# International Association for Hydro-Environment Engineering and Research

IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
 You are here : eLibrary : IAHR World Congress Proceedings : 34th Congress - Brisbane (2011) : THEME 1: Extremes and Variability : Stormwater drainage design under climate change and variability conditions
 Stormwater drainage design under climate change and variability conditions Author : Urban stormwater infrastructure is conventionally designed using either a peak flow method such as the Rational Method or continuous simulation analysis using an appropriate model. The design rainfall intensity in the Rational Method is often based on frequency analysis of observed extreme rainfall events. The fundamental assumption in this approach is that average recurrence interval (ARI) of runoff is the same as that of rainfall. In the context of climate change and variability, the frequency and intensity of extreme rainfall events may change with time. Infrastructure designed on the basis of past rainfall patterns may not be capable of coping with increased rainfall frequency and intensity. Several previous studies have assumed a stationary frequency distribution for observed rainfall (i.e. constant statistical moments) which may not be appropriate in a changing climate. In this paper, the current practice of assuming stationary climatic conditions will first be discussed. We will then examine non-stationarities in a changing climate and their impacts on design criteria. The Log Pearson Type III distribution has been used in Australia for frequency analysis of rainfall intensity in order to generate intensity frequency-duration curves for a particular location. The sources of climate change induced non-stationarities in frequency distributions are (a) shift of location parameter or mean (1st moment) and (b) change of scale parameter or variability (2nd moment). Mathematically this can be expressed as IT=IM +KTS, where IT is the T year ARI rainfall intensity, IM is the mean intensity, S is the standard deviation and KT is a frequency factor which is a function of distribution type and ARI. A modified Log Pearson Type III distribution considering time varying location and scale parameters is proposed in this paper for the design of stormwater drainage infrastructure. File Size : 333,462 bytes File Type : Adobe Acrobat Document Chapter : IAHR World Congress Proceedings Category : 34th Congress - Brisbane (2011) Article : THEME 1: Extremes and Variability Date Published : 01/07/2011 Download Now