分布式降雨径流物理模型的建立和应用

Development and application of a physically-based distributed rainfall-runoff model

根据流域降雨径流的主要过程,考虑流域气象及下垫面要素的空间异质性,建立了具有物理基础的分布式降雨径流模型。模型将流域离散为栅格计算单元,并按水流特性分栅格单元为坡面单元和河网单元。在坡面单元上主要计算降雨、下渗、坡面流、壤中流等水文过程,而河网单元则主要计算河道汇流过程。模型利用空间权重插值方法将雨量站点的降雨量插值到各个计算单元,采用运动波方程来计算坡面流,将壤中流概化为垂向流和侧向流,分别用Green-Ampt公式和运动波方程来模拟,河道汇流也采用运动波方程。模型结构简单、参数的物理意义明确,大多数参数可利用DEM、土壤类型图、植被类型图直接获取,少数敏感参数通过率定确定。模型在浙江省甬江上游黄土岭流域和皎口流域进行了应用和检验,其结果令人满意。

A physically-based distributed rainfall-runoff model is developed to simulate the hydrological processes of watershed during rainfall period for considering the spatial variability of terrain, the land use, the soil type and the rainfall distribution. This model discretizes watershed into a number of square elements, and classifies them into hill-slope and channel ones based on the water flow properties. Each hill-slope grid element has model components for interception, infiltration, overland flow and soil water lateral flow, and each channel element has model components of channel flow. The infiltration and excess rainfall on each hillslope element are calculated using the Green-Ampt infiltration equation. Soil lateral flow is based on the Darey＇s law and the continuity equation, the overland and channel flows are described by one dimensional kinematic wave approximation to the St Venant equations, and the implicit finite differential scheme is used to solve these equations. This model has the characteristics of simple structure ,the process-based equations and the meaningful physical parameters. Most parameters of the model can be derived from the DEM, the digital soil type and the land use data, a few sensitive ones can be determined by the calibration. The model calibration and test are performed in huangtuling watershed（17.9 km^2）, a sub-basin of Yongjiang river in Zhejiang province, south-eastern China, and applied to Jiaokou watershed（259 km^2） , another sub-basin of Yongjiang river, the results are promising.