近50年台湾东部台风强降雨事件的强度与频率变化特征

本研究以曾发布台风警报和最大24小时降雨量不小于50 mm为标准,分别在台湾东部的宜兰、花莲、成功、台东、大武、兰屿等6处测候站1960-2009年的观测资料中,界定出117～151次不等的台风强降雨事件,并取最大24小时降雨量和年次数为强度与频率指标,采用非母数统计验证方法,检视各测候站研究年期内台风强降雨事件之强度和频率序列的趋势变化与阶段变化。分析结果显示,整体而言研究区内台风强降雨事件的降雨强度无显著的变化,但发生频率在1980-1990年间出现跃升之现象。由于晚近台风强降雨事件的发生频率较以往为高,致灾风险相对提升,未来台湾东部地区防灾意识的强化和因应能力的固实有其必要性。

Changes of Intensity and Frequency of Typhoon Heavy Rainfall Events in Eastern Taiwan during 1960-2009

In this study,the typhoon rainfall data of Ilan,Hualian,Chengkung,Taitung,Dawu and Lanyu weather stations located in eastern Taiwan during 1960-2009 are concerned.With the criteria of the issuing of typhoon warnings and 24-hours maximum rainfall above 50 mm,typhoon-induced heavy rainfall events were identified.Trend change and periodic change in the series of 24-hours maximum rainfall are taken as the intensity indicator and the annual number of heavy rainfall events was examined by using some nonparametric statistical methods.The results of data collation show that the number of target events ranges from 117 to 151 stations within the target period of study.Station-based analysis demonstrated that no significant change was found in the intensity series of typhoon heavy rainfall events in the study area.In contrast,there is a periodic increase in frequency of typhoon-induced heavy rainfall events.This change also implies that potential of hydrological and geological hazards will become higher.It is required that all these hazards be taken notice of in the future for disasters prevention.