水文模拟与预报的不确定性问题是国际水文科学研究中的重要课题，如何定量全面地检验流域水文模型的合理性与适用性以及有效地弱化水文模拟与预报的不确定性是其中的关键科学问题。本项目以华南湿润区为实例研究，选择中山大学华南亚热带径流试验场进行水文观测试验，在多重工作假说理论的框架下，建立基于组件技术的模块化流域水文模型和基于贝叶斯理论的多重因子水文模拟评价诊断方法；利用雷达遥感和同位素等技术进行流域水文信息挖掘，建立具有物理机制的水源划分方法，探索水文模拟与预报的不确定性弱化方法；在上述基础上,构建一个基于多重工作假设的流域水文模拟系统，研究模型结构和参数对于不同气候和下垫面条件的适用性，建立科学合理的适用于研究区域的流域水文模型。该项目研究具有国际前沿和多学科交叉的鲜明特色，对于完善水文预报理论、改善预报精度以及为防洪调度提供科学的决策依据，都具有重要的理论意义和实际应用价值。

Research on uncertainty in hydrological modeling and forecast is an important topic in the international hydrological scientific research. The key scientific problems are how to quantitatively and comprehensively evaluate the reasonableness and applicability of watershed hydrological model, and effectively reduce uncertainty in hydrological modeling and forecast. In this project, the humid region in South China is taken an example study area, and hydrological observed experiments will be conducted at the subtropics hydrological experimental station of Sun Yat-Sen University. Based on the theory of Multiply Work Hypotheses, a modular watershed hydrological model based on COM technique and a multi-factor diagnosis method to evaluate hydrological modeling based on Bayesian theory will be established. Simultaneity, Radar, Remote Sensing and isotope techniques are used to explore more useful hydrological information and a physical basis hydrograph separation method will be established, so as to find the new approaches to reduce uncertainty in hydrological modeling and forecast. On the above basis, a hydrologic simulation system based on Multiply Work Hypotheses will be developed to study the applicability of model structure and parameters for different climate and underlying surface conditions, so as to establish a scientific and reasonable watershed hydrological model in the study area. These proposed methods are new and interdisciplinary. The proposed study will have significant theoretical and application values to improve hydrological forecast theory and accuracy, and to provide scientific decision basis for flood control.