A kind of water age determination method of semi-enclosed water area

Abstract

The invention discloses a water age measurement method for a semi-closed water area. The method comprises the following steps that: firstly, establishing the hydrodynamic force mathematical model of awater area to be measured; through the hydrodynamic force mathematical model, calculating the water depth and flow velocity information of each water quality point of the water area to be measured; constructing a convective diffusion mathematical model, and setting the boundary condition of the convective diffusion mathematical model; according to the hydrodynamic force mathematical model, calculating to obtain the water level and flow velocity information of each position of the area to be measured and the boundary condition of the convective diffusion mathematical model; calculating the concentration values of a conservative substance p and a non-conservative substance r of each moment of each water quality point of the area to be measured through the convective diffusion mathematical model; according to the concentration values of a conservative substance p and a non-conservative substance r of each moment of each water quality point of the area to be measured, calculating the instantaneous water age of each corresponding moment of each water quality point of the area to be measured; and finally, according to the instantaneous water age of each corresponding moment of each water quality point of the area to be measured, calculating a time average water age in each time period of each water quality point of the water area to be measured. By use of the method, the water age of the semi-closed water area can be efficiently, conveniently and accurately calculated.

Description

technical field

[0001] The invention belongs to the technical field of hydrodynamic numerical simulation, in particular to a method for measuring water age in semi-enclosed waters. Background technique

[0002] There are more than 1,500 rivers with a drainage area of ​​more than 1,000 square kilometers in my country, more than 2,800 natural lakes with an area of ​​more than 1 square kilometer, and a coastline of more than 18,000 kilometers long and a sea area of ​​​​more than 3 million square kilometers. With the rapid development of the coastal economy, a large amount of pollutants and nutrients are discharged into rivers, lakes and coastal waters, resulting in the deterioration of the water environment. Especially for semi-enclosed waters with poor flow, it is difficult for the water body to exchange and renew with the surrounding water body through physical processes such as convection and diffusion to improve water quality, resulting in more serious deterioration of the ...

Examples

Embodiment

[0094] This embodiment discloses a method for determining the age of water in semi-enclosed waters, such as figure 1 As shown, the steps are as follows:

[0095] Step S1. Determine the model range and grid size according to the range of the water area to be measured, construct a triangular grid or a quadrilateral grid or a mixed grid, interpolate terrain data into the grid, and establish a hydrodynamic mathematical model.

[0096] In this step S1, a hydrodynamic mathematical model is established, mainly including the flow continuity equation and momentum equation:

[0097] The flow continuity equation is:

[0098]

[0099] The momentum equation is:

[0100]

[0101]

[0102] Where x and y are the coordinate axes of the Cartesian coordinate system;

[0103] h=η+d, h is the total water depth, η is the water level, and d is the still water depth;

[0104] u and v represent the average flow velocity along the water depth in the x and y directions, respectively;

[01...

technical field

[0001] The invention belongs to the technical field of hydrodynamic numerical simulation, in particular to a method for measuring water age in semi-enclosed waters. Background technique

[0002] There are more than 1,500 rivers with a drainage area of ​​more than 1,000 square kilometers in my country, more than 2,800 natural lakes with an area of ​​more than 1 square kilometer, and a coastline of more than 18,000 kilometers long and a sea area of ​​​​more than 3 million square kilometers. With the rapid development of the coastal economy, a large amount of pollutants and nutrients are discharged into rivers, lakes and coastal waters, resulting in the deterioration of the water environment. Especially for semi-enclosed waters with poor flow, it is difficult for the water body to exchange and renew with the surrounding water body through physical processes such as convection and diffusion to improve water quality, resulting in more serious deterioration of the ...

Examples

Embodiment

[0094] This embodiment discloses a method for determining the age of water in semi-enclosed waters, such as figure 1 As shown, the steps are as follows:

[0095] Step S1. Determine the model range and grid size according to the range of the water area to be measured, construct a triangular grid or a quadrilateral grid or a mixed grid, interpolate terrain data into the grid, and establish a hydrodynamic mathematical model.

[0096] In this step S1, a hydrodynamic mathematical model is established, mainly including the flow continuity equation and momentum equation:

[0097] The flow continuity equation is:

[0098]

[0099] The momentum equation is:

[0100]

[0101]

[0102] Where x and y are the coordinate axes of the Cartesian coordinate system;

[0103] h=η+d, h is the total water depth, η is the water level, and d is the still water depth;

[0104] u and v represent the average flow velocity along the water depth in the x and y directions, respectively;

[01...

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