基于Z指数的四川干旱时空分布特征

Temporal-spatial Abnormity Characteristics of Drought in Sichuan Province Based on Z Index

采用四川省115个气象站1961—2014年的逐日降水资料,计算各站历年各季的Z干旱指数,根据Z指数的旱涝等级划分标准将其划分为7个等级,参考过去四川省干旱灾害的灾情记录,研究Z指数在四川的适用性,并用多种统计方法研究四川干旱的时间变化和空间分布特征。结果表明:Z指数在四川各季干旱监测中表现均较好,在四川有较好的适用性。四川干旱可划分为6个空间型,其中四川盆地西部区、东部区、南部区、中部区干旱程度加强,而川西高原区和川西南山地区干旱程度减弱;四川盆地东部区出现干旱的频率最高,而盆地西部区和南部区出现干旱的频率最低。四川盆地西部区、东部区和川西高原区较严重的干旱主要发生在夏季,而盆地南部区、中部区和川西南山地区较严重的干旱主要发生在冬季。各分区干旱变化周期不同,盆地西部区具有3~4 a的振荡周期;盆地东部区振荡周期为6~7 a;盆地南部区具有3~4 a和14~16 a的振荡周期;川西高原区具有4~5 a和8 a左右的振荡周期;盆地中部区振荡周期为7~8 a;川西南山地区振荡周期为2~3 a。

Based on the daily precipitation data of 115 meteorological stations in Sichuan Province during 1961-2014,the Z index at each station was calculated for different seasons and years firstly,then seven levels of drought and flood have been divided according to the Z index. Referencing to historical records of drought disasters in Sichuan Province,the applicability of the Z index in Sichuan was evaluated,and the temporal variation and spatial distribution characteristic of drought in Sichuan Province were analyzed by using the various statistical methods. The results show that the Z index was suitable for drought monitoring in four seasons and applicable to characterizing drought events in Sichuan Province. The drought events in Sichuan could be identified into six regions including the west of Sichuan Basin,the east of Sichuan Basin,the south of Sichuan Basin,the western of Sichuan Plateau,the central of Sichuan Basin and the southwest Sichuan. Drought intensity in the west of Sichuan Basin,the east of Sichuan Basin,the south of Sichuan Basin,and the central of Sichuan Basin increased,while it decreased in the western Sichuan Plateau and the southwest Sichuan. The highest drought frequency appeared in the east of Sichuan Basin and the lowest drought frequency occurred in the west of Sichuan Basin and the south of Sichuan Basin. The serious drought and heavy drought in the west of Sichuan Basin,the east of Sichuan Basin and the western Sichuan Plateau mainly occurred in summer,while they occurred in winter in the south of Sichuan Basin,the central of Sichuan Basin,and the southwest Sichuan. The drought period was different for six regions,there were 3-4 years period in the west of Sichuan Basin,6-7 years period in the east of Sichuan Basin,3-4 years and 14-16 years periods in the south of Sichuan Basin,4-5 years and 8-year periods in the western Sichuan Plateau,7-8 years period in the central of Sichuan Basin,and 2-3 years period in the southwest Sichuan.