基于水动力模型的小流域洪水预报研究

Research on flood forecasting of small watershed based on hydrodynamic model

山丘区小流域洪水具有季节性、突发性、水量集中等特点,考虑到山丘区小流域洪水破坏能力强,危害性较大,而洪水预报精度较差,故有必要研究小流域洪水预报,为防洪决策提供支撑。在运用径流曲线法对净雨进行计算的基础上,采用二维水动力模型对地表径流进行模拟,以期得到流域出口断面的流量过程,并将该原理方法应用在福州市赤桥小流域。应用结果表明,选取的10场洪水的确定性系数精度基本上都能达到乙级,峰现时间误差均控制在2 h范围内,洪峰相对误差均能控制在20%范围内,能满足精度要求。经验证,综合考虑土地利用、土壤类型等下垫面情况的径流曲线法能很好地模拟产流过程,二维水动力模型能很好地模拟小流域的地表径流演进过程,能为小流域的洪水预报提供新思路。

The flood of small watershed in the hilly area has the characteristics of seasonality,suddenness and con⁃centration of water,which results in great damage to people downstream.Considering that the flood forecasting ac⁃curacy of small watershed is poor,it is necessary to research the flood forecasting of small watershed to provide support for flood prevention decision.In this paper,the runoff curve method was applied to calculate the net rain first.Then the surface runoff was simulated by the method of two-dimensional hydrodynamic model in order to ob⁃tain the flow process of the outlet section of the basin.Finally,above methods were used in the Chiqiao small wa⁃tershed of Fuzhou.The results show that the deterministic coefficients of ten floods selected can basically reach Grade B.The peak time errors are all controlled within two hours,and the relative errors of flood peak can be con⁃trolled within 20 percent,which can meet the accuracy requirements of flood forecasting.It has been verified that the runoff curve method that comprehensively considers the underlying surface conditions such as land use and soil type can simulate the runoff process well.And the two-dimensional hydrodynamic model can simulate the sur⁃face runoff evolution process well in the small watershed.Overall,these methods can provide a new idea for flood forecasting in small watersheds.