基于产汇流机理的多尺度径流过程实验与模拟研究

Runoff process is one of the most important components of mass cycle in a watershed. The mechanism and numerical simulation of water travel has been an international challenge in hydrological sciences. Taking the experimental system consisting of multiple scale nested watersheds located in the Chuzhou Hydrological Experiment base of Nanjing Hydraulic Research Institute as study areas, the overall objective of this project is to study mechanism and modeling of hydrological processes by using an integrated approach of physical experiment, theoretical and statistical analysis, isotope tracing, and numerical simulation, etc. The specific objectives of the project are as follows:(1) to analyze temporal variation and spatial distribution of water in different soil layer,travel time and dynamic storage of water in a watershed, and impact of landscape features on characteristics of water movement; and reveal generation mechanism of multiple runoff components (e.g., surface runoff, runoff generated from unsaturated zone and saturated zone) in a watershed. (2) to study scale effect of hydrological processes based on analyzing relationships between scale-different processes, and improve methodology for hydrological scaling. (3) to validate REW model (Representative Elementary Watershed) with the recorded data of physical experiments, improve the both models based on well understanding of multiple hydro-physical processes, and finally formulate a set of systematical theory and method of hydro-physical processes modeling. The expected achievements of the project will not only rich the knowledge of hydro-physical processes in a watershed, improve hydrological models, but also could promote development of hydrology sciences.

气候变化影响下，降水强度、水文节律、非稳态加剧，产流汇流机理发生了变异。径流形成过程是流域物质循环的重要组成部分，其运动机理与数值模拟是当今国际水文科学的前沿研究问题。本项目拟开展嵌套流域水文多要素径流观测实验，辨识地表、非饱和带、饱和带的水分运移和存储时空分布特征，探明降雨、入渗、土壤水分的耦合机制，揭示环境变化下的产流机理；结合连续观测和同位素示踪实验，厘清不同雨强、土壤结构、地形和植被条件下的坡面/流域汇流特征，建立不同环境因子下混合水文单元的径流组合模式，阐明不同尺度的流域径流形成机制；建立基于代表性单元流域水文模型，分析不同尺度水文过程间的相互关系，发展完善水文尺度转换方法。研究成果将提升对流域水文过程的认识，对推动水文机理研究的发展起到重要作用。

径流过程的运动机理与数值模拟是当今国际水文科学研究的前沿问题。本研究以实验流域和天然流域为平台开展径流过程水文要素观测实验及模拟研究，阐明了流域水分运移和存储机理，揭示了流域下垫面特征对水分过程的影响机制，完善了水文尺度转换方法，验证与改进了基于代表性单元流域水文模型。研究成果不仅揭示了流域水文物理过程形成的机制，提升了对流域水文过程的认识，而且对推动水文学科的发展起到了重要作用。