The knowledge and simulation of basin water cycle is the scientific and application foundation for water resources planning. The water cycle simulation used to be one process for natural water cycle to move around the land surface. In view of the complex influence of human activities on the basin water cycle, simulations on large-scale natural basin cycle and small-scale artificial cycle have been carried out respectively during recent years but without establishment of any model of the overall process simulation. In addition, due to the special existing state of soil water and its frequently changing characteristics, the simulation and quantitative assessment of the soil water on non-saturated belt has always been a weak link in hydrology and water resources research. The above-mentioned current research obviously cannot satisfy the practical demand of the water resources planning in densely-populated areas which are short of water.
In national key fundamental research subject under National High-tech Program Adopted in March 1997, in view of the great impact of intense human activities in China on the basin water cycle, the theory of dualistic water cycle “nature-artificiality” at basin level has been proposed by taking account of both human activities and natural influences as dual driving factors in basin water cycle. Based on the dualistic model theory, basin dualistic water cycle model has been constructed by the coupling of distributive simulating model and integrated regulating model, and the former mainly simulates major natural process of “slope-rivercourse” on the land surface and the latter mainly simulates the tributary watercycle process with “water intake-water transportation-water use-water discharge” as the basic links. Meanwhile, through considering the influence ofthe underlying surface changes on water cycle by referring to production and confluence parameters, the precise simulation of the whole process of basin water cycle under changing circumstances has been realized. Moreover, under the framework of theories and methods on water resources assessment defined by academicians and experts of the elder generation, the definition of the hierarchical water resources assessment including water resources in a generalized sense and in a narrow sense, and the available quantity of national economy. In addition, by taking dualistic simulation model as the quantitative instrument, the systematic dynamic assessment of the available water resources in the Yellow River Basin including the soil water has been achieved, revealing the evolutionary laws of water resources in the Yellow River by humana ctivities and proving the high precision of the assessment results.
The dualistic patternand model have made breakthroughs in conventional hydrology and water resources research which confines itself only to the separated description between natural and artificial driving forces of basin water cycle and the cycle process, and will be the engine of the future numerical basin. While soil water simulation and soil water resources assessment have further enriched the method and connotation of basin water resources evaluation. In the Yellow River project under National High-tech Program Adopted in March 1997, the dualistic pattern and model of the basin water cycle, the dynamic assessment method of water resources in a generalized sense and the evolutionary law of water resources in the Yellow River have been appraised as "the innovative achievement" by the expert team for project examination and approval of the Ministry of Science and Technology, the technical expert group of the Ministry of Water Resources and some academicians within the same research areaand have been reported to the Ministry of Science and Technology as a significant achievement. The appraisal expert group of the Ministry of Water Resources including many academicians agrees that this outcome has made “significant breakthroughs both in theories and methods up to international leading level”. In 2005, the achievement won Da Yu Award for Advancement in Science and Technology by the Ministry of Water Resources.
The theory of basin dualistic water cycle pattern and the simulation technology attracted widespread attention as soon as it was proposed in 2004, and was applied in the evaluation of the water resources in the Yellow River basin for national integrated planning of water resources. At the invitation of the Yellow River Water Resources Commission and the Yangtze River Water Resources Commission,lectures on this special subject have been organized successively with the participants exceeding one hundred. This achievement has also been initially applied in the administration by the Ministry of Water Resources, the Bureau of Hydrology, the Department of Irrigation, Drainage and Rural Water Supply and General Institute of Water Planning.
