资源环境科技发展态势分析平台

Trends and variability of extreme precipitation events are important for water-related disaster prevention and mitigation as well as water resource management. Using daily precipitation dataset from 143 meteorological stations in the Yangtze River Basin (YRB), a suite of heavy and extreme precipitation indices recommended by the Expert Team on Climate Change Detection and Indices, which has rarely been applied in this region, were analysed during 1960-2012. Results showed that simple daily intensity index, very wet day precipitation, extremely wet day precipitation, extremely heavy precipitation days, maximum 1-day precipitation, maximum 5-day precipitation and maximum consecutive dry days all increased significantly during 1960-2012. In contrast, 10mm precipitation days and maximum consecutive wet days decreased significantly, implying that the precipitation processes in YRB were dominated by precipitation events with shorter durations. Geographically, a wetting tendency was observed in the eastern Tibet Plateau and the middle and lower YRB, while the other regions experienced precipitation deficits. The increasing precipitation was mainly due to the intensification of extreme precipitation events and the decreasing precipitation may be attributed to the decrease of 10mm precipitation days or moderate precipitation events. In addition, the regional trends were of greater magnitudes in the middle and lower YRB, indicating more frequent extreme precipitation events in these sub-regions. Time series analysis revealed that most precipitation indices exhibited neither a stable nor a gradual pattern during 1960-2012, but a clearly upward trend, although non-monotonous, since the late-1980s was evident.