Quantitative evaluation method of the influence of watershed engineering and bay reclamation on water exchange capacity
Patent Information
- Application Number
- CN202611309451.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-27
- Publication Date
- 2026-10-27
AI Technical Summary
[0042]1、通过引入具体的模型验证标准，确保了水动力模拟的可靠性，为后续贡献度量化奠定了坚实的科学基础；同时，采用几何平均法计算半交换周期，有效消除了非结构网格非均匀性带来的计算偏差，使评价结果更能真实反映海湾整体的水交换能力。
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Figure CN122987394A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of computer processing technology, and in particular to a quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity. Background Technology
[0002] With the rapid economic development of coastal areas, human activities have had an increasingly significant impact on bay ecosystems. Large-scale water conservancy projects within the basin have significantly altered river runoff processes, reducing the input flux of freshwater and nutrients. Simultaneously, intensive land reclamation activities in coastal areas have directly changed the natural coastline morphology of bays, shrinking their water area. The combined effect of these two activities often leads to a decline in the bay's water exchange capacity, subsequently triggering a series of ecological and environmental problems such as eutrophication and frequent red tides.
[0003] Currently, the assessment methods for the impact on the water environment of the Gulf mainly suffer from the following technical limitations:
[0004] First, existing evaluations rely heavily on historical data and expert experience for qualitative descriptions, lacking objective quantitative indicators and making it difficult to distinguish the relative contributions of different human activities such as watershed engineering and bay reclamation.
[0005] Secondly, existing numerical simulation studies mostly focus on the effects of a single factor (such as considering only runoff changes or only shoreline changes), failing to effectively decouple the combined effects of multiple human activities.
[0006] Third, the evaluation indicators are relatively simple, often using indicators such as water exchange cycle or residence time, but lack an evaluation framework that can systematically quantify the proportion of contributions from different human activities, making it difficult to provide a direct and scientific basis for targeted ecological restoration decisions.
[0007] Therefore, how to scientifically and quantitatively separate and quantify the impact of water conservancy projects and bay reclamation activities on the bay's water exchange capacity is a technical problem that urgently needs to be solved in the field of marine environmental assessment and management. Summary of the Invention
[0008] To address the aforementioned technical problems, the present invention provides a quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity, the method comprising the following steps:
[0009] S01. Obtain runoff data of the target bay before / after the implementation of the watershed project and shoreline topography data before / after the reclamation of the bay; wherein, the runoff data is a representative runoff process determined by long-term series statistical analysis of the watershed control hydrological station, and the shoreline topography data is a high-precision digital elevation model reconstructed by multi-source remote sensing image interpretation and historical nautical chart data.
[0010] S02. Based on the acquired runoff data and shoreline topography data, construct and verify a three-dimensional numerical model that can simulate the hydrodynamic process of the target bay.
[0011] S03. Based on the aforementioned three-dimensional numerical model, by introducing a conservative tracer module, the initial concentration of the tracer in the waters inside the target bay is set to a first value, and the concentration of the tracer in the outer sea area is set to a second value, simulating the three-dimensional transport process of the tracer; the time required for the tracer concentration at each grid point in the target bay to first decrease from the first value to half of the first value is recorded as the local half-exchange time of that grid point, and the local half-exchange time of all grid points is geometrically averaged to obtain the average half-exchange period characterizing the overall water exchange capacity of the target bay; simulation calculations are performed for the following four scenarios to obtain the average half-exchange period under each scenario;
[0012] The four scenarios include:
[0013] Scenario 1: Using pre-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. natural =19.17 days;
[0014] The second scenario: using post-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. dam_only =18.71 days;
[0015] The third scenario: using pre-project runoff data and post-reclamation shoreline topography data, denoted as T. reclamation_only =17.89 days;
[0016] The fourth scenario: using post-engineering runoff data and post-reclamation shoreline topography data, denoted as T. combined =17.40 days;
[0017] S04. Based on the bay water half-exchange cycle under the four scenarios, calculate the change in water exchange capacity ΔT contributed solely by watershed engineering projects. combined =|T combined -T natural | Change in water exchange capacity ΔT solely contributed by Gulf reclamation dam =|T dam_only -T natural | and the change in water exchange capacity ΔT contributed solely by Gulf reclamation reclamation =|T reclamation_only -T natura l|, and then calculate the individual contribution ratio η of watershed engineering. dam =ΔT dam / (ΔT combined ), and the proportion of Gulf reclamation as a separate contributor η reclamation =ΔT reclamation / (ΔT combined ).
[0018] Preferably, the representative runoff process in step S01 is the annual average flow, monthly average flow, or flow process of a specific typical hydrological year before / after the implementation of the project.
[0019] Preferably, the three-dimensional numerical model constructed in step S02 is an unstructured mesh finite volume ocean model, whose open boundary tidal forcing is driven by the harmonic constants of the eight major tidal constituents M2, S2, N2, K2, K1, O1, P1, and Q1 obtained by assimilation from the global tidal model.
[0020] Preferably, when performing conservative tracer simulation in step S03, the model needs to be warm-started for more than 10 days to eliminate the influence of initial conditions, the time step is set to meet the CFL stability condition, and the total simulation time is more than twice the estimated half-exchange cycle.
[0021] Preferably, in step S03, when performing a geometric average of the local half-exchange time of the grid points, for non-uniform grids, the grid area or volume is used as the weight for weighted geometric average.
[0022] Preferably, step S04 further includes assessing the dominance of watershed engineering and bay reclamation on water exchange capacity based on a preset contribution ratio threshold.
[0023] As a preferred option, if η dam If the value is greater than the threshold, then the watershed engineering is determined to be the main influencing factor, and a decision recommendation to prioritize runoff scheduling optimization is generated.
[0024] If η reclamation If the value exceeds the threshold, then bay reclamation is determined to be the main influencing factor, and decision recommendations are generated to prioritize ecological restoration of the reclamation area or the addition of water exchange channels.
[0025] Preferably, the runoff data obtained in step S01 is long-term series monthly or daily average flow process data of the watershed control hydrological station.
[0026] The shoreline topographic data are high-precision digital elevation model data from different periods reconstructed through remote sensing image interpretation and historical nautical chart data.
[0027] Preferably, the three-dimensional numerical model constructed in step S02 is an unstructured mesh model, whose open-boundary tidal forcing is driven by the main tidal harmonic constants provided by the global or regional tidal model.
[0028] Preferably, the method further includes: calculating the impact of the interaction between watershed engineering and bay reclamation on water exchange capacity, the calculation formula being:
[0029] ;
[0030] In the formula:
[0031] C: Tracer concentration, in kg / m3 or mol / m3 (can be adjusted according to the actual unit);
[0032] D: Total water depth, representing the vertical depth of the water body from the surface to the bottom, in meters;
[0033] t: Time, representing the time variable of the simulation process, in seconds (s) or days (d).
[0034] U, v, ω: The components of the water flow velocity in the horizontal x and y directions and the vertical σ direction, in m / s;
[0035] Kh: Vertical eddy diffusion coefficient, characterizing the tracer's turbulent diffusion capability in the vertical direction, measured in meters. 2 / s;
[0036] Ah: Horizontal eddy diffusion coefficient, characterizing the tracer's turbulent diffusion capability in the horizontal direction, measured in meters. 2 / s;
[0037] The first partial derivative of tracer concentration C with respect to time t represents the rate of change of tracer concentration over time.
[0038] The first partial derivatives of tracer concentration C with respect to spatial coordinates x, y, and σ represent the gradients of tracer concentration in the corresponding spatial directions.
[0039] The partial derivative of the vertical diffusion flux of the tracer with respect to the σ coordinate characterizes the diffusion effect in the vertical direction.
[0040] The partial derivatives of the horizontal diffusion flux of the tracer with respect to the x and y coordinates characterize the horizontal diffusion effect.
[0041] The present invention has at least the following beneficial effects:
[0042] 1. By introducing specific model validation standards, the reliability of hydrodynamic simulation was ensured, laying a solid scientific foundation for subsequent contribution quantification. At the same time, the geometric mean method was used to calculate the half-exchange period, effectively eliminating the calculation bias caused by the non-uniformity of unstructured grids, making the evaluation results more realistically reflect the overall water exchange capacity of the bay.
[0043] 2. By introducing the calculation of interaction contributions, it is possible to identify the synergistic or antagonistic effects between watershed engineering and bay reclamation, two human activities. This approach breaks through the limitations of traditional single-factor or simple superposition analysis, providing a more refined analytical tool for understanding complex human-sea coupled systems. It helps to reveal nonlinear compound influence mechanisms, thus providing a more comprehensive and accurate scientific basis for bay ecological environment management. Attached Figure Description
[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0045] Figure 1 The flowchart illustrates a quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity, as provided in Embodiment 1 of the present invention. Detailed Implementation
[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0047] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.
[0048] Example 1
[0049] This embodiment provides a quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity. The method includes the following steps: Figure 1 As shown:
[0050] S01. Obtain runoff data of the target bay before / after the implementation of the watershed project and shoreline topography data before / after the reclamation of the bay; among which, the runoff data is a representative runoff process determined by long-term series statistical analysis of the watershed control hydrological station, and the shoreline topography data is a high-precision digital elevation model reconstructed by multi-source remote sensing image interpretation and historical nautical chart data.
[0051] Furthermore, the aforementioned representative runoff processes refer to the annual average flow, monthly average flow, or flow processes of a specific typical hydrological year before / after the implementation of the project.
[0052] Secondly, the runoff data obtained above are long-term series monthly or daily average flow process data from the watershed's key hydrological stations.
[0053] The shoreline topographic data consists of high-precision digital elevation models reconstructed from remote sensing image interpretation and historical nautical chart data from different periods.
[0054] Specifically, in terms of runoff data processing, the first step is to identify the main rivers flowing into the target bay and the key control hydrological stations within their basins. For example, the Datong Hydrological Station on the Yangtze River main stream can be selected as the runoff data source. This station controls a basin area of approximately 1.7 million square kilometers, accounting for over 94% of the total Yangtze River basin area, and its hydrological observation data can represent the runoff characteristics entering the estuary bay. By collecting daily flow observation data from this station over a period of 70 years, from 1950 to 2020, a long-term series database is formed. Based on this, statistical analysis and feature extraction are performed.
[0055] On the one hand, taking 2003, the year a certain reservoir project officially began impounding water, as the time node, the data sequence is divided into two periods: "before the project" (1950-2002) and "after the project" (2003-2020);
[0056] On the other hand, the multi-year average flow and monthly average flow process lines for the two periods are calculated respectively, and the flow process of typical hydrological years (such as high-water years, normal-water years, and low-water years) is selected as the representative runoff boundary based on hydrological frequency analysis.
[0057] For example, in a specific bay example, statistical analysis determined that the average annual inflow to the sea before the project was 37,342.5 m³ / s during the flood season, while after the project, the average annual inflow to the sea decreased to 18,253.7 m³ / s. This specific value serves as the quantitative boundary for subsequent scenario simulations. The underlying principle is that the impact of large-scale water conservancy projects on downstream runoff is statistically significant. Through long-term series comparative analysis, interannual natural fluctuations can be filtered out, and the "net effect" characteristics of the project's impact can be extracted, thus providing scientific input for quantitative assessment.
[0058] S02. Based on the acquired runoff data and shoreline topographic data, construct and validate a three-dimensional numerical model that can simulate the hydrodynamic processes of the target bay.
[0059] Furthermore, the three-dimensional numerical model constructed in the embodiment is a finite volume ocean model with an unstructured mesh, and its open boundary tidal forcing is driven by the harmonic constants of the eight major tidal constituents M2, S2, N2, K2, K1, O1, P1, and Q1 obtained by assimilation from the global tidal model.
[0060] Secondly, the constructed three-dimensional numerical model is an unstructured mesh model, and its open-boundary tidal forcing is driven by the main tidal harmonic constants provided by the global or regional tidal model.
[0061] Specifically, finite volume ocean models based on unstructured meshes (such as FVCOM, or Finite-Volume Coastal Ocean Model) are employed. The core advantage of unstructured meshes lies in their geometric flexibility, allowing the computational domain to be discretized using triangular or quadrilateral meshes of varying sizes. -1 In key areas of interest, such as the main channel of Hangzhou Bay, the edges of reclaimed areas, or near complex coastlines, the mesh can be locally refined (e.g., to 100-200 meters) to accurately fit the meandering coastline and capture drastically changing hydrodynamic gradients. In flat areas such as the open sea, a coarser mesh (e.g., 500 meters) can be used to effectively control the overall computational load while maintaining computational accuracy. The finite volume law ensures strict conservation of momentum and mass throughout the computational domain by directly solving the integral equations describing fluid motion (e.g., the three-dimensional shallow water equations) for each mesh cell. This is crucial for this invention, which requires precise tracking of the transport of conservative substances (tracers).
[0062] Tidal forcing is applied at the open boundary of the model (i.e., the boundary connecting the model to the open sea). This is achieved by utilizing data provided by a high-precision global tidal model (such as the TPXO series models). Using tools such as OTPS (OSU Tidal Prediction Software), the harmonic constants (i.e., amplitude and lag angle) of the eight principal tidal constituents (M2, S2, N2, K2, K1, O1, P1, Q1) at each grid node on the open boundary of the model can be extracted from the TPXO model. These harmonic constants, as known forcing terms, are used to calculate and update the water level changes at each moment on the open boundary during model operation, thus correctly inputting the tidal energy from the open sea into the model. The basic principle of model operation is: driven by given initial and boundary conditions (including the tides at the open boundary, the runoff at the river boundary, and the wind field at the sea surface), the water level, velocity, and direction at each grid point in the computational domain at different times are calculated by solving the Navier-Stokes equations. For example, the model uses the M2 harmonic constant provided by TPXO to generate a tidal wave with a period of about 12.42 hours on the open boundary. This wave propagates into the bay and interacts with the runoff from the Yangtze River and the complex topography to jointly shape the complex tidal field in Hangzhou Bay.
[0063] Finally, in the model validation phase, to ensure that the model can accurately represent the real physical world, it is necessary to quantitatively compare the simulation results with synchronous field observation data.
[0064] S03. Based on a three-dimensional numerical model, by introducing a conservative tracer module, the initial concentration of tracer in the waters inside the target bay is set to a first value, and the concentration of tracer in the outer sea area is set to a second value, simulating the three-dimensional transport process of the tracer; the time required for the tracer concentration at each grid point in the target bay to first decrease from the first value to half of the first value is recorded as the local half-exchange time of that grid point, and the local half-exchange time of all grid points is geometrically averaged to obtain the average half-exchange period characterizing the overall water exchange capacity of the target bay; simulation calculations are performed for the following four scenarios to obtain the average half-exchange period under each scenario;
[0065] The four scenarios include:
[0066] Scenario 1: Using pre-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. natural =19.17 days;
[0067] The second scenario: using post-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. dam_only =18.71 days;
[0068] The third scenario: using pre-project runoff data and post-reclamation shoreline topography data, denoted as T.reclamation_only =17.89 days;
[0069] The fourth scenario: using post-engineering runoff data and post-reclamation shoreline topography data, denoted as T. combined =17.40 days.
[0070] The formula for calculating the impact of the interaction between watershed engineering and bay reclamation on water exchange capacity is as follows:
[0071] ;
[0072] In the formula:
[0073] C: Tracer concentration, in kg / m3 or mol / m3 (can be adjusted according to the actual unit);
[0074] D: Total water depth, representing the vertical depth of the water body from the surface to the bottom, in meters;
[0075] t: Time, representing the time variable of the simulation process, in seconds (s) or days (d).
[0076] U, v, ω: The components of the water flow velocity in the horizontal x and y directions and the vertical σ direction, in m / s;
[0077] Kh: Vertical eddy diffusion coefficient, characterizing the tracer's turbulent diffusion capability in the vertical direction, measured in meters. 2 / s;
[0078] Ah: Horizontal eddy diffusion coefficient, characterizing the tracer's turbulent diffusion capability in the horizontal direction, measured in meters. 2 / s;
[0079] The first partial derivative of tracer concentration C with respect to time t represents the rate of change of tracer concentration over time.
[0080] The first partial derivatives of tracer concentration C with respect to spatial coordinates x, y, and σ represent the gradients of tracer concentration in the corresponding spatial directions.
[0081] The partial derivative of the vertical diffusion flux of the tracer with respect to the σ coordinate characterizes the diffusion effect in the vertical direction.
[0082] The partial derivatives of the horizontal diffusion flux of the tracer with respect to the x and y coordinates characterize the horizontal diffusion effect.
[0083] Secondly, in the above embodiments, when performing conservative tracer simulation, a model hot start of more than 10 days is required to eliminate the influence of initial conditions. The time step is set to meet the CFL stability condition, and the total simulation time is more than twice the estimated half-exchange cycle.
[0084] Furthermore, in the embodiment, when performing geometric averaging on the local half-exchange time of grid points, for non-uniform grids, the grid area or volume is used as the weight for weighted geometric averaging.
[0085] Specifically, the embodiment uses FVCOM's dye module to solve the tracer transport equation, taking into account the advection and diffusion effects of the three-dimensional hydrodynamic field on the tracer.
[0086] Simulation setup: The model undergoes a 10-day warm-start to eliminate the influence of initial conditions, followed by a 40-day formal simulation. The time step is set to 30 seconds to ensure stable CFL conditions.
[0087] Half-exchange cycle calculation: Monitor the tracer concentration decay process at each grid point in the bay, record the time it takes for the concentration at each grid point to drop to 0.5, and calculate the average half-exchange cycle of the entire bay by geometric mean.
[0088] Results of the four-scenario simulation:
[0089] Scenario 1 (Before Construction + Before Reclamation): T natural =19.17 days
[0090] Scenario 2 (Post-construction + Pre-reclamation): T dam_only =18.71 days
[0091] Scenario 3 (Before Project + After Reclamation): T reclamation_only =17.89 days
[0092] Scenario 4 (Post-construction + Post-reclamation): T combined =17.40 days
[0093] Measuring the contribution of water exchange capacity
[0094] Calculate the changes in water exchange capacity under the combined effects:
[0095] ΔT combined =|17.40-19.17|=1.77 days
[0096] Calculate the change in water exchange capacity contributed solely by watershed engineering projects:
[0097] ΔT dam =|18.71-19.17|=0.46 days
[0098] Calculate the change in water exchange capacity contributed solely by bay reclamation:
[0099] ΔT reclamation =|17.89-19.17|=1.28 days
[0100] Calculate the contribution ratio:
[0101] Watershed engineering's individual contribution ratio: η dam =0.46 / 1.77=26.0%
[0102] Gulf reclamation's individual contribution percentage: η reclamation =1.28 / 1.77=72.3%
[0103] Impact Assessment and Decision-Making. With a threshold of 50%, calculations show that reclamation activities in the bay are the dominant factor contributing to the decline in water exchange capacity of Hangzhou Bay (72.3% > 30%), and ecological restoration of the reclamation areas should be prioritized.
[0104] S04. Based on the bay water half-exchange cycle under four scenarios, calculate the change in water exchange capacity ΔT contributed solely by watershed engineering projects. combined =|T combined -T natural | Change in water exchange capacity ΔT solely contributed by Gulf reclamation dam =|T dam_only -T natural | and the change in water exchange capacity ΔT contributed solely by Gulf reclamation reclamation =|T reclamation_only -T natura l|, and then calculate the individual contribution ratio η of watershed engineering. dam =ΔT dam / (ΔT combined ), and the proportion of Gulf reclamation as a separate contributor η reclamation =ΔT reclamation / (ΔT combined ).
[0105] Furthermore, the embodiment assesses the dominance of watershed engineering and bay reclamation on water exchange capacity based on a preset contribution ratio threshold, i.e., if η dam If the value is greater than the threshold, then the watershed engineering is determined to be the main influencing factor, and decision recommendations for prioritizing runoff scheduling optimization are generated.
[0106] If η reclamation If the value exceeds the threshold, then bay reclamation is determined to be the main influencing factor, and decision recommendations are generated to prioritize ecological restoration of the reclamation area or the addition of water exchange channels.
[0107] In actual operation, the system presets a contribution ratio threshold (usually set to 50%), which represents the critical point at which a factor becomes the dominant influencing factor. The calculated η... dam and ηreclamation Compare with this threshold: if η dam If the value is greater than the threshold, the system determines that watershed engineering is the primary cause of changes in the bay's water exchange capacity. In this case, the system automatically generates decision recommendations prioritizing optimization of watershed runoff scheduling. For example, it might suggest increasing reservoir discharge during ecologically sensitive periods, simulating natural flood peaks, or optimizing water replenishment plans during dry seasons, aiming to improve water exchange in the bay by restoring runoff dynamics. Conversely, if η is less than the threshold... reclamation If the value exceeds the threshold, the system will determine that bay reclamation is the dominant factor and generate decision recommendations to prioritize ecological restoration of the reclamation area. For example, it may recommend demolishing some inefficient reclamation areas to restore water area, opening artificial tidal channels in the reclamation area to enhance water connectivity, or carrying out ecological transformation of the existing reclamation structure to reduce water obstruction.
[0108] Example 2
[0109] This invention provides a non-transitory computer-readable storage medium storing at least one instruction or at least one program segment, which is loaded and executed by a processor to implement the following steps:
[0110] Acquire runoff data of the target bay before / after the implementation of watershed engineering and shoreline topography data before / after bay reclamation; among which, the runoff data are representative runoff processes determined by long-term series statistical analysis of watershed control hydrological stations, and the shoreline topography data are high-precision digital elevation models reconstructed by multi-source remote sensing image interpretation and historical nautical chart data.
[0111] Based on the acquired runoff and shoreline topography data, a three-dimensional numerical model capable of simulating the hydrodynamic processes of the target bay was constructed and validated.
[0112] Based on a three-dimensional numerical model, by introducing a conservative tracer module, the initial concentration of tracer in the waters inside the target bay is set to a first value, and the concentration of tracer in the outer sea area is set to a second value, simulating the three-dimensional transport process of the tracer. The time required for the tracer concentration at each grid point in the target bay to first decrease from the first value to half of the first value is recorded as the local half-exchange time of that grid point. The local half-exchange time of all grid points is geometrically averaged to obtain the average half-exchange period, which characterizes the overall water exchange capacity of the target bay. Simulation calculations are performed for the following four scenarios to obtain the average half-exchange period under each scenario.
[0113] The four scenarios include:
[0114] Scenario 1: Using pre-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. natural =19.17 days;
[0115] The second scenario: using post-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. dam_only =18.71 days;
[0116] The third scenario: using pre-project runoff data and post-reclamation shoreline topography data, denoted as T. reclamation_only =17.89 days;
[0117] The fourth scenario: using post-engineering runoff data and post-reclamation shoreline topography data, denoted as T. combined =17.40 days;
[0118] Based on the bay water half-exchange cycle under four scenarios, the change in water exchange capacity ΔT contributed solely by watershed engineering projects was calculated. combined =|T combined -T natural | Change in water exchange capacity ΔT solely contributed by Gulf reclamation dam =|T dam_only -T natural | and the change in water exchange capacity ΔT contributed solely by Gulf reclamation reclamation =|T reclamation_only -T natura l|, and then calculate the individual contribution ratio η of watershed engineering. dam =ΔT dam / (ΔT combined ), and the proportion of Gulf reclamation as a separate contributor η reclamation =ΔT reclamation / (ΔT combined ).
[0119] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.
[0120] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.
[0121] Example 3
[0122] This invention provides an electronic device, including a processor and a memory, wherein the memory stores at least one instruction or at least one program segment, and the at least one instruction or the at least one program segment is loaded and executed by the processor to implement the following steps:
[0123] Acquire runoff data of the target bay before / after the implementation of watershed engineering and shoreline topography data before / after bay reclamation; among which, the runoff data are representative runoff processes determined by long-term series statistical analysis of watershed control hydrological stations, and the shoreline topography data are high-precision digital elevation models reconstructed by multi-source remote sensing image interpretation and historical nautical chart data.
[0124] Based on the acquired runoff and shoreline topography data, a three-dimensional numerical model capable of simulating the hydrodynamic processes of the target bay was constructed and validated.
[0125] Based on a three-dimensional numerical model, by introducing a conservative tracer module, the initial concentration of tracer in the waters inside the target bay is set to a first value, and the concentration of tracer in the outer sea area is set to a second value, simulating the three-dimensional transport process of the tracer. The time required for the tracer concentration at each grid point in the target bay to first decrease from the first value to half of the first value is recorded as the local half-exchange time of that grid point. The local half-exchange time of all grid points is geometrically averaged to obtain the average half-exchange period, which characterizes the overall water exchange capacity of the target bay. Simulation calculations are performed for the following four scenarios to obtain the average half-exchange period under each scenario.
[0126] The four scenarios include:
[0127] Scenario 1: Using pre-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. natural =19.17 days;
[0128] The second scenario: using post-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. dam_only =18.71 days;
[0129] The third scenario: using pre-project runoff data and post-reclamation shoreline topography data, denoted as T. reclamation_only =17.89 days;
[0130] The fourth scenario: using post-engineering runoff data and post-reclamation shoreline topography data, denoted as T. combined =17.40 days;
[0131] Based on the bay water half-exchange cycle under four scenarios, the change in water exchange capacity ΔT contributed solely by watershed engineering projects was calculated. combined =|T combined -T natural | Change in water exchange capacity ΔT solely contributed by Gulf reclamation dam =|T dam_only -T natural | and the change in water exchange capacity ΔT contributed solely by Gulf reclamation reclamation =|T reclamation_only -T natura l|, and then calculate the individual contribution ratio η of watershed engineering. dam =ΔT dam / (ΔT combined ), and the proportion of Gulf reclamation as a separate contributor η reclamation =ΔT reclamation / (ΔT combined ).
[0132] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity, characterized in that, The method includes the following steps: S01. Obtain runoff data of the target bay before / after the implementation of the watershed project and shoreline topography data before / after the reclamation of the bay; wherein, the runoff data is a representative runoff process determined by long-term series statistical analysis of the watershed control hydrological station, and the shoreline topography data is a high-precision digital elevation model reconstructed by multi-source remote sensing image interpretation and historical nautical chart data. S02. Based on the acquired runoff data and shoreline topography data, construct and verify a three-dimensional numerical model that can simulate the hydrodynamic process of the target bay. S03. Based on the aforementioned three-dimensional numerical model, by introducing a conservative tracer module, the initial concentration of the tracer in the waters inside the target bay is set to a first value, and the concentration of the tracer in the outer sea area is set to a second value, simulating the three-dimensional transport process of the tracer; the time required for the tracer concentration at each grid point in the target bay to first decrease from the first value to half of the first value is recorded as the local half-exchange time of that grid point, and the local half-exchange time of all grid points is geometrically averaged to obtain the average half-exchange period characterizing the overall water exchange capacity of the target bay; simulation calculations are performed for the following four scenarios to obtain the average half-exchange period under each scenario; The four scenarios include: Scenario 1: Using pre-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. natural =19.17 days; The second scenario: using post-engineering runoff data and pre-reclamation shoreline topography data, denoted as T. dam_only =18.71 days; The third scenario: using pre-project runoff data and post-reclamation shoreline topography data, denoted as T. reclamation_only =17.89 days; The fourth scenario: using post-engineering runoff data and post-reclamation shoreline topography data, denoted as T. combined =17.40 days; S04. Based on the bay water half-exchange cycle under the four scenarios, calculate the change in water exchange capacity contributed solely by watershed engineering projects. Changes in water exchange capacity contributed solely by bay reclamation Changes in water exchange capacity contributed solely by Gulf reclamation Then calculate the individual contribution ratio of watershed engineering. and the proportion of contributions made solely by Gulf reclamation .
2. The quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity according to claim 1, characterized in that, The representative runoff process mentioned in step S01 is the annual average flow, monthly average flow, or flow process of a specific typical hydrological year before / after the implementation of the project.
3. The quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity according to claim 1, characterized in that, The three-dimensional numerical model constructed in step S02 is an unstructured mesh finite volume ocean model, whose open boundary tidal forcing is driven by the harmonic constants of the eight major tidal constituents M2, S2, N2, K2, K1, O1, P1, and Q1 obtained by assimilation from the global tidal model.
4. The quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity according to claim 1, characterized in that, When performing conservative tracer simulation in step S03, the model needs to be warmed up for more than 10 days to eliminate the influence of initial conditions. The time step is set to meet the CFL stability condition, and the total simulation time is more than twice the estimated half-exchange cycle.
5. The quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity according to claim 4, characterized in that, In step S03, when performing a geometric mean on the local half-exchange time of the grid points, for non-uniform grids, the grid area or volume is used as the weight for weighted geometric mean.
6. The quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity according to claim 1, characterized in that, Step S04 further includes assessing the dominance of watershed engineering and bay reclamation on water exchange capacity based on a preset contribution ratio threshold.
7. The quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity according to claim 6, characterized in that, If η dam If the value is greater than the threshold, then the watershed engineering is determined to be the main influencing factor, and a decision recommendation to prioritize runoff scheduling optimization is generated. If η reclamation If the value exceeds the threshold, then bay reclamation is determined to be the main influencing factor, and decision recommendations are generated to prioritize ecological restoration of the reclamation area or the addition of water exchange channels.
8. The quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity according to claim 1, characterized in that, The runoff data obtained in step S01 is the long-term series monthly or daily average flow process data of the watershed control hydrological station. The shoreline topographic data are high-precision digital elevation model data from different periods reconstructed through remote sensing image interpretation and historical nautical chart data.
9. The quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity according to claim 1, characterized in that, The three-dimensional numerical model constructed in step S02 is an unstructured mesh model, whose open-boundary tidal forcing is driven by the main tidal harmonic constants provided by the global or regional tidal model.
10. The quantitative evaluation method for the impact of watershed engineering and bay reclamation on water exchange capacity according to claim 1, characterized in that, The method further includes: calculating the impact of the interaction between watershed engineering and bay reclamation on water exchange capacity, the calculation formula of which is: ； In the formula: C: Tracer concentration, in kg / m3 or mol / m3 (can be adjusted according to the actual unit); D: Total water depth, representing the vertical depth of the water body from the surface to the bottom, in meters; t: Time, representing the time variable of the simulation process, in seconds (s) or days (d). U, v, ω: The components of the water flow velocity in the horizontal x and y directions and the vertical σ direction, in m / s; Kh: Vertical eddy diffusion coefficient, characterizing the tracer's turbulent diffusion capability in the vertical direction, measured in meters. 2 / s; Ah: Horizontal eddy diffusion coefficient, characterizing the tracer's turbulent diffusion capability in the horizontal direction, measured in meters. 2 / s; The first partial derivative of tracer concentration C with respect to time t represents the rate of change of tracer concentration over time. The first partial derivatives of tracer concentration C with respect to spatial coordinates x, y, and σ represent the gradients of tracer concentration in the corresponding spatial directions. The partial derivative of the vertical diffusion flux of the tracer with respect to the σ coordinate characterizes the diffusion effect in the vertical direction. The partial derivatives of the horizontal diffusion flux of the tracer with respect to the x and y coordinates characterize the horizontal diffusion effect.