Flood-season precipitation variations in Tianjin during 1951-2012

The variations of floodseason precipitation in Tianjin were examined in terms of total precipitation, rainy days,different levels of precipitation events and persistent precipitation events based on daily and monthly precipitation observations of 13 weather stations from 1951 to 2012. The result showed that the total precipitation in floodseason had not changed significantly and different levels of precipitation presented a declining tendency during 1951 ~ 2012,especially for heavy rain it decreased significantly. The total precipitation days showed similar tendency as heavy rain. The different levels of precipitation days exhibited declined trend,in which light rain days decreased significantly. There was not linear trend detected in the precipitation intensity during the flood season. It is concluded that the recent drought trend in Tianjin was mainly related to significant reduction in precipitation days,whereas a few heavy precipitation events greatly affected the total precipitation of the flood season.