从全面分析立堵截流风险的角度出发，总结了大落差、高流速型截流工程的两种合理的截流风险变 量和风险率模型，提出了用实测资料法和随机性模拟法计算截流风险率的具体方法和步骤而且用实测资料法 进行了工程实例计算，计算结果表明两种模型具有一致性，并初步揭示了风险率的一些规律；在此基础上，进 一步分析了截流风险的评价和处理准则，提出了截流方案合理风险度的建议，为截流方案风险决策奠定了基础。

According to comprehensive analysis of river closure risk, a summary of two kinds of reasonable risk variables and models characteristic of high drop and high flow velocity in river closure project are presented. This paper also puts forward the specific methods and procedures to calculate river closure risk probability by means of the data surveyed in practice and stochastic simulation method with an illustrating case study made on the data surveyed in practice. The calculation results tentatively indicate the consistency of the two models and some rules of risk probability. Based on the case study and, evaluation and treatment of river closure risk are further analyzed. A suggestion of reasonable risk severity is given that lays a basic foundation for risk decision of river closure scheme.