ABSTRACT
This chapter systematically analyzes the regional characteristics of China and their impacts on water yield and reveals the spatial heterogeneity of water yield mechanisms across the country. This heterogeneity exhibits several key characteristics: the coexistence of saturation-excess and infiltration-excess runoff, the coexistence of water yield in cold and non-cold regions, the coexistence of water yield in mountainous areas and plains, and the coexistence of water yield in soil and rock structure. Furthermore, the functional requirements of the model are proposed with the goal of realizing national-scale fine hydrological simulation and dynamic water resources assessment. Several widely used semi-distributed and distributed hydrological models are examined. It was found that the existing distributed hydrological models are inadequate in capturing the spatial heterogeneity of water yield mechanisms across China. Through comprehensive comparison, the water and energy transfer processes model (WEP) was selected as the foundational model for constructing national-scale dynamic water resources assessment model in China (i.e., China Water Assessment Model or CWAM). Finally, the architecture, main modules, and implementation program of the CWAM were proposed.
