《Journal of Hydrologic Engineering》杂志刊登“重新审视非水文极端事件的重现期和风险”

作  者：Jose D. Salas,Jayantha Obeysekera

刊  物：《Journal of Hydrologic Engineering》，2013年4月4日印刷

摘  要：目前是应用于水工建筑物设计的是概率方法通常假设极端事件是静止的。然而，过去几十年的研究表明，水文记录呈现出某种类型的不稳定性，比如呈现出某种趋势和变化。江河流域的人为干预（如城市化）、低频气候变化的影响（例如太平洋年际变化）、因温室气体增加导致的气候变化被认为是流域水文循环变化以及极端洪水和极端海平面的幅度与频率变化的主要影响因素。文献中提供了几种解决极端水文现象不稳定性的方法，如给定参数随时间变化的频率分析法。本文的目的是要表明，用来设计与洪水相关的水工结构的一些基于静止世界的基本概念和方法可以扩展为变化世界的概念和方法。特别的，可以将重现期和风险的概念是通过考虑发生概率随着时间推移的变化来设定。基于过去的研究（就像统计和气候变化的文献所呈现的），本文提出了一个简单而统一的框架来估算具有不稳定性的水文事件的重现期和风险。应用表明，不稳定情况下重现期和风险的估计值与相应静止状况下的估计值有很大的不同。同时专家建议，不稳定性分析有助于制定有关水工结构风险评估。

Revisiting the Concepts of Return Period and Risk for Nonstationary Hydrologic Extreme Events

Authors: Jose D. Salas,Jayantha Obeysekera

Journal: Journal of Hydrologic Engineering, Published: 01 April 2013

Abstract: Current practice using probabilistic methods applied for designing hydraulic structures generally assume that extreme events are stationary. But many studies in the past decades have shown that hydrological records exhibit some type of nonstationarity such as trends and shifts. Human intervention in river basins (e.g. urbanization), the effect of low frequency climatic variability (e.g. Pacific Decadal Oscillation), and climate change due to increased greenhouse gasses in the atmosphere have been suggested to be the leading causes of changes in the hydrologic cycle of river basins and changes in the magnitude and frequency of extreme floods and extreme sea levels. To tackle nonstationarity in hydrologic extremes several approaches have been proposed in literature such as frequency analysis where the parameters of a given model vary with time. The aim of this paper is to show that some basic concepts and methods used in designing flood-related hydraulic structures assuming a stationary world can be extended into a nonstationary framework. In particular, the concepts of return period and risk are formulated by extending the geometric distribution to allow for changing exceeding probabilities over time. Building on previous developments suggested in statistical and climate change literature, we present a simple and unified framework to estimate the return period and risk for nonstationary hydrologic events along with examples and applications so that it can be accessible to a broad audience in the field. The applications demonstrate that the return period and risk estimates for nonstationary situations can be quite different than those corresponding to stationary conditions. They also suggest that the nonstationary analysis can be helpful in making appropriate assessment of the risk of a hydraulic structure during the planned project life.

原文链接：http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HE.1943-5584.0000820