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

Abstract

The application discloses a kind of fish fattening field suitable ecological flow and system of deducing method, including the following steps: constructing the index system of hydraulic habitat of fattening field for quantifying habitat patch spatial heterogeneity, the hydraulic habitat index value of different flow conditions is analyzed and calculated using two-dimensional hydrodynamic model in the study water area, the flow corresponding to the most suitable hydraulic habitat index value of the fish habitat studied is selected as the suitable ecological flow of fattening field.The present application not only considers the target organism but also considers other organisms in the river, and is more conducive to creating suitable flow conditions for multiple species coexistence, and has certain scientific significance and reference value for fish fattening field protection and ecological restoration.

Description

Technical Field

[0001] This invention belongs to the technical field of river habitat ecological restoration, specifically relating to a method and system for calculating suitable ecological flow in fish fattening farms. Background Technology

[0002] The aquatic environment necessary for fish to complete their life cycle is called fish habitat, which includes spawning grounds, fattening grounds, overwintering grounds, and migration channels, and is crucial for fish survival and reproduction. Research on river fish habitats has always been a hot topic in aquatic ecosystem protection and restoration. Theoretical research primarily focuses on qualitative analysis of the suitability of fish habitats and the ecological significance of various indicators. Most studies on ecological flow in fish habitats focus on the spawning period. However, considering the different conditions required by fish at different life stages, the ecological flow during other life stages, such as the fattening period, should also be considered. Regarding fish fattening grounds, water flow not only affects fish survival but also significantly impacts their food resources. Currently, few studies analyze the ecological water requirements of fish and their required food biomass.

[0003] Current research on ecological flow in river fish habitats mainly focuses on fish spawning grounds, with habitat simulation being the most widely used method. This method combines hydraulic models with the life stages of target organisms in the river, quantitatively quantifying the relationship between river flow and corresponding habitat area, thereby determining the ecological water requirement for specific life stages of the target organisms. Yi Yujun established a habitat suitability model for the Chinese sturgeon and simulated the spawning habitat of the Chinese sturgeon downstream of the Gezhouba Dam, obtaining the suitable ecological flow for Chinese sturgeon spawning. Cai Yupeng, through investigation of the spawning sections of the Chinese sturgeon during their natural reproduction period, determined the preferred water depth, flow velocity, and substrate of the Chinese sturgeon during the spawning period, and quantified the relationship between flow and suitable area during the spawning period, deriving the suitable ecological flow during the spawning period of the Chinese sturgeon. Guo Wenxian, Li Jian, and others combined the PHABSIM model and Delft3D with habitat simulation models, respectively, to quantify the relationship between flow and the suitable area of ​​the spawning grounds of the four major Chinese carps. Hou Jun et al. established a habitat suitability model for the spawning period of *Young husbandi* in Lhasa through numerical simulation and statistics, and derived the environmental flow during the spawning period of *Young husbandi* using habitat simulation. Li Youguang et al. used crucian carp and aquatic insects as indicator species, constructed a multi-species habitat suitability model based on fuzzy logic, 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 Shi River.

[0004] However, most existing studies on ecological flow in fish habitats only consider the spawning period, which is a sensitive time for fish, without considering the impact of other life stages, such as the fattening period. Furthermore, regarding fish fattening grounds, water flow not only affects fish survival but also significantly impacts their food resources; there is a lack of research on ecological water demand that combines fish with their required food biomass. Finally, current research often focuses on a single point or cross-section in a river, combining specific fish behaviors (such as spawning) and hydraulic factors (flow velocity, water depth, etc.) to construct fitness curves and then deduce suitable ecological flow. However, fish life activity needs are closely related to the spatial heterogeneity of water flow. Studying the response process between fish life activity needs and water flow spatial heterogeneity from the perspective of habitat water flow spatial characteristics is of great significance for understanding the functional characteristics of fish fattening grounds. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for estimating suitable ecological flow in fish fattening farms. This method considers not only the target organisms but also other organisms in the river, which is more conducive to creating suitable water flow conditions for the coexistence of multiple species. It has certain scientific significance and reference value for the protection and ecological restoration of fish fattening farms.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for estimating suitable ecological flow in a fish fattening farm is characterized by the following steps: constructing a hydraulic habitat index system for fattening farms to quantify 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 in the study water area; and selecting the flow rate corresponding to the hydraulic habitat index value most suitable for the habitat of the fish under study as the suitable ecological flow for the fattening farm.

[0008] Furthermore, a hydraulic habitat index system for fattening farms is established, including a hydraulic index layer, a habitat patch layer, and a patch landscape ecological index layer. Based on the hydraulic index of the hydraulic index layer, the patch types of the habitat patch layer are classified, and then the index values ​​of the patch landscape ecological index layer are calculated based on the patch types.

[0009] Furthermore, the hydraulic index layers include water depth and flow velocity, and the patch types include deep pool areas and rapid flow areas.

[0010] Areas, shallow waters, and slow-flowing areas along the shore.

[0011] Furthermore, methods for classifying plaque types include:

[0012] Establish membership functions for water depth and flow velocity;

[0013] Based on the membership functions of water depth and flow velocity, water depth is divided into three levels: shallow, medium, and deep; flow velocity is...

[0014] It is divided into two levels: slow and fast.

[0015] Based on the classification results of water depth and flow velocity, the if-and-then rule is used to classify deep pool areas and shallow shoal areas.

[0016] The plaques were classified into four types: the basin, the rapid current area, the slow current area along the bank, and the area with slow currents along the bank.

[0017] Furthermore, the method for calculating the water depth membership degree is as follows:

[0018]

[0019] y represents the membership degree, h represents the water depth, and m represents the water depth. i k is the parameter of the membership function. i The water depth endpoint values ​​are used for division.

[0020] Furthermore, the method for calculating the membership degree of flow velocity is as follows:

[0021]

[0022] y represents membership degree, v represents flow velocity, and n represents the number of nodes. i p is the parameter of the membership function. i The endpoint values ​​for the divided flow velocity.

[0023] Furthermore, the patch landscape ecological indicator layer includes patch area ratio and diversity index, among which, patch

[0024] PALND (Patch Area Ratio) refers to the ratio of the area of ​​a certain type of patch to the area of ​​the water body. The formula is:

[0025]

[0026] a ij Let A be the area of ​​a certain type of patch ij, and A be the area of ​​the water body.

[0027] The SHDI diversity index is used to describe the evenness and quantity of patch type distribution. The calculation formula is as follows:

[0028] N represents the number of habitat patches, P i It is the proportion of the area occupied by habitat patches.

[0029] Another object of the present invention is to provide a system for calculating the appropriate ecological flow in a fish fattening farm as described above, comprising:

[0030] A module for constructing a hydraulic habitat index system was established to create a hydraulic habitat index system for fattening farms to quantify the spatial heterogeneity of habitat patches.

[0031] The hydraulic index system calculation module for the study 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 in the study water area.

[0032] The suitable flow estimation module is used to select the flow rate corresponding to the most suitable hydraulic habitat index value for the study fish species from the hydraulic habitat index system calculation module of the study area as the suitable ecological flow rate for the fattening farm.

[0033] An electronic device includes a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the above method.

[0034] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0035] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention considers the water flow conditions required for fish fattening and the survival of prey organisms. It combines the relationship between the function of fattening farms and the spatial heterogeneity of water flow, classifying various river patch types based on hydraulic factors. It then considers suitable patches for the survival of fish and prey organisms during the fattening period, using the ecological flow corresponding to the patch with the largest area suitable for the fish's habitat and the highest patch diversity index as the suitable ecological flow for fish fattening. Compared to previous methods where hydraulic factors mostly describe single points or cross-sectional scales in rivers, this method uses habitat patches as a local mesoscale, making it more convenient for practical application. Furthermore, this method classifies river habitat patches (the fattening ecological significance of habitat patches is shown in Table 1) and uses the highest "diversity index" as one of the criteria for judging the suitable ecological flow for fattening. This considers not only the target organisms but also other organisms in the river, making it more conducive to creating suitable water flow conditions for the coexistence of multiple species. The method of this invention has certain scientific significance and reference value for the protection and ecological restoration of fish fattening farms. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the method for determining the suitable ecological flow in a fish fattening farm according to an embodiment of the present invention;

[0037] Figure 2 This is a two-dimensional hydrodynamic model of the ayu fattening river section according to an embodiment of the present invention, wherein (a) is a topographic map and (b) is a grid map;

[0038] Figure 3 The results of the two-dimensional hydrodynamic model calculation of the ayu fattening section in an embodiment of the present invention are: (a) water depth map, (b) flow velocity map.

[0039] Figure 4 These are membership function diagrams of water depth and flow velocity according to an embodiment of the present invention: (a) membership function diagram of water depth, and (b) membership function diagram of flow velocity.

[0040] Figure 5 This is a distribution map of different types of habitat patches under three flow rates according to an embodiment of the present invention. (a) Q = 6.28m 3 / s, (b)Q=89.09m 3 / s, (c)Q=239.60m 3 / s;

[0041] Figure 6 This is a graph showing the variation of the diversity index with flow rate in an embodiment of the present invention;

[0042] Figure 7 This is a graph showing the variation of the area ratio of various types of habitat patches with flow rate according to an embodiment of the present invention;

[0043] Figure 8 This is a graph showing the change in the ratio of shallow and deep pool patch area as a function of flow rate, according to an embodiment of the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0046] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0047] like Figure 1 As shown in the figure, an embodiment of the present invention discloses a method for calculating the suitable ecological flow in a fish fattening farm, comprising the following steps:

[0048] Step 1: Construct a hydraulic habitat index system for fattening farms to quantify the spatial heterogeneity of habitat patches;

[0049] The hydraulic habitat index system of the fattening farm uses water depth and flow velocity as the hydraulic index layer, and four types of fattening habitat patches—deep pools (resting and sheltering areas), rapids (material transport areas), shallows (feeding and fattening areas), and slow-moving waters along the shore (food sources)—as the habitat patch layer. Patch area ratio and diversity index serve as the patch landscape ecological index layer. The ecological significance of the hydraulic habitat index system for fish fattening is shown in Table 1.

[0050] Table 1. Hydraulic habitat indicators and their ecological significance in fattening farms

[0051]

[0052] The habitat patch layer is classified into patch types based on the water depth and flow velocity of the hydraulic index layer. Then, the patch area ratio and diversity index of the landscape ecological index layer are calculated based on the patch types. When classifying patch types, the membership functions for water depth and flow velocity are first established as shown in the following formula:

[0053] water depth membership function

[0054]

[0055] y represents the membership degree, h represents the water depth, and m represents the water depth. i k is the parameter of the membership function. i The endpoint values ​​for the water depth division.

[0056] The method for calculating the membership degree of flow velocity is as follows:

[0057]

[0058] y represents membership degree, v represents flow velocity, and n represents the number of nodes. i p is the parameter of the membership function. i The endpoint values ​​for the divided flow velocity.

[0059] Water depth is classified into three levels—shallow, medium, and deep—based on the water depth membership function, and flow velocity is classified into two levels—slow and fast—based on the flow velocity membership function. The water depth and flow velocity classification results are then used to classify four types of patches—deep pool areas, shallow shoals, rapid current areas, and slow-flowing areas along the shore—using the if-and-then rule (Table 2).

[0060] Table 2 if-and-then rules

[0061]

[0062] This embodiment uses the patch area ratio (PALND) and diversity index to quantify the spatial heterogeneity of habitat patches. Based on the patch types classified in Table 2, the PALND for a certain type is calculated. The PALND refers to the ratio of the habitat patch area to the water area for the four classifications mentioned above. The calculation formula is as follows:

[0063]

[0064] a ij Let A be the area of ​​a certain type of patch ij, and A be the area of ​​the water body.

[0065] The Natural Landscape Diversity Index (SHDI) describes the evenness and number of patch types, reflecting landscape heterogeneity. SHDI = 0 when a habitat patch contains only one type. The calculation formula is as follows:

[0066]

[0067] N represents the number of habitat patches, P i It is the proportion of the area occupied by habitat patches.

[0068] 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 study water area;

[0069] A two-dimensional hydrodynamic model of the Yufei River section was established using mike21HD based on measured topographic maps. The model includes: measured topography of the Yufei River section, inlet flow (upper boundary of the model), and outlet water level (lower boundary of the model). The Yufei River section was then divided into unstructured meshes, and the measured topography was interpolated to form a mesh with topographic data. Finally, the upper and lower boundary conditions were input into the model, and hydrodynamic calculations were performed using the Hydrodynamic module in mike21HD Flow Model FM. The upper boundary of the model represents the flow inlet, and the lower boundary represents the water level outlet. Based on the hydrological conditions of this river section, different flow conditions and corresponding water levels within the low to high flow range were selected as the boundary input conditions for the two-dimensional hydrodynamic model of the Yufei River section. The flow field within the Yufei River section under different flow conditions was calculated, and the flow velocity, water depth, and distribution within the river section were analyzed. After obtaining the velocity, water depth, and distribution, the Yufei River section was divided into patch types according to the rules in Table 2. The patch area ratio and diversity index are calculated based on the area and number of patches of different types and the water area.

[0070] Step 3: Select the flow rate corresponding to the most suitable hydraulic habitat index for the fish species under study as the appropriate ecological flow rate for the fattening farm.

[0071] Using the ratio of habitat patch area to water area and diversity index in the hydraulic index system of fattening farm as indicators of suitable ecological flow for fish research, the results of statistical analysis of these two indicators under different flow conditions were used. The ecological flow corresponding to the largest proportion of suitable habitat patch area and the highest patch diversity index was taken as the suitable ecological flow for fish fattening.

[0072] The following is a specific example. Taking the Nanxi River, the second largest tributary of the Oujiang River system in Zhejiang Province, as the research section for the fattening farm of sweetfish (Plecoglossus altivelis), a two-dimensional hydrodynamic model of the sweetfish fattening farm was established (see...). Figure 2 Based on the characteristics of water depth and flow velocity values ​​obtained from two-dimensional hydrodynamic calculations (see...), Figure 3Based on the suitable water depth (0.5m~1.5m) and current velocity (0.5m / s~1.0m / s) range for sweetfish, the water depth is divided into <0.5m, 0.5m~1.5m, and >1.5m. Therefore, in this embodiment, k1 is 0m, k2 is 0.5m, k3 is 1.0m, and k4 is 1.5m. (See [link to embodiment]). Figure 4 (a) The membership formula for water depth is:

[0073]

[0074] The flow velocities are divided into <0.5 m / s, 0.5 m / s to 1.0 m / s, and >1.0 m / s. Therefore, in this embodiment, p1 takes the value 0 m / s, p2 takes the value 0.5 m / s, and p3 takes the value 1 m / s. The membership function of their flow velocities (see...) Figure 4 (b) is:

[0075]

[0076] Water depth was classified into three levels (shallow, medium, and deep) based on the water depth membership function, and flow velocity was classified into two levels (slow and fast) based on the flow velocity membership function. Then, the classification results based on water depth and flow velocity were combined with the if-and-then rule (Table 2) to classify four types of patches: deep pools, shallow shoals, rapid currents, and slow-flowing areas along the bank. Next, the area, number, and water area of ​​each patch type were calculated under different flow rates to obtain the patch area ratio and diversity index. Finally, the ratio of habitat patch area to water area and the diversity index were selected from the hydraulic index system of the fattening farm as indicators for studying the suitable ecological flow for sweetfish. Hydrodynamic calculations were performed using the Hydrodynamic module in the mike21HD Flow Model FM, and the changes in these two indicators under different flow conditions were statistically analyzed to determine the suitable flow conditions for sweetfish fattening.

[0077] The distribution of different types of habitat patches was calculated based on the three flow rates obtained in this embodiment. Figure 5 As shown, according to Figure 5 It can statistically analyze low and medium flow rates (6.28m). 3 / s, minimum daily flow rate), medium flow rate (89.09m³ / ...). 3 / s (average flow in June) and high flow (239.60m) 3 Dynamic changes in habitat patches under high-flow pulse ( / s): The area and distribution of various types of habitat patches in the fattening farm change with flow rate, with high (239.60m) 3 / s), low (6.28m) 3The area ratio of different habitat types varies greatly under a flow rate of / s. Patches are concentrated in fast-flowing or slow-flowing areas along the banks, making them unsuitable for sweetfish fattening. Medium flow rate (89.09m³ / s) 3 The various types of patches are interspersed under / s) with little difference in area ratio, and the river flow pattern is diverse, which is suitable for the fattening of sweetfish.

[0078] Based on low flow (6.28m) 3 / s), medium flow rate (89.09m³ / s) 3 / s) and high flow (239.60m) 3 Analysis results under three flow conditions ( / s) predict that there exists a flow rate that makes the water flow characteristics and patch distribution in the fattening section suitable for sweetfish fattening. The proportion of the water area occupied by the most suitable sweetfish habitat patch and the diversity index from the hydraulic habitat index system of the fattening farm were selected as indicators to study the suitable ecological flow for sweetfish. Statistical analysis was performed on 6.28m... 3 / s, 26.49m 3 / s (minimum flow rate for 30 days), 89.09m 3 / s, 152.90m 3 / s (30-day maximum flow), 239.60m 3 / s, 376.30m 3 / s (7-day maximum flow), 694.00m 3 / s (maximum flow rate over 3 days), 1256.00m 3 / s (maximum daily flow), 1827.00m 3 For the changes in the above two indicators under a total of 9 flow levels (s / s, minor flood), see [link / data]. Figure 6 , Figure 7 and Figure 8 We analyzed the suitable flow conditions for fattening sweetfish.

[0079] The diversity index as a function of flow obtained from this embodiment (Figure) Figure 6 ), Patch area ratio of different habitat types as a function of flow rate () Figure 7 ), Patch area ratio of shallow water and deep pool as a function of flow rate ( Figure 8 We can conclude that the average monthly flow in June was 89.09 m³. 3 The habitat diversity index corresponding to / s is the highest, and the proportion of water area occupied by patches suitable for sweetfish inhabiting shallow waters and deep pools is also the largest, with the proportion of water area occupied by each type of patch being relatively even. It is considered that 89.09m 3 / s represents the suitable flow rate for fattening sweetfish.

[0080] In this embodiment, two indicators, "the ratio of water area occupied by habitat patches" and "diversity index," are used as criteria for determining the suitable ecological flow of fish fattening farms. The "ratio of water area occupied by habitat patches" refers to the flow rate corresponding to the maximum area ratio of patches suitable for fish fattening (such as the flow rate corresponding to the maximum area ratio of shallow waters where ayu fattening feeds on attached algae and deep pools where ayu rests). The "diversity index" describes the evenness and quantity of patch type distribution, reflecting the heterogeneity of the landscape. The higher the diversity index, the richer the river patch types, and the more suitable it is for the coexistence of multiple organisms.

[0081] This invention is not limited to the scraping fish ayu, but can be extended to other fish species. The main differences in applicability to different fish species are the different classifications of habitat patches and the different criteria used to determine which patch area has the highest proportion when estimating suitable ecological flow for fattening.

[0082] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and scope of protection of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the scope of protection of the present invention.

Claims

1. A method for determining the suitable ecological flow in a fish fattening farm, characterized in that, Includes the following steps: A hydraulic habitat index system for fattening farms was constructed to quantify the spatial heterogeneity of habitat patches. The hydraulic habitat index values ​​of fattening farms under different flow conditions were analyzed and calculated using a two-dimensional hydrodynamic model for the study water area. The flow rate corresponding to the hydraulic habitat index value most suitable for the study fish was selected as the suitable ecological flow rate for fattening farms. The hydraulic habitat index system for fattening farms is established, which includes a hydraulic index layer, a habitat patch layer, and a patch landscape ecological index layer. Based on the hydraulic index of the hydraulic index layer, the patch types of the habitat patch layer are classified, and then the index values ​​of the patch landscape ecological index layer are calculated based on the patch types. The hydraulic index layer includes water depth and flow velocity, and the patch types include deep pool areas, rapid current areas, shallow shoal areas, and slow-flowing areas along the shore. The patch landscape ecological index layer includes the patch area ratio (PALND) and the diversity index. The PALND refers to the ratio of a certain type of patch area to the total water area, and its formula is: a ij Let A be the area of ​​a certain type of patch ij, and A be the area of ​​the water body. The SHDI diversity index is used to describe the evenness and quantity of patch type distribution. The calculation formula is as follows: N represents the number of habitat patches, P i It is the proportion of the area occupied by habitat patches.

2. The method for determining the suitable ecological flow in a fish fattening farm according to claim 1, characterized in that, Methods for classifying plaque types include: Establish membership functions for water depth and flow velocity; Based on the membership functions of water depth and flow velocity, water depth is divided into three levels: shallow, medium, and deep, and flow velocity is divided into two levels: slow and fast. Based on the classification results of water depth and flow velocity, the four types of patches—deep pool areas, shallow shoal areas, rapid current areas, and slow-flowing areas along the shore—are classified using the if-and-then rule.

3. The method for determining the suitable ecological flow in a fish fattening farm according to claim 2, characterized in that, The method for calculating the membership degree of water depth is as follows: y represents the membership degree, h represents the water depth, and m represents the water depth. i k is the parameter of the membership function. i The endpoint values ​​for the water depth division.

4. The method for determining the suitable ecological flow in a fish fattening farm according to claim 2, characterized in that, The method for calculating the membership degree of flow velocity is as follows: y represents membership degree, v represents flow velocity, and n represents the number of nodes. i p is the parameter of the membership function. i The endpoint values ​​for the divided flow velocity.

5. A system for calculating the suitable ecological flow in a fish fattening farm as described in any one of claims 1-4, characterized in that, include: A module for constructing a hydraulic habitat index system was established to create a hydraulic habitat index system for fattening farms to quantify the spatial heterogeneity of habitat patches. The hydraulic index system calculation module for the study 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 in the study water area. The suitable flow estimation module is used to select the flow rate corresponding to the most suitable hydraulic habitat index value for the study fish species from the hydraulic habitat index system calculation module of the study area as the suitable ecological flow rate for the fattening farm.

6. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 4.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 4.

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