中文摘要：

进行流域梯级水电站开发，对相邻两座同期建设的水电工程组成的梯级施工导流系统进行整体风险分析意义重大。基于风险分析理论，考虑梯级施工导流系统水文和水力的不确定性，建立了系统整体风险数学模型。在此基础上构建了不同洪水组合情况下的风险计算模型，并利用Monte—Carlo方法耦合主要风险因素进行模型求解。同时，针对洪水过程遭遇情况下的风险模型，通过引入起始时间差随机因素来计算下游导流系统施工洪水过程。工程实例分析证明，风险分析模型和方法是可靠、有效的，为流域梯级开发条件下施工导流标准选取及导流方案优选提供重要依据。

英文摘要：

For the cascade hydropower plant development it is important to conduct a risk analysis on the cascade system of construction diversion, which is composed of two adjacent hydropower stations undergoing synchronous con- struction. Based on the risk assessment theory, and considering the hydrologic and hydraulic uncertainties, an inte- grated risk analysis model is developed. The risk calculations for different combinations of flood events can thus be carried out using the integrated risk analysis model and the Monte-Carlo method to couple with major risk factors. Aiming at the condition of floods encounter, the flooding process designed for the construction period of the downstream diversion system can be obtained by introducing an initial time difference stochastic factor into the risk calculation. The result from an engineering case study shows that the proposed risk analysis model and the derived risk calculations are reliable and effective, which provide an important basis for the adoption of the diversion construction standard and the optimization of diversion construction planning under the condition of cascade hydropower plant development along a river reach.