干支流不同典型洪水组成的梯级水库防洪极限风险分析

不同的典型洪水组成对梯级水库的联合防洪调度风险有重要影响,为研究其对极限风险的具体影响以提高梯级水库洪水资源利用率,以黄河上游龙羊峡和刘家峡梯级水库为例,选取干流和支流实测洪水流量资料的年最大洪量过程,按洪峰在洪水过程中出现的位置划分为4场典型洪水,并从中各筛选出4场典型洪水过程线组合成16种情景,采用同倍比放大法推出梯级水库入库设计洪水,以下游水库设计洪水位作为极限风险控制指标,通过调洪演算得到防洪极限风险率。经分析干流洪峰靠后支流洪峰靠前的典型洪水组合对刘家峡水库的极限风险起决定作用。不同起调水位的联合防洪补偿调度计算结果表明,视不同来水情况可将刘家峡水库起调水位抬升至1 728~1 730m,以充分利用黄河流域的洪水资源。

Extreme Risk Analysis of Different Typical Floods Combination in Main Stream and Interval for Cascade Reservoirs Flood Control

Different typical floods have much influence on risk of joint flood control of cascade reservoirs. In order to study specific impacts of extreme risk and improve flood resources availability, taking Longyangxia and Liujiaxia cascade reservoirs in the upper reaches of the Yellow River as a study object, maximum flood flow process of main stream and tributary are selected according to the measured data. On the basis of peak flow position in flood process, four different type of floods are classified, from which picked out four typical flood process forming 16 kinds of situation. The multiplied with homogeneous enlargement method is used to determine the design inflow flood of reservoirs. Taking design water level of downstream reservoir as extreme risk control indicator, the extreme risk rate was obtained through flood regulating calculation. The flood combination of peak-after in main stream and peak-forward in tributary is the main influencing factor of extreme risk. Calculating result of joint flood compensating regulation at different water levels implies that adjusting water level of Liujiaxia reservoir could be heightened to 1 728-1 730 m in different conditions for making full use of flood resources in the Yellow River.