基于事件过程的珠江流域极端小时降水变化特征

Changes of event-based extreme hourly precipitation in Pearl River Basin

  • 摘要: 全球变暖背景下极端降水事件频发,对生态环境和人类社会构成严峻挑战,深入理解其变化特征对防洪减灾具有重要意义。本文利用多源数据融合的逐小时降水数据集,基于事件过程的极端小时降水(Event-based Extreme Hourly Precipitation,EEHP)分析框架,探讨珠江流域2000—2023年EEHP的时空变化特征,重点分析主导时间分布模式、历时-强度组合模式及其空间分布格局。结果表明:①EEHP总频次呈上升趋势,然而平均降水量和持续时间普遍呈下降趋势,年内高发期集中于5—6月,且日内降水主峰值多发于上午7:00—8:00和下午16:00 2个时段。②EEHP的各项指标具有相似的空间分布格局,总体为“西低东高”的分布特征。③前峰型时间分布模式为珠江流域EEHP的主导类型(占比87.4%),主要分布于流域西部的云贵-广西、东部的广东-福建及两广沿海地区,在春夏季最为活跃。④长历时-低强度EEHP是珠江流域事件占比最高的类型,低强度事件的空间分布呈“西北低、东南高”格局,高强度事件的空间分布则相对均匀;不同组合类型的EEHP事件平均强度与平均历时呈现明显的逆向关系,平均历时随着平均强度增加而显著减小。

     

    Abstract: Under the background of global warming, extreme precipitation events are becoming more and more frequent, posing severe challenges to the ecological environment and human society. It is of great significance to deeply understand their changing characteristics for flood prevention and disaster reduction. This paper uses the hourly precipitation dataset fused by multi-source data and the Event-based Extreme Hourly Precipitation (EEHP) analysis framework to explore the spatiotemporal variation characteristics of EEHP in the Pearl River Basin from 2000 to 2023, mainly focusing on the analysis of the dominant temporal distribution pattern, diastolic-intensity combination mode and its spatial distribution pattern. The results showed that: ① The total frequency of EEHP showed an upward trend, but the average precipitation and duration generally showed a downward trend. The high incidence period during the year was concentrated in May and June, and the main-peak of EEHP events during the day was mostly in the morning (7:00—8:00) and afternoon (16:00). ② The indicators of EEHP have a similar spatial distribution pattern, generally characterized by "low in the west and high in the east". ③ The pre-peak temporal distribution model (TDP1) was the dominant type of EEHP in the Pearl River Basin (accounting for 87.4%), with most active in spring and summer. It was mainly distributed in Yunnan-Guizhou-Guangxi in the west of the basin, Guangdong-Fujian in the east, and the coastal areas of Guangdong-Guangxi. ④ The long-duration-low-intensity EEHP is the type with the highest proportion of events in the Pearl River Basin. The spatial distribution of low-intensity events shows a pattern of "low in the northwest and high in the southeast", while the spatial distribution of high-intensity events is relatively uniform. The average intensity and duration of EEHP events across different types exhibit a pronounced inverse relationship, with the duration decreasing significantly as the intensity increases.

     

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