Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 6 1st Alexander von Humboldt International Conference 2006 10.5194/adgeo-6-201-2006 http://www.adv-geosci.net/6/201/2006/ http://www.adv-geosci.net/6/201/2006/adgeo-6-201-2006.html http://www.adv-geosci.net/6/201/2006/adgeo-6-201-2006.pdf 201 205 2006-02-06 The variation of floods in the middle reaches of the Yangtze River and its teleconnection with El Niño events Y.-J. Wu W. A. Gough T. Jiang H.-T. Kung School of Urban And Environmental Sciences, Central China Normal University, Wuhan 430079, China Environmental Science, University of Toronto at Scarborough, 1265 Militaty Trail, Scarborough, Ontario, M1C 1A4, Canada Nanjing Institute of Geography and Limnology, CAS, Nanjing 210008, China Department of Earth Sciences, The University of Memphis, Memphis, Tennessee 38152, USA Middle reaches of the Yangtze River are the worst flooded segments along the Yangtze River. It is important to understand and study the variations of frequency and magnitude of historical floods in this area and how were they related to or affected by EI Niño in a long historical period. We applied the statistics and time series to study and analyze historical floods (1470-2000) and EI Niño events (1525-1995). The results show that the more floods occurred in the latest 200 years. The power-spectral analysis suggests the main cycle of flood variation is longer than that of EI Niño events. El Nino shows the fluctuations of about 2-year and 3~4 year period while the flood variation is not so significant but can also be identified in the period of 2, 8 and 40 years (it exceeds the level of confidence 0.03). Time series analyses of the fluctuation of flood and El Nino indicate that there is a significant correlation between the two at both high and moderate frequency sections. The result shows that the response of the floods along the middle reaches of the Yangtze River to the effects of El Nino events is not only delayed one or more than one year as suggested by many Chinese scientists, but it also can be somewhat longer delayed up to about 8 years. The result also indicates that the shorter the interval of EI Niño events, the sooner the flood events follows. In other words, flood could be delayed with longer time if the interval time of EI Niño events is longer.