Numerical simulation of the transport and diffusion of dissolved pollutants in the Changjiang (Yangtze) River estuary  

作　　者：吴德安 严以新 

机构地区：[1]State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University [2]College of Harbor, Coastal and Offshore Engineering, Hohai University

出　　处：《Chinese Journal of Oceanology and Limnology》2010年第3期649-657,共9页中国海洋湖沼学报（英文版）

基　　金：Supported by the Public Welfare Special Scientific Research Project funded by the Ministry of Water Resources of China (No. 200701026);National Natural Science Foundation of China (No. 50709007);the Startup Fund of Hohai University (No. 2084/40801107)

摘　　要：Based on a coupled hydrodynamic–ecological model for regional and shelf seas (COHERENS), a three-dimensional baroclinic model for the Changjiang (Yangtze) River estuary and the adjacent sea area was established using the sigma-coordinate in the vertical direction and spherical coordinate in the horizontal direction. In the study, changing-grid technology and the "dry-wet" method were designed to deal with the moving boundary. The minimum water depth limit condition was introduced for numerical simulation stability and to avoid producing negative depths in the shallow water areas. Using the Eulerian transport approaches included in COHERENS for the advection and dispersion of dissolved pollutants, numerical simulation of dissolved pollutant transport and diffusion in the Changjiang River estuary were carried out. The mass centre track of dissolved pollutants released from outlets in the south branch of the Changjiang River estuary water course has the characteristic of reverse current motion in the inner water course and clockwise motion offshore. In the transition area, water transport is a combination of the two types of motion. In a sewage-discharge numerical experiment, it is found that there are mainly two kinds of pollution distribution forms: one is a single nuclear structure and the other is a double nuclear (dinuclear) structure in the turbid zone of the Changjiang River estuary. The rate of expansion of the dissolved pollutant distribution decreased gradually. The results of the numerical experiment indicate that the maximum turbid zone of the Changjiang River estuary is also the zone enriched with pollutants. Backward pollutant flow occurs in the north branch of the estuary, which is similar to the backward salt water flow, and the backward flow of pollutants released upstream is more obvious.Based on a coupled hydrodynamic-ecological model for regional and shelf seas （COHERENS）, a three-dimensional baroclinic model for the Changjiang （Yangtze） River estuary and the adjacent sea area was established using the sigma-coordinate in the vertical direction and spherical coordinate in the horizontal direction. In the study, changing-grid technology and the ＂dry-wet＂ method were designed to deal with the moving boundary, The minimum water depth limit condition was introduced for numerical simulation stability and to avoid producing negative depths in the shallow water areas. Using the Eulerian transport approaches included in COHERENS for the advection and dispersion of dissolved pollutants, numerical simulation of dissolved pollutant transport and diffusion in the Changjiang River estuary were carried out. The mass centre track of dissolved pollutants released from outlets in the south branch of the Changjiang River estuary water course has the characteristic of reverse current motion in the inner water course and clockwise motion offshore. In the transition area, water transport is a combination of the two types of motion. In a sewage-discharge numerical experiment, it is found that there are mainly two kinds of pollution distribution forms： one is a single nuclear structure and the other is a double nuclear （dinuclear） structure in the turbid zone of the Changjiang River estuary. The rate of expansion of the dissolved pollutant distribution decreased gradually. The results of the numerical experiment indicate that the maximum turbid zone of the Changjiang River estuary is also the zone enriched with pollutants. Backward pollutant flow occurs in the north branch of the estuary, which is similar to the backward salt water flow, and the backward flow of pollutants released upstream is more obvious.

关 键 词：COHERENS model Changjiang （Yangtze） River estuary discharge outlet dissolved pollutants Euler transport distribution 

分 类 号：X52[环境科学与工程—环境工程]