基于SPI的黄河流域干旱时空特征分析

Temporal and Spatial Characteristics of Drought Based on Standardized Precipitation Index in the Yellow River Basin

利用黄河流域65个站点,近60a(1958—2012年)的日降水资料,采用标准化降水指数(SPI)对黄河流域的干旱时空特征做了初步分析,并对流域降水变点(1979年)前后的特旱时空分布特征进行了对比研究。结果表明:随着时间尺度的增加,SPI指数随机性减弱,持续性加强。黄河流域干旱的发生发展缓慢、持续时间久、影响范围广;9月SPI检测特旱发生概率比较高的地区主要集中在黄河流域西部,12月SPI检测特旱发生概率比较高的地区集中在黄土高原地区;黄河流域降水变点前,特旱发生概率较高的地区集中在流域南部,降水变点后,特旱发生概率较高的地区集中在流域西部、中部与东北部。变化环境下,黄土高原和黄河下游特旱事件的频率变大。

Standardized Precipitation Index （SPI） was used to analyze the spatio-temporal characteristics in the Yellow River. Based on daily rainfall data of 65 sites nearly 60 years along the river, the spatial-tempo- ral characteristics of the rivers droughts and the changes in the rate of precipitation were analyzed. The re- sults showed that, as time progressed, SPI had a weakened randomness and a strengthened constancy. O- verall, the occurrence of drought increased slowly due to a wide range of influences. SPI9 showed that the western region of the Yellow River Basin had a higher chance of suffering drought, while SPI12 showed the same result in the case of the Loess Plateau. After a change of precipitation point, the drought region had shifted from south to west and northeast. Extreme droughts in the Loess Plateau and downstream Yellow River regions would become more frequent with changes in environment.