我国水旱灾害频繁、水资源短缺问题十分严峻。流域水循环机理与水资源演化规律在水利工程基础科学域占有十分重要的地位。流域水循环机理包括流域降水径流过程的非线性关系，“土壤-植物-大气”界面过程的水文生态学机理。气候变化和人类活动影响水资源演变规律与调控，是水利工程基础水文水资源研究的核心问题。China suffers frequent floods and droughts, and faces severe water shortage. The water circulation mechanism and water resources evolution laws in river basins have been playing very crucial roles in hydraulic engineering. The water circulation mechanism includes the non-linear relationship of rainfall-runoff process, as well as the hydrological and ecological mechanisms of “soil-plant-atmosphere” interaction. The climate change and human activities affect the water resources evolution laws and water control, which are the core issues of the water resources research in hydraulic engineering. 长期以来，国内外暴雨洪水计算、洪水预测预报主要是线性理论体系，包括Nash单位线模型等。然而，水文系统的真实过程是非线性。1975年8月，我国发生震惊中外的河南“75.8”特大暴雨洪水和重大梯级垮坝事件，说明传统的工程水文计算系统、暴雨洪水产汇流线性系统模式等存在重大的基础缺陷，提出了暴雨洪水预测预报与跨坝洪水复核计算的水文非线性问题。以后，我国长江流域、东北松花江、辽河、淮河流域等相继发生特大洪水灾害，水利工程水库流域洪水预测预报与洪水调度成为水利工程科学基础水循环研究的突出方面。Since long time ago, the rainstorm flood calculation and flood forecast worldwide have been mainly based upon the linear theoretical system, including the Nash unit linear model. Nevertheless, the true process of the hydrological system appears to be non-linear. The world-wide astonishing “Aug. 1975” Specially Heavy Rainstorm Flood and Cascaded Dam Collapse Event in Henan Province, China, indicated that there were obvious basic defects in conventional hydrological calculation system and the rainstorm flood conflux linear system model, and that the rainstorm flood forecast and dam overflow flood recheck is not linear. Thereafter, especially heavy food disasters occurred one after another in the Yangtze River Basin, Songhua River Basin, Liaohe River Basin, and Huaihe River Basin in China. Therefore, flood forecast and flood regulation in the reservoir watersheds of hydraulic projects have become an essential of the basic water circulation study regarding the hydraulic engineering. 与暴雨洪水问题相反，与水资源短缺与环境变化影响联系的流域水循环动力学过程与生态水文过程，是水科学工程领域的重要科学基础问题。在我国，华北水资源短缺问题最为突出，农业用水占水资源总量80%。如何在传统的“四水”转化基础上（即“降水-地表水-土壤水-地下水”）发展耦合植物生态调控的的“五水”转化水循环机理，成为寻求高效农业节水与区域水资源调控的重要理论与基础。Contrary to the rainstorm flood issue, the water circulation dynamic process and ecological & hydrological process relating to the water resources shortage and environmental change falls into the water science engineering. The North China suffers the most serious water shortage, where agricultural water consumption accounts for 80% of the total. The essential theory concerning measures for effective agricultural water conservation and regional water resources regulation is based upon how to develop the “five waters” circulation mechanism through developing coupled plant ecological regulation in the basis of conventional “four waters” (namely, rainfall - surface water - soil water - ground water) conversion mechanism.在流域尺度上，与水循环基础直接联系的流域水资源演化规律，成为国内外水利工程水资源规划与水资源可持续性的核心问题。黄河是我国第二大外流河流，称为中国的“母亲河”。但是，上个世纪90年代黄河出现持续8年的断流、水资源危机直接影响国计民生，为世界瞩目。1999年，国家启动了“973”重大基础项目“黄河流域水资源演化规律与可再生维持机理”以及国家自然科学基金会重点研究项目等。国际上，实施了水利工程科学基础的水文水资源研究计划，包括：全球变化和人类活动影响的非线性过程、资料缺乏地区水文研究计划（PUBs），全球水资源评估计划（WWAP）等。流域水循环机理与水资源演化规律研究是当前国内外瞩目的重大科学问题。The water resources evolution laws which are directly related to the water circulation basis in the river basin have become a worldwide core issue in the water resources planning of hydraulic projects and water resources sustainability. The Yellow River is the second largest exoreic river in China, and it is nicknamed as “the River of Mother” in China. Nevertheless, since the 1990s, it has experienced eight consecutive years’ flow cutoff. The water resources crisis has directly affected the national economy and the people’s livelihood, receiving attention from all over the world. In 1999, China initiated the “973” key fundamental project - “Water Resources Evolution Rules and Renewability Mechanism in the Yellow River Basin”, and other key research programs funded by the National Natural Science Foundation. Internationally, a hydrological water resources research program regarding the basic mechanism of hydraulic engineering has been implemented, including such researches as the Non-Linear Process Affected by Global Climate Change and Human Activities, the Prediction in Ungauged Basins (PUBs), and the World Water Assessment Program (WWAP), etc. The study on the water circulation mechanism and water resources evolution laws in river basins is one important challenge that attracts worldwide attention.