Abstract: Using the methods of Mann-Kendall test, moving T-test and R/S, the spatiotemporal variations of precipitation extreme events in the semiarid region in north China during the period of 1961-2010 were analyzed based on the daily precipitation data from 49 meteorological stations within or adjacent to the study area. The results showed that the maximum 5-day precipitation, daily heavy precipitation, precipitation intensity, maximum consecutive humid days, consecutive drought days, heavy precipitation days and annual precipitation in the study area were in a decrease trend in recent 50 years. In which the maximum 5-day precipitation and the daily heavy precipitation passed the significance test at 0.1 level (P<0.1). An analysis based on Hurst index showed that the six extreme precipitation indices will continually decrease in the future, especially for CWD. The abrupt change of consecutive drought days occurred around 1985 and 1995, and that of other six extreme precipitation indices occurred around 1999-2000. Except the change of consecutive drought days, other six indices decreased from the northwest to the southeast. There was a certain regional difference of variation trend of the extreme precipitation indices, these indices were dominated by a decrease trend in the east of the study area but an increase trend in some areas of the central part. There was a significant positive correlation between the annual precipitation and the extreme precipitation indices except for the consecutive drought days, and the extreme precipitation indices were the good indicators for annual precipitation in the study area.

Key words: extreme precipitation, variation trend, abrupt change, spatiotemporal variation, north China, semiarid region