中文摘要：

干旱作为当今全球范围内危害严重且频发的一种自然灾害之一,对人类和自然系统都产生较大影响。该文基于陕西省长历时的典型测站逐日降水资料,采用标准化降水指数（standardized precipitation index,SPI）、干旱频率、干旱站次比和干旱强度等干旱指标,揭示陕西省干旱时间与空间尺度上的变化特征,为区域水资源合理调配提供参考。结果表明：1）研究区域整体上干旱范围有扩大的趋势,研究时段内干旱较为频繁且持续时间较长,其中,区域内各个站点干旱发生频率均值为70.0%,轻旱和中旱发生频率较高,重旱和特旱发生频率相对较低;2）干旱站次比呈现出季节性特点,其中,春季、冬季干旱站次比呈增加趋势,夏季、秋季干旱站次比呈减少趋势;3）干旱强度变化不明显,其中,春季、冬季的干旱强度呈增强趋势,夏季、秋季干旱强度呈减弱趋势;干旱站次比和干旱强度变化趋势基本一致;4）干旱呈现出较明显的区域变化特征,其中,既有覆盖全省范围的全域性干旱,也有局部地区干旱,并且干旱频率、干旱站次比和干旱强度空间上分布上也存在差异。

英文摘要：

Drought has become one of the most severe and frequent natural hazards, with major impacts on both human and natural systems. The large spatial coverage and long duration characteristics make it one of the most widespread and costliest hazards. With the rapid development of the economy and society, the acceleration of the urbanization process, and the sharp increase of the urban population, the water consumption of the various industries has increased rapidly, which puts forward higher requirements for the limited water resources. The increase of urban living and industrial water consumption occupies the agricultural water consumption, which makes the agricultural drought and water shortage more severe. Taking Shaanxi Province in the Northwest China, located in the 105°29′E-111°15′E and 31°42′N-39°35′N as the study area, the paper uses the standardized precipitation index（SPI）, the drought frequency, ratio of number of stations with drought to total number of stations and drought intensity to analyze the spatial and temporal change patterns of drought at different time scales in Shaanxi Province based on the long-term daily observed precipitation data, provided by the China National Climate Center（CNCC）.The study on the regional spatial and temporal variability of agriculture drought helps to promote the efficient use of the regional water resources and improve the regional drought resistance. The results showed that： 1） Generally, the drought in Shaanxi Province had an expanding tendency for the period of 1971-2013. The drought over the studied time period occurred frequently and the duration of drought was relatively long. The average drought frequency for the 34 meteorological stations was 70.0%. The frequencies of light drought and moderate drought were 23.7% and 23.3%, respectively, and the frequencies of severe drought and specially severe drought were relatively low, with the values of 14.2% and 8.8%, respectively. 2） The ratio of number of stations with drought to total number of