A method for determining a tidal water supplementing threshold of a tidal river channel

Abstract

The application discloses a tidal river tidal water intake threshold value determination method in the technical field of river regulation, carries out the collection and analysis of basic data such as hydrology, topography, water quality, pollutants and salinity of a river and an outer sea, determines a river control section and water quality improvement targets and salinity control targets, establishes a tidal river hydrodynamic water quality mathematical model, simulates and calculates hydrodynamic water quality results under different engineering regulation schemes, and counts tidal water intake Q, water quality concentration C and salinity P of the river control section under different regulation schemes. According to the tidal river tidal water intake threshold value determination method, the reasonable tidal water intake for improving the water environment of the tidal river by using tidal resources can be determined, key technical support for determining the tidal river engineering regulation task and scale is provided, and the problem that the increase of the tidal water intake causes the invasion of salt water and affects the safety of production and living water is avoided.

Description

Technical Field

[0001] This invention relates to the field of river management technology, specifically a method for determining the threshold of tidal water intake and replenishment in tidal rivers. Background Technology

[0002] Utilizing tidal resources to introduce relatively high-quality offshore seawater is one of the important ways to solve the water environment problems of coastal tidal rivers. Through engineering measures such as dredging, restoring aquaculture areas to tidal flats, and converting farmland back to tidal flats, the volume of tidal river channels can be increased, enhancing the river's tidal capacity and increasing tidal volume and tidal dynamics. This can effectively improve the dilution, self-purification, and circulation capabilities of tidal river water. However, increased tidal volume and enhanced tidal dynamics can also lead to saltwater intrusion, which directly affects the quality of groundwater resources and will impact the drinking water supply for residents in some coastal areas. Simultaneously, saltwater intrusion can also lead to soil salinization, reducing irrigated and arable land areas and affecting agricultural production. Therefore, determining a scientifically reasonable tidal volume is an important technical basis for engineering measures in tidal river management and a key technical parameter for utilizing tidal resources to improve the water environment of tidal rivers.

[0003] Based on this, the present invention designs a method for determining the threshold of tidal water intake and replenishment in tidal channels to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the threshold of tidal water intake in tidal channels, in order to solve the problem mentioned in the background art that increasing the tidal intake of tidal channels can effectively improve the dilution, self-purification and circulation capacity of tidal channel water, but the increase in tidal intake will lead to saltwater intrusion, affecting the safety of water for production and daily life.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for determining the threshold of tidal water intake and replenishment in tidal channels, comprising the following steps:

[0006] 1) Conduct basic data collection and analysis of river channels and offshore waters. The collected basic data includes monitoring data on river channel and offshore waters hydrology, topography, water quality, pollutants, salinity, etc., and analyzes characteristic river flow, characteristic offshore tide level, river water quality status and exceeding indicators, etc.

[0007] 2) Determine the river control sections and water quality improvement targets, salinity control targets. Control sections should preferably be located near the river mouth; the water quality exceedance index at the river control section is A, with a concentration of C1; the concentration of the offshore seawater quality index A is C2; the target concentration for river water quality improvement is C3, where C1 < C3 ≤ C2; the salinity control target at the river control section is Pmax, which is the maximum salinity allowed at that section.

[0008] 3) Establish a mathematical model for the hydrodynamic and water quality of tidal channels, simulate and calculate the hydrodynamic and water quality results under different engineering treatment schemes, and statistically analyze the tidal volume Q, water quality concentration C, and salinity P at the control sections of the river under different treatment schemes. The upper boundary of the mathematical model is the flow rate, which should preferably be the multi-year average flow rate of the river, and the lower boundary is the tidal level process, which should preferably be the multi-year average high tide level process. At least three engineering treatment schemes should be used to obtain as many hydrodynamic and water quality calculation results as possible. The tidal volume statistics are based on a high tide phase, and the water quality concentration and salinity statistics are based on the maximum values ​​within the same period.

[0009] 4) Based on the mathematical models calculated under different governance schemes, the tidal volume Q, water quality concentration C, and salinity P of the river control section are used to establish the relationship between water quality concentration C and tidal volume Q, and between salinity P and tidal volume Q. Regression analysis is then performed, and a univariate polynomial equation is recommended for fitting.

[0010] 5) Based on the relationship curve between salinity P and tidal volume Q at the river control section, and in conjunction with the maximum salinity that can be achieved at the section, determine the maximum allowable tidal volume Qmax; based on the relationship curve between water quality concentration C and tidal volume Q at the river control section, and in conjunction with the target concentration C3 for water quality improvement at the section, determine the minimum tidal volume Qmin that can achieve the target.

[0011] 6) Compare and analyze the maximum tidal volume Qmax and the minimum tidal volume Qmin, and determine the tidal volume threshold Qs with priority given to salinity control. When Qmax > Qmin, the tidal volume threshold is Qmin ≤ Qs < Qmax; when Qmax ≤ Qmin, the tidal volume threshold is Qs ≤ Qmax.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention, based on the proposed method for determining the threshold of tidal water intake for tidal channel replenishment, can determine the reasonable tidal intake when using tidal resources to improve the water environment of tidal channels, providing key technical support for determining the engineering management tasks and scale of tidal channels, and also avoiding the problem of saltwater intrusion affecting the safety of production and domestic water use due to increased tidal intake.

[0013] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the 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.

[0015] Figure 1 This is a schematic diagram of the Longjiang tidal channel and the open sea in Fuqing. Detailed Implementation

[0016] 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.

[0017] Please see Figure 1 This invention, taking the Longjiang River in Fuqing as an example, provides a method for determining the threshold of tidal water intake and replenishment in tidal channels:

[0018] (1) Conduct basic data collection and analysis of the Longjiang River channel and its offshore waters in Fuqing. The collected basic data includes monitoring data on the hydrology, topography, water quality, pollutants, and salinity of the Longjiang River channel and Fuqing Bay. For example, data on the Longjiang River channel in Fuqing... Figure 1 As shown, the average annual flow rate of the Longjiang River in Fuqing is 18.83 m³ / h. 3 The high tide process in the open sea is shown in Table 1. The water quality exceeding the standard in the river is NH3-N.

[0019] Table 1. High Tide Level Processes in the Open Sea

[0020]

[0021]

[0022] (2) Determine the control sections of the Fuqing Longjiang River and the targets for water quality improvement and salinity control. The control sections of the Fuqing Longjiang River should preferably be located near the river mouth, such as... Figure 1 As shown, the water quality exceeding standard at the Longjiang River control section in Fuqing is NH3-N with a concentration of 2.3 mg / L, while the concentration of NH3-N in the outer sea is 1.5 mg / L. The target concentration for improving river water quality is 2.0 mg / L, and the salinity control target at the river control section is 2 PSU, which is the maximum salinity allowed at this section.

[0023] (3) Establish a mathematical model of hydrodynamics and water quality in the Longjiang River channel in Fuqing, simulate and calculate the hydrodynamic and water quality results under different engineering treatment schemes, and statistically analyze the tidal volume Q, water quality concentration C, and salinity P at the control sections of the river channel under different treatment schemes. The simulation range of the mathematical model is as follows: Figure 1 As shown, the upper boundary is the South Gate, with a flow rate of 18.83 m³ / s, and the lower boundary is the multi-year average high tide level process, as shown in Table 1. The engineering treatment schemes include Scheme 1, Scheme 2, and Scheme 3. Table 2 shows the tidal volume Q, water quality concentration C, and salinity P at the river control sections under different treatment schemes.

[0024] Table 2. Tidal volume Q, water concentration C, and salinity P under different treatment schemes

[0025] Operating conditions <![CDATA[Inflow volume / 10,000 m 3 > <![CDATA[NH3-N / mg / L]]> Salinity / PSU status quo 499 2.30 0.90 Option 1 549 2.11 1.28 Option 2 604 1.98 2.12 Option 3 664 1.91 3.54

[0026] (4) Based on the mathematical models calculated for different governance schemes, the tidal volume Q, water quality concentration C, and salinity P at the river control section are used to establish the relationships between water quality concentration C and tidal volume Q, and between salinity P and tidal volume Q. Regression analysis is then performed, preferably using a univariate quadratic equation for fitting. The relationship between water quality concentration C and tidal volume Q is fitted using a univariate quadratic regression equation: Q = 929.78C² - 4331.6C + 5544.2, R² 2 =0.9915; The relationship between salinity P and tidal volume Q was fitted using a quadratic regression equation: Q = -17.374P² + 137.79P + 393.49, R² 2 =0.9941.

[0027] (5) Based on the relationship curve between salinity P and tidal volume Q at the river control section, the maximum allowable salinity at the control section is 2 PSU. Therefore, the maximum allowable tidal volume Qmax = -17.374 * 2.02 + 137.79 * 2.0 + 393.49 = 5,995,700 m³ 3 Based on the relationship curve between water quality concentration C and tidal volume Q at the river control section, and combined with the target water quality improvement concentration C3 at this section, the minimum tidal volume Qmin required to achieve this target is determined to be: Qmin = 929.78 * 2.02 - 4331.6 * 2.0 + 5544.2 = 6,001,200 m³. 3 .

[0028] (6) Compare and analyze the maximum tidal volume Qmax and the minimum tidal volume Qmin, and determine the tidal volume threshold Qs with priority given to salinity control. Qmax = 5,995,700 m³ 3 <Qmin=6.0012 million m 3 Therefore, the tidal volume threshold of the Longjiang River in Fuqing is Qs≤Qmax=5,995,700 m³. 3 .

[0029] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0030] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for determining the threshold of tidal water intake and replenishment in a tidal channel, characterized in that: Includes the following steps: Step 1: Collect and analyze basic data on rivers and the open sea; the collected basic data includes hydrological, topographical, water quality, pollutant, and salinity monitoring data of rivers and the open sea, and analyze characteristic flow of rivers, characteristic tide levels of the open sea, water quality status of rivers and indicators exceeding standards; Step 2: Determine the river control section and water quality improvement targets, salinity control targets; the water quality exceeding standard index of the river control section is A, and the concentration is C1; the concentration of the offshore seawater quality index A is C2; the target concentration for river water quality improvement is C3, where C1 < C3 ≤ C2; the salinity control target of the river control section is Pmax, which is the maximum salinity allowed to be reached at this section. Step 3: Establish a mathematical model of hydrodynamics and water quality in the tidal channel, simulate and calculate the hydrodynamic and water quality results under different engineering treatment schemes, and statistically analyze the tidal volume Q, water quality concentration C, and salinity P of the control section of the channel under different treatment schemes; the upper boundary of the mathematical model is the flow rate, which is the multi-year average flow rate of the channel, and the lower boundary is the tidal level process, which is the multi-year average high tide level process. Step 4: Based on the mathematical model calculations of the tidal volume Q, water quality concentration C, and salinity P of the river control section under different engineering treatment schemes, establish the relationship between water quality concentration C and tidal volume Q, and between salinity P and tidal volume Q, and perform regression analysis, using a univariate polynomial equation for fitting. Step 5: Based on the relationship curve between salinity P and tidal volume Q at the river control section, and combined with the maximum salinity that the section can reach, determine the maximum allowable tidal volume Qmax; Based on the relationship curve between water quality concentration C and tidal volume Q at the river control section, and combined with the target concentration C3 for water quality improvement at this section, the minimum tidal volume Qmin that can achieve this target is determined. The tidal volume is calculated during a high tide period, and the water quality concentration and salinity are calculated based on the maximum values ​​during the same period. Step 6: Compare and analyze the maximum tidal volume Qmax and the minimum tidal volume Qmin, and determine the tidal volume threshold Qs with priority given to salinity control; when Qmax > Qmin, the tidal volume threshold is Qmin ≤ Qs < Qmax; When Qmax ≤ Qmin, the tidal volume threshold is Qs ≤ Qmax.

2. The method for determining the threshold of tidal water intake and replenishment in a tidal channel according to claim 1, characterized in that: There should be no fewer than three engineering treatment plans in order to obtain as many hydrodynamic and water quality calculation results as possible.

3. The method for determining the threshold of tidal water intake and replenishment in a tidal channel according to claim 1, characterized in that: The control section mentioned in step two is set near the river mouth.

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