Changes in monthly precipitation and flood hazard in the Yangtze River Basin, China

A study of change of meteorological and hydrological variables (precipitation, intense precipitation, and river flow) in the Yangtze River Basin was conducted for particular calendar months. Significant changes were found in many monthly precipitation datasets collected between 1961 and 2000. The strongest relative increase was detected in January, when the monthly precipitation is low in absolute terms. Changes in the monthly precipitation in spring and summer, from April to August, some of which are statistically significant, are of direct importance to seasonal flood hazard. The significant precipitation rise detected in June, July, and August tends to aggravate the flood hazard. Results of change detection in time series of intense precipitation in the Yangtze River Basin indicate that more precipitation falls in intense events at the expense of moderate and weak events. Significant upward trends in the discharge of the River Yangtze in surnmer months in the middle and lower regions were also detected. Finally, precipitation in the Yangtze River Basin and discharge in the mainstream Yangtze (gauges Yichang and Datong) in summer 1998 have been examined, in order to interpret the background of the catastrophic flood which is considered to be the costliest flood ever, worldwide. Copyright (C) 2007 Royal Meteorological Society.