Comparison of event and daily precipitations

One-minute rainfall data from 18 weather stations in middle and eastern China from 1961—2000 were used to derive event and daily precipitation values. Statistical relationships of event and daily precipitations were compared at different rainfall levels. Half-day rainfall of either 08:00—20:00 or 20:00—8:00 from 811 weather stations nationwide were used to derive two data sets of daily rainfall according to different criteria of weather station (08:00—08:00)and hydrological station (20:00—20:00). Effects of daily boundary on characteristics of daily rainfall were analyzed. It was found that most events occured on the same day or across one day. The mean, 90% percentile, 95% percentile and maximum values of rainfall calculated from event precipitation data were found to be 1.2, 1.2, 1.3 and1.5 times of values calculated from daily precipitation. The 10a, 20a, 50a and 100 are turn level precipitations calculated from daily rainfall data were found to be comparable to those calculated from event data after multiplying coefficients of 1.39,1.42,1.44 and1.45, respectively. Daily precipitation boundary weather station criterion and hydrological station criterion had no significant impact on rainy days with rainfalls of <250.0 mm, whereas rainy days with rainfalls ≥ 250.0mm based on the weather station criterion were significantly larger than those based on hydrological station criterion. Daily rainfall values in return levels based on weather station criterion were larger than those based on hydrological station criterion for Yangtze River Basin, Pearl River Basin and most of Northwest China, whereas the relationship is reverse for the southeast coast, northern part of North China and Northeast China.