中文摘要：

梯级水库中的上游水库遭遇不利的突发事件而发生溃坝，会给下游水库及防护区带来严覆的洪灾损失。以岗南、黄壁庄梯级水库为例，拟定岗南水库遭遇地震的突发事件，确定了水库溃坝工况，建立溃坝洪水计算模型，对岗南水库在不同预泄时长后溃坝的洪水过程进行模拟，黄壁庄水库针对上游入库溃坝洪水采用按调度规则调洪和以最大泄洪能力泄流两种溃坝应急调度方式进行模拟分析。结果表明：有预泄的溃坝调度可以在一定程度上缓解岗南水库溃坝洪水对下游造成的洪灾损失，且预泄时间越长缓解程度越明显；黄壁庄水库的两种调度方式都能保证水库自身安全，但从出库洪水对下游防护区的洪灾损失大小角度考虑，按调度规则调洪优于以最大泄洪能力泄流的方式。

英文摘要：

The present paper is to introduce our simulation analysis on the emergency flood control operation for the cascade reservoirs by taking Gangnan and Huangbizhuang （in Hebei province） reservoirs as our case studies. It is known that dam breaking of the upper stream reservoir would cause a great flood risk for the lower reservoir and its area to be protected in the case of cascade reservoirs. For example, it is supposed that the dam break would not occur on the assumption that Gangnan reservoir would be operating normally without the inflow in non-flood seasons. However, if the reservoir is subject to earth- quake with the dam destroyed, the protected zone and Huangbizhuang reservoir downstream are supposed to suffer from its break-down. It is then supposed five dam break conditions to Gangnan reservoir. First, the dam of Gangnan reservoir was break just after an earthquake. The second condition to the fifth are as follows, the dam of Gangnan reservoir was not broke as soon as an earthquake occurred, but broke after the cascade reservoirs had discharged 3 h, 6 h, 9 h, and 12 h since it was struck by the earthquake, respectively. The analysis of the dam structures and types would allow us to determine dam break form of the Gangnan reservoir. Thus, we have established a flood calculation model to simulate the dam-break flood when the dam of Gangnan reservoir is broken after different flood pre-discharge times. Here we have worked out two emergency flood regulations, one being done by the operation regulations and the other by the maximum flood bearing capacity, say, that of the Huang Bizhuang reservoir. The re- sults of our simulation show that the longer the cascade reservoirs pre- discharge time, and the smaller danger rate the Huangbizhuang reser- voir was to meet. Therefore, the damages of the downstream reaches would be less. To a certain extent, pre-discharge operation can sig- nificantly reduce the likeliness of the break-down flood threat. The duration, which Huang Bizhuang reservoir discharge would exceed