Abstract: With the one-dimensional and two-dimensional unsteady flow equations as the governing equations,a one-dimensional and two-dimensional coupled flood evolution mathematical model is established to study the flood routing in Xianxian County using finite volume method for discretization based on the topographic data of Xianxian County and the hydrological data of Hutuo River Basin. The model is verified by using the water level data of Hutuo River under the current flood capacity,and the results are basically consistent. In the case of flood inflow of 10-,20-,and 50-year return period,the simulation calculation was carried out,and the opening time of different entrance gates and the water level process of major sections of the river are obtained through simulation. The dike height at main positions of the river channel is compared with the flood height,and the time when the floodplain water level reaches the maximum are compared. Rresults reveal that the water level at major positions of the river has increased obviously with the increasing of return period. In particular,in the case of floods with the return period over 20 years,the water level of river channel in the downstream of Yaozhuang is gradually higher than the embankment height,leading to overflow of the embankment. The research findings offer basis for flood control decision in future.

Key words: flood simulation, one- and two-dimensional hydrodynamic coupling models, finite volume method, water level process, floodplain in Xianxian County