考虑蓄满产流机制的流域分布式产汇流模型

洪水预报通常基于降雨径流模拟进行。以山坡水文学理论的蓄满产流机制为出发点，展开了对山区流域降雨径流模拟的研究，以此建立分布式三水源产汇流模型。首先，对研究流域进行离散化，以数字高程数据为基础提取流域的地形数字特征，使离散化坡面单元的数据同时完成自动匹配，实现参数的空间离散化，为模型的应用提供参数支撑。其次，采用水流连续方程和达西公式计算单元坡面内的产流量；以圣维南方程组简化的运动波方程为控制方程，推导出坡面流近似的偏微分方程，利用特征线法对每一单元坡面进行汇流计算。所建分布式水文模型可模拟从非饱和壤中流漫溢到坡面单元上形成饱和坡面流的暴雨径流过程。同时借由马斯京根-康吉法衔接了坡面离散单元水文子过程与主河道的汇合。最后选取美国古德温河流域典型的降雨过程进行次洪过程模拟，采用确定性系数、相关系数来评定模拟精度，结果表明其模拟精度达到了径流过程模拟和作业预报的精度要求。总体来说，所建分布式产汇流模型不但适用于单一坡面的径流分析，且能够应用于一般流域以进行降雨径流过程的模拟，在一定程度上可为防洪调度提供参考依据。

Distributed Hydrological Model Considering Saturation-excess Runoff Mechanism

Flood forecasting is usually based on the simulation of rainfall-runoff models. In this study, based on the saturation excess runoff mechanism, a distributed three-source runoff model was developed for rainfall-runoff simulation in mountainous areas. Firstly, a watershed was delineated into several hillslope units and a digital terrain analysis was conducted to extract the topographic features from the DEM dataset, the discretization of the parameters was realized by the digitization of the watershed at the same time and providing the necessary support for the application of the model. Secondly, the runoff yield in the slope surface unit was calculated by using the flow continuity equation and Darcy formula. Taking the simplified kinematic wave equation of Saint-Venant equations being as the governing equation, the approximate partial differential equation of slope surface flow was derived, and the confluence of each slope surface unit was calculated with characteristic line method. Storm runoff can then be simulated from the unsaturated lateral flow to the saturated overland flow on the hillslope unit of the proposed distributed runoff model. Moreover, outflows from the hillslope units were confluent and routed by using an improved Muskingum-Cunge method in the main channel. To test the applicability of the model, the simulations by using the hydrological records of Goodwin Creek experimental watershed in USA were assessed by the deterministic coefficient, correlation coefficient. The results showed that the proposed distributed runoff model can afford precise rainfall-runoff simulations and the accuracy can meet the requirement of forecasting. In general, the developed model can extend the applicability for rainfall-runoff routing from small hillslopes to mid-size or larger watersheds.