徐州地区2009—2013年旱情及其对农业的影响

利用降水数据，采用Mann-Kendall检验和SPI指数方法从不同时间尺度分析徐州地区干旱发展趋势，结合实地调研结果，给出近年干旱形成的原因。降水趋势分析表明，徐州地区1951—2013年降水量呈逐年减少趋势，其中春、秋和冬季更显著。年尺度的SPI指数结果显示，徐州地区干旱有显著增强趋势。从季度尺度SPI指数分析来看，春、秋和冬季干旱程度整体有增强趋势，夏季相反但并不明显。计算了2009—2013年徐州地区的逐月SPI指数，发现除2011年各月主要呈现为中旱外，其余年份各月则以轻旱为主。自然降水过程通常不能满足小麦生长需水量，需要灌溉补偿。部分县乡存在农田水利设施薄弱、缺乏合理灌溉措施等问题，这也是加重其农业干旱的重要原因之一。

Drought severity in Xuzhou City during period from 2009 to 2013 and its influence on agriculture

Based on precipitation data and field investigation, we used the Mann-Kendall test and the standard precipitation index(SPI)method to analyze the trends of drought in Xuzhou City at different temporal scales and tried to determine the reasons for the drought disasters in recent years. The precipitation trend analysis showed that the precipitation over Xuzhou City gradually decreased during the period from 1951 to 2013, especially in the spring, autumn, and winter. The annual SPI analysis showed that the drought severity had significantly increased over the study area. Through analysis of the seasonal SPI, we found that the drought severity showed an increasing trend on the whole in the spring, autumn, and winter, while the situation was opposite in the summer and the trend was not significant. The monthly SPI over the period from 2009 to 2013 in Xuzhou City was calculated, and the results showed that there was a moderate drought in the year 2011 and mild droughts in other years. The water demand of wheat growth cannot be satisfied by natural rainfall alone; it requires compensation from irrigation water. Some counties and townships are facing problems such as insufficient farmland water infrastructure and inefficient irrigation techniques, which are among the main factors aggravating the agricultural drought in the city.