Study Of Urban Flood Numerical Simulation In Jinan City

The urbanization process becomes quicker in recent years, which is the reason that the number of flood disasters worldwide has been increasing significantly. The increasing volume of surface runoff and flood peak discharge and the appearance time of flood peak ahead are the main phenomena. Besides, many problems of flood protection of city appear due to less urban infrastructure for flood prevention and deficient city's construction plan. Flood inundation model is the main part of flood management system and could provide forecasting and evaluation of city flood risk for relative department. Jinan city has its own special terrain where there are hills in the south and Huang River dam in the north and XiaoQing River is the only outlet for water-flow. This paper set up flood inundation models including 1D river network model,2D surface runoff model and 1D-2D coupling model for Jinan city with DHI MIKE software.Firstly, developing the one-dimension river model and compared two different hydrological models which are NAM and Urban. Given to the complicated terrain in Jinan city where there are big different underling surfaces between north and south, NAM model was used to set the river model. Simulation results in good agreement with the measured data.Secondly,2D surface model is used with MIKE21 software. Two kinds of computational grid are applied and feasibility study and sensibility analysis were used for topography generalization, grid size and roughness,and is successfully applied to the model of Jinan City model.Thirdly, developing the coupled 1D and 2D model and simulated the flood inundation of Jinan city. The model solved the problem of interactions between two components which includes streets, sewer system and rivers and the result shows distribution of water logging when rainfall coming within the second ring road of Jinan, which reflects the real situation in low-lying areas. This model also verified reliability of surface rainfall-runoff model.Lastly, water and rain information has been analyzed since there are recording data for Jinan city and the typical rainfall process of the city is designed with the coupled model, and finally rainfall regimes are determined which are suitable for long-duration and short-duration rainfall of Jinan. Pre-plan database of flood simulation was set based on designed and historical of typical rainfall process. According to weather forecast flood control department could predict water-depth distribution through inquiring simulation pre-plan database and take measures to arrange schedule of flood protection and emergency in advance.