长江中下游地区雨涝指数构建及其应用

Construction and application of a flood-waterlogging index in the middle and lower reaches of the Yangtze River

  • 摘要: 为客观识别区域暴雨洪涝过程、定量评估区域暴雨过程强度,基于极端事件中持续时间和强度关系理论,采用近5 d最大降水强度作为降水相当强度指标,构建雨涝指数和区域雨涝过程强度的算法,利用1961-2019年长江中下游地区逐日降水资料,分析长江中下游地区的区域雨涝过程次数、强度以及雨涝趋势变化特征。结果表明:① 1961-2019年长江中下游地区区域雨涝过程次数整体呈增加趋势,21世纪以来区域雨涝过程发生次数明显增多,持续5~9 d的区域雨涝过程占全部雨涝过程的2/3以上;②区域内雨涝日数总体呈现南多北少分布,雨涝日数变化趋势表现为西北部减少、东南部增多;③年降水量和雨涝趋势的时空变化使得长江中下游地区的旱涝差异进一步增大,降水多的东南部更涝,降水少的北部和西部愈加干旱。

     

    Abstract: In order to objectively identify the regional rainstorm and flood processes and quantitatively assess the intensity of regional rainstorm processes, based on the intensity-duration curve for extreme rainfall, the maximum precipitation intensity within 5 days is regarded as an index to define a flood-waterlogging event and the intensity of regional flood-waterlogging processes. Using the daily precipitation dataset at 502 meteorological stations in the middle and lower reaches of the Yangtze River from 1961 to 2019, the frequency, intensity and variation trend of the regional flood-waterlogging processes in the middle and lower reaches of the Yangtze River are analyzed. The results show that the frequency of the regional waterlogging processes in this region exhibits an increasing trend in recent 60 years. It is obvious that the regional flood-waterlogging processes occur more frequently in the last 20 years, and the proportion of the regional flood-waterlogging processes lasting for 5-9 days to all the waterlogging processes is two-thirds or above. The regional flood-waterlogging days display the spatial distribution of "more in the southern area and less in the northern area" and "decreasing in the northwestern area and increasing in the southeastern area". Moreover, the spatio-temporal variations of the annual precipitation and flood-waterlogging lead to a stronger difference of drought and flood between different areas in this region. The eastern area with more precipitation gets wetter, but the northern and western area with less precipitation gets drier.

     

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