Hydrologic Risk Analysis Of Reservoir's Flood Protection

Water resources is the material foundation of human survival and development of social economy, it is an important natural resource which can not be substituted. China is one of the seriously water-deficient countries, with the growth of population and the development of social economy, the demands for quantity and quality of water resources are more and more intensity, the utilization of water resources and discharge of wastewater are more and more increased, however, the available fresh water resource is limited, all of these make the problem of water resources supply and demand especially seriously, so that the national economy is sharply restricted. As one of important water projects, reservoir carries dual tasks of the flood protection and the flood benefit which plays a significant part in water resources management. It is not only a huge wealth source, but also a kind of accident source. Although the probability of accident occurrence is very small, the destruction can result in enormous loses. So there is a great theoretic and practical significance for objective judging of flood protection and flood benefit.The paper brings out the water-deficient problem of our country and the dilemma of reservoir between in flood protection and efficiency, based on an overall review of national and international researches on risk analysis of flood protection, an idea of adjusting limit water level of reservoir during flood season to solve the problem is put out. Taking YueCheng reservoir in Zhanghe Basin as a study object, with the analysis of different periods design floods and the study of statistical property of observed annual highest recorded stage of the reservoir, the potential of raising formerly limit water level of the reservoir is found, and according to the different adjustment schemes of limit water level, the paper do the researches on the flood protection risk and benefit.The flood protection risk and efficiency analysis with different adjustment schemes of limit water level is an important point in this paper. Based on the uncertainty analysis of key factors, the influence on reservoirs flood protection risk caused by limit water level adjustment is evaluated from the two aspects of ultimate risk and dam overflow risk analysis. According to principle of the long series simulated for flood routing, taking a long series of day average inflow as input, the benefits with different adjustment schemes of limit water level is confirmed. Finally, based on a systematic analysis of main factors influencing limit water level of the reservoir, the limit water level during flood season schemes are synthetically augmented from many aspects.