气候暖干化背景下黄土高原旱涝时空演变特征

Spatiotemporal Evolution of Drought and Flood in the Loess Plateau under Climate Drying-warming

选取58个国家气象基准站1960—2010年逐年降水资料,采用Kriging插值、Mann-Kendall检测及Morlet小波分析等方法,对该区降水及旱涝时空特征进行分析。结果表明:黄土高原暖干化趋势明显,气温、降水突变年份分别在1995年、1990年左右。旱涝等级呈上升趋势,尤以半湿润区最为明显。干旱区发生旱、涝频率最高,涝情略微严重,但干旱更易发生,大旱频次高值中心分散分布,洪涝发生频率西部低、中部高。该区旱涝情势存在多尺度的周期变化,25～30 a的振荡最强,推测涝期即将结束,旱期将要开始。研究成果可为黄土高原旱涝灾害防御提供参考。

In this paper,the spatiotemporal evolutions of annual precipitation,drought and flood were researched using the Kriging interpolation,Mann-Kendall test and Morlet wavelet analysis based on the annual precipitation data observed by 58 meteorological stations in the Loess Plateau during the period from 1960 to 2010 and the background of climate change and peculiar geographic location in China.The results revealed that the annual temperature in the Loess Plateau was increased,but the annual precipitation was decreased in the whole area and the semiarid and semi-humid regions.Precipitation variation was the highest in arid zone but the lowest in semi-humid regions.There was a regional difference of annual precipitation,the annual precipitation was gradually decreased from the southeast to the northwest,and drought trend became more obvious.The sharp change of mean annual temperature and precipitation occurred in 1996 and 1990 respectively.The drought and flood levels were in an increase trend,especially in the semi-humid regions.Occurring frequencies of drought and flood were the highest in arid zone.Drought occurred more easily than flood,and the centers with high drought occurring frequency were dispersed;the occurring frequency of flood was the lowest in the west but the highest in the central area.There were the fluctuation periodicities of drought and flood in the Loess Plateau,the 25-30-year fluctuation was the strongest,and it was considered that the current flood period would be ended,but a new drought period would begin.