Study And Application Of Extreme Risk Rate For Casacade Reservoir Flood Control Based On Uncertainties Of Design Flood

Water is the source of life, and has always been an important guarantee for the development and progress of human society. Today, due to the precipitation of the uneven distribution of time and space, and between inter-annual variations violent, causing floods and droughts frequently occurring, so the limited water resources has not been maximized utilization. Cascade reservoirs as a major engineering measures built on the river, charged with the important responsibility of regulating floods and drought disasters and the redistribution of water resources. Scientific and rational cascade reservoir flood control, and timely storing flood can effectively alleviate water shortages and conflicts between disaster-prone, and the reservoir is a key priority of cascade reservoir flood control.This article is mainly based on the concept of extreme risk, to study the extreme risk of cascade reservoirs, mainly from the point of view of the uncertainty of hydrological design flood downstream reservoir. The flood composition is divided into two parts, namely an upstream tributary to the River runoff and interval water. First, different typical floods had important influence on risk of joint flood control of cascade reservoirs, according to the position of the flood peak appears in the division during the four typical flood, and from each selected four typical flood hydrograph, combined into16kinds of scenarios, analyzing the impact of different shapes typical cascade reservoir inflow flood on extreme risk rate, and multiplied with homogeneous amplification method, so as to get design inflow flood of reservoirs, and took design water level of downstream reservoir as extreme risk control indicator, through flood regulating calculation, the extreme risk rate was obtained. Second, combining fused tail effect statistically extreme value theory and probability distribution, based on the measured data and the use of mathematical models of probability theory and mathematical statistics methods of frequency analysis, flood storage were obtained by programming the calculation of reservoir operation, specific analysis of flood control and extreme risk of the upper Yellow River Longyangxia and Liujiaxia cascade reservoirs for Liu reservoir, obtained in a typical composition of the flood affected Liujiaxia reservoirs for the extreme risk of a major flood peak runoff in the main stream and tributaries to flood peak forward combination for the linear selection, the result shows that the use of GEV distribution for extreme the resulting design flood volume is larger than conventional P-Ⅲ type curve design magnanimity should be large, so that using GEV makes the design results somewhat more secure.