Journal of Chongqing University (English Edition) [ISSN 1671-8224]
Vol. 7 No.1
March 2008
1
Article ID: 1671-8224(2008)01-0001-07
To cite this article: SI Hu, BI Hai-pu. Numerical simulation of pollutant diffusion and decay process after a water pollution incident in the Three Gorges Reservoir [J]. J
Chongqing Univ: Eng Ed [ISSN 1671-8224], 2008, 7(1): 1-7.
Numerical simulation of pollutant diffusion and decay process after
a water pollution incident in the Three Gorges Reservoir
∗
SI Hu
1,2,†
, BI Hai-pu
1,‡
1
College of Resource & Environment Science, Chongqing University, Chongqing 400030, P.R. China
2
Key Lab for the Exploitation of Southwestern Resource & the Environment Disaster Control Engineering, the
Ministry of Education, Chongqing University, Chongqing 400030, P.R. China
Received 30 September 2007; received in revised form 30 December 2007
Abstract: We established a hydrodynamic model to simulate the pollutant transport and decay process in the case of a pollution
incident in the sections of the Yangtze and the Jialing passing through the city area of Chongqing. The Boussinesq assumptions
and the Navier-Stokes equations of incompressible fluid were applied to setting up the pollutant diffusion equations and the
equations for the decay process. E. coli was taken as the example pollutant, and chloride dosage, light, temperature and ultraviolet
intensity were considered in the equations for bacterial decay process. The calculated values of the fluid velocities in the two
rivers agree well with corresponding measured results, indicating an ideal accuracy of the model. In simulation, the concentration
of E. coli in water was assumed to be zero before the accident. The upriver boundary velocity was −1.35 m/s for the Jialing flow
and 1.75 m/s for the Yangtze flow, and the downriver boundary was water depth set at 0. Simulation results show that the bacteria
are transported downstream along the riverbank. A long and narrow pollutant belt develops at 12 h after the start of the accident
ascribed to the quick longitudinal transfer. After the pollution sources are cut off, the pollutant concentration decreases slowly,
mostly by advection and diffusion, suggesting inadequate self-purification ability of the rivers and the necessity of effective
decontaminating measures in the case of a pollution incident. The model can be a useful tool for understanding the polluting
situations of an improper discharge incident and evaluating the effects of decontaminating measures for the water body of the
Three Gorges Reservoir.
Keywords: water pollution control; Navier-Stokes equations; river pollution; emergency analysis of water pollution; the Three
Gorges Reservoir; pollutant decay; pollutant diffusion
CLC number: X507 Document code: A
1 Introduction
1
The Yangtze is the largest river in China, holding
†
Corresponding author, SI Hu (司鹄): Prof.; PhD adviser; Research
interest: environmental hydrodynamics; E-mail: sihu@cqu.edu.cn.
‡
BI Hai-pu (毕海普): Postgraduate; Research interest: environ-
mental hydrodynamics; E-mail: bihaipu@yahoo.com.cn.
∗
Funded by Chongqing University Postgraduates’ Science and
Innovation Fund (No.200701Y1B0270213).
about 35% of the water resources of the country [1],
providing drinking water and carrying wastewater and
trash away throughout the valley. The Three Gorges
reservoir is filled with a giant water body of 1 084 km
2
[2], which is susceptible to improper waste discharge in
the upper reaches of the Yangtze River. The notorious
pollution accidents of the Tuojiang River in 2004 and
the Songhuajiang River in 2005 evidenced the
calamities caused by an environmental underemphasis
in the circumstances of a large water body for the living
beings therein and in downstream reaches [3]. Chinese
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