Dongting Lake Basin is composed of a complex flow regime of rivers network, in recent years a large number of floods occurred in the Dongting Lake Basin, Lake water level crisis, flood prevention and control have become a focus in the middle Yangtze River. However Numerical modelling of flood events often requires a simultaneous description of the flow through relatively narrow channel networks and across extended plains. MIKE FLOOD integrates the one-dimensional models, MIKE 11 for rivers system and the two-dimensional model MIKE21 for lake into a single, dynamically coupled modelling system. Using a coupled approach enables the best features of both the one - dimensional and the two dimensional models to be utilised, whilst at the same time avoiding many of the limitations of resolution and accuracy encountered when using MIKE 11 or MIKE 21 separately. Further, it is a key to describe flooding across plains that the hydrodynamic model can represent flow across dry land or drying of flooded areas. A method based on a point to point approach to dynamically linked 1-D and 2-D hydrodynamic models is described. It uses an explicit predictor type implementation of the link and it is demonstrated using a simple example that the method provides a numerically sound approach. The ability of a 2-D model to describe critical flows, by using a local Froude number dependent upwinding scheme, is demonstrated by comparison of simulated and with observed data. The results indicated that the numerical simulation analysis carried out over a period of 2011 to 2014 in the Dongting Lake Basin clarify the water exchange ability of Dongting Lake including the flood evolution process, different flow fields, water level variation. We found that for each station water level variation in Dongting Lake is approximately 10m for maximum, increasing in summer and reducing in winter.

Full text: IJEIR_1943_Final.pdf