北部湾经济区汛期不同历时降水变化特征

Variation Characteristics of Precipitation with Different Durations in Rainy Season at Beibu Gulf Economic Zone

选取北部湾经济区12测站1961~2011年逐日降水数据,采用降水发生率和贡献率指标,分析汛期（4~9月）各历时降水的时空变化规律,利用Mann-Kendall检验法探讨汛期各历时降水的变化趋势,得出如下结论：汛期降水量占全年降水量80%以上;各历时降水发生率随降水历时增加大致呈指数形式递减,贡献率则先增加后减小;从引发洪涝灾害的角度分析,2~4 d致灾程度最高;各历时降水发生率与贡献率空间差异表现基本一致,均表现为1~2 d、≥10 d差异较大,3~9 d差异较小;各历时降水发生率与贡献率变化趋势表现基本一致,即1 d、≥5d表现为下降,2~4 d表现为上升。

On basis of daily precipitation data from 12 rain-gauge stations over Beibu Gulf Economic Zone from 1961 to 2011, the spatial-temporal variation characteristics of precipitation with different durations in rainy season（from April to September） were analyzed. The incidence rate and contribution rate of precipitation were defined and used to assess the spatial and temporal variations. The Mann-Kendall test method was used to discuss the trend of precipitation durations during rainy season. The results show that the amount of precipitation during rainy season is over 80 percent of annual precipitation; the incidence rate of precipitation events decreases exponentially with the increase of precipitation durations, while the corresponding contribution rate firstly increases and then decreases. As far as disaster is concerned, precipitation events for 2-4 d are most likely to trigger flood disasters. The spatial distribution of precipitation events for different durations have a similar variation trend such as 1-2 d and ≥10 d have great difference and 3-9 d have little difference. The precipitation events for different durations throughout the region have a similar variation trend such as 1 d and ≥5 d are downward trend while 2-4 d are upward trend.