1976—2020年弥河流域不同等级降雨时空分布特征

Temporal-Spatial Distribution Characteristics of Different Rainfall Levels in the Mihe River Basin from 1976 to 2020

为了对弥河流域的降雨特征及未来演变趋势进行研究,基于流域15个气象站1976—2020年的逐日降雨数据,应用Mann-Kendall检验、反距离插值和重标极差(R/S)分析法,研究不同等级降雨量与降雨时间的时空分布特征,并探讨不同等级降雨对年降雨的影响以及流域未来降雨结构的发展趋势。结果表明:研究期内弥河流域年降雨量呈逐年增加趋势,除大雨外,其他等级降雨量呈增长态势,降雨时间总体呈减少趋势,仅中雨、暴雨时间呈增加态势;流域年降雨量从上游向下游呈递减趋势,与大雨、暴雨空间变化一致,年降雨时间与小雨时间空间分布格局一致;中雨对年降雨量的贡献率最高,为27.99%,小雨的发生率最高,为72.07%;相关性分析显示,流域年降雨量与降雨时间分别受暴雨降雨量、小雨时间的影响最大;流域暴雨降雨量、暴雨时间与年降雨量都表现出较强的持续性,未来变化趋势与过去相一致,降雨等级存在向暴雨转变的趋势。

To study the rainfall characteristics and future trend in the Mihe River Basin,based on daily rainfall data of 15 stations in the basin from 1976 to 2020,Mann-Kendall non-parametric test,inverse distance interpolation and rescaled range(R/S)analysis were used to analyze the characteristics of temporal-spatial variation for rainfall and rainfall days at different rainfall levels.The impacts of the different rainfall levels variation on the annual rainfall were explored and the future trend of rainfall structure was discussed.The results show that during the research period,the annual rainfall shows an increasing trend,except for heavy rainfall,other rainfall levels also show an upward trend.The rainfall days generally decrease,and only the moderate rainfall days and rainstorm days show an upward trend.Spatial distribution characteris-tics of the annual rainfall shows a decreasing trend from the upstream to the downstream of the basin,which is consistent with the spatial variation of heavy and rainstorm rainfall.The spatial distribution characteristics of the annual rainfall days and light rainfall days show a similar pattern.The highest contribution rate of moderate rainfall to annual rainfall is 27.99%,and the highest incidence rate of light rainfall is 72.07%.According to the correlation analysis,the changes of the annual rainfall and the rainfall days in the basin are most affected by the rainstorm and light rainfall days,respectively.The indicators related to rainstorm,rainstorm days and annual rainfall show strong persistence,the future trend is consist-ent with that of the past,indicating that the rainfall levels have a trend of transferring to rainstorm.