In order to simulate changes in the water quality of the Miyun Reservoir due to continuous descent of surface water level, a 3-D ecological hydrodynamic model was developed through coupling the water quality analysis simulation program ( WASP ) with the environmental fluid dynamics code ( EFDC ). 为模拟近年来密云水库水位不断下降引起的水质变化的问题,开发了三维生态动力学模型来进行密云水库水质模拟,该模型耦合了水质模型WASP和水动力学模型EFDC。