Abstract: Using the flood control system in the middle and lower reaches of the Yangtze River as study objects,a numerical model for the real-tmie evaluation of the storage discharge re-lationship in the rivers and lakes of the reaches is presented.The model is a further development of the flowsed mient transport model for the purpose of flood control planning.The model is used to assess the flood prevention schemes for the reaches in this study.To accommodate the needs of quickly and accurately evaluating the storaged ischarge relationship in real-time,we propose an iterative scrolling algorithm and calibration techniques,as well as an expermiental procedure for flood control operation based on hydrodynamics.The real-tmie evaluation objective can thus beachieved.We discuss the coupling between the flood model and the flood control operation model in the context of numerical study of the real time evaluation of the storage discharge relationship in the middle and lower reaches of the Yangtze River.Atrial operation of the numerical model is conducted during the Yangtze River flooding seasons.The result shows that the numerical model is able to effectively address key issues that arise from executing the real-tmie evaluation of the storaged ischarge relationship,and from optmiizing the flood control projects.The result provides the theoretical basis for flood control planning and real-tmie flood operations.Our results have been used in the planning of flood control projects and flood operations for the middle and lower reaches of the Yangtze River.