基于守恒稳定格式的二维坡面降雨动力波洪水模型  

Well-balanced two-dimensional dynamic wave model for rainfall-induced overland flood

作　　者：吴钢锋[1] 贺治国[2] 刘国华[1] 

机构地区：[1]浙江大学水工结构与水环境研究所,浙江杭州310058 [2]浙江大学海洋学院,浙江杭州310058

出　　处：《浙江大学学报（工学版）》2014年第3期514-520,共7页Journal of Zhejiang University：Engineering Science

基　　金：国家"973"重点基础研究发展规划资助项目(2013CB035900);国家自然科学基金资助项目(51009120);教育部留学回国启动基金资助项目(20101174)

摘　　要：基于结构网格,采用有限体积法建立二维动力波洪水模型,用于模拟坡面地形条件下降雨洪水的运动规律.该模型在连续方程的源项中分别添加了降雨项和下渗项,其中土壤的下渗强度采用Green-Ampt入渗模型来计算.该模型采用中心迎风格式计算界面通量,并通过对界面两侧变量的线性重构,使得该模型具有空间上的二阶精度.为了保证模型的稳定性,采用半隐式的方法对底床摩擦项进行离散,同时利用中心差分方法对底床坡度项进行离散来保证数值格式的和谐性.对于坡面降雨洪水的模拟,负水深的产生是影响模型稳定的关键因素.本模型在库朗特数小于0.25时,能够保证任何时刻的计算水深都是非负的,而无须在计算过程中采用重新分配水深的方法来处理负水深,因此,相比于现有的大部分模型,该模型具有更强的鲁棒性和稳定性.采用该模型分别对2个非规则坡面地形条件下降雨产流实验进行模拟,计算结果与实测值吻合较好,表明该模型能够较准确地模拟复杂地形条件下坡面降雨洪水的运动规律以及土壤的下渗特性.Based on the structured grid,a two-dimensional dynamic wave flood model using finite volume method was developed to simulate the rainfall-induced overland flood propagation over irregular topographies.The rainfall and infiltration terms were added to the source term of continuity equation.The infiltration rate was calculated using Green-Ampt method.A central-upwind scheme was used to calculate the flux across the interface of computational mesh,and the linear reconstruction of flow variables was adopted to achieve the second-order accuracy in space.The friction source term was discretized using a semi-implicit method to ensure the stability of the model.A central difference method was used to discretize the bed slope source term to maintain the well-balanced property.Negative water depth is a key factor for the stability of the model to simulate the rainfall-induced overland flood.The model can guarantee the positivity of water depth when the Courant number is kept less than 0.25.There is no need to redistribute water depth to deal with negative water depth.Therefore,the present model is more robust and stable in com-parison with the most of existing models.The established model was tested against two experiments with rainfall overland floods over irregular topographies.The numerical results agree very well with the observations,which show that the model is capable of predicting the rainfall-induced overland flood propagation over irregular topographies and the infiltration process of soil with a good accuracy.

关 键 词：动力波洪水模型 有限体积法 中心迎风格式 线性重构 GREEN-AMPT入渗模型 坡面洪水 

分 类 号：TV122.1[水利工程—水文学及水资源]