Simulation method for habitat suitability of cowfish under reservoir retaining

Abstract

The invention belongs to the technical field of ecological protection, and provides a method for simulating the habitat suitability of a cowfish under reservoir retaining. Comprising the steps of reservoir retaining time node and food source determination, dolphin suitability curve fitting, two-dimensional hydrodynamic water quality model construction, dolphin comprehensive suitability model construction and dolphin comprehensive suitability and potential habitat area calculation. According to the method, through the two-dimensional hydrodynamic water quality model and the comprehensive suitability model of the cowfish, the influence of reservoir impounding on the space-time change process of the habitat suitability of the cowfish can be quantitatively and accurately simulated and evaluated, and the calculation accuracy of the suitability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological protection, and in particular to a method for simulating the suitability of a finless porpoise habitat under reservoir impoundment. Background Art

[0002] The finless porpoise is not only sensitive to changes in the aquatic environment but also has profound impacts on the survival and abundance of other species. Reservoir impoundment has complex and irreversible impacts on the ecological environment, altering habitat factors and, in turn, the spatial distribution of the finless porpoise itself and its food sources. Changes in the spatial distribution of the finless porpoise's food sources can also impact the finless porpoise's spatial distribution. Suitability is a value between 0 and 1, with higher values ​​indicating greater suitability for the species, 1 representing optimal conditions, and 0 indicating unsuitable conditions. Suitability is typically expressed in three formats: binary, univariate, and multivariate. The binary format has only two possible values: 0 and 1, meaning suitable and unsuitable, and seeks the most suitable habitat range for the target species. The univariate format determines the suitability of each physical variable individually, characterizing the behavioral characteristics or preferences of the target species using continuous curves to establish the suitable range for each physical factor. The multivariate format fully considers the comprehensive effects and mutual influences of multiple habitat factors on the survival and reproduction environment of the target species, which is more comprehensive than the univariate format and binary format.

[0003] Existing technologies lack an integrated simulation of the hydrodynamics, water quality, and habitat suitability of the finless porpoises affected by reservoir impoundment. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the present invention aims to provide a method for simulating the suitability of finless porpoise habitats under reservoir impoundment, thereby solving the problem that the existing finless porpoise habitat suitability simulation methods lack the analysis of the impact before and after reservoir impoundment.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for simulating the suitability of finless porpoise habitats under reservoir impoundment, comprising:

[0007] Determine the time point for reservoir impoundment in the target area and select the food source for the finless porpoises in the target area;

[0008] Determining the habitat factors of the food sources in the target area, fitting a suitable exponential relationship for each of the habitat factors, and obtaining a finless porpoise suitability curve;

[0009] Constructing a two-dimensional hydrodynamic and water quality model within the target area;

[0010] Construct a comprehensive fitness model for finless porpoises;

[0011] The finless porpoise suitability curve, the two-dimensional hydrodynamic water quality model and the finless porpoise comprehensive suitability model are integrated to obtain a finless porpoise habitat suitability simulation model, and the finless porpoise habitat suitability impact model is used to calculate the finless porpoise comprehensive suitability and potential habitat area of ​​each grid unit to obtain the target habitat suitability simulation result.

[0012] Preferably, determining the habitat factors of the food sources in the target area, fitting a suitable exponential relationship for each of the habitat factors, and obtaining a finless porpoise suitability curve comprises:

[0013] Collecting water depth and suitability data within the target area;

[0014] An exponential relationship is fitted to the water depth and suitability data to obtain a water depth suitability curve; the finless porpoise suitability curve includes the finless porpoise suitability curve; the expression of the water depth suitability curve is:

[0015]

[0016] Where h represents the water depth data; f(h) represents the water depth suitability fitting data corresponding to h.

[0017] Preferably, constructing a two-dimensional hydrodynamic and water quality model within the target area includes:

[0018] Calculate the Coriolis force coefficient; the expression of the Coriolis force coefficient is: Wherein, f is the Coriolis force coefficient; ω is the average angular velocity of the Earth's rotation; is the dimension of the target area;

[0019] Calculate the lake surface wind stress; the expression of the lake surface wind stress is:

[0020]

[0021] in, are the components of the wind stress on the lake surface in the x and y directions respectively; ρ a is the air density; C w is the wind stress drag coefficient; u w 、v w are the components of wind stress in the x and y directions at a height of 10 m above the water surface;

[0022] The water flow resistance is calculated according to the Manning formula; the expression of the water flow resistance is:

[0023]

[0024] Among them, S fx 、S fyare the components of the water flow resistance in the x and y directions respectively; n is the Manning roughness coefficient; u and v are the average flow velocities in the x and y directions respectively;

[0025] Calculate the bottom slope; the expression of the bottom slope is:

[0026]

[0027] Among them, S ox 、S oy are the components of the bottom slope in the x and y directions respectively; Z b is the bottom bed elevation;

[0028] Calculate the diffusion coefficient; the expression of the diffusion coefficient is:

[0029]

[0030] Among them, K x , K y are the components of the diffusion coefficient in the x and y directions respectively; α and β are the first constant coefficient and the second constant coefficient respectively; g is the acceleration due to gravity; c is the Xie Cai coefficient;

[0031] The source term is obtained by integrating the Coriolis coefficient, the lake surface wind stress, the water flow resistance, and the bottom slope. The expression of the source term is:

[0032]

[0033] Where S is the source term; C is the vertical average concentration of the transported species; S c is the source and sink term of transported materials; D c is the degradation term of pollutants.

[0034] Preferably, constructing a two-dimensional hydrodynamic and water quality model within the target area includes:

[0035] Calculate the conserved variable vector; the expression of the conserved variable vector is: Wherein, U is the conserved variable vector;

[0036] Calculate a first flux vector; the expression of the first flux vector is: Wherein, F(U) is the first flux vector in the x-axis direction;

[0037] Calculate the second flux vector; the expression of the second flux vector is: Wherein, G(U) is the second flux vector in the y-axis direction;

[0038] The conserved variable vector, the first flux vector, the second flux vector, and the source term are integrated to obtain the two-dimensional hydrodynamic and water quality model; the expression of the two-dimensional hydrodynamic and water quality model is:

[0039]

[0040] Where E is the flux term.

[0041] Preferably, constructing a two-dimensional hydrodynamic and water quality model within the target area includes:

[0042] Converting the target area into a topographic map, and performing grid division on the topographic map to obtain a model grid;

[0043] Set the upstream inlet boundary and input boundary;

[0044] Setting the outlet boundaries before and after the reservoir is impounded according to the reservoir impoundment time node;

[0045] The model grid, the upstream inlet boundary, the input boundary, and the outlet boundary are updated to the two-dimensional hydrodynamic and water quality model.

[0046] Preferably, constructing a two-dimensional hydrodynamic and water quality model within the target area further comprises:

[0047] Performing finite volume discretization on the shallow water equation in the two-dimensional hydrodynamic and water quality model based on an unstructured grid, and discretizing the transport equation in the two-dimensional hydrodynamic and water quality model to obtain a discrete calculation formula;

[0048] The discrete calculation formula is calibrated and verified using the pre-collected monitoring data of the target area.

[0049] Preferably, a comprehensive fitness model for finless porpoises is constructed, including:

[0050] Calculate the comprehensive suitability of food; the expression of the comprehensive suitability of food is: CSI gi =(I hi I vi I Ti I mi ) 1 / 4 Among them, CSI gi I is the comprehensive suitability of the food; hi is the water depth suitability index of unit i; I vi is the flow rate suitability index of unit i; I Ti is the water temperature suitability index of unit i; I mi is the ammonia nitrogen suitability index of unit i;

[0051] A fitness model is constructed based on the comprehensive suitability of the food to obtain the comprehensive fitness model of the finless porpoise. The expression of the comprehensive fitness model of the finless porpoise is: CSI fi =(SI hi SI vi CSI gi ) 1 / 3 ;CSI fi is the output value of the comprehensive fitness model for finless porpoises; SI hi is the water depth suitability of unit i; SI vi is the flow rate suitability of unit i.

[0052] Preferably, a system for simulating the suitability of a finless porpoise habitat under reservoir impoundment comprises:

[0053] A condition determination module is used to determine the reservoir impoundment time node in the target area and select the food source of the finless porpoise in the target area;

[0054] a curve fitting module for determining the habitat factors of the food sources in the target area, fitting a suitable exponential relationship for each of the habitat factors, and obtaining a finless porpoise suitability curve;

[0055] A water quality model building module, used to build a two-dimensional hydrodynamic water quality model in the target area;

[0056] The fitness model construction module is used to construct a comprehensive fitness model for finless porpoises;

[0057] The suitability simulation module is used to integrate the finless porpoise suitability curve, the two-dimensional hydrodynamic water quality model and the finless porpoise comprehensive suitability model to obtain a finless porpoise habitat suitability simulation model, and use the finless porpoise habitat suitability impact model to calculate the finless porpoise comprehensive suitability and potential habitat area of ​​each grid unit to obtain the target habitat suitability simulation result.

[0058] Preferably, an electronic device comprises: at least one processor, and a memory communicatively connected to the processor; wherein the memory stores instructions that can be executed by the processor, and the instructions are executed by the processor so that the processor can execute the aforementioned method for simulating the suitability of the finless porpoise habitat under reservoir impoundment.

[0059] Preferably, a non-transitory computer-readable storage medium storing computer instructions is provided, wherein the computer instructions are used to enable a computer to execute the aforementioned method for simulating the suitability of a finless porpoise habitat under reservoir impoundment.

[0060] The present invention discloses the following technical effects:

[0061] The present invention provides a method for simulating the habitat suitability of finless porpoises under reservoir impoundment. By using a two-dimensional hydrodynamic water quality model and a comprehensive finless porpoise suitability model, the present invention solves the problem that existing finless porpoise habitat suitability simulation methods lack the analysis of the impact before and after reservoir impoundment, and realizes quantitative and accurate simulation and evaluation of the impact of reservoir impoundment on the spatiotemporal variation process of the finless porpoise's habitat suitability. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0063] Figure 1 A schematic diagram of a process flow for simulating the suitability of a finless porpoise's habitat under reservoir impoundment provided by an embodiment of the present invention;

[0064] Figure 2 A flowchart of the simulation of the suitability of the finless porpoise habitat under reservoir impoundment provided by an embodiment of the present invention;

[0065] Figure 3 A schematic diagram of data collection provided by an embodiment of the present invention, Figure 3 (a) is a schematic diagram of the multi-year average runoff into the lake at seven flow stations. Figure 3 (b) is a schematic diagram of the multi-year average water level process;

[0066] Figure 4 The statistical diagram of habitat suitability before and after dam construction provided by the embodiment of the present invention is as follows: Figure 4 (a) is a statistical map of the suitable habitat area for finless porpoises from June to October before and after the dam construction. Figure 4 (b) Statistical chart showing the changes in the suitable habitat area for finless porpoises from June to October before and after the dam construction;

[0067] Figure 5 A schematic diagram of the simulation of the spatial distribution of the suitability of the finless porpoise habitat provided by the embodiment of the present invention, Figure 5 (a) is a schematic diagram of the simulated spatial distribution of the suitability of the finless porpoise habitat during the flood season. Figure 5 (b) Schematic diagram of the simulated spatial distribution of habitat suitability for finless porpoises during the non-flood season. DETAILED DESCRIPTION

[0068] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0069] The purpose of the present invention is to provide a method for simulating the suitability of a finless porpoise habitat under reservoir impoundment, so as to solve the problem that the existing finless porpoise habitat suitability simulation method lacks analysis of the impact before and after reservoir impoundment.

[0070] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] Figure 1 A schematic diagram of the simulation process for the suitability of the finless porpoise habitat under reservoir impoundment provided by an embodiment of the present invention. Figure 2 The flowchart of the simulation of the suitability of the finless porpoise habitat under the reservoir impoundment provided by the embodiment of the present invention is as follows: Figure 1 and Figure 2 As shown, the present invention provides a method for simulating the suitability of the finless porpoise habitat under reservoir impoundment, comprising:

[0072] Step 100: Determine the reservoir impoundment time node in the target area and select the food source of the finless porpoise in the target area;

[0073] Step 200: determining the habitat factors of the food sources in the target area, fitting a suitable exponential relationship for each of the habitat factors, and obtaining a finless porpoise suitability curve;

[0074] Step 300: constructing a two-dimensional hydrodynamic and water quality model within the target area;

[0075] Step 400: constructing a comprehensive fitness model for finless porpoises;

[0076] Step 500: Integrate the finless porpoise suitability curve, the two-dimensional hydrodynamic water quality model, and the finless porpoise comprehensive suitability model to obtain a finless porpoise habitat suitability simulation model, and use the finless porpoise habitat suitability impact model to calculate the finless porpoise comprehensive suitability and potential habitat area of ​​each grid unit to obtain a target habitat suitability simulation result.

[0077] Preferably, determining the habitat factors of the food sources in the target area, fitting a suitable exponential relationship for each of the habitat factors, and obtaining a finless porpoise suitability curve comprises:

[0078] Collecting water depth and suitability data within the target area;

[0079] An exponential relationship is fitted to the water depth and suitability data to obtain a water depth suitability curve; the finless porpoise suitability curve includes the finless porpoise suitability curve; the expression of the water depth suitability curve is:

[0080]

[0081] Where h represents the water depth data; f(h) represents the water depth suitability fitting data corresponding to h.

[0082] Specifically, constructing a two-dimensional hydrodynamic and water quality model within the target area includes:

[0083] Calculate the Coriolis force coefficient; the expression of the Coriolis force coefficient is: Wherein, f is the Coriolis force coefficient; ω is the average angular velocity of the Earth's rotation; is the dimension of the target area;

[0084] Calculate the lake surface wind stress; the expression of the lake surface wind stress is:

[0085]

[0086] in, are the components of the wind stress on the lake surface in the x and y directions respectively; ρ a is the air density; C w is the wind stress drag coefficient; u w 、v w are the components of wind stress in the x and y directions at a height of 10 m above the water surface;

[0087] The water flow resistance is calculated according to the Manning formula; the expression of the water flow resistance is:

[0088]

[0089] Among them, S fx 、S fy are the components of the water flow resistance in the x and y directions respectively; n is the Manning roughness coefficient; u and v are the average flow velocities in the x and y directions respectively;

[0090] Calculate the bottom slope; the expression of the bottom slope is:

[0091]

[0092] Among them, S ox 、S oy are the components of the bottom slope in the x and y directions respectively; Z b is the bottom bed elevation;

[0093] Calculate the diffusion coefficient; the expression of the diffusion coefficient is:

[0094]

[0095] Among them, K x , K yare the components of the diffusion coefficient in the x and y directions respectively; α and β are the first constant coefficient and the second constant coefficient respectively; g is the acceleration due to gravity; c is the Xie Cai coefficient;

[0096] The source term is obtained by integrating the Coriolis coefficient, the lake surface wind stress, the water flow resistance, and the bottom slope. The expression of the source term is:

[0097]

[0098] Where S is the source term; C is the vertical average concentration of the transported species; S c is the source and sink term of transported materials; D c is the degradation term of pollutants.

[0099] Preferably, constructing a two-dimensional hydrodynamic and water quality model within the target area includes:

[0100] Calculate the conserved variable vector; the expression of the conserved variable vector is: Wherein, U is the conserved variable vector;

[0101] Calculate a first flux vector; the expression of the first flux vector is: Wherein, F(U) is the first flux vector in the x-axis direction;

[0102] Calculate the second flux vector; the expression of the second flux vector is: Wherein, G(U) is the second flux vector in the y-axis direction;

[0103] The conserved variable vector, the first flux vector, the second flux vector, and the source term are integrated to obtain the two-dimensional hydrodynamic and water quality model; the expression of the two-dimensional hydrodynamic and water quality model is:

[0104]

[0105] Where E is the flux term.

[0106] Furthermore, a two-dimensional hydrodynamic and water quality model within the target area is constructed, including:

[0107] Converting the target area into a topographic map, and performing grid division on the topographic map to obtain a model grid;

[0108] Set the upstream inlet boundary and input boundary;

[0109] Setting the outlet boundaries before and after the reservoir is impounded according to the reservoir impoundment time node;

[0110] The model grid, the upstream inlet boundary, the input boundary, and the outlet boundary are updated to the two-dimensional hydrodynamic and water quality model.

[0111] Specifically, constructing a two-dimensional hydrodynamic and water quality model within the target area also includes:

[0112] Performing finite volume discretization on the shallow water equation in the two-dimensional hydrodynamic and water quality model based on an unstructured grid, and discretizing the transport equation in the two-dimensional hydrodynamic and water quality model to obtain a discrete calculation formula;

[0113] The discrete calculation formula is calibrated and verified using the pre-collected monitoring data of the target area.

[0114] Furthermore, a comprehensive fitness model for finless porpoises was constructed, including:

[0115] Calculate the comprehensive suitability of food; the expression of the comprehensive suitability of food is: CSI gi =(I hi I vi I Ti I mi ) 1 / 4 Among them, CSI gi I is the comprehensive suitability of the food; hi is the water depth suitability index of unit i; I vi is the flow rate suitability index of unit i; I Ti is the water temperature suitability index of unit i; I mi is the ammonia nitrogen suitability index of unit i;

[0116] A fitness model is constructed based on the comprehensive suitability of the food to obtain the comprehensive fitness model of the finless porpoise. The expression of the comprehensive fitness model of the finless porpoise is: CSI fi =(SI hi SI vi CSI gi ) 1 / 3 ;CSI fi is the output value of the comprehensive fitness model for finless porpoises; SI hi is the water depth suitability of unit i; SI vi is the flow rate suitability of unit i.

[0117] Specifically, a system for simulating the suitability of a finless porpoise's habitat under reservoir impoundment includes:

[0118] A condition determination module is used to determine the reservoir impoundment time node in the target area and select the food source of the finless porpoise in the target area;

[0119] a curve fitting module for determining the habitat factors of the food sources in the target area, fitting a suitable exponential relationship for each of the habitat factors, and obtaining a finless porpoise suitability curve;

[0120] A water quality model building module, used to build a two-dimensional hydrodynamic water quality model in the target area;

[0121] The fitness model construction module is used to construct a comprehensive fitness model for finless porpoises;

[0122] The suitability simulation module is used to integrate the finless porpoise suitability curve, the two-dimensional hydrodynamic water quality model and the finless porpoise comprehensive suitability model to obtain a finless porpoise habitat suitability simulation model, and use the finless porpoise habitat suitability impact model to calculate the finless porpoise comprehensive suitability and potential habitat area of ​​each grid unit to obtain the target habitat suitability simulation result.

[0123] Preferably, an electronic device comprises: at least one processor, and a memory communicatively connected to the processor; wherein the memory stores instructions that can be executed by the processor, and the instructions are executed by the processor so that the processor can execute the aforementioned method for simulating the suitability of the finless porpoise habitat under reservoir impoundment.

[0124] Optionally, a non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to enable a computer to execute the aforementioned method for simulating the suitability of the finless porpoise habitat under reservoir impoundment.

[0125] Specifically, data on the target area was collected and organized, and literature research was conducted. A timeline for reservoir impoundment was determined, and food sources for the finless porpoise within the target area were selected. This example uses a lake as an example. The finless porpoise population in this lake remains relatively stable, accounting for approximately half of the current population, making it a critical habitat for the finless porpoise. The year 2003 was used as the impoundment timeline for the reservoir. The dominant fish species in the lake, the four major carps (black carp, grass carp, silver carp, and bighead carp), serve as a food source for the finless porpoise.

[0126] Furthermore, the habitat factors that affect the finless porpoise and its food source, the four major carps, were investigated, and the suitability index relationship was fitted to obtain the corresponding suitability curve. For the study of the habitat of the four major carps, the three key habitat factors of water depth, flow rate and water temperature were mainly considered. In terms of the water quality of a certain lake, the main pollutants are total phosphorus, total nitrogen and ammonia nitrogen, and studies have shown that ammonia nitrogen is highly toxic to fish. Therefore, ammonia nitrogen was selected as one of the key stress factors for the four major carps in a certain lake among the water quality factors. Finally, water depth, flow rate, water temperature and ammonia nitrogen were selected as the key habitat elements of the four major carps and a suitability curve was drawn. The habitat factors of the finless porpoise include water depth and flow rate. The specific function expression of the water depth suitability curve of the finless porpoise is as follows:

[0127]

[0128] The preference patterns of finless porpoises obtained from the statistical observation data of the flow of finless porpoises show that the flow velocity range of the waters where finless porpoises are active is 0.3m / s to 1.2m / s. The relationship between the relative number of finless porpoises and flow velocity was obtained by using the finless porpoise swimming behavior model constructed using the Boltzmann equation, and finally the finless porpoise suitability curve was obtained.

[0129] Specifically, a two-dimensional hydrodynamic and water quality model of the target area was constructed. The shoreline of a particular lake was irregular, so an unstructured triangular mesh was more suitable for fitting it. Localized meshing was used in areas with large topographic variations. By coupling the two-dimensional shallow water equations with the mass transport equations, the conservation model governing the two-dimensional hydrodynamic and water quality model was obtained as follows:

[0130]

[0131] Where U is the conserved variable vector; F and G are the flux vectors in the x and y directions respectively; x and y are the horizontal coordinates in space; h is the water depth; u and v are the average flow velocities in the x and y directions respectively; g is the acceleration of gravity; S o 、S f Represent the bottom slope term and friction slope respectively; S w 、S e are wind stress and Coriolis force source terms respectively; C is the vertical average concentration of transported substances (such as TP, TN and other pollutant indicators); K x and K y are the diffusion coefficients in the longitudinal and transverse directions, S c is the source and sink term of transported materials; D c =-k c hC, is the degradation term of the pollutant, k c S is the comprehensive degradation coefficient of the substance. ox 、S oy are the bottom slopes in the x and y directions respectively, and the calculation formula is:

[0132]

[0133] The water flow resistance is calculated using the Manning formula:

[0134]

[0135] The water body is driven by wind, and the flow velocity and direction change accordingly. The wind stress expression on the lake surface is:

[0136]

[0137] Among them, ρ a Approximately take ρ a =1.205kg / m 3 (20℃ standard atmospheric pressure); ρw Take 1.0×10 3 kg / m 3 .

[0138] The Coriolis force reflects the influence of the Earth's rotation on water bodies and is related to the water flow velocity, the angular velocity of the Earth's rotation, and the latitude of the calculation domain. The calculation formula for the Coriolis force coefficient f is:

[0139]

[0140] Among them, ω is 7.29×10 -5 rad / s; is the latitude of the study area, with positive direction in the northern hemisphere and negative direction in the southern hemisphere.

[0141] K x and K y are the diffusion coefficients in the longitudinal and transverse directions, respectively. These two diffusion coefficients can be estimated using the following formula:

[0142]

[0143] The value range of α is 5.93 to 13, and the value range of β is 0.15 to 1.2. In actual situations, pollutants diffuse anisotropically, and the value of α / β is usually much larger than 1.

[0144] Furthermore, the control equations are discretely solved and the model is calibrated and verified. Can be expanded to:

[0145]

[0146] Among them, K xx , K xy , K yx , K yy is the component of the two-dimensional diffusion coefficient tensor, and its specific value is calculated according to the Preston method, as shown in the following formula:

[0147] K XX =K x cos 2 θ+K y sin 2 θ

[0148] K XY =K YX =(K x -K y )cosθsinθ

[0149] K YY =K y sin 2 θ+Ky cos 2 θ

[0150] Where θ is the angle of the flow direction relative to the x-axis, K x and K y are the diffusion coefficients along the longitudinal and transverse directions, respectively.

[0151] Transform the transport equation into the control volume Ω i The above points can be obtained:

[0152]

[0153] Using Green's formula, the area is decomposed into a line integral along the boundary of the control volume, and after discretization, we can get:

[0154]

[0155] Among them, Q ij =l ij h ij U ij represents the flow rate through the interface j of unit i, Γ ij is the diffusion flux at the interface.

[0156] The convection term expression is as follows:

[0157]

[0158] in, A i is the area of ​​grid cell i; subscript i represents the grid cell, such as the triangular grid JKI; subscript j represents the cell edge, such as JI; S i Represents the flow characteristics of the interface, that is, the flow of substances in unit i into or out of the unit with the water flow, is the transported material flowing out with water in unit i, is the inflow; Ψ is the flux limiter, which is a nonlinear function of the gradient r factor of the transport variable; Q j is the flux through the j-th edge of unit i; U j is the normal flow velocity of the jth edge of unit i; l j is the length of the j-th side of unit i.

[0159] The diffusion term of the material transport equation can be expressed as:

[0160]

[0161] Among them, the local coordinate X is perpendicular to the edge JI, and the local coordinate Y is parallel to the edge JI; Γ j is the diffusion flux at the interface. is the concentration gradient along the X and Y directions in the local coordinate system, determined by the Green-Gauss formula:

[0162]

[0163] Among them, Y I,J =Y J -Y I , Y I,J is the distance between the grid nodes J and I in the Y direction in the local coordinate system; J is the coordinate value of the grid node J in the Y direction in the local coordinate system; D,M =Y M -Y D ; Y D,M A is the distance between the coordinate values ​​of the grid nodes M and D in the Y direction in the local coordinate system; JMID is the sum of the areas of triangles JMI and IDJ.

[0164] Preferably, a simulation scheme is set up. The hydrological conditions of a lake vary greatly both intra-annually and inter-annually. The multi-year average hydrological conditions can reflect the average state of the hydrological conditions in a specific time period and have good universality in simulation analysis. The multi-year average runoff process of seven flow stations in the basin from 2009 to 2022 is used as the upstream inlet flow boundary of the hydrodynamic model (reference Figure 3 (a)); The multi-year average water level process at a lake outlet station is used as the model downstream outlet boundary condition to characterize the interaction between the lake and the river. The multi-year average water level process for 20 years before and after the dam construction is selected to characterize the regulatory effect of the dam and other reservoir construction on the lake. That is, the multi-year average water level process from 1983 to 2002 is regarded as the outlet boundary before the reservoir construction, while the process from 2003 to 2022 is regarded as the effect of the Three Gorges Dam after the dam construction (refer to Figure 3 (b)). Figure 4 (a) is a statistical chart of the suitable habitat area for finless porpoises from June to October before and after the dam was built. Figure 4 (b) is a statistical chart showing the changes in the suitable habitat area for finless porpoises from June to October before and after the dam was built. Figure 5 (a) is the simulation result of the spatial distribution of habitat suitability for finless porpoises in August 2017 (flood season). Figure 5 (b) is the simulation result of the spatial distribution of habitat suitability of finless porpoises in November 2019 (non-flood season).

[0165] Specifically, the comprehensive suitability of finless porpoises and their potential habitat area were calculated for each grid cell. The comprehensive suitability of finless porpoises' food sources is expressed as follows:

[0166] CSI gi =(I hi I vi I Ti Imi ) 1 / 4

[0167] Among them, CSI ki is the comprehensive suitability index of the finless porpoise food source in unit i, I hi , I vi , I Ti , I mi The suitability of each habitat factor of the food source in unit i.

[0168] Calculate the comprehensive fitness of the finless porpoise. The model expression is as follows:

[0169] CSI fi =(SI hi SI vi CSI gi ) 1 / 3

[0170] Among them, CSI fi is the comprehensive fitness of finless porpoise in unit i, SI hi 、SI vi The suitability of water depth and flow velocity for finless porpoises in unit i is calculated based on the corresponding suitability curves from the unit simulation results of the two-dimensional hydrodynamic water quality model; CSI ki is the comprehensive suitability of the four major carps as food sources for the finless porpoise in unit i.

[0171] Calculate the potential suitable habitat area for finless porpoises in the target area. Consider the area of ​​each grid cell A i The potential suitable habitat area for the finless porpoise can be calculated using the weighted available area method. The calculation formula is as follows:

[0172]

[0173] WUA is the potential suitable habitat area for finless porpoises; CSI is the i is the comprehensive suitability of the finless porpoise unit numbered i; A i is the surface area of ​​the unit with unit number i, and N is the total number of grid cells.

[0174] The beneficial effects of the present invention are as follows:

[0175] The present invention uses a two-dimensional hydrodynamic water quality model and a comprehensive finless porpoise suitability model to quantitatively and accurately simulate and evaluate the impact of reservoir impoundment on the spatiotemporal variation of the habitat suitability of the finless porpoise, thereby improving the calculation accuracy of the suitability.

[0176] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0177] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for simulating the suitability of a finless porpoise's habitat under reservoir impoundment, characterized in that: include: Determine the time point for reservoir impoundment in the target area and select the food source for the finless porpoises in the target area; Determining the habitat factors of the food sources in the target area, fitting a suitable exponential relationship for each of the habitat factors, and obtaining a finless porpoise suitability curve; Constructing a two-dimensional hydrodynamic and water quality model within the target area; Construct a comprehensive fitness model for finless porpoises; The finless porpoise suitability curve, the two-dimensional hydrodynamic water quality model and the finless porpoise comprehensive suitability model are integrated to obtain a finless porpoise habitat suitability simulation model, and the finless porpoise habitat suitability impact model is used to calculate the finless porpoise comprehensive suitability and potential habitat area of ​​each grid unit to obtain the target habitat suitability simulation result.

2. The method for simulating the habitat suitability of finless porpoises under reservoir impoundment according to claim 1, characterized in that: Determine the habitat factors of the food source in the target area, perform a suitable exponential relationship fitting on each habitat factor, and obtain a finless porpoise suitability curve, including: Collecting water depth and suitability data within the target area; An exponential relationship is fitted to the water depth and suitability data to obtain a water depth suitability curve; the finless porpoise suitability curve includes the finless porpoise suitability curve; the expression of the water depth suitability curve is: Where h represents the water depth data; f(h) represents the water depth suitability fitting data corresponding to h.

3. The method for simulating the habitat suitability of finless porpoises under reservoir impoundment according to claim 2, characterized in that: Constructing a two-dimensional hydrodynamic and water quality model within the target area, including: Calculate the Coriolis force coefficient; the expression of the Coriolis force coefficient is: Wherein, f is the Coriolis force coefficient; ω is the average angular velocity of the Earth's rotation; is the dimension of the target area; Calculate the lake surface wind stress; the expression of the lake surface wind stress is: in, are the components of the wind stress on the lake surface in the x and y directions respectively; ρ a is the air density; C w is the wind stress drag coefficient; u w 、v w are the components of wind stress in the x and y directions at a height of 10 m above the water surface; The water flow resistance is calculated according to the Manning formula; the expression of the water flow resistance is: Among them, S fx 、S fy are the components of the water flow resistance in the x and y directions respectively; n is the Manning roughness coefficient; u and v are the average flow velocities in the x and y directions respectively; Calculate the bottom slope; the expression of the bottom slope is: Among them, S ox 、S oy are the components of the bottom slope in the x and y directions respectively; Z b is the bottom bed elevation; Calculate the diffusion coefficient; the expression of the diffusion coefficient is: Among them, K x , K y are the components of the diffusion coefficient in the x and y directions respectively; α and β are the first constant coefficient and the second constant coefficient respectively; g is the acceleration of gravity; c is the Xie Cai coefficient; The source term is obtained by integrating the Coriolis coefficient, the lake surface wind stress, the water flow resistance, and the bottom slope. The expression of the source term is: Where S is the source term; C is the vertical average concentration of the transported species; S c is the source and sink term of transported materials; D c is the degradation term of pollutants.

4. The method for simulating the habitat suitability of finless porpoises under reservoir impoundment according to claim 3, characterized in that: Constructing a two-dimensional hydrodynamic and water quality model within the target area, including: Calculate the conserved variable vector; the expression of the conserved variable vector is: Wherein, U is the conserved variable vector; Calculate a first flux vector; the expression of the first flux vector is: Wherein, F(U) is the first flux vector in the x-axis direction; Calculate the second flux vector; the expression of the second flux vector is: Wherein, G(U) is the second flux vector in the y-axis direction; The conserved variable vector, the first flux vector, the second flux vector, and the source term are integrated to obtain the two-dimensional hydrodynamic and water quality model; the expression of the two-dimensional hydrodynamic and water quality model is: Where E is the flux term.

5. The method for simulating the habitat suitability of finless porpoises under reservoir impoundment according to claim 4, characterized in that: Constructing a two-dimensional hydrodynamic and water quality model within the target area, including: Converting the target area into a topographic map, and performing grid division on the topographic map to obtain a model grid; Set the upstream inlet boundary and input boundary; Setting the outlet boundaries before and after the reservoir is impounded according to the reservoir impoundment time node; The model grid, the upstream inlet boundary, the input boundary, and the outlet boundary are updated to the two-dimensional hydrodynamic and water quality model.

6. The method for simulating the habitat suitability of finless porpoises under reservoir impoundment according to claim 5, characterized in that: Constructing a two-dimensional hydrodynamic and water quality model within the target area also includes: Performing finite volume discretization on the shallow water equation in the two-dimensional hydrodynamic and water quality model based on an unstructured grid, and discretizing the transport equation in the two-dimensional hydrodynamic and water quality model to obtain a discrete calculation formula; The discrete calculation formula is calibrated and verified using the pre-collected monitoring data of the target area.

7. The method for simulating the habitat suitability of finless porpoises under reservoir impoundment according to claim 6, characterized in that: Construct a comprehensive fitness model for finless porpoises, including: Calculate the comprehensive suitability of food; the expression of the comprehensive suitability of food is: CSI gi =(I hi I vi I Ti I mi ) 1 / 4 Among them, CSI gi I is the comprehensive suitability of the food; hi is the water depth suitability index of unit i; I vi is the flow rate suitability index of unit i; I Ti is the water temperature suitability index of unit i; I mi is the ammonia nitrogen suitability index of unit i; A fitness model is constructed based on the comprehensive suitability of the food to obtain the comprehensive fitness model of the finless porpoise. The expression of the comprehensive fitness model of the finless porpoise is: CSI fi =(SI hi SI vi CSI gi ) 1 / 3 ;CSI fi is the output value of the comprehensive fitness model for finless porpoises; SI hi is the water depth suitability of unit i; SI vi is the flow rate suitability of unit i.

8. A system for simulating the suitability of a finless porpoise habitat under reservoir impoundment, characterized in that: include: A condition determination module is used to determine the reservoir impoundment time node in the target area and select the food source of the finless porpoise in the target area; a curve fitting module for determining the habitat factors of the food sources in the target area, fitting a suitable exponential relationship for each of the habitat factors, and obtaining a finless porpoise suitability curve; A water quality model building module, used to build a two-dimensional hydrodynamic water quality model in the target area; The fitness model construction module is used to construct a comprehensive fitness model for finless porpoises; The suitability simulation module is used to integrate the finless porpoise suitability curve, the two-dimensional hydrodynamic water quality model and the finless porpoise comprehensive suitability model to obtain a finless porpoise habitat suitability simulation model, and use the finless porpoise habitat suitability impact model to calculate the finless porpoise comprehensive suitability and potential habitat area of ​​each grid unit to obtain the target habitat suitability simulation result.

9. An electronic device, characterized in that: include: At least one processor, and a memory communicatively connected to the processor; wherein the memory stores instructions that can be executed by the processor, and the instructions are executed by the processor so that the processor can execute a method for simulating the suitability of the habitat of finless porpoises under reservoir impoundment according to any one of claims 1 to 8.

10. A non-transitory computer-readable storage medium storing computer instructions, characterized in that: The computer instructions are used to enable a computer to execute a method for simulating the suitability of a finless porpoise habitat under reservoir impoundment according to any one of claims 1 to 8.

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