1981—2023年雅鲁藏布江流域极端降水变化特征

Changes of Extreme Precipitation in the Yarlung Zangbo River Basin from 1981 to 2023

  • 摘要: 雅鲁藏布江(简称雅江)作为青藏高原上最大的河流,该流域不仅是西藏地区主要农业生产区,也是国家重大水利工程建设区,其地形复杂、气候多样,在全球气候变暖背景下,极端气候事件频发,严重影响重大工程建设。本文利用1981—2023年雅江流域16个站的逐日降水资料,采用多种统计方法分析流域极端降水时空变化特征。结果表明:(1)时间变化上,雅江流域极端降水指数除CWD呈微弱减少趋势外,其余均呈上升趋势,但增幅不大。流域大部分极端降水指数最大值出现于1998年,而最小值出现在1983年。(2)空间分布上,极端降水绝对指数、相对指数、RX1day、RX5day、CWD和PRCPTOT呈自西向东递增分布,而CDD的空间分布相反,SDII空间分布不均。流域内68.7%~94.0%站点的极端降水指数趋于增多且分布不均。(3)雅江流域R20、R25、R95p、R99p、R95day、R99day、RX1day、RX5day、SDII在2012年左右发生从少到多的突变,R5、R10、CWD、CDD和PRCPTOT无明显突变。(4)雅江流域极端降水指数在1981—2023年存在24 a左右的主振荡周期,在1981—2010年存在14 a的次振荡周期。过去43 a雅江流域极端降水以短时强降水为主,集中程度增加,导致易发洪涝、干旱等极端事件。

     

    Abstract: As the largest river on the Qinghai-Tibet Plateau, the Yarlung Zangbo River Basin is not only the major agricultural production area in Tibet but also the site of a major national water conservancy project. With its complex terrain and diverse climate, it is necessary to analyze the spatiotemporal variations of regional extreme precipitation in the context of global warming, based on daily precipitation data of 16 stations in the Basin from 1981 to 2023. The results show that: (1)Temporally, the extreme precipitation indices showed an increasing trend, except for CWD, which showed a slight decreasing trend. Most of the extreme precipitation indices occurred in 1998, while the minimum values occurred in 1983. (2) Spatially, the absolute indices, relative indices, RX1day, RX5day, CWD and PRCPTOT of extreme precipitation increased from west to east, while the spatial distribution of CDD showed an opposite pattern, and the spatial distribution of SDII was uneven. Extreme precipitation indices at 68.7%~94.0% of stations in the Basin tended to increase, with an uneven spatial distribution. (3) Abrupt changes of R20, R25, R95p, R99p, R95day, R99day, RX1day, RX5day and SDII in the Basin changed from less to more around 2012, while there was no significant abrupt changes of R5, R10, CWD, CDD and PRCPTOT. (4) The extreme precipitation indices in the Yarlung Zangbo River Basin showed a main oscillation period of about 24 years during 1981—2023, and a secondary quasi-period of 14 years during 1981—2010. Over the past 43 years, extreme precipitation in the Yarlung Zangbo River Basin was mainly short-term heavy precipitation, with an increasing concentration, thereby increasing the risk of extreme events such as floods and droughts.

     

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