The Haihe River basin is widely recognized as an area in China which is most severely affected by human activities. The water resources utilization and recycling in the basin is very complex, and the characteristic of the dualistic water cycle is becoming more and more prominent. The ever-growing demand of water for modern industry and domestic life nearly dries up all the natural runoff. Meanwhile, industrial, agricultural and domestic wastewater discharges cause severe deterioration in water quality. Consequently, many of water courses are either dried out or being heavily polluted. Modern water resources management can no longer rely on the "monitoring-rehabilitation" model which was originally developed based on the natural water cycle. This paper analyzes the critical characteristics, water balance, and evolution of water flux process based on the theory of dualistic water cycle. Referring to the water cycle in the Haihe River basin, a schematic diagram was drawn to describe the dualistic water cycle pattern. Ten different parameters affecting mainly the evolution of water flux in the "dualistic water cycle" are closely examined using the newly-collected data. As a result, this paper proposes several water management and control strategies to achieve healthy water status for the Haihe River basin. dualistic water cycle, water resources, social water cycle flux, human activities, Haihe River Citation: Liu J H, Qin D Y, Wang H, et al. Dualistic water cycle pattern and its evolution in Haihe River basin.The water cycle in natural river basins is becoming increasingly complex with the ever expanding human activities in modern society. Natural water cycle traditionally relies on solar radiation and the Earth's gravity as the main driver. This has been changed to a dual-power driven, "naturalartificial" system. Water quality cannot be simply defined by relatively simple components of the natural organic compounds, minerals and sediment; there are thousands of chemical components added in water, including fertilizers, pesticides, industrial detergents, persistent organic compounds, medical antibiotics, hormones and many others. Thus, characteristics and signatures of "dualistic" water cycle in river basins are presented in both quantity and quality of water flux. In 1997, Raskin et al.[1] developed one of the earliest global assessment models of freshwater resources. Their model did not consider the influence of human activities. Subsequently, another model, Water global assessment and prognosis (Water GAP) tool (Döll [2,3]) was developed to make up for the shortage. Water GAP consists of two modules: the world's water consumption module and the world's hydrological module; and it can be regarded as the first global "dualistic" water cycle model. In addition, the SWAT model [4,5] operates at a regional scale; Imbe's model [6] which simulates evaluation and rehabilitation of urban water cycle, operates at the city level.In China, Wang et al. [7] proposed the theory of "dualistic water cycle" and developed the WEP-L...
