Hydrodynamic model-based spawning migration type fish full life history stage suitable habitat inversion method

Abstract

The invention relates to the field of fish habitat evaluation, in particular to a spawning migration type fish full life history stage suitable habitat inversion method based on a hydrodynamic model, and the method mainly comprises the steps: (1) collecting spawning migration type fish data, hydrological data and topographic data; (2) determining life history stages of the fishes and the actual number of the fishes; (3) establishing one-dimensional hydrodynamic models of different life history stages; (3) grouping the water depth and the flow velocity of each life history stage, and calculating the number frequency of fishes in each interval; (4) constructing a habitat suitability curve of water depth and flow velocity; and (5) evaluating a suitable habitat. According to the method, the suitable habitat of the spawning migration type fish in the whole life history stage can be efficiently and accurately evaluated, and protection strategy formulation and measure implementation of aquatic organisms are facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fish habitat evaluation, in particular to a method for inferring suitable habitat of anadromous fish in whole life history stage based on a hydrodynamic model. BACKGROUND

[0002] As the top community in aquatic ecosystems, the change of fish community structure is directly related to the overall change of aquatic community and aquatic habitat. Fish life cycle is complex, and the suitable habitat conditions required by different life history stages are different. The survival and development of anadromous fish (such as Coreius guichenoti) depend on specific habitat requirements, and the reproduction and early life stages show obvious strong response to habitat changes, making them one of the most vulnerable groups in river ecosystems that are affected by habitat changes. In recent years, with the intensification of human activities such as hydropower development, river regulation, agricultural irrigation, etc., the connectivity of rivers is reduced and the natural hydrological regime of rivers is disturbed. These comprehensive pressure factors directly and indirectly destroy the suitable habitat required for the integrity of the life history of anadromous fish, leading to a significant reduction in their population or even regional extinction. Therefore, evaluating the suitable habitat of anadromous fish in whole life history stage is one of the important prerequisites for implementing fish protection and habitat restoration.

[0003] The core of fish habitat evaluation is to construct a habitat suitability curve, that is, to determine the preferred range of fish to habitat factors (water depth and flow velocity). At present, the suitability curve is mostly obtained through laboratory controlled experiments. Experimental control mainly adjusts the change of a single environmental factor to determine the tolerance of fish, and then constructs the habitat suitability curve. In fact, there is an essential difference between the experimental environment and the actual habitat of the natural river, which does not consider the differences of specific locations in the natural habitat, which may lead to different habitat factor preference choices. Especially for the habitat of anadromous fish, the laboratory controlled experiment cannot fully reflect the complex habitat conditions of the actual river. When a river section has broken habitat, fish may be forced to occupy suboptimal habitat with a higher frequency, and the range of suitable habitat factors will also change. Therefore, how to accurately and efficiently construct the habitat suitability curve of anadromous fish in natural environment and carry out habitat evaluation in whole life history stage has become a technical problem to be solved for fish protection and river ecological function improvement. SUMMARY

[0004] To solve the above problems, the present application provides a method for inferring suitable habitat of anadromous fish in whole life history stage based on a hydrodynamic model, which can efficiently and accurately evaluate the suitable habitat of anadromous fish in natural environment, and is helpful for the strategy making and measure implementation of river fish protection and habitat restoration.

[0005] To achieve the above purpose, the technical scheme of the present application is as follows:

[0006] The application discloses a method for inverting suitable habitats of fish in different life history stages based on a water power model, and the method comprises the following steps.

[0007] S1: Investigate the life history activity characteristics, spawning ground distribution and spawning quantity of the fish in the river through investigation reports and reference books; collect the river hydrological data through a hydrological yearbook; and obtain the river bed terrain data of the river bottom through a digital elevation data platform;

[0008] S2: The data obtained in step S1 are used to determine the hydrological data of the fish in different life history stages, the actual fish quantity and the river section terrain;

[0009] S3: A one-dimensional water power model of the river in different life history stages is established by using the obtained data; the hydrological data of the fish in different life history stages obtained in step S2 are input into the established one-dimensional water power model, model operation is carried out, and the water depth and flow velocity corresponding to the fish distribution position in different life history stages are simulated;

[0010] S4: According to the Sturges rule, the water depth and flow velocity in different life history stages obtained in step S3 are grouped respectively, and the fish quantity frequency distribution in different water depth and flow velocity intervals is calculated;

[0011] S5: The habitat suitability index of the water depth and flow velocity is divided according to the fish quantity frequency distribution obtained in step S4, and the habitat suitability curve of the water depth and flow velocity is obtained;

[0012] S6: The water depth and flow velocity suitability index of each river section in different life history stages is evaluated according to the habitat suitability curve obtained in step S5, and the river section between the river sections which simultaneously meet the suitable water depth and suitable flow velocity is determined as the suitable habitat.

[0013] Further, the hydrological data collection in step S1 comprises the water level and flow data corresponding to the fish quantity investigation in the hydrological year.

[0014] Further, the fish life history stage division in step S2 is divided into three stages of reproduction, juvenile fish and adult fish, and the flow and water level corresponding to different time ranges.

[0015] Further, the fish quantity estimation in each life history stage in step S2 is as follows.

[0016] The fish quantity in the reproduction period is estimated by the absolute spawning quantity of the female spawning fish and the sex ratio;

[0017] The juvenile fish quantity is estimated by the spawning quantity, the natural mortality rate and the hatching rate;

[0018] The adult fish quantity is estimated by the previously determined fish quantity in the reproduction period.

[0019] Further, the terrain data in step S2 extracts river cross sections from DEM every 2 km.

[0020] Further, in step S3, a one-dimensional hydrodynamic model of the river is established using the MIKE11 module in the MIKE ZERO software platform. The law of motion of the river flow conforms to the Saint-Venant equation, as shown in formula (1) and formula (2) below. The flow and water level data corresponding to different life history stages of the fish are input into the model as the inflow and outflow boundaries of the model. The river section data are input as the terrain basis of the model. The model is run, and the cross section water depth and flow velocity corresponding to the distribution position of the fish at different life history stages are extracted.

[0021] Continuity equation

[0022] Momentum equation

[0023] In the formula, A is the cross-sectional area (m 2 ); Q is the flow (m 3 / s); x and t are the longitudinal coordinate (m) and time (s), respectively; g is the acceleration of gravity; z is the water level (m); K is the flow transport capacity; q is the inflow or outflow of the tributary (m 3 / s), the inflow takes a positive value, and the outflow takes a negative value; v x is the flow velocity component of the tributary inflow or outflow along the main stream direction (m / s), and if the inflow is perpendicular to the main stream direction, v x = 0.

[0024] Further, in step S4, the Sturges rule is calculated by the following calculation formula:

[0025] I = 1 + log2(n)

[0026] In the formula, I is the number of groups of water depth or flow velocity, and n is the number of data of water depth or flow velocity.

[0027] Further, in step S5, habitat suitability index division, if the fish number frequency contribution value in a certain water depth or flow velocity interval exceeds 60%, the habitat suitability index of the interval is set to 1; if the fish number frequency contribution value in a certain water depth or flow velocity interval is less than 10%, the habitat suitability index of the interval is set to 0. Accordingly, the habitat suitability curve of each life history stage of the fish is constructed.

[0028] Further, in step S6, river sections with water depth and flow velocity suitability index of 1 are selected respectively, and the common river sections are obtained by spatial superposition of these river sections.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] This invention discloses an inversion method for assessing suitable habitats for spawning migratory fish throughout their entire life cycle based on a hydrodynamic model. This method fully considers the relationship between fish population distribution and hydrodynamic conditions at different life stages in the natural environment, overcoming the limitations of controlled experiments in laboratory settings for constructing habitat suitability curves for spawning migratory fish. It effectively assesses suitable habitats for spawning migratory fish throughout their entire life cycle in the natural environment, providing a more scientific and reasonable basis for river habitat restoration and fish conservation.

[0031] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the following detailed description is provided with reference to the embodiments of the present invention and in conjunction with the accompanying drawings. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0033] Figure 1 This is the overall flowchart of the present invention;

[0034] Figure 2 The habitat suitability curves for water depth and current velocity during the breeding season of spawning migratory fish are shown in the present invention.

[0035] Figure 3 The habitat suitability curves for water depth and current velocity during the juvenile stage of spawning migratory fish are presented in this invention.

[0036] Figure 4 The habitat suitability curves for water depth and current velocity during the adult stage of spawning migratory fish are presented in this invention.

[0037] Figure 5 This diagram shows the results of the habitat assessment for different life stages of spawning migratory fish according to the present invention. Detailed Implementation

[0038] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0039] like Figure 1 This paper presents a method for retrieving suitable habitats for spawning migratory fish throughout their entire life cycle based on a hydrodynamic model. This embodiment uses the Jinsha River as the study area and the typical spawning migratory fish, *Cyprinus circinus*, as an example to illustrate the suitable habitat retrieval process for spawning migratory fish in this application. Specifically:

[0040] S1: Investigate the life history activity characteristics, spawning ground distribution, and spawning quantity of Coreius guichenoti in the Jinshajiang River through investigation reports and research literature; collect the flow and water level data of the Jinshajiang River hydrological stations through hydrological yearbooks; and collect the river terrain data of the Jinshajiang River through a geographic elevation data platform.

[0041] S2: Determine the water level and flow data during the reproduction, juvenile fish, and adult fish stages of Coreius guichenoti in the full life history stage of Coreius guichenoti based on the data obtained in step S1, and calculate the number of reproduction, juvenile fish, and adult fish based on the spawning quantity. Extract the river cross-section data every 2 km from the river terrain data of the Jinshajiang River obtained in step S1.

[0042] S3: Establish a one-dimensional hydrodynamic model of the river, input the water level and flow data of Coreius guichenoti in different life history stages into the model, perform model operation, and obtain the cross-section water depth and flow velocity corresponding to the fish distribution position in different life history stages.

[0043] S4: Group the cross-section water depth and flow velocity in different life history stages obtained in step S3 according to the Sturges rule, and match the fish quantity distribution frequency in step S2 corresponding to different water depth and flow velocity intervals.

[0044] S5: Divide the fish quantity frequency distribution of the water depth and flow velocity intervals in different life history stages obtained in step S4 according to the habitat suitability, obtain the habitat suitability curve, and the results are shown in Figure 2 、 Figure 3 、 Figure 4 .

[0045] S6: According to the habitat suitability curve in step S5, filter out the river cross-sections with a water depth and flow velocity suitability index of 1 for Coreius guichenoti in different life history stages in the Jinshajiang River, superimpose them, extract the river sections between the continuous adjacent river cross-sections as suitable habitats, and the results are shown in Figure 5 .

[0046] As shown in Figure 2 , the Coreius guichenoti reproduction period needs to meet the water depth range of 4.68-10.53 m and the flow velocity range of 0.34-3.18 m / s to effectively support the spawning process. As shown in Figure 3 , the optimal water depth and flow velocity ranges required during the key juvenile development stage are 7.6-12.8 m and 1.04-3 m / s, respectively. As shown in Figure 4 , the suitable water depth and flow velocity ranges for adult fish are 2.36-9.65 m and 0.12-1.57 m / s, respectively;

[0047] As shown in Figure 5 , there are ten spawning grounds distributed in the Panzhihua-Caohai river section, with a total area of about 0.76 km 2After spawning, the habitat suitable for the growth of juvenile fish is mainly concentrated in the downstream river section from Pingshan to Yibin, with a total area of about 0.36km 2 While the suitable habitat for adult fish is widely distributed, covering the section from Panzhihua to Qiaojia and the section from Pingshan to Yibin, with a total area of about 1.94km 2 , which provides sufficient space for the key life activities such as foraging and migration of adult fish.

[0048] The above is only an embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A method for inverting suitable habitats for all life history stages of anadromous fish based on a hydrodynamic model, characterized in that, The method comprises the following steps: S1: Investigate the life history activity characteristics, spawning ground distribution, and spawning quantity of the river-spawning migratory fish species through investigation reports, reference materials, etc.; collect river hydrological data through hydrological yearbooks; and obtain river bottom terrain data through a digital elevation data platform; S2: Clearly define the hydrological data of the life history stages of the river-spawning migratory fish species, the actual fish quantity, and the river cross section terrain obtained in step S1; S3: Establish a one-dimensional hydrodynamic model of the river at different life history stages by using the obtained data; input the hydrological data at different life history stages obtained in step S2 into the established one-dimensional hydrodynamic model, perform model operation, and simulate the flow velocity and water depth corresponding to the fish distribution position at different life history stages; S4: Group the water depth and flow velocity at different life history stages obtained in step S3 according to the Sturges rule, and calculate the fish quantity frequency distribution in different water depth and flow velocity intervals; S5: Divide the habitat suitability index of the water depth and flow velocity according to the fish quantity frequency distribution obtained in step S4, and obtain the habitat suitability curve of the water depth and flow velocity; S6: Evaluate the water depth and flow velocity suitability index of each river cross section at different life history stages according to the habitat suitability curve obtained in step S5, and determine the river section between the river cross sections that simultaneously meet the suitable water depth and suitable flow velocity as the suitable habitat.

2. The method according to claim 1, wherein the method is characterized by, The hydrological data collection in step S1 includes the water level and flow data corresponding to the fish quantity investigation in the hydrological year.

3. The method according to claim 1, wherein the method is characterized by, The fish life history stage division in step S2 is divided into three stages of reproduction, juvenile fish, and adult fish, which correspond to the flow and water level in different time ranges.

4. The method according to claim 1, wherein the method is characterized by, The fish quantity estimation in each life history stage in step S2 is as follows: The fish quantity in the reproduction stage is estimated by the absolute spawning quantity of the female spawning fish and the sex ratio; The juvenile fish quantity is estimated by the spawning quantity, considering the comprehensive influence of the natural mortality rate and the hatching rate; The adult fish quantity is estimated by the previously determined fish quantity in the reproduction stage.

5. The method according to claim 1, wherein the method is characterized by, The terrain data in step S2 is the river cross section extracted from the DEM every 2 km.

6. The method according to claim 1, wherein the method is characterized by, In step S3, the MIKE11 module in the MIKE ZERO software platform is used to establish a one-dimensional hydrodynamic model of the river, the river flow movement law conforms to the Saint-Venant equation, as shown in the following formula (1) and the following formula (2), the flow and water level data corresponding to different life history stages of the fish are input into the model as the inflow and outflow boundaries of the model, and the river cross section data are input as the terrain basis of the model, the model is run, and the cross section water depth and flow velocity corresponding to the fish distribution position at different life history stages are extracted. continuity equation momentum equation where A is the cross-sectional area (m 2 ); Q is the flow rate (m 3 / s); x and t are the longitudinal coordinate (m) and time (s), respectively; g is the acceleration due to gravity; z is the water level (m); K is the conveyance capacity; q is the inflow or outflow of the tributary (m 3 / s), with inflow taken as positive and outflow taken as negative; v x is the flow velocity component of the tributary inflow or outflow in the direction of the main flow (m / s), with v x = 0 if the inflow is perpendicular to the direction of the main flow.

7. The method according to claim 1, wherein the method is characterized by, In step S4, the Sturges rule is calculated by the following formula: I = 1 + log2(n) In the formula, I is the number of water depth or flow velocity grouping, and n is the number of water depth or flow velocity data.

8. The method according to claim 1, wherein the method is characterized by, In step S5, if the fish quantity frequency contribution value in a water depth or flow velocity interval exceeds 60%, the habitat suitability index of the interval is set to 1; if the fish quantity frequency contribution value in a water depth or flow velocity interval is less than 10%, the habitat suitability index of the interval is set to 0. Accordingly, the habitat suitability curve of each life history stage of fish is constructed.

9. The method according to claim 1, wherein the method is characterized by, In step S6, the river sections with the water depth and flow velocity suitability indexes of 1 are screened out respectively, and the common river sections are obtained by spatial superposition of the river sections.

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