Abstract:

In order to understand the different level precipitation days and better services for agricultural production, according to the daily precipitation data from 1953 to 2011 in Lishui, and based on the study of annual and monthly trend of different levels of precipitation events, the author used Mann-Kendall test to study the time-frequency characteristics and abrupt change of significant precipitation events, in order to further explore the multi-time-scale characteristics of different level precipitation days in Lishui. The results showed: the total precipitation days had a significant decreasing trend at -3.70 d/10 a in Lishui over the past 59 years, and the light rain days accounted for 72.6% of total precipitation days, and its decreasing trend passed the 99% significance test. At the same time, torrential rain days had increased slowly, and the other levels of precipitation days showed a decreasing trend, but not obvious. The results of Mann-Kendall test showed that the precipitation days increased at first, and then decreased, its abrupt change occurred in 2002.