Multi-trophic-level habitat suitability evaluation technical method based on hydrodynamic process

Abstract

The invention discloses a multi-trophic-level habitat suitability evaluation technical method based on a hydrodynamic process, and relates to the technical field of habitat suitability evaluation of subjects such as ecology, biology and hydrology, and the method comprises the following steps: collecting watershed hydrodynamic and habitat data, and obtaining watershed topographic factors; simulating a watershed hydrodynamic process and a water quality distribution condition based on the watershed terrain factors; based on the simulation result of the watershed hydrodynamic process and the water quality distribution condition, considering the production effect, respiration effect, digestion effect and sedimentation effect of chlorophyll, and calculating the distribution condition of chlorophyll concentration in the simulation watershed; drawing a change curve of the cover degree of the emergent aquatic plants / submerged plants under different water depth conditions in the drainage basin; and constructing a fish suitability distribution curve, and evaluating habitat suitability distribution of each nutrition level in different life cycles. According to the method, the habitat suitability of multiple nutrition levels and multiple growth stages can be comprehensively and accurately reflected.

Description

Technical Field

[0001] The invention relates to the technical field of habitat suitability assessment in disciplines such as ecology, biology, and hydrology, and more specifically to a multi-trophic level habitat suitability assessment technical method based on hydrodynamic processes. Background Art

[0002] Ecological environment is the basis for species survival and diversity development. Habitat protection is often more important than individual species protection. Habitat suitability refers to the ability of a habitat to provide suitable survival and reproduction for biological species, that is, the potential supply capacity of the habitat. High habitat suitability can promote the healthy and stable development of biodiversity and ecosystems. However, under the influence of high-intensity human activities and climate change, habitat problems have become prominent. At present, explaining the interactions between different species in a watershed, accurately assessing the suitability of different types of habitats, and proposing suggestions for habitat protection and restoration are important research branches in ecology, and are also one of the hot issues involving biology, hydrology and other disciplines.

[0003] Maintaining ecological balance is of vital importance to maintaining the stability of the ecosystem, and species diversity is an important component of ecological balance. Species at multiple trophic levels in a watershed are the basis for building a complete food chain and maintaining the balanced and healthy development of the ecosystem. Due to the biodiversity and complex hierarchy of the watershed ecosystem, evaluating the health of the ecological environment from different trophic levels will produce different results, and there are interactions between different trophic levels, which brings great difficulties and uncertainties to the overall and accurate evaluation of the suitability of the watershed habitat.

[0004] At present, the methods for assessing habitat suitability at home and abroad mainly include constructing a weight assessment system based on subjective or objective weighting methods, and simulation assessment based on hydrodynamics or habitat models. However, most of these methods only consider a certain trophic level such as plankton, emergent plants, and fish, and have shortcomings such as limited applicability, making it difficult to reflect the interactions between different trophic levels.

[0005] Therefore, how to comprehensively and accurately reflect the habitat suitability of multiple trophic levels and multiple growth stages is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] In view of this, the present invention provides a multi-trophic level habitat suitability assessment technology method based on hydrodynamic processes, which solves the problems existing in the background technology.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A multi-trophic level habitat suitability assessment technical method based on hydrodynamic processes includes the following steps:

[0009] Collect watershed hydrodynamic and habitat data and obtain watershed topographic factors;

[0010] Based on the basin topographic factors, simulate the basin hydrodynamic process and water quality distribution;

[0011] Based on the simulation results of the watershed hydrodynamic process and water quality distribution, the distribution of chlorophyll concentration in the simulated watershed is calculated by considering the production, respiration, degradation and sedimentation of chlorophyll.

[0012] Draw the change curve of emergent plant / submerged plant coverage under different water depth conditions in the basin;

[0013] Construct fish suitability distribution curves to evaluate the distribution of habitat suitability at each trophic level during different life cycles.

[0014] Optionally, collect watershed hydrodynamic and habitat data, specifically:

[0015] Conduct field surveys to obtain the hydrodynamic conditions and habitat factor characteristics of the watershed in different seasons, including flow velocity, water depth, chlorophyll concentration, and the cover of emergent vegetation at different life stages, the cover of submerged vegetation, and the distribution frequency of fish.

[0016] Optionally, obtain the basin terrain factors, specifically:

[0017] The acoustic Doppler current profiler was used to monitor the terrain in the basin, CAD files were drawn, ArcGIS10.2 was used to read the terrain factors and hydrological characteristic data in the basin, and a digital elevation model was constructed.

[0018] Optionally, simulate the watershed hydrodynamic process and water quality distribution, including the following steps:

[0019] Based on the basin topographic factors, a hydrodynamic model is constructed to simulate the hydrodynamic process of the two-dimensional basin;

[0020] The water quality module is coupled to the hydrodynamic model to simulate the water quality distribution in the basin.

[0021] Optionally, the method further includes: combining measured data, calibrating adjustment parameters, verifying the accuracy of the hydrodynamic model, and controlling the calibration error of the hydrodynamic model within 10%.

[0022] Optionally, simulate the water quality distribution in the basin, including:

[0023] The expression of dissolved oxygen DO is:

[0024]

[0025] The expression of biochemical oxygen demand BOD is:

[0026]

[0027] The expression of ammonia nitrogen NH3 is:

[0028]

[0029] The expression of ammonium NH4 is:

[0030]

[0031] The expression of nitrite nitrogen NO2 is:

[0032]

[0033] The expression of nitric nitrogen NO3 is:

[0034]

[0035] The expression of soluble phosphate PO4 is:

[0036]

[0037] The expression for FC degradation by fecal Escherichia coli is:

[0038]

[0039] The expression of TC degradation by total E. coli is:

[0040]

[0041] The expression for photosynthesis in water is:

[0042]

[0043] The expression for respiration is:

[0044]

[0045] The expression of the light limitation function F1(h) is:

[0046]

[0047] Among them, I Z The calculation formula is:

[0048] I Z =I0e -(KW+KC×P)d

[0049] The expression of the nutrient limitation function F(N,P) for plant photosynthesis is:

[0050]

[0051] Where: DO is the content of dissolved oxygen, mg / L; reaera is atmospheric reoxygenation, phtsyn is photosynthesis in water, respT is respiration, bodd is BOD degradation, nitriDO is nitrification oxygen demand, sod is sediment oxygen demand, K2 is atmospheric reoxygenation rate, C S represents the saturated dissolved oxygen in the water body; K3 represents the degradation coefficient of organic matter at 20℃, 1 / d; BOD represents the content of biochemical oxygen demand, mg / L; θ3 represents the Arrhenius temperature coefficient of organic matter degradation, T represents temperature; HS_BOD represents the half-saturated oxygen concentration in the BOD degradation process, mg O2 / L; K4 represents the nitrification reaction rate at 20℃, 1 / day; NH3 represents the concentration of ammonia nitrogen, mg / L; θ4 represents the temperature coefficient of nitrification; HS_nitr represents the half-saturated oxygen concentration of nitrification, mg O2 / L; HS_SOD represents the half-saturated oxygen concentration of sediment degradation, mg O2 / L; bodn represents the release of ammonia nitrogen from BOD degradation, nitrif represents the nitrification reaction, that is, the conversion of ammonia nitrogen into nitrite nitrogen, plantn represents the uptake of ammonia nitrogen by plants, bactn represents the uptake of ammonia nitrogen by bacteria, hr represents the respiration of heterotrophic organisms; Y BOD Indicates the ammonia nitrogen content in organic matter, mg NH3 / mgBOD; UN p It represents the coefficient of ammonia nitrogen uptake by plants, P represents plant photosynthesis, UN b represents the coefficient of bacterial uptake of ammonia nitrogen; HS_NH3 represents the half-saturated concentration of bacterial uptake of ammonia nitrogen, mg NH3 / L; R2 represents the respiration rate of animals and bacteria, g O2 / m 2 / day; θ2 represents the temperature coefficient of heterotrophic respiration; NH4 represents the concentration of ammonium, mg / L; bodn2 represents the release of ammonium by BOD degradation, plantn2 represents the uptake of ammonium by plants, bactn2 represents the uptake of ammonium by bacteria, and Y BOD2 Indicates the ratio of ammonium released by BOD degradation, UN p2 The coefficient representing the ammonium uptake by plants, UN b2represents the coefficient of bacterial uptake of ammonium; HS_NH4 represents the half-saturated concentration of bacterial uptake of ammonium, mg NH4 / L; NO2 represents the concentration of nitrite, mg / L; nitri represents the conversion of nitrite to nitrate, θ5 represents the temperature coefficient of the conversion of nitrite to nitrate; NO3 represents the concentration of nitrate, mg / L; deni represents denitrification; K5 represents the rate of conversion of nitrite to nitrate at 20°C, 1 / day; K6 represents the rate of denitrification reaction at 20°C, 1 / day; θ6 represents the Arrhenius temperature coefficient of denitrification; PO4 represents the concentration of soluble phosphate, mg / L; bodp represents the concentration of phosphorus released by BOD degradation, mg / L; plantp represents the concentration of phosphorus taken up by plants, mg / L; bactp represents the concentration of phosphorus taken up by bacteria, mg / L; Y2 represents the phosphorus content in organic matter, mgP / mg BOD; HS_PO4 represents the half-saturated phosphorus concentration of organic matter degradation / half-saturated phosphorus concentration of bacterial uptake, mg P / L; IP p Indicates the coefficient of plant phosphorus uptake, UP b represents the coefficient of phosphorus uptake by microorganisms; FC represents the degradation concentration of fecal coliform bacteria, mg / L; K dF represents the degradation coefficient of fecal coliform bacteria, 1 / day; C F Indicates the concentration of fecal coliform bacteria, 1 / 100ml; TC indicates the total degradation concentration of Escherichia coli, mg / L; K dT represents the degradation coefficient of total E. coli, 1 / day; C T represents the concentration of total E. coli, 1 / 100ml; R1 represents the photosynthetic respiration rate at 20℃, g O2 / m 2 / day; θ1 represents the Arrhenius temperature coefficient of plant respiration, F1(h) represents the light limitation function, and F(N,P) represents the nutrient limitation function of plant photosynthesis; I Z represents the solar radiation at depth Z below the water surface, I opt It represents the optimal light intensity for algae growth; I0 represents the solar radiation on the water surface, KW represents the extinction coefficient of all substances except algae, and KC represents the algae extinction coefficient factor.

[0052] Optionally, the distribution of chlorophyll concentration in the watershed is expressed as:

[0053]

[0054] Where: CHL represents the concentration of chlorophyll a in water, mg / L; prodCH represents the production concentration of chlorophyll a, mg / L; respCH represents the respiratory consumption concentration of chlorophyll a, mg / L; deathCH represents the degradation concentration of chlorophyll a, mg / L; sediCH represents the sedimentation concentration of chlorophyll a, mg / L; phtsyn represents photosynthesis; k11 The carbon-oxygen mass ratio of primary productivity, mg carbon / mg oxygen; k 10 represents the mass ratio of chlorophyll a to carbon, mg CHL / mg carbon; F(N,P) represents the nutrient limitation function for plant photosynthesis, respT represents the oxygen content consumed by plant respiration, k8 represents the mortality rate of chlorophyll a, 1 / day; k9 represents the deposition rate of chlorophyll a, M / day; dz represents the depth of the water layer, m.

[0055] Optionally, when drawing the variation curve of emergent plant / submerged plant coverage under different water depth conditions in the basin, the relationship between coverage and water depth is set to be a quadratic function, and the relationship between emergent plant / submerged plant coverage and water depth is expressed as:

[0056] PBSI t (PBSI c ) = ad 2 +bd+c

[0057] Where: PBSI t (PBSI c ) represents the coverage of emergent plants / submerged plants in the basin, %; d represents the water depth, m; a, b, c are parameters calculated based on measured data.

[0058] Optionally, constructing a fish suitability distribution curve specifically includes the following steps:

[0059] Collect the frequency of fish occurrence at different hydrodynamic conditions in the basin, including fish species and various life stages, i.e. spawning period, migration period, feeding period, and wintering period;

[0060] According to the HASTurges empirical formula, the number of groups and the size of the interval between groups of the frequency distribution of flow velocity and water depth are calculated respectively;

[0061] The calculated maximum and minimum values ​​are used as the thresholds of each variable. The fitness of the group with the highest frequency distribution of fish is determined to be the best, with a value of 1. The ratio of the frequency of the remaining groups to the highest frequency group is the fitness of the group.

[0062] The single-factor fitness curve function SI was constructed respectively, and the fitness index values ​​of flow velocity and water depth for multiple species of fish of different spawning types and different life stages were obtained. The fish suitability distribution curve was constructed, and the normal function expression of the curve was obtained:

[0063]

[0064]

[0065] Where: hsi Vrepresents the distribution suitability of fish to flow velocity, σ V represents the standard deviation of the fish distribution suitability curve for flow velocity; v represents flow velocity, m / s; u V The mean value of the fish distribution suitability curve for flow velocity, hsi D represents the distribution suitability of fish to water depth, σ D represents the standard deviation of the fish distribution suitability curve for water depth; d represents the water depth, m; u D Represents the mean of the fish distribution suitability curve for water depth.

[0066] Optionally, assess the distribution of habitat suitability at each trophic level during different life cycles, specifically:

[0067] Taking into account the hydrodynamic process and different habitat factors, an expression of habitat suitability for different spawning types of fish is constructed to simulate the distribution of fish habitat suitability:

[0068] HSI p =hsi V ×hsi D ×(kchl×CHL)

[0069] HSI n =hsi V ×hsi D ×(kchl×CHL)×(kpbsi t ×PBSI t )

[0070] HSI c =hsi V ×hsi D ×(kchl×CHL)×(kpbsi c ×PBSI c )

[0071] Where: HSI p Indicates the habitat suitability for floating spawning fish, HSI n Indicates the habitat suitability for fish that lay sticky eggs, HSI c represents the habitat suitability of fish that lay eggs; kchl represents the relationship between the distribution suitability of different species of fish and chlorophyll concentration; CHL represents the concentration of chlorophyll a in the water body, mg / L; kpbsi t The relationship between the distribution suitability of different fish species laying sticky eggs and the cover of emergent plants, kpbsi c Indicates the relationship between the distribution suitability of different species of fish that lay submerged eggs and the coverage of submerged plants; hsi V Indicates the distribution suitability of fish to flow velocity, hsi DIndicates the distribution suitability of fish to water depth, PBSI t Indicates the coverage of emergent plants in the basin, PBSI c It indicates the coverage of submerged macrophytes in the watershed;

[0072] Taking into account the germination, seedling, flowering and fruiting periods of emergent plants and submerged plants as well as the spawning, migration, foraging and overwintering periods of fish, the distribution of habitat suitability at each trophic level during different life cycles is analyzed and evaluated.

[0073] It can be seen from the above technical solution that, compared with the prior art, the present invention provides a multi-trophic level habitat suitability assessment method based on hydrodynamic processes, which has the following beneficial effects:

[0074] (1) The present invention relates to the simulation of the growth suitability of emergent plants, the growth suitability of submerged plants, and the suitability of fish habitats. It takes into account the different life cycles of algae, emergent plants, submerged plants, and fish, as well as the interactions between various trophic levels. It has high accuracy and comprehensive considerations, and can reflect the distribution of habitat suitability at different trophic levels in a watershed.

[0075] (2) The simulation results of the present invention are highly accurate, have a wide range of applications, and are easy to obtain data. They can clearly, intuitively, and comprehensively display the distribution of habitat suitability at different trophic levels in a watershed, comprehensively consider hydrodynamic processes, vegetation distribution, fish habitats, etc., and comprehensively evaluate the habitat suitability of the watershed. Based on this, different types of habitat protection measures can be proposed in the watershed. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0077] Figure 1 A flow chart of a multi-trophic level habitat suitability assessment technology method based on hydrodynamic processes provided by the present invention;

[0078] Figure 2 The relationship curve between the habitat suitability of the wheatear fish provided by the present invention and the water depth and flow rate in the basin at different life cycles; wherein 2a is the spawning period, 2b is the feeding period, and 2c is the wintering period;

[0079] Figure 3 The terrain file of the main stream section of Yongding River from Sanjiadian to Nancai Village provided by the present invention; wherein 3a is the grid division of the research section, and 3b is the terrain of the research section;

[0080] Figure 4 The hydrodynamic simulation results of the research river section provided by the present invention; wherein 4a is the water level simulation result of the research river section of Yongding River, and 4b is the flow velocity simulation result of the research river section of Yongding River;

[0081] Figure 5 The water quality simulation results of the research river section provided by the present invention; wherein 5a is the BOD concentration, 5b is the NH4 concentration, 5c is the PO4 concentration, and 5d is the Chla concentration;

[0082] Figure 6 The growth suitability curve of the flathead fish provided by the present invention; wherein 6a is the water depth suitability distribution curve of the flathead fish, and 6b is the flow velocity suitability distribution curve of the flathead fish;

[0083] Figure 7 The simulation results of the habitat suitability of the wheatear fish in the research river section provided by the present invention; wherein 7a is the spawning period, 7b is the feeding period, and 7c is the wintering period. DETAILED DESCRIPTION

[0084] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0085] The embodiment of the present invention discloses a multi-trophic level habitat suitability assessment method based on hydrodynamic processes, such as Figure 1 As shown, the following steps are included:

[0086] Collect watershed hydrodynamic and habitat data and obtain watershed topographic factors;

[0087] Based on the basin topographic factors, simulate the basin hydrodynamic process and water quality distribution;

[0088] Based on the simulation results of the watershed hydrodynamic process and water quality distribution, the distribution of chlorophyll concentration in the simulated watershed is calculated by considering the production, respiration, degradation and sedimentation of chlorophyll.

[0089] Draw the change curve of emergent plant / submerged plant coverage under different water depth conditions in the basin;

[0090] Construct fish suitability distribution curves to evaluate the distribution of habitat suitability at each trophic level during different life cycles.

[0091] This embodiment is based on the simulation of hydrodynamic processes, comprehensively considers multiple types of habitats including trophic levels such as phytoplankton, emergent plants, submerged plants, and fish, and identifies the characteristics of different life cycles. A multi-trophic level habitat suitability assessment method based on hydrodynamic processes is designed, which can comprehensively and accurately reflect the suitability range of habitats at different trophic levels.

[0092] Next, Figure 1 The steps shown are explained in detail for a deeper understanding.

[0093] 1. Collection of watershed hydrodynamics and habitat data

[0094] Field surveys were conducted to obtain the hydrodynamic conditions and habitat factor characteristics of the watershed in different seasons, including flow velocity, water depth, chlorophyll concentration, and the coverage of emergent vegetation at different life stages (germination, seedling, development, and fruiting), the coverage of submerged vegetation at different life stages (germination, seedling, development, and fruiting), and the distribution frequency of fish at different life stages (spawning, migration, foraging, and overwintering), etc., in order to calibrate the model and verify the relationship curve.

[0095] 2. Acquisition of basin topographic factors

[0096] The acoustic Doppler current profiler (ADCP) was used to monitor the terrain in the basin, CAD files were drawn, ArcGIS10.2 was used to read the terrain factors and hydrological characteristic data in the basin, and a digital elevation model was constructed.

[0097] 3. Basin hydrodynamic process and water quality simulation

[0098] Based on the basin topographic factors, a hydrodynamic model is constructed to simulate the hydrodynamic processes such as flow velocity and water depth in the two-dimensional basin field; combined with the measured data, the parameters are calibrated and adjusted to verify the accuracy of the hydrodynamic model, and the calibration error of the hydrodynamic model is controlled within 10%;

[0099] Based on the hydrodynamic model, the water quality module is coupled to simulate the water quality distribution in the basin, including: dissolved oxygen DO, biochemical oxygen demand BOD, ammonia nitrogen NH3, ammonium NH4, nitrite nitrogen NO2, nitrate nitrogen NO3, soluble phosphate PO4, fecal coliform degradation FC, total Escherichia coli degradation TC, etc.

[0100] The expression of dissolved oxygen DO is:

[0101]

[0102] The expression of biochemical oxygen demand BOD is:

[0103]

[0104] The expression of ammonia nitrogen NH3 is:

[0105]

[0106] The expression of ammonium NH4 is:

[0107]

[0108] The expression of nitrite nitrogen NO2 is:

[0109]

[0110] The expression of nitric nitrogen NO3 is:

[0111]

[0112] The expression of soluble phosphate PO4 is:

[0113]

[0114] The expression for FC degradation by fecal Escherichia coli is:

[0115]

[0116] The expression of TC degradation by total E. coli is:

[0117]

[0118] The expression for photosynthesis in water is:

[0119]

[0120] The expression for respiration is:

[0121]

[0122] The expression of the light limitation function F1(h) is:

[0123]

[0124] Among them, I Z The calculation formula is:

[0125] I Z =I0e -(KW+KC×P)d

[0126] The expression of the nutrient limitation function F(N,P) for plant photosynthesis is:

[0127]

[0128] Where: DO is the content of dissolved oxygen, mg / L; reaera is atmospheric reoxygenation, phtsyn is photosynthesis in water, respT is respiration, bodd is BOD degradation, nitriDO is nitrification oxygen demand, sod is sediment oxygen demand, K2 is atmospheric reoxygenation rate, C S represents the saturated dissolved oxygen in the water body; K3 represents the degradation coefficient of organic matter at 20℃, 1 / d; BOD represents the content of biochemical oxygen demand, mg / L; θ3 represents the Arrhenius temperature coefficient of organic matter degradation, T represents temperature; HS_BOD represents the half-saturated oxygen concentration in the BOD degradation process, mg O2 / L; K4 represents the nitrification reaction rate at 20℃, 1 / day; NH3 represents the concentration of ammonia nitrogen, mg / L; θ4 represents the temperature coefficient of nitrification; HS_nitr represents the half-saturated oxygen concentration of nitrification, mg O2 / L; HS_SOD represents the half-saturated oxygen concentration of sediment degradation, mg O2 / L; bodn represents the release of ammonia nitrogen from BOD degradation, nitrif represents the nitrification reaction, that is, the conversion of ammonia nitrogen into nitrite nitrogen, plantn represents the uptake of ammonia nitrogen by plants, bactn represents the uptake of ammonia nitrogen by bacteria, hr represents the respiration of heterotrophic organisms; Y BOD Indicates the ammonia nitrogen content in organic matter, mg NH3 / mg BOD; UN p It represents the coefficient of ammonia nitrogen uptake by plants, P represents plant photosynthesis, UN b represents the coefficient of bacterial uptake of ammonia nitrogen; HS_NH3 represents the half-saturated concentration of bacterial uptake of ammonia nitrogen, mg NH3 / L; R2 represents the respiration rate of animals and bacteria, g O2 / m 2 / day; θ2 represents the temperature coefficient of heterotrophic respiration; NH4 represents the concentration of ammonium, mg / L; bodn2 represents the release of ammonium by BOD degradation, plantn2 represents the uptake of ammonium by plants, bactn2 represents the uptake of ammonium by bacteria, and Y BOD2 Indicates the ratio of ammonium released by BOD degradation, UN p2 The coefficient representing the ammonium uptake by plants, UN b2represents the coefficient of bacterial uptake of ammonium; HS_NH4 represents the half-saturated concentration of bacterial uptake of ammonium, mgNH4 / L; NO2 represents the concentration of nitrite, mg / L; nitri represents the conversion of nitrite to nitrate, θ5 represents the temperature coefficient of the conversion of nitrite to nitrate; NO3 represents the concentration of nitrate, mg / L; deni represents denitrification; K5 represents the rate of conversion of nitrite to nitrate at 20°C, 1 / day; K6 represents the rate of denitrification reaction at 20°C, 1 / day; θ6 represents the Arrhenius temperature coefficient of denitrification; PO4 represents the concentration of soluble phosphate, mg / L; bodp represents the concentration of phosphorus released by BOD degradation, mg / L; plantp represents the concentration of phosphorus taken up by plants, mg / L; bactp represents the concentration of phosphorus taken up by bacteria, mg / L; Y2 represents the phosphorus content in organic matter, mg P / mg BOD; HS_PO4 represents the half-saturated phosphorus concentration of organic matter degradation / half-saturated phosphorus concentration of bacterial uptake, mgP / L; UP p Indicates the coefficient of plant phosphorus uptake, UP b represents the coefficient of phosphorus uptake by microorganisms; FC represents the degradation concentration of fecal coliform bacteria, mg / L; K dF represents the degradation coefficient of fecal coliform bacteria, 1 / day; C F Indicates the concentration of fecal coliform bacteria, 1 / 100ml; TC indicates the total degradation concentration of Escherichia coli, mg / L; K dT represents the degradation coefficient of total E. coli, 1 / day; C T represents the concentration of total E. coli, 1 / 100ml; R1 represents the photosynthetic respiration rate at 20℃, g O2 / m 2 / day; θ1 represents the Arrhenius temperature coefficient of plant respiration, F1(h) represents the light limitation function, and F(N,P) represents the nutrient limitation function of plant photosynthesis; I Z represents the solar radiation at depth Z below the water surface, I opt It represents the optimal light intensity for algae growth; I0 represents the solar radiation on the water surface, KW represents the extinction coefficient of all substances except algae, and KC represents the algae extinction coefficient factor.

[0129] 4. Assessment of chlorophyll concentration in the watershed

[0130] Based on the hydrodynamic process and water quality simulation results in the basin, the distribution of chlorophyll concentration in the simulated basin was calculated by considering the production, respiration, digestion and sedimentation of chlorophyll:

[0131]

[0132] Where: CHL represents the concentration of chlorophyll a in water, mg / L; prodCH represents the production concentration of chlorophyll a, mg / L; respCH represents the respiratory consumption concentration of chlorophyll a, mg / L; deathCH represents the degradation concentration of chlorophyll a, mg / L; sediCH represents the sedimentation concentration of chlorophyll a, mg / L; phtsyn represents photosynthesis; k 11 The carbon-oxygen mass ratio of primary productivity, mg carbon / mg oxygen; k 10 represents the mass ratio of chlorophyll a to carbon, mg CHL / mg carbon; F(N,P) represents the nutrient limitation function for plant photosynthesis, respT represents the oxygen content consumed by plant respiration, k8 represents the mortality rate of chlorophyll a, 1 / day; k9 represents the deposition rate of chlorophyll a, M / day; dz represents the depth of the water layer, m.

[0133] 5. Assessment of plant cover in the watershed

[0134] The variation curve of emergent plant / submerged plant coverage under different water depth conditions in the basin is drawn. The relationship between coverage and water depth is set as a quadratic function. The relationship between emergent plant / submerged plant coverage and water depth is expressed as follows:

[0135] PBSI t (PBSI c ) = ad 2 +bd+c

[0136] Where: PBSI t (PBSI c ) represents the coverage of emergent plants / submerged plants in the basin, %; d represents the water depth, m; a, b, c are parameters calculated based on measured data.

[0137] 6. Construction of fish suitability curve

[0138] Collect the frequency of fish occurrence at different hydrodynamic conditions in the basin, including fish species and life stages, i.e. spawning period, migration period, feeding period, and wintering period;

[0139] According to the HASTurges empirical formula, the hydrodynamic conditions such as the number of groups and the size of the interval between groups of the frequency distribution of flow velocity and water depth are calculated respectively;

[0140] The calculated maximum and minimum values ​​are used as the thresholds of each variable. The fitness of the group with the highest frequency distribution of fish is determined to be the best, with a value of 1. The ratio of the frequency of the remaining groups to the highest frequency group is the fitness of the group.

[0141] The single-factor fitness curve function SI was constructed respectively, and the fitness index values ​​of multi-species fish with different spawning types (fish laying floating eggs, fish laying sticky eggs, fish laying sinking eggs) and different life stages (spawning period, migration period, feeding period, wintering period) for flow velocity and water depth were obtained. The fish suitability distribution curve was constructed and the normal function expression of the curve was obtained:

[0142]

[0143]

[0144] Where: hsi V represents the distribution suitability of fish to flow velocity, σ V represents the standard deviation of the fish distribution suitability curve for flow velocity; v represents flow velocity, m / s; u V The mean value of the fish distribution suitability curve for flow velocity, hsi D represents the distribution suitability of fish to water depth, σ D represents the standard deviation of the fish distribution suitability curve for water depth; d represents the water depth, m; u D Represents the mean of the fish distribution suitability curve for water depth.

[0145] 7. Assessment of fish habitat suitability in the watershed

[0146] The expression formula of habitat suitability of different spawning types of fish is constructed. The distribution of fish laying floating eggs is related to flow velocity, water depth, and chlorophyll concentration. The distribution of fish laying sticky eggs is related to flow velocity, water depth, and emergent plant cover. The distribution of fish laying sinking eggs is related to flow velocity, water depth, and submerged plant cover. Taking into account the hydrodynamic process and different habitat factors, the distribution of fish habitat suitability is simulated:

[0147] HSI p =hsi V ×hsi D ×(kchl×CHL)

[0148] HSI n =hsi V ×hsi D ×(kchl×CHL)×(kpbsi t ×PBSI t )

[0149] HSI c =hsi V ×hsi D ×(kchl×CHL)×(kpbsi c ×PBSI c )

[0150] Where: HSI p Indicates the habitat suitability for floating spawning fish, HSI n Indicates the habitat suitability for fish that lay sticky eggs, HSI c represents the habitat suitability of fish that lay eggs; kchl represents the relationship between the distribution suitability of different species of fish and chlorophyll concentration (the two are assumed to be linear); CHL represents the concentration of chlorophyll a in the water body, mg / L; kpbsi t represents the relationship between the distribution suitability of different species of fish laying sticky eggs and the cover of emergent plants (the two are assumed to be in a linear relationship), kpbsi c It indicates the relationship between the distribution suitability of different species of fish that lay submerged eggs and the coverage of submerged plants (the two are assumed to be in a linear relationship); hsi V Indicates the distribution suitability of fish to flow velocity, hsi D Indicates the distribution suitability of fish to water depth, PBSI t Indicates the coverage of emergent plants in the basin, PBSI c It indicates the coverage of submerged macrophytes in the watershed;

[0151] Since the effect of water depth on the cover of emergent plants and submerged plants varies in different life stages, and the effect of hydrodynamic processes and different habitat factors on fish varies, it is necessary to consider the entire life cycle of vegetation and fish, including the germination, seedling, flowering and fruiting periods of emergent and submerged plants and the spawning, migratory, foraging and overwintering periods of fish, to analyze and evaluate the distribution of habitat suitability at each trophic level in different life cycles.

[0152] Next, the technical solution of the present invention is further understood in conjunction with an embodiment of a multi-trophic level habitat suitability assessment based on hydrodynamic processes for the Sanjiadian-Nancaicun main stream section of the Yongding River in Beijing.

[0153] S1: Watershed hydrodynamics and habitat data collection

[0154] Combined with field surveys and literature research, the hydrodynamic conditions and habitat factor characteristics of the basin in different seasons were obtained, including flow velocity, water depth, chlorophyll concentration, cover of emergent vegetation at different life stages (germination, seedling, flowering, and fruiting), cover of submerged vegetation at different life stages (germination, seedling, flowering, and fruiting), and distribution frequency of wheatear fish at different life stages (spawning, migration, foraging, and wintering). The response relationship between wheatear fish and flow velocity and water level during the spawning, foraging, and wintering periods was constructed, such as Figure 2 As shown, 2a is the spawning period, 2b is the feeding period, and 2c is the wintering period.

[0155] S2: Acquisition of watershed topographic factors

[0156] Acoustic Doppler current profiler (ADCP) was used to monitor the topography in the basin, and CAD files were drawn. ArcGIS 10.2 was used to read the topographic factors and hydrological characteristics data in the basin and construct a digital elevation model. The topographic files of the main stream of the Yongding River from Sanjiadian to Nancai Village were obtained, such as Figure 3 As shown, 3a is the grid division of the studied river section, and 3b is the topography of the studied river section.

[0157] S3: Basin hydrodynamic process and water quality simulation

[0158] Based on the basin topographic factors, a hydrodynamic model is constructed to simulate the hydrodynamic processes such as flow velocity and water depth in the two-dimensional basin field; combined with the measured data, the parameters are calibrated and adjusted to verify the accuracy of the hydrodynamic model, and the calibration error of the hydrodynamic model is controlled within 10%;

[0159] Based on the hydrodynamic model, the water quality module is coupled to simulate the water quality distribution in the basin, including: dissolved oxygen DO, biochemical oxygen demand BOD, ammonia nitrogen NH3, ammonium NH4, nitrite nitrogen NO2, nitrate nitrogen NO3, soluble phosphate PO4, fecal coliform degradation FC, total Escherichia coli degradation TC, etc.

[0160] The expression of dissolved oxygen DO is:

[0161]

[0162] The expression of biochemical oxygen demand BOD is:

[0163]

[0164] The expression of ammonia nitrogen NH3 is:

[0165]

[0166] The expression of ammonium NH4 is:

[0167]

[0168] The expression of nitrite nitrogen NO2 is:

[0169]

[0170] The expression of nitric nitrogen NO3 is:

[0171]

[0172] The expression of soluble phosphate PO4 is:

[0173]

[0174] The expression for FC degradation by fecal Escherichia coli is:

[0175]

[0176] The expression of TC degradation by total E. coli is:

[0177]

[0178] The expression for photosynthesis in water is:

[0179]

[0180] The expression for respiration is:

[0181]

[0182] The expression of the light limitation function F1(h) is:

[0183]

[0184] Among them, I Z The calculation formula is:

[0185] I Z =I0e -(KW+KC×P)d

[0186] The expression of the nutrient limitation function F(N,P) for plant photosynthesis is:

[0187]

[0188] Where: DO is the content of dissolved oxygen, mg / L; reaera is atmospheric reoxygenation, phtsyn is photosynthesis in water, respT is respiration, bodd is BOD degradation, nitriDO is nitrification oxygen demand, sod is sediment oxygen demand, K2 is atmospheric reoxygenation rate, C Srepresents the saturated dissolved oxygen in the water body; K3 represents the degradation coefficient of organic matter at 20℃, 1 / d; BOD represents the content of biochemical oxygen demand, mg / L; θ3 represents the Arrhenius temperature coefficient of organic matter degradation, T represents temperature; HS_BOD represents the half-saturated oxygen concentration in the BOD degradation process, mg O2 / L; K4 represents the nitrification reaction rate at 20℃, 1 / day; NH3 represents the concentration of ammonia nitrogen, mg / L; θ4 represents the temperature coefficient of nitrification; HS_nitr represents the half-saturated oxygen concentration of nitrification, mg O2 / L; HS_SOD represents the half-saturated oxygen concentration of sediment degradation, mg O2 / L; bodn represents the release of ammonia nitrogen from BOD degradation, nitrif represents the nitrification reaction, that is, the conversion of ammonia nitrogen into nitrite nitrogen, plantn represents the uptake of ammonia nitrogen by plants, batth represents the uptake of ammonia nitrogen by bacteria, hr represents the respiration of heterotrophic organisms; Y BOD Indicates the ammonia nitrogen content in organic matter, mg NH3 / mg BOD; UN p It represents the coefficient of ammonia nitrogen uptake by plants, P represents plant photosynthesis, UN b represents the coefficient of bacterial uptake of ammonia nitrogen; HS_NH3 represents the half-saturated concentration of bacterial uptake of ammonia nitrogen, mg NH3 / L; R2 represents the respiration rate of animals and bacteria, g O2 / m 2 / day; θ2 represents the temperature coefficient of heterotrophic respiration; NH4 represents the concentration of ammonium, mg / L; bodn2 represents the release of ammonium by BOD degradation, plantn2 represents the uptake of ammonium by plants, bactn2 represents the uptake of ammonium by bacteria, and Y BOD2 Indicates the ratio of ammonium released by BOD degradation, UN p2 The coefficient representing the ammonium uptake by plants, UN b2 represents the coefficient of bacterial uptake of ammonium; HS_NH4 represents the half-saturated concentration of bacterial uptake of ammonium, mgNH4 / L; NO2 represents the concentration of nitrite, mg / L; nitri represents the conversion of nitrite to nitrate, θ5 represents the temperature coefficient of the conversion of nitrite to nitrate; NO3 represents the concentration of nitrate, mg / L; deni represents denitrification; K5 represents the rate of conversion of nitrite to nitrate at 20°C, 1 / day; K6 represents the rate of denitrification reaction at 20°C, 1 / day; θ6 represents the Arrhenius temperature coefficient of denitrification; PO4 represents the concentration of soluble phosphate, mg / L; bdop represents the concentration of phosphorus released by BOD degradation, mg / L; plantp represents the concentration of phosphorus taken up by plants, mg / L; bactp represents the concentration of phosphorus taken up by bacteria, mg / L; Y2 represents the phosphorus content in organic matter, mg P / mg BOD; HS_PO4 represents the half-saturated phosphorus concentration of organic matter degradation / half-saturated phosphorus concentration of bacterial uptake, mgP / L; UP p Indicates the coefficient of plant phosphorus uptake, UP brepresents the coefficient of phosphorus uptake by microorganisms; FC represents the degradation concentration of fecal coliform bacteria, mg / L; K dF represents the degradation coefficient of fecal coliform bacteria, 1 / day; C F Indicates the concentration of fecal coliform bacteria, 1 / 100ml; TC indicates the total degradation concentration of Escherichia coli, mg / L; K dT represents the degradation coefficient of total E. coli, 1 / day; C T represents the concentration of total E. coli, 1 / 100ml; R1 represents the photosynthetic respiration rate at 20℃, g O2 / m 2 / day; θ1 represents the Arrhenius temperature coefficient of plant respiration, F1(h) represents the light limitation function, and F(N,P) represents the nutrient limitation function of plant photosynthesis; I Z is the solar radiation at depth Z below the water surface, I opt is the optimal light intensity for algae growth; I0 is the solar radiation on the water surface, KW is the extinction coefficient of all substances except algae, and KC is the algae extinction coefficient factor.

[0189] Through the FM module of the MIKE 21 model, the terrain file extracted above is input to construct the hydrodynamic model of the river section and simulate the hydrodynamic process of the two-dimensional flow field. The simulation results of the flow velocity and water level of the river section are as follows: Figure 4 As shown, 4a is the water level simulation result of the Yongding River study section, and 4b is the flow velocity simulation result of the Yongding River study section.

[0190] On the basis of hydrodynamics, the calculation formulas of dissolved oxygen DO, biochemical oxygen demand BOD, ammonia nitrogen NH3, ammonium NH4, nitrite nitrogen NO2, nitrate nitrogen NO3, soluble phosphate PO4, fecal coliform degradation FC, and total coliform degradation TC are written into the Ecolab module and coupled to the hydrodynamic results to display the simulation results of BOD, NH4, and PO4, such as Figure 5 As shown in 5a, 5b, and 5c.

[0191] S4: Assessment of watershed chlorophyll concentration

[0192] Based on the hydrodynamic process and water quality simulation results in the basin, the distribution of chlorophyll concentration in the simulated basin was calculated by considering the production, respiration, digestion and sedimentation of chlorophyll:

[0193]

[0194] Where: CHL represents the concentration of chlorophyll a in water, mg / L; prodCH represents the production concentration of chlorophyll a, mg / L; respCH represents the respiratory consumption concentration of chlorophyll a, mg / L; deathCH represents the degradation concentration of chlorophyll a, mg / L; sediCh represents the sedimentation concentration of chlorophyll a, mg / L; phtsyn represents photosynthesis; k 11 The carbon-oxygen mass ratio of primary productivity, mg carbon / mg oxygen; k 10 represents the mass ratio of chlorophyll a to carbon, mg CHL / mg carbon; F(N,P) represents the nutrient limitation function for plant photosynthesis, respT represents the oxygen content consumed by plant respiration, k8 represents the mortality rate of chlorophyll a, 1 / day; k9 represents the deposition rate of chlorophyll a, M / day; dz represents the depth of the water layer, m.

[0195] The above chlorophyll calculation formula is written into the Eco lab module, coupled with the simulation results of the hydrodynamic process and water quality in the river section, and the distribution of chlorophyll concentration is shown as follows: Figure 5 As shown in 5d.

[0196] S5: Assessment of plant cover in the watershed

[0197] Since the wheatear fish lays sticky eggs, only the influence of emergent plants on the suitability of fish spawning habitat is considered. The variation curve of emergent plant coverage under different water depths in the basin is drawn, and the relationship between coverage and water depth is set as a quadratic function. Combining the measured data and literature data, the relationship expression between emergent plant coverage and water depth is obtained as follows:

[0198] PBSI t (PBSI c )=-1.501d 2 -1.550d+0.6

[0199] Where: PBSI t (PBSI c ) represents the coverage of emergent plants / submerged plants in the basin, %; d represents the water depth, m.

[0200] S6: Construction of fish habitat suitability curve

[0201] according to Figure 2 The response relationship between the flow velocity and water depth of the wheatear fish during the spawning period, feeding period and wintering period is shown in the figure. The fish suitability distribution curve is drawn. Assuming that the fish habitat suitability is in a normal function relationship with the flow velocity and water depth, the normal function expression of the curve is obtained. Figure 6, where 6a is the water depth suitability distribution curve of the wheatear fish, 6b is the flow velocity suitability distribution curve of the wheatear fish, A is the spawning period, B is the feeding period, and C is the wintering period.

[0202] During the spawning period:

[0203]

[0204]

[0205] During the feeding period:

[0206]

[0207]

[0208] During the wintering period:

[0209]

[0210]

[0211] Where: hsi V Indicates the distribution suitability of fish to flow velocity; v represents flow velocity, m / s; hsi D Indicates the distribution suitability of fish to water depth; d represents water depth, m.

[0212] S7: Assessment of fish habitat suitability in the watershed

[0213] The expression formula for the habitat suitability of the wheatear fish was constructed. The distribution of wheatear fish during the feeding and wintering periods is related to flow velocity, water depth, and chlorophyll concentration, and the distribution of wheatear fish during the spawning period is related to flow velocity, water depth, and emergent plant cover. The distribution of fish habitat suitability was simulated by comprehensively considering the hydrodynamic process and different habitat factors:

[0214] HSI p =hsi V ×hsi D ×(kchl×CHL)

[0215] HSI n =hsi V ×hsi D ×(kchl×CHL)×(kpbsi t ×PBSI t )

[0216] Where: HSI p Indicates the habitat suitability of wheatear fish during the foraging / wintering period, HSI nrepresents the habitat suitability of the spawning period of the wheatear fish; kchl represents the relationship between the distribution suitability of the wheatear fish and the chlorophyll concentration (the linear relationship between the two is set to 0.5); CHL represents the concentration of chlorophyll a in the water body, mg / L; kpbsi t It represents the relationship between the distribution suitability of different species of fish that lay sticky eggs and the cover of emergent plants (the linear relationship between the two is set to 0.5); hsi V Indicates the distribution suitability of fish to flow velocity, hsi D Indicates the distribution suitability of fish to water depth, PBSI t Indicates the coverage of emergent plants in the basin.

[0217] The above formula is written into the Eco lab module, coupled with the hydrodynamic process and water quality changes in the river section, to simulate the spatial distribution characteristics of the habitat suitability of wheatear fish during the spawning period, foraging period, and wintering period, such as Figure 7 As shown, 7a is the spawning period, 7b is the feeding period, and 7c is the wintering period.

[0218] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0219] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-trophic level habitat suitability assessment method based on hydrodynamic processes, characterized in that: The following steps are involved: Collect watershed hydrodynamic and habitat data and obtain watershed topographic factors; Based on the basin topographic factors, simulate the basin hydrodynamic process and water quality distribution; Based on the simulation results of the watershed hydrodynamic process and water quality distribution, the distribution of chlorophyll concentration in the simulated watershed is calculated by considering the production, respiration, degradation and sedimentation of chlorophyll. Draw the change curve of emergent plant / submerged plant coverage under different water depth conditions in the basin; Construct fish suitability distribution curves to evaluate the distribution of habitat suitability at each trophic level during different life cycles.

2. The multi-trophic level habitat suitability assessment technical method based on hydrodynamic processes according to claim 1 is characterized in that: Collect watershed hydrodynamic and habitat data, specifically: Conduct field surveys to obtain the hydrodynamic conditions and habitat factor characteristics of the watershed in different seasons, including flow velocity, water depth, chlorophyll concentration, and the cover of emergent vegetation at different life stages, the cover of submerged vegetation, and the distribution frequency of fish.

3. The multi-trophic level habitat suitability assessment technical method based on hydrodynamic processes according to claim 1 is characterized in that: Get the basin terrain factors, specifically: The acoustic Doppler current profiler was used to monitor the terrain in the basin, CAD files were drawn, ArcGIS10.2 was used to read the terrain factors and hydrological characteristic data in the basin, and a digital elevation model was constructed.

4. The multi-trophic level habitat suitability assessment method based on hydrodynamic processes according to claim 1 is characterized in that: Simulating the hydrodynamic process and water quality distribution in the basin includes the following steps: Based on the basin topographic factors, a hydrodynamic model is constructed to simulate the hydrodynamic process of the two-dimensional basin; The water quality module is coupled to the hydrodynamic model to simulate the water quality distribution in the basin.

5. The multi-trophic level habitat suitability assessment method based on hydrodynamic processes according to claim 4 is characterized in that: The method also includes: combining measured data, calibrating and adjusting parameters, verifying the accuracy of the hydrodynamic model, and controlling the calibration error of the hydrodynamic model within 10%.

6. The multi-trophic level habitat suitability assessment method based on hydrodynamic processes according to claim 4 is characterized in that: Simulate the water quality distribution in the basin, including: The expression of dissolved oxygen DO is: The expression of biochemical oxygen demand BOD is: The expression of ammonia nitrogen NH3 is: The expression of ammonium NH4 is: The expression of nitrite nitrogen NO2 is: The expression of nitric nitrogen NO3 is: The expression of soluble phosphate PO4 is: The expression for FC degradation by fecal Escherichia coli is: The expression of TC degradation by total E. coli is: The expression for photosynthesis in water is: The expression for respiration is: The expression of the light limitation function F1(h) is: Among them, I Z The calculation formula is: I Z =I0e -(KW+KC×P)d The expression of the nutrient limitation function F(N,P) for plant photosynthesis is: Where: DO is the content of dissolved oxygen, mg / L; reaera is atmospheric reoxygenation, phtsyn is photosynthesis in water, respT is respiration, bodd is BOD degradation, nitriDO is nitrification oxygen demand, sod is sediment oxygen demand, K2 is atmospheric reoxygenation rate, C S represents the saturated dissolved oxygen in the water body; K3 represents the degradation coefficient of organic matter at 20℃, 1 / d; BOD represents the content of biochemical oxygen demand, mg / L; θ3 represents the Arrhenius temperature coefficient of organic matter degradation, T represents temperature; HS_BOD represents the half-saturated oxygen concentration in the BOD degradation process, mg O2 / L; K4 represents the nitrification reaction rate at 20℃, 1 / day; NH3 represents the concentration of ammonia nitrogen, mg / L; θ4 represents the temperature coefficient of nitrification; HS_nitr represents the half-saturated oxygen concentration of nitrification, mgO2 / L; HS_SOD represents the half-saturated oxygen concentration of sediment degradation, mg O2 / L; bodn represents the release of ammonia nitrogen from BOD degradation, nitrif represents the nitrification reaction, that is, the conversion of ammonia nitrogen into nitrite nitrogen, plantn represents the uptake of ammonia nitrogen by plants, bactn represents the uptake of ammonia nitrogen by bacteria, hr represents the respiration of heterotrophic organisms; Y BOD Indicates the ammonia nitrogen content in organic matter, mg NH3 / mg BOD; UN p It represents the coefficient of ammonia nitrogen uptake by plants, P represents plant photosynthesis, UN b represents the coefficient of bacterial uptake of ammonia nitrogen; HS_NH3 represents the half-saturated concentration of bacterial uptake of ammonia nitrogen, mg NH3 / L; R2 represents the respiration rate of animals and bacteria, g O2 / m 2 / day; θ2 represents the temperature coefficient of heterotrophic respiration; NH4 represents the concentration of ammonium, mg / L; bodn2 represents the release of ammonium by BOD degradation, plantn2 represents the uptake of ammonium by plants, bactn2 represents the uptake of ammonium by bacteria, and Y BOD2 Indicates the ratio of ammonium released by BOD degradation, UN p2 The coefficient representing the ammonium uptake by plants, UN b2 represents the coefficient of bacterial uptake of ammonium; HS_NH4 represents the half-saturated concentration of bacterial uptake of ammonium, mg NH4 / L; NO2 represents the concentration of nitrite, mg / L; nitri represents the conversion of nitrite to nitrate, θ5 represents the temperature coefficient of the conversion of nitrite to nitrate; NO3 represents the concentration of nitrate, mg / L; deni represents denitrification; K5 represents the rate of conversion of nitrite to nitrate at 20°C, 1 / day; K6 represents the rate of denitrification reaction at 20°C, 1 / day; θ6 represents the Arrhenius temperature coefficient of denitrification; PO4 represents the concentration of soluble phosphate, mg / L; bodp represents the concentration of phosphorus released by BOD degradation, mg / L; plantp represents the concentration of phosphorus taken up by plants, mg / L; bactp represents the concentration of phosphorus taken up by bacteria, mg / L; Y2 represents the phosphorus content in organic matter, mg P / mg_BOD; HS_PO4 represents the half-saturated phosphorus concentration of organic matter degradation / half-saturated phosphorus concentration of bacterial uptake, mg P / L; UP p Indicates the coefficient of plant phosphorus uptake, UP b represents the coefficient of phosphorus uptake by microorganisms; FC represents the degradation concentration of fecal coliform bacteria, mg / L; K dF represents the degradation coefficient of fecal coliform bacteria, 1 / day; C F Indicates the concentration of fecal coliform bacteria, 1 / 100ml; TC indicates the total degradation concentration of Escherichia coli, mg / L; K dT represents the degradation coefficient of total E. coli, 1 / day; C T represents the concentration of total E. coli, 1 / 100ml; R1 represents the photosynthetic respiration rate at 20℃, g O2 / m 2 / day; θ1 represents the Arrhenius temperature coefficient of plant respiration, F1(h) represents the light limitation function, and F(N, P) represents the nutrient limitation function of plant photosynthesis; I Z represents the solar radiation at depth Z below the water surface, I opt It represents the optimal light intensity for algae growth; I0 represents the solar radiation on the water surface, KW represents the extinction coefficient of all substances except algae, and KC represents the algae extinction coefficient factor.

7. The multi-trophic level habitat suitability assessment method based on hydrodynamic processes according to claim 1 is characterized in that: The distribution of chlorophyll concentration in the watershed is expressed as: Where: CHL represents the concentration of chlorophyll a in water, mg / L; prodCH represents the production concentration of chlorophyll a, mg / L; respCH represents the respiratory consumption concentration of chlorophyll a, mg / L; deathCH represents the degradation concentration of chlorophyll a, mg / L; sediCH represents the sedimentation concentration of chlorophyll a, mg / L; phtsyn represents photosynthesis; k 11 The carbon-oxygen mass ratio of primary productivity, mg carbon / mg oxygen; k 10 represents the mass ratio of chlorophyll a to carbon, mg CHL / mg carbon; F(N, P) represents the nutrient limitation function of plant photosynthesis, respT represents the oxygen content consumed by plant respiration, k8 represents the mortality rate of chlorophyll a, 1 / day; k9 represents the deposition rate of chlorophyll a, M / day; dz represents the depth of the water layer, m.

8. The multi-trophic level habitat suitability assessment method based on hydrodynamic processes according to claim 1 is characterized in that: When drawing the variation curve of emergent plant / submerged plant coverage under different water depth conditions in the basin, the relationship between coverage and water depth is set as a quadratic function, and the relationship between emergent plant / submerged plant coverage and water depth is expressed as: PBSI t (PBSI c )=ad 2 +bd+c Where: PBSI t (PBSI c ) represents the coverage of emergent plants / submerged plants in the basin, %; d represents the water depth, m; a, b, c are parameters calculated based on measured data.

9. The multi-trophic level habitat suitability assessment method based on hydrodynamic processes according to claim 1 is characterized in that: Constructing the fish suitability distribution curve includes the following steps: Collect the frequency of fish occurrence at different hydrodynamic conditions in the basin, including fish species and life stages, i.e. spawning period, migration period, feeding period, and wintering period; According to the HASTurges empirical formula, the number of groups and the size of the interval between groups of the frequency distribution of flow velocity and water depth are calculated respectively; The calculated maximum and minimum values ​​are used as the thresholds of each variable. The fitness of the group with the highest frequency distribution of fish is determined to be the best, with a value of 1. The ratio of the frequency of the remaining groups to the highest frequency group is the fitness of the group. The single-factor fitness curve function SI was constructed respectively, and the fitness index values ​​of flow velocity and water depth for multiple species of fish of different spawning types and different life stages were obtained. The fish suitability distribution curve was constructed, and the normal function expression of the curve was obtained: Where: hsi V represents the distribution suitability of fish to flow velocity, σ V represents the standard deviation of the fish distribution suitability curve for flow velocity; v represents flow velocity, m / s; u V The mean value of the fish distribution suitability curve for flow velocity, hsi D represents the distribution suitability of fish to water depth, σ D represents the standard deviation of the fish distribution suitability curve for water depth; d represents the water depth, m; u D Represents the mean of the fish distribution suitability curve for water depth.

10. The multi-trophic level habitat suitability assessment method based on hydrodynamic processes according to claim 1 is characterized in that: Assess the distribution of habitat suitability at each trophic level during different life cycles, specifically: Taking into account the hydrodynamic process and different habitat factors, an expression of habitat suitability for different spawning types of fish is constructed to simulate the distribution of fish habitat suitability: HSI p =hsi V ×hsi D ×(kchl×CHL) HSI n =hsi V ×hsi D ×(kchl×CHL)×(kpbsi t ×PBSI t ) HSI c =hsi V ×hsi D ×(kchl×CHL)×(kpbsi c ×PBSI c ) Where: HSI p Indicates the habitat suitability for floating spawning fish, HSI n Indicates the habitat suitability for fish that lay sticky eggs, HSI c represents the habitat suitability of fish that lay eggs; kchl represents the relationship between the distribution suitability of different species of fish and chlorophyll concentration; CHL represents the concentration of chlorophyll a in the water body, mg / L; kpbsi t The relationship between the distribution suitability of different fish species laying sticky eggs and the cover of emergent plants, kpbsi c Indicates the relationship between the distribution suitability of different species of fish that lay submerged eggs and the coverage of submerged plants; hsi V Indicates the distribution suitability of fish to flow velocity, hsi D Indicates the distribution suitability of fish to water depth, PBSI t Indicates the coverage of emergent plants in the watershed, PBSI c It indicates the coverage of submerged macrophytes in the watershed; Taking into account the germination, seedling, flowering and fruiting periods of emergent plants and submerged plants as well as the spawning, migration, foraging and overwintering periods of fish, the distribution of habitat suitability at each trophic level during different life cycles is analyzed and evaluated.

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