赣江上游平江流域近30年不同量级降雨时空分布特征

为研究全球气候变暖影响下的赣江上游平江流域不同量级降雨时空分布特征,基于1989—2018年逐小时降雨数据,运用Mann-Kendall趋势检验法、Morlet小波分析等方法对不同量级降雨在年、季、月、时尺度上进行了分析。结果表明:(1)近30年来,小、中、大、暴雨占年雨量的比率分别为18.64%,29.76%,29.70%,21.90%,降雨集中在春、夏季,小、中、大、暴雨峰值分别出现在3月、4月、6月、6月,百年一遇暴雨量为175.5 mm;(2)空间分布特征:暴雨在各尺度上多为“南低北高”,小雨、大雨总体表现为“西低东高”,中雨随机性较强,在各尺度上差异较大;(3)年小雨、年中雨量呈下降趋势,年大雨、年暴雨量呈上升趋势,2月、11月中雨量分别通过α=0.05及0.01显著性检验分别表现为下降、上升趋势;(4)小时降雨量在09:00至次日06:00随时间变化递增,其与降雨侵蚀力在空间分布上均表现出自东北向中南递减而后向西南递增的特点,其雨带在空间上随时间的推移表现出自中部向两侧扩散的特征;(5)年降雨量受中、大雨量的影响第一、二主周期表现为26～27 a,7～8 a,受暴雨量的第一主周期影响第三主周期表现为4～5 a。综上,不同量级降雨时空分布不均,具有朝极端降水发展的趋势,未来应更加注意5—6月流域北部由暴雨带引发的洪涝灾害。

Spatial and Temporal Distribution Characteristics of Rainfall of Different Magnitudes in Pingjiang Basin of Upper Ganjiang River in Recent 30 Years

In order to study the temporal and spatial distribution characteristics of different magnitudes of rainfall in Pingjiang basin in the upper reaches of Ganjiang River under the influence of global warming, based on its hourly rainfall data from 1989 to 2018, Mann Kendall trend test method and Morlet wavelet analysis are used to analyze different magnitudes of rainfall on annual, seasonal, monthly and hourly scales. The results show that:(1)in the past 30 years, the proportions of light rain, moderate rain, heavy rain and excessive rain of annual rainfall were 18.64%, 29.76%, 29.70% and 21.90%, respectively; the rainfall mainly concentrated in spring and summer, and the peak values of light, moderate, heavy and excessive rain appeared in March, April, June and June, respectively, with a 100 year return period of 175.5 mm;(2)distribution characteristics of space was that excessive rainfall on each time scale were low in the south and high in the north of the basin, light rain and heavy rain were generally low in the west and high in the east of the basin, moderate rainfall was obviously different at different times scales;(3)the annual light and moderate rainfall showed a downward trend, the annual heavy rain and excessive rain showed an upward trend, the moderate rainfall in February and November showed a downward and upward trend, respectively, by passing the significance tests of 0.05 and 0.01, respectively;(4)the hourly rainfall increased with time from 09:00 to 06:00 the next day, and its spatial distribution and rainfall erosivity decreased from northeast to central and south China, and then increased to southwest, and its rain belt showed the characteristics of diffusion from the middle to both sides over time;(5)annual rainfall was affected by moderate and heavy rain the first and second main cycles were 26～27 years, 7～8 years, and the third main cycle was 4～5 years under the influence of the first main cycle of heavy rainfall. The uneven distribution of different magnitudes of rainfall in time and space had a trend towards extreme precipitation, and more attention should be paid to floods caused by heavy rain belt in the northern part of the basin in May and June.