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A mathematical model of salinity control in a river with an effect of internal waves using two explicit finite difference methods
(2021-01-01)
Othata, Pornpon
;
Pochai, Nopparat
—Salinity is related to the quantity of salt in rivers, and that salt can take several different forms. Salinity is determined by water evaporation to dryness, and form residual measuring. The total salt content in water can in influence the taste of water. Drinking water at levels of salinity greater than around 1.0 g/L is drastically and rapidly unpalatable. In this research, two models, the internal wave hydrodynamic model and the salinity dispersion model, are proposed. The internal waves hydrodynamic model provides salinity internal wave and salinity flow velocity. The salinity dispersion model provides the salinity level. A modified salinity control model is also used in a river with a barrage dam. The suggested model provides salinity control releasing fresh water from a barrage dam where the salinity level is not higher than the standard and does not waste too much fresh water. An explicit finite difference method which is unconditionally stable is used for approximating the degree of salinity from the proposed model under many conditions.
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A simple numerical model for water quality assessment with constant absorption around nok phrao island of trang river
(2020-01-01)
Kraychang, Witsarut
;
Pochai, Nopparat
Nok Phrao Island is given to the island by the indigenous people. It is located near the Trang estuary with several rivers flowing through. Since this island is the assembly point of different river currents, it consequently causes problems with the quality of water. This island area accumulates different pollution such as municipal and industrial pollution. This problem affects today life of the local people such as their occupation, healthy, and ecosystem. However, there are some problems which are still unsolved because of many influential factors which cannot yet be identified. In order to overcome these obstacles, mathematical models could be useful before conducting operations on the Nok Phrao Island. In this research, mathematical models were applied to assess the water quality at Nok Phrao Island by assuming observation points in the models to get a pollutant concentration before and after the implementation of biological treatment from the wastewater treatment station. The mathematical models proposed in this research could be recommended for the assessment of the standard water quality at Nok Phrao Island to account for the increase in population or growth of industries around Nok Phrao Island in the future.
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Numerical treatment to a water-quality measurement model in an opened-closed reservoir
(2015-12-01)
Kraychang, Witsarut
;
Pochai, Nopparat
Measuring the water quality in water sources or the Monkey Cheeks Project with opened-closed reservoir. It can be measured by the field measurement, using the water quality monitoring tools and the water quality models consist of hydrodynamic model and dispersion model, to calculate the quality of the water. Hydrodynamic model, using the shallow water equation as a governing equation, is used to describe the water current, having source of wave maker and bottom topography as the required data, bringing about the elevation and velocities of water. Dispersion model, using the advection-diffusion equation as the governing equation, is used to describe the spread of the pollutant concentration of water, having pollutant concentration at point source and calculated water velocities from the first model as the input data, bringing the time-dependent pollutant concen- tration of water at any point. In this research, the three-dimensional surface fitting technique is employed, the anisotropic bottom topography data is represented by a surface function in the hydrodynamic model, in order to have a more realistic water current and water quality approximations in opened-closed reservoir.
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A numerical computation of a non-dimensional form of stream water quality model with hydrodynamic advection-dispersion-reaction equations
(2009-11-01)
Pochai, Nopparat
Mathematical models of water quality assessment problems often arise in environmental science. The modelling often involves numerical methods to solve the equations. In this research, two mathematical models are used to simulate pollution due to sewage effluent in the nonuniform flow of water in a stream with varied current velocity. The first is a hydrodynamic model that provides the velocity field and elevation of the water flow. The second is a dispersion model, where the commonly used governing factor is the one-dimensional advection-dispersion-reaction equation that gives the pollutant concentration fields. In the simulation processes, we used the Crank-Nicolson method system of a hydrodynamic model and the backward time central space scheme for the dispersion model. Finally, we present a numerical simulation that confirms the results of the techniques. © 2009 Elsevier Ltd. All rights reserved.

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