REGIONAL ESTIMATION OF SHORT-DURATION RAINFALL EXTREMES

The present study proposes a method for estimating the distribution of short-duration (e.g., 1 hour) extreme rainfalls at sites where data f or the time interval of interest do not exist, but rainfall data for l onger-duration (e.g., 1 day) are available (partially-gaged sites). Th e proposed method is based on the recently developed ''scale-invarianc e'' (or ''scaling'') theory. In this study, the scaling concept implie s that statistical properties of the extreme rainfall processes for di fferent temporal scales are related to each other by a scale-changing operator involving only the scale ratio. Further, it is assumed that t hese hydrologic series possess a simple scaling behaviour. The suggest ed methodology has been applied to extreme rainfall data from a networ k of 14 recording raingages in Quebec (Canada). The Generalised Extrem e Value (GEV) distribution was used to estimate the rainfall quantiles . Results of the numerical application have indicated that for partial ly-gaged sites the proposed scaling method is able to provide extreme rainfall estimates which are comparable with those based on available at-site rainfall data (C) 1998 Published by Elsevier Science Ltd. All rights reserved.