Water age measurement method for semi-closed 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 ...

AI Technical Summary

Problems solved by technology

The particle tracking method based on Lagrange ignores the influence of the diffusion process, and the calculated water age is too large compared with the actual water age, which underestimates the actual exchange capacity of the water body

In addition, for the calculation range with a large space-time scale, the Lagrangian particle tracking method needs to release a large number of tracer particles under the condition of sufficient accuracy, and the calculation of particle trajectories requires a lot of computing time and storage space. high performance requirements

However, the average water age calculation method based on Euler’s point of view considers the convection and diffusion process, but the calculation formula is often more complicated, and it is difficult to calculate directly, and the current calculation formula is generally only applicable to the steady-state hydrodynamic environment with small changes. For water areas with large influence and reciprocating flow, the calculation results of water age are prone to fluctuations and shocks due to changes in the hydrodynamic environment and cannot tend to a stable value.

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