Genesis of 2010 storm-flood in Yangtze River Basin and its comparison with 1998 flood

In the main flood season,the strong rainfall process successively occurred in the Dongting Lake and Poyang Lake systems,the areas along the mainstream of the middle and lower Yangtze River,the Jialing River Basin and Minjiang River Basin in the upper Yangtze River and upper and middle Hanjiang River,which formed the basin-wide flood disaster.Through analysis and comparison of flood in 2010 and 1998,it is discovered that there are 4 common points of the 2 floods in climatic background and macro-scale atmospheric circulation: both the 2 floods occurred after El Nino phenomenon emerged in middle-east Pacific in previous year;summer monsoon was weak;typhoon was less;subtropical high over the Western Pacific was obviously strong and abnormally westward.However,there were some obvious differences in the 2 floods : the snow cover on Qinghai-Tibet Plateau from 1997 to 1998 was abnormally more,while the snow cover on Qinghai-Tibet Plateau from 2009 to 2010 was less;2 flood season blocking highs existed in Eurasian mid-high latitude region in the flood season of 1998,while there was no obvious blocking high in the same region in the flood season of 1998.