two levels: slow and fast according to the flow velocity membership function. The water depth and flow velocity classification results are then used to judge and classify the four types of patches: deep pools, shoals, rapids, and slow shore flows through if-and-then rules (Table 2).

[0057] Table 2 if-and-then rule table

[0058]

[0059] This example uses patch area ratio and diversity index to quantify the spatial heterogeneity of habitat patches. According to the patch types classified in Table 2, the patch area ratio of a certain type is calculated. The patch area ratio (PALND) refers to the ratio of the patch area of ​​the above four types of habitats to the water area. The calculation formula is:

[0060]

[0061] a ij is the area of ​​a certain type of patch ij, and A is the water area.

[0062] The diversity index (SHDI) is used to describe the uniformity and quantity of patch type distribution, reflecting the heterogeneity of the landscape. When there is only one type of habitat patch, SHDI = 0. The calculation formula is as follows:

[0063]

[0064] N is the number of habitat patches, p i is the proportion of area occupied by habitat patches.

[0065] Step 2: Use a two-dimensional hydrodynamic model to analyze and calculate the hydraulic habitat index system of the fattening farm under different flow conditions in the research waters;

[0066] The two-dimensional hydrodynamic model of the fattening river section was established based on the measured topographic map using mike21HD. The two-dimensional hydrodynamic model of the fattening river section includes: the measured topography of the fattening river section, the flow at the inlet of the fattening river section (upper boundary of the model), and the water level at the outlet of the fattening river section (lower boundary of the model). After that, the fattening river section was divided into unstructured grids, and then the measured topography was interpolated to form a grid with topographic data information. Finally, the upper and lower boundary conditions of the model were input, and the hydrodynamic calculation was performed using the Hydrodynamic module in the mike21HD Flow Model FM. The upper boundary of the model is the flow inlet, and the lower boundary is the water level outlet. According to the hydrological conditions of the river section, different flow conditions and corresponding water levels in the range from low to high flow were selected as the boundary input conditions of the two-dimensional hydrodynamic model of the fattening river section, and the flow field in the fattening river section under different flow conditions was calculated, and the flow velocity, water depth and distribution in the river section were analyzed and calculated. After obtaining the velocity, water depth and distribution, the fattening river section was divided into patch types according to the rules in Table 2. The patch area ratio and diversity index were calculated based on the area and number of the divided patch types and the water area.

[0067] Step 3, select the flow corresponding to the hydraulic habitat index that is most suitable for the fish species being studied as the suitable ecological flow for the fattening farm;

[0068] The ratio of water area occupied by habitat patches and the diversity index in the hydraulic index system of fattening farms were used as indicators for studying the suitable ecological flow for fish. The two indicators under different flow conditions were statistically analyzed, and the ecological flow corresponding to the largest proportion of patches suitable for fish habitat and the highest patch diversity index was taken as the suitable ecological flow for fish fattening.

[0069] The following is a specific example. The fattening farm of sweetfish (Plecoglossus altivelis) in Nanxi River, the second largest tributary of the Oujiang River system in Zhejiang Province, was used as the research river section, and a two-dimensional hydrodynamic model of the sweetfish fattening farm was established (see Figure 2 ), according to the characteristics of water depth and flow velocity in the water area calculated by two-dimensional hydrodynamics (see Figure 3 ), combined with the suitable water depth (0.5m~1.5m) and flow velocity (0.5m / s~1.0m / s) of sweetfish, the water depth is divided into <0.5m, 0.5m~1.5m, and >1.5m. Therefore, in this embodiment, k 1 Values: 0m, k 2The value is 0.5m, k 3 The value is 1.0m, k 4 The value is 1.5m. In this embodiment, see Figure 4 (a) The membership formula of water depth is obtained as follows:

[0070]

[0071] The flow velocity is divided into <0.5m / s, 0.5m / s~1.0m / s and >1.0m / s. Therefore, in this embodiment, p 1 Value: 0m / s, p 2 The value is 0.5m / s, p 3 The membership function of the velocity is 1m / s (see Figure 4 (b)) is:

[0072]

[0073] According to the water depth membership function, the water depth is divided into three levels: shallow, medium, and deep. According to the flow velocity membership function, the flow velocity is divided into two levels: slow and fast. Then, the classification results of water depth and flow velocity are combined with the if-and-then rule (Table 2) to judge and classify the four types of patches: deep pools, shoals, rapids, and slow shore flows. Then, the area, number, and water area of ​​the patch types divided under different flow rates are calculated to obtain the patch area ratio and diversity index. Finally, the two indicators of the water area ratio occupied by habitat patches and the diversity index in the hydraulic index system of the fattening farm are selected as indicators for studying the suitable ecological flow for sweetfish. The hydrodynamic calculation is performed using the Hydrodynamic module in the mike21HD Flow Model FM. The changes of these two indicators under different flow conditions are statistically analyzed to analyze the flow conditions suitable for sweetfish fattening.

[0074] The distribution of different types of habitat patches is obtained by calculating the three flow rates obtained in this embodiment. Figure 5 As shown, according to Figure 5 It can statistically analyze low and medium flow (6.28m 3 / s, minimum flow rate in 1 day), medium flow rate (89.09m 3 / s, average flow in June) and high flow (239.60m 3 / s, high flow pulse) under the dynamic characteristics of habitat patches: the area and distribution of various types of habitat patches in the fattening farm change with the flow rate, high (239.60m 3 / s), low (6.28m 3 / s) flow, the area ratios of different types of habitats vary greatly. The river channels are mostly concentrated with rapids or slow-flow patches near the banks, which are not suitable for fattening sweetfish. 3 / s), various types of patches are distributed alternately, with little difference in area ratio, and the flow pattern of the river is diversified, which is suitable for fattening sweetfish.

[0075] According to low flow (6.28m 3 / s), medium flow (89.09m 3 / s) and high flow (239.60m 3 / s) under three flow conditions, it is expected that there is a flow rate that makes the water flow characteristics and various patch distributions in the fattening river section suitable for sweetfish fattening. The two indicators of the water area ratio and diversity index of the most suitable patches for sweetfish in the fattening field hydraulic habitat index system are selected as the indicators for studying the suitable ecological flow rate for sweetfish. 3 / s、26.49m 3 / s (30-day minimum flow), 89.09m 3 / s、152.90m 3 / s (maximum flow rate in 30 days), 239.60m 3 / s、376.30m 3 / s (maximum flow in 7 days), 694.00m 3 / s (maximum flow in 3 days), 1256.00m 3 / s(maximum flow rate in one day), 1827.00m 3 / s (small flood) There are 9 flow levels in total. The changes of the above two indicators are shown in Figure 6 , Figure 7 and Figure 8 , analyze the flow conditions suitable for fattening sweetfish.

[0076] According to the diversity index obtained in this embodiment, the flow rate changes ( Figure 6 ), the ratio of each type of habitat patch area changes with flow ( Figure 7 ), the ratio of shallow and deep pool area changes with flow rate ( Figure 8 ) It can be concluded that the average monthly flow in June is 89.09m 3 / s corresponds to the largest habitat diversity index value, and the proportion of shallow and deep pool patches suitable for sweetfish habitat is also the largest, and the proportion of water area occupied by various types of patches is relatively uniform. 3 / s is the appropriate flow rate for fattening sweetfish.

[0077] In this embodiment, the two indicators of "ratio of water area occupied by habitat patches" and "diversity index" are used as the judgment conditions for the suitable ecological flow of fish fattening farms, among which "ratio of water area occupied by habitat patches" refers to the flow corresponding to the largest ratio of the area occupied by patches suitable for fish fattening research (such as the flow corresponding to the largest ratio of the shallows with algae suitable for fattening sweetfish and the deep pools suitable for sweetfish resting in the case described); "diversity index" describes the uniformity and quantity of the distribution of patch types, reflecting the heterogeneity of the landscape. The higher the diversity index, the richer the types of river patches, and the more suitable it is for the coexistence of multiple organisms.

[0078] The present invention is not limited to the scraping fish sweetfish, but can be extended to other fish species. The applicability of different fish species mainly lies in the different classification of habitat patches and the different conditions for judging which patch area accounts for the highest proportion when seeking suitable ecological flow for fattening.

[0079] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calculating the suitable ecological flow rate for fish fattening farms. It is characterized in that The following steps are involved: A hydraulic habitat index system for fattening farms was constructed to quantify the spatial heterogeneity of habitat patches. A two-dimensional hydrodynamic model was used to analyze and calculate the hydraulic habitat index values ​​of fattening farms under different flow conditions in the study waters. The flow rate corresponding to the hydraulic habitat index value most suitable for the fish under study was selected as the suitable ecological flow for the fattening farm.

2. The method for calculating the suitable ecological flow rate of a fish fattening farm according to claim 1, It is characterized in that The hydraulic habitat indicator system for fattening farms includes hydraulic indicator layer, habitat patch layer and patch landscape ecological indicator layer. The patch types of the habitat patch layer are divided according to the hydraulic indicators of the hydraulic indicator layer, and the indicator values ​​of the patch landscape ecological indicator layer are calculated according to the patch types.

3. The method for calculating the suitable ecological flow rate of a fish fattening farm according to claim 2, It is characterized in that The hydraulic indicator layer includes water depth and flow velocity, and the patch types include deep pools, rapids, shallows, and slow currents along the shore.

4. The method for calculating the suitable ecological flow rate for fish fattening farm according to claim 3, It is characterized in that The classification methods of plaque types include: Establish the membership function of water depth and flow velocity; According to the membership function of water depth and flow velocity, the water depth is divided into three levels: shallow, medium and deep, and the flow velocity is divided into two levels: slow and fast. According to the results of water depth and flow velocity classification, the four types of patches, namely deep pools, shallows, rapids and slow currents along the shore, were judged and classified through if-and-then rules.

5. The method for calculating the suitable ecological flow rate of a fish fattening farm according to claim 4, It is characterized in that The calculation method of water depth membership is: y is the degree of membership, h is the water depth, m i is the parameter of the membership function, k i The water depth endpoint value of the division.

6. The method for calculating the suitable ecological flow rate for fish fattening farm according to claim 4, It is characterized in that The flow velocity membership calculation method is: y is the degree of membership, v is the flow rate, n i is the parameter of the membership function, p i is the flow velocity endpoint value of the division.

7. The method for calculating the suitable ecological flow rate for fish fattening farm according to claim 3, It is characterized in that The patch landscape ecological indicator layer includes patch area ratio and diversity index, among which the patch area ratio PALND refers to the ratio of a certain type of patch area to the water area, and the formula is: aij is the area of ​​a certain type of patch ij, and A is the water area; The diversity index SHDI is used to describe the uniformity and quantity of patch type distribution. The calculation formula is: N is the number of habitat patches, p i is the proportion of area occupied by habitat patches.

8. A system for implementing the method for deriving the suitable ecological flow rate for a fish fattening farm as claimed in any one of claims 1 to 7, It is characterized in that include: The hydraulic habitat indicator system construction module establishes a hydraulic habitat indicator system for fattening farms to quantify the spatial heterogeneity of habitat patches; The calculation module of the hydraulic index system of the research area is used to analyze and calculate the hydraulic index values ​​of the fattening farm under different flow conditions using a two-dimensional hydrodynamic model for the research waters; The suitable flow calculation module is used to select the flow corresponding to the hydraulic habitat index value that is most suitable for the fish under study from the hydraulic habitat index system calculation module of the study area as the suitable ecological flow for the fattening farm.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program. It is characterized in that When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, It is characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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