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

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Bibliographic fields
reftype Journal Article
Abstract Current practice using probabilistic methods applied for designing hydraulic structures generally assume that extreme events are stationary. However, 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 in addition to 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 the literature such as frequency analysis, in which the parameters of a given model vary in accordance 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 the statistical and climate change literature, the writers 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 an appropriate assessment of the risk of a hydraulic structure during the planned project-life.
Author Salas, Jose D.; Jayantha Obeysekera
DOI 10.1061/(ASCE)HE.1943-5584.0000820
Issue 3
Journal Journal of Hydrologic Engineering
Pages 554-568
Title Revisiting the Concepts of Return Period and Risk for Nonstationary Hydrologic Extreme Events
Volume 19
Year 2014
Bibliographic identifiers
_record_number 21526
_uuid 2d7eac05-0cb2-4046-8ffb-59d369bde630