Abstract:

Based on the minutely precipitation data at Yichang station of Hubei Province during 1956-2013, the evolution characteristics of rainstorm hyetograph in Yichang were investigated. And the design hyetographs of rainstorm for 6 h, 12 h and 24 h durations were calculated by using the same frequency analysis method. The results show that the rainstorm lasting for 12 hours to 24 hours or more and 50 mm to 100 mm precipitation more frequently occurred in the early stage of flood season (from May to September) during 1956-2013 in Yichang, while that lasting below 12 hours and 30 mm to 70 mm precipitation most likely happened in the middle and later stage of flood season. The occurrence frequencies of rainstorm and heavy rainstorm with short duration, medium and long duration and long duration slowly increased in Yichang during 1956-2013, while that of heavy rainstorm with extra-long duration obviously decreased. The peak and duration of rainstorm with short duration tended to increase in Yichang during 1956-2013. The change of hourly precipitation for the rainstorm with medium and long duration wasn’t significant, but the distribution and peak position of rainfall moved backward in time, and the duration tended to increase. The hourly rainfall of the long duration rainstorm tended to decrease, and the distribution and peak position moved forward in time, the duration tended to decline. The design hyetograph of rainstorm for 6 h, 12 h and 24 h durations in Yichang uniformly presented typical single-peak pattern, and the peak position located at the 20, 34 and 113 time interval respectively.

Key words: rainstorm pattern, rainfall duration, rainstorm intensity, same frequency analysis method

摘要：

利用湖北省宜昌市宜昌基准站1956—2013年逐分钟降雨资料，对宜昌市区暴雨雨型的演变特征进行分析，并采用同频率分析法推求该地区历时6 h、12 h、24 h的设计暴雨雨型。结果表明：宜昌市区1956—2013年汛期（5—9月）前期易发生持续12～24 h或24 h以上、降雨量50～100 mm的暴雨，而中后期易发生持续12 h以下、降雨量30～70 mm的暴雨。1956—2013年，宜昌市区短历时、中长历时、长历时暴雨和大暴雨发生次数缓慢增加，而特长历时大暴雨明显减少。其中，短历时暴雨的峰值趋于增大，持续时间趋于增加；中长历时暴雨的小时雨量无显著变化，但雨量分布、雨峰趋于后移，持续时间趋于增加；长历时暴雨的小时雨量趋于减少，雨量分布、雨峰趋于前移，持续时间趋于缩短。宜昌市区历时6 h、12 h、24 h的设计暴雨雨型均为典型的单峰型，雨峰分别位于第20、34、113时段。

关键词: 暴雨雨型, 降雨历时, 暴雨强度, 同频率分析法