涉水工程洪水风险基本概念的探讨

Preliminary Probe on Basic Concept of Flood Risk for Wading Project

洪水风险是水文学中一个非常重要的研究课题。本文论述了洪水风险的确切含义,指出现存的两种洪水风险理念:次风险和年风险,前者认为年内最大和次大洪水引起的风险都应在工程设计中考虑,后者认为只有年内最大洪水引起的风险在设计中才能考虑。提出了以频率表征洪水风险度的思路,与次风险度对应的称作次频率,与年风险度对应的称为年频率。阐明了基于年风险度和次风险度为基础的防洪标准是不同的。探讨了以年最大洪水信息为基础的年风险度和以年内最大及次大洪水信息为基础的年风险度的差异,研究表明前者符合现行防洪标准要求,后者不完全符合防洪标准要求。

Flood risk is a very important subject in hydrology.Firstly,the exact meaning of flood risk has been discussed,and two concepts of flood risk in the current situation,time risk and annual risk,have been pointed out.In the former,Both risks resulting from annual maximum flood and submajor flood are considered simultaneously in the design.In the latter,only risk resulting from annual maximum flood is considered in the design.Secondly,frequency or probability is defined as flood risk degree in this paper.While time frequency corresponds to time flood risk degree,annual frequency corresponds to annual flood risk degree.Lastly,the analysis and calculation show that the standards for flood control of annual flood risk degree and time flood risk degree are different from each other.The difference between annual flood risk degree based on annual maximum flood value and that based on annual maximum and submajor flood value has been discussed.The former accords with current standard for flood control of water-related engineering,whereas the latter is not consistent fully with the current standard for flood control.