Method for setting, scheduling and arranging design of coastal plain drainage storage lake

Abstract

The present application relates to the technical field of hydraulic engineering, and more particularly to a method for setting, scheduling and layout design of coastal plain drainage storage lake, which is based on the methods of cave, lake in front of gate, etc., and proposes to set a drainage storage lake on the seaweed outside the plain drainage gate to realize continuous drainage of the plain area, which is a feasible and practical technology, solves the land use problem of excavating lake in front of gate, realizes the dual functions of storage during flood period and continuous drainage at high and low tide levels, and does not change the property of sea area.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering technology, and in particular to a method for the design, scheduling and layout of drainage and storage lakes in coastal plains. Background Technology

[0002] Drainage in coastal plains is affected by tides from the open sea. Floodgates are opened for drainage during low tide and closed to block the tide during high tide. During the period when the gates are closed at high tide, the small storage capacity of the river channels can easily lead to waterlogging.

[0003] Currently, common methods include temporarily storing water in mountainous areas by adding cave reservoirs or excavating lakes in front of sluice gates in coastal plains, thereby increasing the storage capacity of river channels. However, cave reservoirs often require a large excavation depth and are generally used in mountainous areas; while excavating lakes in front of sluice gates in coastal plains is often difficult to implement due to land constraints and generally has limited benefits, showing obvious limitations.

[0004] Therefore, this case is brought. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method for setting up drainage and storage lakes in coastal plains, enabling continuous drainage in the plains during both high and low tides. This solves the shortcomings of cave reservoirs and sluice gate lakes, which are only used for storage, and avoids land use problems.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for setting up a drainage and storage lake in a coastal plain includes the following steps:

[0008] A drainage and storage lake is arranged on the mudflats outside the plain drainage gate. One side of the drainage and storage lake is adjacent to the existing seawall, and the other side is isolated from the open sea by a newly built seawall.

[0009] An intake gate for the flood storage lake will be installed on the existing seawall adjacent to the flood storage lake, and a water diversion channel will be installed between the intake gate for the flood storage lake and the upstream channel of the plain flood drainage gate.

[0010] A flood control and drainage gate for a reservoir was installed on the newly built seawall.

[0011] The second objective of this invention is to provide a scheduling method based on the aforementioned coastal plain drainage and storage lake, including scheduling during the plain drainage period and scheduling during the plain non-drainage period;

[0012] The scheduling during the plain drainage period includes the following steps:

[0013] When the tide level in the open sea is higher than the water level of the upstream river channel of the plain drainage gate and the drainage and storage lake, the plain drainage gate and the drainage gate of the storage lake are closed, and the water inlet gate of the storage lake is opened to allow the plain floodwater to enter the drainage and storage lake.

[0014] Or when the tide level in the open sea is lower than the water level of the upstream river channel of the plain drainage gate and the drainage and storage lake, open the plain drainage gate and the drainage gate of the storage lake, close the water intake gate of the storage lake, drain the plain floodwater and empty the drainage and storage lake;

[0015] The scheduling during non-flood drainage periods in the plains includes the following steps:

[0016] The opening and closing of the plain drainage gates are determined according to the water level control requirements of the plain river channels;

[0017] Open the flood discharge gate of the flood storage lake, close the water intake gate of the flood storage lake, and maintain the connection between the flood discharge and flood storage lake and the open sea.

[0018] The third objective of this invention is to provide a method for the layout and design of drainage and flood control lakes in coastal plains, comprising the following steps:

[0019] S1. Construct a one-dimensional hydrodynamic model for coastal plains that require drainage;

[0020] S2. Using a one-dimensional hydrodynamic model, calculate the drainage capacity of the plain when no drainage and storage lake is set up, and analyze the characterization parameters of the drainage capacity of the plain. If the calculated characterization parameters meet the regional drainage requirements, then the region does not need to set up a drainage and storage lake. If the calculated characterization parameters do not meet the regional drainage requirements, then the region needs to set up a drainage and storage lake. Proceed to step S3.

[0021] S3. Based on the conditions of the project site, taking into account the site environment and the existing drainage gate layout, and combined with the surrounding landscape requirements, determine the location, shape, capacity and normal water level of the drainage and storage lake, and preliminarily determine the scale of the drainage gate and the intake gate of the storage lake, including the net width of the gate and the bottom elevation of the gate.

[0022] S4. Using a one-dimensional hydrodynamic model, calculate the drainage capacity of the plain when drainage and storage lakes are arranged, and analyze the characterization parameters of the drainage capacity of the plain area.

[0023] S5. Based on the drainage effect and site conditions obtained from the characterization parameter analysis, repeat S3 and S4, continuously adjust the layout of the drainage and storage lakes and the scale of the drainage gates and intake gates of the storage lakes, and calculate the drainage effect until the optimal scheme that allows the site conditions and meets the drainage requirements of the plain is formed.

[0024] Furthermore, the one-dimensional hydrodynamic model includes continuity equations and motion equations:

[0025] (1) Continuity equation:

[0026]

[0027] (2) Equations of motion:

[0028]

[0029] Where Z is the cross-sectional water level under no-pressure conditions; t is time; B1 is the width of the river channel cross-section; x is the longitudinal distance along the direction of water flow; A is the water-passing area; g is the acceleration due to gravity; J is the frictional drop; and v is the water flow velocity.

[0030] Furthermore, the calculation of drainage capacity includes the following steps:

[0031] If the longest flooding duration T ≤ the allowable flooding duration, the drainage capacity is determined based on the highest water level and must satisfy the following formula:

[0032] H P +e+R P +c≥Hd;

[0033] Among them, H P The design water level is the highest level for frequent flooding; e is the height of the water surface obstructed by wind; R P c represents the rise due to wind and waves; d represents the safety freeboard; Hd represents the top elevation of the dike.

[0034] The formula for calculating the wind-induced water surface height e is as follows:

[0035]

[0036] K is the overall friction coefficient; f is the design wind speed; D is the length of the wind zone;

[0037] Among them, the wind and waves rise R P The calculation formula is:

[0038]

[0039] Rp is the wave run-up with a cumulative frequency of p, in meters; KΔ is the roughness and permeability coefficient of the slope; Kv is an empirical coefficient; Kp is the conversion factor for the cumulative run-up frequency. For dikes where wave crossing is not permitted, the cumulative run-up frequency is taken as 2% according to the specifications; m1 is the slope ratio; L is the wavelength of the wave in front of the dike, in meters; H is the average wave height in front of the dike, in meters.

[0040] Among them, the safety superelevation (c) is determined according to the standard for the grade of the dike project.

[0041] Furthermore, in step S3, the initially determined scale of the regulating lake is determined by taking 10% of the upstream multi-year average runoff and the normal water level as the local multi-year average tide level.

[0042] Furthermore, in step S3, the net width and bottom elevation of the drainage gate and intake gate of the regulating reservoir must meet the flow rate requirements of the corresponding design frequency upstream.

[0043]

[0044] In the formula: Q is the design flow rate at the sluice gate; σ is the submergence coefficient; ε is the lateral contraction coefficient; B is the width of the sluice gate; m is the flow coefficient;

[0045] H0 is the head of the water in front of the weir at the near-velocity head, i.e. H1 is the water depth in front of the sluice gate, and H1 = the water level during flooding. p - Elevation of the gate bottom; v0 is the approach velocity.

[0046] The advantages of this invention are as follows: In order to improve the flood control capacity of plain areas, based on methods such as caves and lakes in front of sluice gates, it is proposed to set up a flood control and storage lake on the mudflats outside the flood control gate in the plain area to realize continuous flood control in the plain area. This is a feasible and practical technology that solves the land use problem of excavating lakes in front of sluice gates, realizes the dual functions of flood season regulation and storage and continuous flood control at high and low tide levels, and does not change the marine characteristics. Attached Figure Description

[0047] Figure 1 This is a flowchart illustrating the layout design of drainage and flood control lakes in the coastal plains, as shown in the example.

[0048] Figure 2 This is a schematic diagram of the layout of the coastal plain drainage and storage lakes in the embodiment.

[0049] Figure 3 This is a schematic diagram illustrating the scheduling when the offshore tide level is higher than the water level of the upstream river channel and the drainage and storage lake of the plain drainage gate, as shown in the embodiment.

[0050] Figure 4 This is a schematic diagram illustrating the scheduling when the offshore tide level is lower than the water level of the upstream river channel and the drainage and storage lake of the plain drainage gate, as shown in the embodiment.

[0051] Figure 5 This is a schematic diagram of the scheduling during non-drainage periods in the plains, as shown in the example.

[0052] Label Explanation

[0053] PZ1 - Plain drainage gate; TH2 - Drainage and storage lake; D3 - Newly built seawall; H4 - Upstream river channel; H5 - Water diversion channel; JZ6 - Storage lake intake gate; PZ7 - Storage lake drainage gate. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to embodiments. It should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., used in this document indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0055] This embodiment proposes a design method for the setting, scheduling, and layout of drainage and storage lakes in coastal plains, enabling continuous drainage in the plains during both high and low tides. This overcomes the shortcomings of traditional reservoirs and sluice gate lakes, which are primarily used for storage, and avoids land use difficulties. Specifically, it includes:

[0056] I. Setup Method

[0057] like Figure 2 As shown, the existing drainage infrastructure includes an existing seawall between the inland plain and the open sea, and a plain drainage gate PZ1 is installed on the existing seawall. Water in the upstream river channel H4 can be discharged to the open sea through the plain drainage gate PZ1. However, the existing drainage infrastructure is prone to waterlogging. As an improvement, this embodiment arranges a drainage and storage lake TH2 on the tidal flat outside the plain drainage gate PZ1. One side of the drainage and storage lake TH2 is adjacent to the existing seawall, and the other side is isolated from the open sea by a newly built seawall D3. At the same time, a water intake gate JZ6 for the water storage lake is arranged on the existing seawall adjacent to the water storage lake TH2. A water diversion channel H5 is arranged between the water intake gate JZ6 and the upstream river channel H4 of the plain drainage gate PZ1. A drainage and storage lake gate PZ7 is arranged on the newly built seawall D3.

[0058] II. Scheduling Methods

[0059] (1) During the plain drainage period

[0060] Flood drainage scenario 1: such as Figure 3 As shown, when the tide level in the open sea is higher than the water level of the upstream river channel H4 of the plain drainage gate and the drainage and storage lake TH2, the plain drainage gate PZ1 and the drainage gate PZ7 of the storage lake are closed, and the water inlet gate JZ6 of the storage lake is opened to allow the plain floodwater to enter the drainage and storage lake TH2.

[0061] Flood drainage scenario 2: such as Figure 4 As shown, when the tide level in the open sea is lower than the water level of the upstream river channel H4 of the plain drainage gate and the regulating lake TH2, the plain drainage gate PZ1 and the regulating lake drainage gate PZ7 are opened, and the regulating lake inlet gate JZ6 is closed to drain the plain floodwater and empty the regulating lake TH2.

[0062] As the tide level in the open sea rises and falls, drainage scenario 1 and drainage scenario 2 are repeated continuously, enabling continuous drainage in the plain area during both high and low tide periods.

[0063] (2) During non-drainage periods in plains

[0064] like Figure 5 As shown, the opening and closing of the plain drainage gate PZ1 are determined according to the water level control requirements of the plain river channel.

[0065] Open the drainage gate PZ7 of the flood control and storage lake, close the inlet gate JZ6 of the flood control and storage lake, maintain the connection between the flood control and storage lake TH2 and the open sea, and maintain the coastal wetland function of the flood control and storage lake TH2 in order to adapt to the national marine use policy.

[0066] III. Layout and Design Methods for Drainage and Regulating Lakes in Coastal Plains

[0067] like Figure 1 As shown, it includes the following steps:

[0068] S1. For coastal plains that require drainage, a one-dimensional hydrodynamic model is constructed as a tool for determining the scale of drainage and storage lakes and calculating drainage effects;

[0069] The one-dimensional hydrodynamic model includes continuity equations and motion equations:

[0070] (1) Continuity equation:

[0071]

[0072] (2) Equations of motion:

[0073]

[0074] Where Z is the cross-sectional water level under no-pressure conditions; t is time; B1 is the width of the river channel cross-section; x is the longitudinal distance along the direction of water flow; A is the water-passing area; g is the acceleration due to gravity; J is the frictional drop; and v is the water flow velocity.

[0075] S2. Using a one-dimensional hydrodynamic model, calculate the drainage capacity of the plain when no drainage and storage lake is set up, and analyze the characterization parameters of the drainage capacity of the plain. If the calculated characterization parameters meet the regional drainage requirements, then the region does not need to set up a drainage and storage lake. If the calculated characterization parameters do not meet the regional drainage requirements, then the region needs to set up a drainage and storage lake. Proceed to step S3.

[0076] The calculation of drainage capacity includes the following steps:

[0077] If the longest flooding duration T ≤ the allowable flooding duration, the drainage capacity is determined based on the highest water level and must satisfy the following formula:

[0078] H P +e+R P +c≥Hd;

[0079] Among them, H P The design water level is the highest level for frequent flooding; e is the height of the water surface obstructed by wind; R P c represents the rise due to wind and waves; d represents the safety freeboard; Hd represents the top elevation of the dike.

[0080] The formula for calculating the wind-induced water surface height e is as follows:

[0081]

[0082] K is the overall friction coefficient; f is the design wind speed; D is the length of the wind zone;

[0083] Among them, the wind and waves rise R P The calculation formula is:

[0084]

[0085] Rp is the wave run-up with a cumulative frequency of p, in meters; KΔ is the roughness and permeability coefficient of the slope; Kv is an empirical coefficient; Kp is the conversion factor for the cumulative run-up frequency. For dikes where wave crossing is not permitted, the cumulative run-up frequency is taken as 2% according to the specifications; m1 is the slope ratio; L is the wavelength of the wave in front of the dike, in meters; H is the average wave height in front of the dike, in meters.

[0086] Among them, the safety superelevation 'c' is determined by referring to the "Design Code for Dike Engineering" according to the grade of the dike project;

[0087] S3. Based on the conditions of the project site, taking into account factors such as the topography of the tidal flat area, the orientation of the seawall, and the layout of the original drainage gate, and in combination with the surrounding landscape requirements, determine the layout plan (including location and shape) and scale (including reservoir capacity and normal water level) of the drainage and storage lake, and preliminarily determine the scale (including the net width of the gate and the bottom elevation of the gate) of the storage lake drainage gate and the storage lake intake gate.

[0088] Specifically, the preliminary layout plan mainly considers the existing drainage gate layout and landscape effect;

[0089] Specifically, the initially determined scale of the regulating lake is based on 10% of the upstream multi-year average runoff, and the normal water level is based on the local multi-year average tide level.

[0090] The net width and bottom elevation of the drainage gate and intake gate of the regulating reservoir must meet the flow requirements of the corresponding design frequency upstream.

[0091]

[0092] In the formula: Q is the design flow rate at the sluice gate; σ is the submergence coefficient; ε is the lateral contraction coefficient; B is the width of the sluice gate (i.e., the net width of the sluice gate); m is the flow coefficient;

[0093] H0 is the head of the water in front of the weir at the near-velocity head, i.e. H1 is the water depth in front of the sluice gate, and H1 = the water level during flooding. p - Gate bottom elevation (from which the gate bottom elevation is obtained); v0 is the approach velocity;

[0094] S4. Using a one-dimensional hydrodynamic model, calculate the drainage capacity of the plain when drainage and storage lakes are arranged, and analyze the characterization parameters of the drainage capacity of the plain. The calculation of the characterization parameters here is the same as the calculation process in step S2, and will not be repeated.

[0095] S5. Based on the drainage effect and site conditions obtained from the characterization parameter analysis, repeat S3 and S4, continuously adjust the layout of the drainage and storage lakes and the scale of the drainage gates and intake gates of the storage lakes, and calculate the drainage effect until the optimal scheme that allows the site conditions and meets the drainage requirements of the plain is formed.

[0096] The above embodiments are only used to explain the concept of the present invention, and are not intended to limit the protection of the present invention. Any non-substantial modifications made to the present invention using this concept should fall within the protection scope of the present invention.

Claims

1. A method for designing the layout of drainage and flood control lakes in coastal plains, characterized in that, A drainage and storage lake is arranged on the mudflats outside the plain drainage gate. One side of the drainage and storage lake is adjacent to the existing seawall, and the other side is isolated from the open sea by a newly built seawall. An intake gate for the flood storage lake will be installed on the existing seawall adjacent to the flood storage lake, and a water diversion channel will be installed between the intake gate for the flood storage lake and the upstream channel of the plain flood drainage gate. Install flood control and drainage gates for the newly built seawall; The scheduling during flood drainage in plains includes the following steps: When the tide level in the open sea is higher than the water level of the upstream river channel of the plain drainage gate and the drainage and storage lake, the plain drainage gate and the drainage gate of the storage lake are closed, and the water inlet gate of the storage lake is opened to allow the plain floodwater to enter the drainage and storage lake. Or when the tide level in the open sea is lower than the water level of the upstream river channel of the plain drainage gate and the drainage and storage lake, open the plain drainage gate and the drainage gate of the storage lake, close the water intake gate of the storage lake, drain the plain floodwater and empty the drainage and storage lake; Dispatching during non-flood drainage periods in plains includes the following steps: The opening and closing of the plain drainage gates are determined according to the water level control requirements of the plain river channels; Open the drainage gates of the flood control lake, close the inlet gates of the flood control lake, and maintain the connection between the flood control lake and the open sea; The design method for the layout of drainage and storage lakes in coastal plains includes the following steps: S1. Construct a one-dimensional hydrodynamic model for coastal plains that require drainage; S2. Using a one-dimensional hydrodynamic model, calculate the drainage capacity of the plain when no drainage and storage lake is set up, and analyze the characterization parameters of the drainage capacity of the plain area. If the calculated characterization parameters meet the regional drainage requirements, then the region does not need to set up a drainage and storage lake. If the calculated characterization parameters do not meet the regional drainage requirements, then the region needs to set up a drainage and storage lake. Proceed to step S3. S3. Based on the conditions of the project site, taking into account the site environment factors and the existing plain drainage gate layout factors, and combined with the surrounding landscape requirements, determine the layout location, shape, reservoir capacity and normal water level of the drainage and storage lake, and preliminarily determine the scale of the drainage gate and the intake gate of the storage lake, including the net width of the gate and the bottom elevation of the gate. S4. Using a one-dimensional hydrodynamic model, calculate the drainage capacity of plains with drainage and storage lakes, and analyze the characterization parameters of drainage capacity in plain areas. S5. Based on the drainage effect and site conditions obtained from the characterization parameter analysis, repeat steps S3 and S4, continuously adjust the layout of the drainage and storage lake and the scale of the drainage gate and the water intake gate of the storage lake, and calculate the drainage effect until the optimal solution that meets the requirements of plain drainage is formed under site conditions. The calculation of drainage capacity includes the following steps: If the longest flooding duration T ≤ the allowable flooding duration, the drainage capacity is determined based on the highest water level and must satisfy the following formula: ； in, The design water level is the highest level for frequent flooding; e is the height of the water surface obstructed by wind. C is for climbing high to withstand wind and waves; C is for safe extra-high altitude. This refers to the top elevation of the dike. The formula for calculating the wind-induced water surface height e is as follows: ； K is the overall friction coefficient; f is the design wind speed; D is the length of the wind zone; Among them, the waves rise The calculation formula is: ； Wave climb rate with a cumulative frequency of p, in meters; The roughness and permeability coefficient of the slope; This is an empirical coefficient; For the conversion factor of the cumulative run-up frequency, for dikes where wave crossing is not permitted, the cumulative run-up frequency is taken as 2% according to the specifications; The slope ratio; Wavelength in front of the dike, measured in meters; The average wave height in front of the dike, in meters; Among them, the safety superelevation 'c' is determined according to the standard for the grade of the dike project; In step S3, the net width and bottom elevation of the floodgates and intake gates of the regulating reservoir must meet the flow requirements of the corresponding design frequency upstream. ； In the formula: Q is the design flow rate at the sluice gate; σ is the submergence coefficient; ε is the lateral contraction coefficient; B is the width of the sluice gate; m is the flow coefficient; The head of the water in front of the weir is the head of the water approaching the velocity head, i.e. , The water depth in front of the sluice gate =Design frequency highest flood level H p - Elevation of the gate bottom; The approximate flow velocity.

2. The method for designing and arranging drainage and storage lakes in coastal plains as described in claim 1, characterized in that, In step S3, the scale of the drainage and storage lake is initially determined, with the reservoir capacity taken as 10% of the upstream multi-year average runoff and the normal water level taken as the local multi-year average tide level.

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