Bivariate structure load return period and joint flood quantile estimation

Currently, flood hazard event and hydrological failure scenario judged by the widely used bivariate return period may violate the real case. In this study, the exceedance probability of the highest water level in the reservoir was adopted to measure the safety design criteria of flood control. The estimation methods for structural load return period and most likely joint design values of flood peak and volume were presented. The Geheyan reservoir located at Qingjiang basin was selected as a case study to perform the application and comparative study. In this Geheyan reservoir example, it is demonstrated that compared with structural load return period, the design standards of most likely joint design values of OR and AND return period are higher or lower systematically. Meanwhile, design standards were either over-estimated or under-estimated to some extent in most likely joint design values of Kendall and survival Kendall return period. The presented structural load return period considers the interaction between flood characteristic variables, i. e. peak and volume, and operation rules of the reservoir. Consequently, it is in accordance with the essential implication of design flood and can achieve the specified flood control standards, which will provide more scientific and reasonable basis for flood control design and risk assessment of the reservoir. © 2018, China Water Power Press. All right reserved.