Method for regulating and controlling water and sand of harbor branch by utilizing estuary branch sluice
By using the river estuary branch gate for water flow regulation, the problem of imbalance in the evolution of the river estuary port in the branch estuary is solved, the hydrodynamic conditions and riverbed silt are improved, and the healthy development of the river situation is promoted.
Patent Information
- Application Number
- CN202510072475.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-17
- Publication Date
- 2025-05-06
AI Technical Summary
The evolution of ports in sub-shaped estuaries is imbalanced, resulting in adverse effects on river development, flood control, shipping, ecology, etc. The existing governance measures such as Dingshunba and siltation dredging have problems with silting and local hydraulic erosion.
By using existing river gates at the estuary branch to regulate water flow, medium dry water and small and medium flood control, the runoff flood discharged upstream enters the port where there is insufficient water power or river silt, strengthen the weak water and sand power, and improve the evolution of the port.
It has improved the hydrodynamic conditions and changes in riverbed siltation in the port bank, promoted the development of river waves in a favorable direction, alleviated the problems of riverbed erosion and siltation, and improved the adaptability of the evolutionary form of the port bank.
Smart Images
Figure CN119933076A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for regulating water and sediment in a branching harbor by utilizing a river mouth branching gate, and belongs to the technical field of water conservancy and hydropower engineering. Background Art
[0002] Natural water flow and sediment movement and human activities can change the river morphology and cause river channel evolution; multi-branched estuaries in developed coastal areas are affected by runoff floods, tides, human river activities, etc., and their branch evolution is particularly complex. For branched rivers, changes in the distribution of water flow and sediment often cause different rise and fall changes in each branch. Some branches may gradually erode and expand due to increased water flow, while other branches may gradually shrink due to reduced water flow. When this kind of branch evolution is not suitable for the development of the national economy, it is often necessary to implement branch management projects. According to different management purposes, common management measures for bifurcated rivers include: (1) Fixation of bifurcated channels, i.e. engineering measures to fix or stabilize bifurcated channels, mainly by building management buildings at upstream nodes, bifurcated channel entrances, and the head and tail of river islands; the engineering measures commonly used for node control and stabilization of bifurcated channels are smooth revetments; the engineering measures at the head and tail of river islands are usually to build upper and lower dikes respectively. (2) Improvement of bifurcated channels, including adjusting water flow and adjusting riverbed, the former such as building spur dams or spur dikes, the latter such as dredging or blasting. (3) Blockage of bifurcated channels, mainly refers to blocking bifurcated channels (blocking bifurcated channels to strengthen the main channel), often considering the requirements for navigation of bifurcated channels, intentionally silting up or blocking a bifurcated channel, and the common engineering measure is to build a lock dam. For the channel regulation scheme aimed at improving the channel relationship, the common construction of Dingshun Dam regulation structure usually requires regular maintenance of Dingshun Dam. In addition, due to the complex evolution of water and sediment at the branch estuary, the Dingshun Dam regulation scheme often cannot adapt well to the changes in river boundary conditions and is prone to local hydraulic scour problems; while dredging or blasting measures often have siltation problems. Therefore, for rivers with dams at the branch estuaries, the water and sediment regulation potential of the dams at the branch estuaries should be fully tapped, and the water and sediment regulation of the estuary ports should be carried out through the regulation of the dams at the branch estuaries to achieve the goal of improving the channel relationship.
[0003] For the management of bifurcated rivers with the purpose of improving the relationship between branches, the common management scheme is to build Dingshun Dam at the bifurcated mouth or to dredge the branch channel. The present invention proposes to regulate the water flow through the bifurcated mouth dam to improve the hydrodynamic conditions of the branch channel, thereby achieving the management goal of improving the relationship between branches. Summary of the invention
[0004] In view of the shortcomings of the prior art, the present invention provides a method for regulating water and sediment in a branching harbor by using an estuary branching gate, comprising the following steps: (1) Conducting analysis on the evolution of estuaries and river channels Collect data on the topography, geology, hydrology, sediment, river-related construction, operation and management of major water projects, river sand mining, river (waterway) regulation, and previous research results of the river estuaries, analyze the evolution process, characteristics and causes of the river channels at the estuaries and branches, and predict the future evolution trend of the river channels at the estuaries and branches based on the changes in the main influencing factors that cause riverbed evolution; (2) Establish a mathematical model of hydrodynamic sediment in estuaries and conduct model verification and calibration Using basic data such as topography, hydrology, sediment, and major river-related structures, a two-dimensional hydrodynamic sediment mathematical model of estuaries and branches was established based on the Mike21 water flow and sediment numerical simulation analysis software, and the model was verified using the hydrological, sediment data and topographic change data measured at the hydrological station. (3) Simulation and analysis of sediment movement in estuaries and harbors Using the verified two-dimensional hydrodynamic sediment mathematical model of estuaries and harbors, simulate the flow and sediment movement of estuaries and harbors under typical runoff, flood and tidal combined conditions, analyze the dynamic characteristics of flood and tidal currents in estuaries and harbors, as well as the laws of sediment transport and riverbed scouring and deposition; (4) Analyze whether there are water and sediment problems in the estuaries and their adverse effects on the development of the river and the health and safety of the river. Based on the needs of estuaries and branches for flood and tide prevention, shipping, ecological environment, and safety of major water-related projects on the evolution and development of river regimes, combined with the river regime characteristics, evolution characteristics and trends of estuaries and branches, numerical simulation results of water flow movement and riverbed scouring and siltation changes, as well as on-site field investigations and surveys of estuaries and branches and historical flood and tidal flow characteristics, this paper analyzes whether there are water and sediment problems in estuaries and branches and their adverse effects.
[0005] (5) Propose a preliminary plan and idea for using the existing dam gates at the river mouth to control water and sediment in the river estuary Based on the analysis of the water and sediment problems and regulation needs in estuaries and branches, a water and sediment regulation plan for estuaries and branches is proposed; the general regulation idea is to fully tap the water and sediment regulation potential of the branch dams and the river without affecting flood control and taking into account the downstream ecological needs, and to regulate low water and small floods through the dispatching of the branch dams, so that as much runoff and flood water from the upstream as possible can enter the branches with insufficient water power or significant siltation and decline in the river channel, enhance the water and sediment dynamics of weak branches, improve the evolution of branches and branches, and promote the healthy development of the river; (6) Combined with numerical simulation and analysis, determine the maximum flood flow Qmax that can be regulated The maximum flood that can be regulated is determined based on the maximum water level allowed by the sluice gate and the safe discharge flow allowed in the downstream river, combined with numerical simulation and trial analysis; it is necessary to control the maximum flood level H on the gate during flood regulation not to exceed the designed maximum water level Z on the gate, that is, H≤Z, and to control the discharge flow Q of the fully opened branch gate after regulation not to exceed the safe discharge flow Q allowed by the branch gate 允 , that is, Q≤Q 允 ; (7) Simulate and compare the movement of water and sediment before and after regulation to evaluate the effectiveness of using estuary diversion gates to regulate water and sediment Using the two-dimensional hydrodynamic and sediment mathematical model of the estuary, numerical simulation of water flow and sediment under typical flood and tidal conditions was carried out before and after the implementation of the branch gate control scheme. By comparing the changes in hydrodynamics and riverbed scouring and siltation in the estuary before and after the implementation of the control scheme, the effect of water and sediment control using the estuary branch gate was analyzed and evaluated.
[0006] Preferably, the mathematical model based on Mike21 software in step (2) is based on the Navier-Stokes equations with incompressibility and uniform distribution of Reynolds values, and is subject to the Boussinesq assumption and the assumption of hydrostatic pressure; The two-dimensional non-steady shallow water equations are: Formula 1: ; Formula 2: ; Formula 3: ; Where: For time; is the Cartesian coordinate system coordinate; is the water level; is the still water depth; is the total water depth; They are The velocity component in the direction; is the Coriolis force coefficient, , is the Earth's rotation angular velocity, is the local latitude; is the acceleration due to gravity; is the density of water; are the radiation stress components respectively; is the horizontal viscous stress term, is the source-sink term, is the water flow velocity of the source and sink.
[0007] Preferably, in step (2), the model adopts an unstructured triangular grid, and the grid size is comprehensively determined based on the accuracy of the modeled topographic map, the degree of terrain undulation, the size of important river-related structures, etc. The grid size should be equivalent to the interval of elevation measurement points in the modeled topographic mapping. The local grid in the area where the terrain undulation is drastic and important river-related structures are located should be encrypted, and the scale of the encrypted grid should be equivalent to the scale of the river-related structures. The model roughness can refer to Tables 8-1-4 to 8-1-6 of the "Hydraulic Calculation Manual (Second Edition)" compiled by the School of Water Resources and Hydropower Engineering of Wuhan University, and is preliminarily given based on the river channel type, riverbed morphology, riverbed composition, distribution of river-related structures, etc., and is finally determined through model verification and adjustment. The upper boundary of the model is set at the section of each river hydrological station, and the upper boundary adopts the flow rate. The lower boundary of the model is set at the section where the hydrological station or tidal station is located after the confluence of the estuary and branch, and the lower boundary adopts the water level.
[0008] Preferably, the mathematical model verification in step (2) is divided into hydrodynamic model verification and sediment model verification. The hydrodynamic model verification includes water (tide) level verification, flow velocity verification, and flow direction verification. The sediment model verification includes verification of the sediment content process and bed scouring and silting changes. The verification accuracy should meet the relevant provisions of the Technical Specifications for Simulation Tests of Water Transport Engineering JTS-T231-2021.
[0009] Preferably, in step (4), when the evolution of the estuary is unbalanced, as manifested in that some estuaries are seriously deepened and the diversion ratio continues to increase, threatening the safety of flood control and tide prevention or bringing scouring risks to water-related projects such as bridges, river-crossing pipelines, and embankments, or some estuaries are seriously silted up, the diversion ratio continues to decrease, flood discharge and tide intake are not smooth, or navigation is affected, and the river flow develops in an unfavorable direction, it is considered that the estuary estuary has a serious water and sediment problem, and measures need to be taken to improve the channel relationship.
[0010] Preferably, in step (6), a mathematical model is first used to calculate the highest water level before the gate under different flow conditions of upstream discharge after the implementation of the branch gate control scheme, and a flow-water level relationship line Q0~H between the discharge flow Q0 and the highest water level H on the gate is established. Then, according to the flow-water level relationship on the gate, when H=Z, the corresponding discharge flow Q0' is the maximum discharge flow that satisfies the highest flood level H on the gate not exceeding the designed highest water level Z on the gate during the sluice gate control; finally, it is checked whether Q0' exceeds the safe discharge flow Q 允 , if Q0'≤Q 允 , then Qmax=Q0'; if Q0'>Q 允 , then Q 允 That is the maximum downstream flow Qmax that can be regulated.
[0011] Preferably, for safety reasons, when calculating the maximum flow rate Qmax that can be regulated, the branch gate scheduling method is: the gate of the weir on the side of the branch with insufficient water power is fully opened to discharge flood water, and the gates of the other branch gates are fully closed.
[0012] Preferably, each component gate of the branch gate allows safe discharge flow Q 允 Determined according to the flood control standards of the downstream river.
[0013] Preferably, the comparison of hydrodynamic changes in step (7) includes comparison of flow rates, characteristic water levels of sections, and characteristic flow velocities of sections of each branch before and after the implementation of the weir control scheme; the comparison of riverbed scouring and siltation changes is comparison of average scouring and siltation values of each branch before and after the implementation of the weir control scheme; after the implementation of the control scheme, when the flow rate and flow velocity of branches that originally had insufficient hydrodynamics significantly increase, and the overall siltation is weakened or the overall siltation is transformed into overall scouring, it is considered that a better water and sediment control effect has been achieved.
[0014] Aiming at the problem that the imbalance of evolution of bifurcated estuaries (two or more branches) has an adverse impact on river health and safety such as river development, flood control, shipping, and ecology, the present invention proposes a method of using the existing dam facilities at the bifurcated estuaries to regulate low water and small and medium-sized floods in the estuary branches, thereby improving the hydrodynamic conditions of the estuary branches and the changes in riverbed scouring and silting, and promoting the development of the river in a favorable direction. Compared with traditional measures such as building Dingshun dams or dredging channels at bifurcated estuaries, the present invention proposes to regulate water flow through bifurcated estuaries dams to improve the hydrodynamic conditions of channels, thereby achieving the management goal of improving the relationship between channels. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 Schematic diagram of a river channel with a dam built at the branch mouth Figure 2 It is the flow-water level relationship line diagram between the discharge flow Q0 and the highest water level H on the gate; Figure 3 This is the water level change diagram of the branch 1 before and after the branch gate regulates the upstream water flow of 3780m³ / s; Figure 4 This is the water level change diagram of Branch 2 before and after the branch gate regulates the upstream water flow of 3780m³ / s; Figure 5 This is the average flow velocity change diagram of the 1st section of the harbor before and after the branch gate regulates the upstream water flow of 3780m³ / s; Figure 6 This is the average flow velocity change diagram of the 2nd section of the harbor before and after the branch gate regulates the upstream water flow of 3780m³ / s; Figure 7 This is a graph showing the average flow velocity changes in the three sections of the harbor before and after the branch gate regulates the upstream water flow of 3780m³ / s. DETAILED DESCRIPTION
[0016] The present invention is described in detail below in conjunction with the accompanying drawings. Example 1
[0017] The method for regulating water and sediment in a branching harbor by using a branching sluice at an estuary according to the present invention comprises the following steps: (1) Conducting analysis on the evolution of estuaries and river channels Collect information on the topography, geology, hydrology, sediment, river-related construction, operation and management of major water projects, river sand mining, river (waterway) regulation, and previous related research results of the river estuaries, analyze the evolution process, characteristics and causes of the river channels at the estuaries and branches, and predict the future evolution trend of the river channels at the estuaries and branches based on the changes in the main influencing factors that cause riverbed evolution.
[0018] (2) Establish a mathematical model of hydrodynamics and sedimentation in estuaries and harbors and conduct model verification and calibration.
[0019] Using basic data such as topography, hydrology, sediment, and major river-related structures, a two-dimensional hydrodynamic and sediment mathematical model of estuaries and branches was established based on the Mike21 water flow and sediment numerical simulation analysis software. The model was verified using the hydrological, sediment and topographic change data measured at the hydrological station.
[0020] The mathematical model based on Mike21 software is based on the Navier-Stokes equations with incompressibility and uniform distribution of Reynolds values, and is subject to the Boussinesq assumption and the assumption of hydrostatic pressure.
[0021] The two-dimensional non-steady shallow water equations are: (Formula 1) (Formula 2) (Formula 3) Where: For time; is the Cartesian coordinate system coordinate; is the water level; is the still water depth; is the total water depth; They are The velocity component in the direction; is the Coriolis force coefficient, , is the Earth's rotation angular velocity, is the local latitude; is the acceleration due to gravity; is the density of water; are the radiation stress components respectively; is the horizontal viscous stress term, is the source-sink term, is the water flow velocity of the source and sink.
[0022] The model uses unstructured triangular grids, and the grid size is determined comprehensively based on the accuracy of the modeled topographic map, the degree of terrain undulation, and the size of important river-related structures. The grid size should be equivalent to the interval of the elevation measurement points of the modeled topographic map. The local grids in areas with drastic terrain undulations and important river-related structures should be encrypted, and the scale of the encrypted grid should be equivalent to the scale of the river-related structures. The model roughness can refer to Table 8-1-4 to Table 8-1-6 of the "Hydraulic Calculation Manual (Second Edition)" compiled by the School of Water Resources and Hydropower Engineering of Wuhan University. It is initially given based on the river channel type, riverbed morphology, riverbed composition, distribution of river-related structures, etc., and is finally determined through model verification and adjustment. The upper boundary of the model is set at the section of each river hydrological station, and the upper boundary uses flow. The lower boundary of the model is set at the section where the hydrological station (or tidal station) is located after the confluence of the estuary branch, and the lower boundary uses water level.
[0023] The mathematical model verification is divided into hydrodynamic model verification and sediment model verification. The hydrodynamic model verification includes water (tide) level verification, flow velocity verification, and flow direction verification; the sediment model verification includes the verification of the sediment content process and bed scouring and siltation changes. The verification accuracy should meet the relevant provisions of the "Technical Specifications for Simulation Tests of Water Transport Engineering" (JTS-T 231-2021).
[0024] (3) Simulation and analysis of sediment movement in estuaries and harbors Using the verified two-dimensional hydrodynamic and sediment mathematical model of estuaries and branches, the water flow and sediment movement in estuaries and branches under typical runoff, flood and tidal combination conditions are simulated, and the dynamic characteristics of floods and tidal currents in estuaries and branches, as well as the laws of sediment transport and riverbed scouring and siltation are analyzed.
[0025] (4) Analyze whether there are water and sediment problems in the estuaries and their adverse effects on the development of the river and the health and safety of the river. Based on the needs of flood and tide control, navigation, ecological environment, and safety of major water-related projects for the evolution and development of estuaries and branches, combined with the river flow characteristics, evolution characteristics and trends, numerical simulation results of water flow movement and riverbed scouring and silting change characteristics of estuaries and branches, as well as the on-site investigation and survey of estuaries and branches and the dynamic characteristics of historical floods and tidal currents, the author analyzes whether there are water and sediment problems and their adverse effects in estuaries and branches. When the evolution of branches is unbalanced (manifested in the serious deepening of some branches and the continuous increase of diversion ratio, threatening the safety of flood control and tide control or bringing scouring risks to bridges, cross-river pipelines, embankments and other water-related projects, or the serious silting of some branches and branches, the continuous decrease of diversion ratio, the poor flood discharge and tide collection or the impact on navigation, etc.), and the river flow develops in an unfavorable direction, it is considered that there are serious water and sediment problems in estuaries and branches, and measures need to be taken to improve the relationship between branches and channels.
[0026] like Figure 1In the multi-branch estuary shown in the figure, there are river sluices at the mouths of River 1 and River 2. The estuary sluice on River 1 is a branching sluice, consisting of the South Gate and the North Gate. The river channel in the estuary area is divided into multiple branches (Branch 1, Branch 2, and Branch 3). The riverbed of Branch 3 has been greatly deepened, the low water level has continued to drop during low water, and the diversion ratio has continued to increase, increasing the burden of flood control, threatening the stability of the embankment foot, and aggravating the scouring of the foundation of wading structures; Branch 1 and Branch 2 are silted up, especially Branch 2, which is seriously silted up and almost cut off, resulting in poor flood and tide flow and affecting the ecological landscape. Therefore, measures need to be taken to improve the evolution relationship of the estuary branches and promote the development of the river regime in a favorable direction.
[0027] (5) Propose a preliminary plan and idea for using the existing dam gates at the river mouth to control water and sediment in the river estuary Based on the analysis of the water and sediment problems and regulation needs of estuaries and branches, a water and sediment regulation plan for estuaries and branches is proposed. The general regulation idea is to fully tap the water and sediment regulation potential of the branch gates and the river sluices without affecting flood control and taking into account the downstream ecological needs. Through the dispatching of the branch gates, medium low water and small floods are regulated, so that as much runoff and floods discharged from the upstream as possible enter the branches with insufficient water power or significant siltation and decline in the river channel, enhance the water and sediment power of weak branches, improve the evolution of branches, and promote the healthy development of the river.
[0028] by Figure 1 The water and sediment control idea of a multi-branch estuary dam shown in the figure is taken as an example. The conventional scheduling plan of the dam is that when the upstream water is small, the South Gate and the North Port are partially opened at the same time, and the normal water storage level is maintained on the dam. When the water on the dam is large (exceeding the design value of discharge control 1500m³ / s), the South Gate and the North Port are fully opened, and the upstream water is naturally diverted. The idea of using the branch gate for water and sediment control proposed in the present invention is to make full use of the potential of the branch gate to control the upstream water, aiming at the riverbed scouring of Branch 3 and the siltation of Branch 1 and Branch 2, and to control the upstream water from the North Gate as much as possible under the premise of ensuring safety and maintaining the downstream ecological needs. Specifically, when the upstream water flow is small, the normal water storage level is maintained on the gate, and only the North Gate is opened, or the South Gate only releases the ecological flow and the other upstream water is released from the North Gate; when the upstream water flow is large (exceeding the original control design value but not exceeding the maximum flood flow Qmax allowed for regulation), the South Gate is maintained closed or partially opened, and the North Gate is fully opened to release water. At this time, the gate should be guaranteed; when the upstream water flow is large (exceeding the maximum flood flow Qmax allowed for regulation), the South and North Gates are fully opened, and the upstream water flow is no longer regulated.
[0029] (6) Combined with numerical simulation and analysis, determine the maximum flood flow Qmax that can be regulated The maximum flood that can be regulated is determined based on the maximum water level allowed by the sluice gate and the safe discharge flow allowed in the downstream river, combined with numerical simulation and trial analysis. It is necessary to control the maximum flood level H on the gate during flood regulation not to exceed the designed maximum water level Z on the gate, that is, H≤Z, and to control the discharge flow Q of the fully opened branch gate after regulation not to exceed the safe discharge flow Q allowed by the branch gate 允 , that is, Q≤Q 允 .
[0030] Specifically, the mathematical model is first used to calculate the highest water level in front of the gate under different flow conditions of upstream discharge after the implementation of the branch gate control plan, and the flow-water level relationship line Q0~H between the discharge flow Q0 and the highest water level H on the gate is established, such as Figure 2 Then, according to the relationship between the flow and water level on the gate, when H=Z, the corresponding discharge flow Q0' is the maximum discharge flow that satisfies the highest flood level H on the gate and does not exceed the designed highest water level Z on the gate when the sluice is regulated. Finally, check whether Q0' exceeds the safe discharge flow Q 允 , if Q0'≤Q 允 , then Qmax=Q0'; if Q0'>Q 允 , then Q 允 That is the maximum downstream flow Qmax that can be regulated.
[0031] For safety reasons, when calculating the maximum flow rate Qmax that can be controlled, the branch gate scheduling method is: the gate of the weir on the side of the harbor with insufficient water power is fully opened to discharge flood water, and the gates of the other branch gates are fully closed.
[0032] Each component of the branch gate allows safe discharge flow Q 允 Determined according to the flood control standards of the downstream river.
[0033] by Figure 1 Take a river with a branch gate as an example. The maximum water level Z allowed on the branch gate is 5.30m. The flood discharge standard for the river branch 1 and branch 2 is about once in 20 years. The corresponding safe discharge volume Q of the north gate of the branch gate is 北允 About 4800m³ / s, the flood safety standard of branch 3 is once in 50 years, and the allowable safe discharge volume of the South Gate of the branch gate is Q 南允 The mathematical model analysis shows that when the upstream water flow Q0 is 3780m³ / s, the South Gate is closed and the North Gate is fully opened to discharge flood water (that is, all the upstream water is discharged from the North Gate). At this time, the highest flood level H on the gate is about 5.30m, which can meet the safety discharge requirements at the same time, that is, the maximum regulated flood flow Qmax is determined to be 3780m³ / s.
[0034] (7) Simulate and compare the movement of water and sediment before and after regulation to evaluate the effectiveness of using estuary diversion gates to regulate water and sediment Using the two-dimensional hydrodynamic and sediment mathematical model of the estuary, numerical simulation of water flow and sediment under typical flood and tidal conditions was carried out before and after the implementation of the branch gate control scheme. By comparing the changes in hydrodynamics and riverbed scouring and siltation in the estuary before and after the implementation of the control scheme, the effect of water and sediment control using the estuary branch gate was analyzed and evaluated.
[0035] The comparison of hydrodynamic changes includes the comparison of the flow rate, cross-section characteristic water level, and cross-section characteristic flow velocity of each branch before and after the implementation of the weir control plan; the comparison of riverbed scouring and silting changes is the comparison of the average scouring and silting values of each branch before and after the implementation of the weir control plan. After the implementation of the control plan, when the flow rate and flow velocity of the branch that originally had insufficient hydrodynamics increased significantly, the overall siltation was weakened or the overall siltation turned into overall scouring, it is considered that a good water and sediment control effect has been achieved.
[0036] by Figure 1 Take a river with a branch gate as an example. When the upstream water flow is 3780m³ / s, the non-regulation scheme is to fully open both the South Gate and the North Gate for flood discharge. The regulation scheme is to close the South Gate and only fully open the North Gate for flood discharge. After the implementation of the regulation scheme, the flow of Harbor 1 and Harbor 2 increased significantly, and the discharge of Harbor 3 decreased significantly. The average discharge of Harbor 1 and Harbor 2 increased by about 74% and 86% respectively compared with the non-regulation scheme, and the average discharge of Harbor 3 decreased by about 38% compared with the non-regulation scheme. After regulation, the high and low water levels of Harbor 1 and Harbor 2 increased overall compared with before regulation. The increase in low water level was more obvious than that in high water level. The increase in upstream water level was generally greater than that in downstream, as shown in Figure 2. Figure 3 , Figure 4 After regulation, the average flow velocity of Harbor 1 and Harbor 2 increased by 0.45m / s and 0.27m / s respectively, and the average flow velocity of Harbor 3 decreased by 0.33m / s. Figure 5~Figure 7 ; After multiple consecutive floods with this flow rate, the river channel of Harbor 3 was scoured by an average of 0.18m without the control plan of the river dam, and the river channels of Harbor 2 and Harbor 1 were silted by an average of 0.08m and 0.04m respectively. With the control plan, the river channel of Harbor 3 was silted by an average of 0.10m, and the river channels of Harbor 2 and Harbor 1 were scoured by an average of 0.18m and 0.16m respectively. It can be seen that the control of the branch gate can alleviate the scouring of the riverbed of Harbor 3 to a certain extent and prevent the further deepening of the riverbed of Harbor 3. At the same time, it is conducive to alleviating the silting of the riverbeds of Harbor 1 and Harbor 2, which plays an important role in improving the evolution of the three ports and promoting the development of the river in a favorable direction.
[0037] It should be pointed out that the river is a bifurcated river, including two branches and multiple branches; the bifurcated gate refers to a dam gate set at the bifurcated mouth, that is, the bifurcated mouth island divides the dam gate into two gates or multiple gates.
[0038] The above-described embodiments only express the preferred embodiments of the present invention, and the description thereof is relatively specific and detailed, but the present invention is not limited to these embodiments. It should be noted that it is obvious to those skilled in the art. Without departing from the purpose of the present invention, any improvement made shall fall within the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A method for regulating water and sediment in a branching harbor by using a branching sluice at an estuary, characterized in that: The following steps are involved: (1) Conducting analysis on the evolution of estuaries and river channels Collect data on the topography, geology, hydrology, sediment, river-related construction, operation and management of major water projects, river sand mining, river regulation, and previous research results of the river estuaries, analyze the evolution process, characteristics and causes of the river channels at the estuaries and branches, and predict the future evolution trend of the river channels at the estuaries and branches based on the changes in the main influencing factors that cause riverbed evolution; (2) Establish a mathematical model of estuary hydrodynamics and sedimentation and conduct model verification and calibration Using basic data such as topography, hydrology, sediment, and major river-related structures, a two-dimensional hydrodynamic sediment mathematical model of estuaries and branches was established based on the Mike21 water flow and sediment numerical simulation analysis software, and the model was verified using the hydrological, sediment data and topographic change data measured at the hydrological station. (3) Simulation and analysis of sediment movement in estuaries and harbors Using the verified two-dimensional hydrodynamic sediment mathematical model of estuaries and harbors, simulate the flow and sediment movement of estuaries and harbors under typical runoff, flood and tidal combined conditions, analyze the dynamic characteristics of flood and tidal currents in estuaries and harbors, as well as the laws of sediment transport and riverbed scouring and deposition; (4) Analyze whether there are water and sediment problems in the estuaries and their adverse effects on the development of the river and the health and safety of the river. Based on the needs of flood and tide prevention, shipping, ecological environment, and safety of major water-related projects on the evolution and development of estuaries and branches, combined with the river flow characteristics, evolution characteristics and trends, numerical simulation results of water flow movement and riverbed scouring and silting change characteristics of estuaries and branches, as well as on-site field investigations and surveys of estuaries and branches and historical flood and tidal flow characteristics, we analyzed whether there are water and sediment problems in estuaries and branches and their adverse effects; (5) Propose a preliminary plan and idea for using the existing dam gates at the river mouth to control water and sediment in the river estuary Based on the analysis of the water and sediment problems and regulation needs in estuaries and branches, a water and sediment regulation plan for estuaries and branches is proposed; the general regulation idea is to fully tap the water and sediment regulation potential of the branch dams and the river without affecting flood control and taking into account the downstream ecological needs, and to regulate low water and small floods through the dispatching of the branch dams, so that as much runoff and flood water from the upstream as possible can enter the branches with insufficient water power or significant siltation and decline in the river channel, enhance the water and sediment dynamics of weak branches, improve the evolution of branches and branches, and promote the healthy development of the river; (6) Combined with numerical simulation and analysis, determine the maximum flood flow Qmax that can be regulated The maximum flood that can be regulated is determined based on the maximum water level allowed by the sluice gate and the safe discharge flow allowed in the downstream river, combined with numerical simulation and trial analysis; it is necessary to control the maximum flood level H on the gate during flood regulation not to exceed the designed maximum water level Z on the gate, that is, H≤Z, and to control the discharge flow Q of the fully opened branch gate after regulation not to exceed the safe discharge flow Q allowed by the branch gate 允 , that is, Q≤Q 允 ; (7) Simulate and compare the movement of water and sediment before and after regulation to evaluate the effectiveness of using estuary diversion gates to regulate water and sediment Using the two-dimensional hydrodynamic and sediment mathematical model of the estuary, numerical simulation of water flow and sediment under typical flood and tidal conditions was carried out before and after the implementation of the branch gate control scheme. By comparing the changes in hydrodynamics and riverbed scouring and siltation in the estuary before and after the implementation of the control scheme, the effect of water and sediment control using the estuary branch gate was analyzed and evaluated.
2. The method for regulating water and sediment in a harbor by using an estuary branching sluice according to claim 1, characterized in that: The mathematical model based on Mike21 software in step (2) is based on the Navier-Stokes equations with incompressibility and uniform distribution of Reynolds values, and is subject to the Boussinesq assumption and the assumption of hydrostatic pressure; The two-dimensional non-steady shallow water equations are: Formula 1: ； Formula 2: ； Formula 3: ； Where: For time; is the Cartesian coordinate system coordinate; is the water level; is the still water depth; is the total water depth; They are The velocity component in the direction; is the Coriolis force coefficient, , is the Earth's rotation angular velocity, is the local latitude; is the acceleration due to gravity; is the density of water; are the radiation stress components respectively; is the horizontal viscous stress term, is the source-sink term, is the water flow velocity of the source and sink.
3. The method for regulating water and sediment in a harbor by using an estuary branching sluice according to claim 1, characterized in that: In step (2), the model adopts an unstructured triangular grid, and the grid size is determined comprehensively based on the accuracy of the modeled topographic map, the degree of terrain undulation, the size of important river-related structures, etc. The grid size should be equivalent to the interval of the elevation measurement points of the modeled topographic map. The local grid in the area where the terrain undulation is drastic and there are important river-related structures should be encrypted, and the scale of the encrypted grid should be equivalent to the scale of the river-related structures. The model roughness can refer to Tables 8-1-4 to 8-1-6 of the "Hydraulic Calculation Manual (Second Edition)" compiled by the School of Water Resources and Hydropower Engineering of Wuhan University, and is preliminarily given based on the river channel type, riverbed morphology, riverbed composition, distribution of river-related structures, etc., and is finally determined through model verification and adjustment. The upper boundary of the model is set at the section of each river hydrological station, and the upper boundary adopts the flow rate. The lower boundary of the model is set at the section where the hydrological station or tidal station is located after the confluence of the estuary and branch, and the lower boundary adopts the water level.
4. The method for regulating water and sediment in a harbor by using an estuary branching sluice according to claim 1, characterized in that: The mathematical model verification in step (2) is divided into hydrodynamic model verification and sediment model verification. The hydrodynamic model verification includes water level verification, flow velocity verification, and flow direction verification; the sediment model verification includes verification of the sediment content process and bed scouring and silting changes. The verification accuracy should meet the relevant provisions of the Technical Specifications for Simulation Tests of Water Transport Engineering JTS-T231-2021.
5. The method for regulating water and sediment in a harbor by using an estuary branching sluice according to claim 1, characterized in that: In step (4), when the evolution of the estuaries is unbalanced, as manifested in that some estuaries are seriously deepened and the diversion ratio continues to increase, threatening the safety of flood and tide control or bringing scouring risks to water-related projects such as bridges, cross-river pipelines, and embankments; or when some estuaries are seriously silted up, the diversion ratio continues to decrease, flood discharge and tide collection are not smooth, or navigation is affected, and the river flow develops in an unfavorable direction, it is considered that there are serious water and sediment problems in the estuaries and estuaries, and measures need to be taken to improve the relationship between the estuaries and the channels.
6. The method for regulating water and sediment in a harbor by using an estuary branching sluice according to claim 1, characterized in that: In step (6), a mathematical model is first used to calculate the highest water level in front of the gate under different flow conditions of upstream discharge after the implementation of the branch gate control scheme, and a flow-water level relationship line Q0~H between the discharge flow Q0 and the highest water level H on the gate is established. Then, according to the flow-water level relationship on the gate, when H=Z, the corresponding discharge flow Q0' is the maximum discharge flow that satisfies the highest flood level H on the gate not exceeding the designed highest water level Z on the gate during the sluice gate control; finally, it is checked whether Q0' exceeds the safe discharge flow Q 允 , if Q0'≤Q 允 , then Qmax=Q0'; if Q0'>Q, then Q 允 That is the maximum downstream flow Qmax that can be regulated.
7. The method for regulating water and sediment in a harbor by using an estuary branching sluice according to claim 6, characterized in that: For safety reasons, when calculating the maximum flow rate Qmax that can be controlled, the branch gate scheduling method is: the gate of the weir on the side of the harbor with insufficient water power is fully opened to discharge flood water, and the gates of the other branch gates are fully closed.
8. The method for regulating water and sediment in a harbor by using an estuary branching sluice according to claim 6, characterized in that: Each component of the branch gate allows safe discharge flow Q 允 Determined according to the flood control standards of the downstream river.
9. The method for regulating water and sediment in a harbor by using an estuary branching sluice according to claim 1, characterized in that: The comparison of hydrodynamic changes in step (7) includes comparison of flow, cross-section characteristic water level, and cross-section characteristic flow velocity of each branch before and after the implementation of the weir control plan; the comparison of riverbed scouring and sedimentation changes is comparison of average scouring and sedimentation values of each branch before and after the implementation of the weir control plan; after the implementation of the control plan, when the flow and flow velocity of the branch that originally had insufficient hydrodynamics significantly increase, and the overall siltation is weakened or the overall siltation is transformed into overall scouring, it is considered that a good water and sediment control effect has been achieved.