中文摘要：

为了研究赣江下游人河污染物对河流水质的影响，建立了基于WASP（ Water quality Analysis Simulation Program ）模型富营养化原理和 ELADI （ Eulerian-Lagrangian Alternating Direction Implicit Method ）有限差分方法的正交曲线平面二维水环境模型WESC2D（ Two-Dimensional Water Environment Simulation Code）。模型采用基于双线性插值及亚网格技术的欧拉一拉格朗日方法求解对流项，在简单的浓度峰输运和赣江下游溶解氧变化过程算例检验的基础上，计算与分析了赣江下游人河排污口氨氮污染负荷与水质之间的动态响应关系。模拟与分析结果表明，WESC2D模型的计算结果与解析解吻合良好，有效地减少了欧拉-拉格朗日方法的数值耗散，并为赣江下游污染负荷与水质响应关系计算提供了重要工具。

英文摘要：

In this paper, a new model WESC2D （Two-Dimensional Water Environmental Simulation Code） using an orthogonal curvilinear grid system is developed for the impact study of pollutants discharged into the lower reach of Ganjiang River. The model development is based on the eutrophication principle of the Water Quality Analysis Simula- tion Program （WASP） model and the Eulerian-Lagrangian alternating direction implicit （ELADI） scheme. The model convection terms are solved by the Eulerian-Lagrangian method based on the hilinear interpolation and sub-grld scale method. The simulation of WESC2D is compared to the analytic solution to the problem of simple concentration peak transport, and to the field measurement of dissolved oxygen from the lower reach of Ganjiang River. The dynamic rela- tionship between the pollution loads and the water quality at sewage outlets along the reach is also examined. Results show that the simulation of WESC2D agrees well with the analytical solution at a substantially reduced numerical cost compared to that of using the general Eulerian-Lagrangian Method （ELM）. The new model WESC2D provides an important tool for the study on the relationship between the pollution loads and the water quality in the lower reach of Ganjiang River.