HR: 11:25h
AN: H52A-04    [Abstracts]
TI: Comparison by Simulation of Two Methods for Frequency Analysis of Annual Flood Data When Flow Records are Fragmented.
AU: * Clarke, R T
EM: clarke@iph.ufrgs.br
AF: Instituto de Pesquisas Hidr ulicas - UFRGS, Avenida Bento Gon‡alves 9500, Porto Alegre, RS 90040-193 Brazil
AB: The frequency analysis of flood events is made more difficult where flow records are fragmented. The problem is particularly acute in developing countries, where it is essential for planning purposes to utilize to the full whatever records are found to exist. When a flow record is fragmented, a "peaks over a threshold" analysis is one possible approach, but the choice of threshold is not always straightforward. This paper adopts the alternative approach in which annual maximum discharges are used, considered as censored where years are incomplete. A new method for the analysis of fragmented flow records is compared by simulation with a well-known alternative. In both methods, a GEV distribution is used to model the frequency of annual maximum discharges; estimates of floods with T-year return period, given by the two methods, are compared, together with the results of tests for time-trend in the data when discharges are censored. Extension to the multi-site case is discussed, for which preliminary results are given.
UR: http://www.iph.ufrgs.br
DE: 1821 Floods
DE: 1860 Runoff and streamflow
DE: 1869 Stochastic processes
SC: Hydrology [H]
MN: 2005 Joint Assembly