Analysis on spatiotemporal variability characteristics of drought in Shaanxi Province using standardized precipitation index

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 stations had a seasonal change pattern. It had increasing trends in spring and winter, while had decreasing trends in summer and autumn. 3) The change pattern for drought intensity was not obvious. The drought intensity in spring and winter increased, while decreased in summer and autumn. We can conclude that the change patterns for ratio of number of stations with drought to total number of stations and drought intensity were similar. 4) Different regions had different drought change patterns, including provincial drought, regional drought and single station drought. The spatial distributions of drought frequency, ratio of number of stations with drought to total number of stations and drought intensity also had difference. © 2017, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.