中文摘要：

洪水资源利用有助于缓解北方地区的水资源紧缺形势,风险适度性作为洪水资源利用三大适度性之一,用于指导洪水资源的合理开发与安全利用。在水库汛限水位调整中,提出采用不同频率设计洪水进行不同汛限水位条件下的洪水调节计算,并结合水库的经济与生态供水目标进行长系列用水调度模拟和供水效益分析,综合确定风险适度性的方法。对密云水库的计算分析表明,主汛期汛限水位从原设计的147.00 m安全抬高至目前的152.00m是可靠的,其风险阈值上限为153.20 m;后汛期汛限水位可从目前的154.00 m安全抬高至155.40 m。两种情况下水库供水保证率可以分别提高0.30%和0.01%,且大坝和下游防护区的防洪风险率分别为0.01%和1%,与原设计一致,满足洪水资源安全利用的风险适度性要求。

英文摘要：

Flood utilization can alleviate the shortage in water resources in North China. As an important part of flood utilization criteria,the risk-moderate criterion ensures reasonable and safe exploitation of water resources. For the adjustment of flood limit water levels（ FLWL）,an analysis method is proposed,which determines risk-moderate criterion by computing flood regulation with the designed floods of different return periods and modeling long-time series water supply with reservoir scheduling model. This method is applied to Miyun Reservoir in Beijing. Results show that the uplift of the major-flood-period FLWL from the initial value of 147. 00 m to the current value of 152. 00 m is relatively reliable,and its upper threshold can be 153. 20 m further. The upper threshold of later-flood-period FLWL for reliable flood utilization is 155. 40 m,compared with 154. 00 m at present. The water supply assurance rates increase by 0. 3% and 0. 01% in these two cases,respectively; and the risk rates of the dam and downstream flood control areas are kept within 0. 01% and 1%,respectively. These risk rates satisfy the designed standard and risk-moderate criteria of flood utilization.