甘肃冬小麦主产区40年干旱变化特征及影响风险评估

Variation characteristics of drought and influence risk assessment for the main growing areas of winter wheat in Gansu Province during 40 years

干旱是影响甘肃省冬小麦生产的主要气象灾害。运用1971-2010年甘肃省冬小麦主产区8县（区）气象站降水资料及冬小麦产量资料，分析了40 a 干旱时空变化特征，建立了干旱影响冬小麦产量的风险评估指数，对冬小麦在不同季节受不同等级干旱风险进行了分析评估。结果表明，春旱以陇东黄土高原出现频率最高，为0．35～0．39次？a -1；徽成盆地及两江流域出现频率最少，为0．18次？a -1；初夏旱出现频次最高的地区为环县，为0．35次？a -1，最少为西峰、成县及秦安；伏旱出现频率最高地区为环县及麦积，最低为张家川；秋旱出现频率最高为环县，最低为武都。各地干旱均以轻旱为主，其次为中旱。40 a 中，20世纪90年代干旱出现频次最多，80年代最少。进入21世纪，秋旱发生频次明显减少，春旱则有相对增多的趋势。冬小麦全生育期徽成盆地及两江流域受旱灾影响风险最小，种植保险率最高，为92％～93％；其次为关山区，种植保险率为91％，干旱风险较小；渭河流域及渭北旱区风险较大，种植保险率为88％～89％；陇东黄土高原种植保险率最低，为83％～85％，冬小麦生长受干旱胁迫最大。

Drought is the main meteorological disaster affected winter wheat growing in Gansu Province .Using the data of precipitation and winter wheat yield from eight weather stations of counties during 1971 to 2010 which located in main growing areas of winter wheat in Gansu Province ,has analyzed the spatial and temporal variation characteristics of drought during 40 years ,set up the risk assessing index for drought disaster impacted to the winter production ,carried out the analysis and evaluation to the risk of different grade of drought for the winter wheat in different season .The re-sults showed that ：The highest frequency of drought in spring was occurred in the Longdong loess plateau ,as 0 .35 to 0 .39 times per year ;the least frequency in the Huicheng Basin and Liangjiang Rivers Basin ,as 0 .18 times per year . The highest frequency of drought in early summer was occurred in Huan County ,as 0 .35 times per year ;the least fre-quency in Xifeng City ,Cheng County and Qinan County .The highest frequency of drought in hot summer was occurred in Huan County and Maiji District ,the least frequency in Zhangjiachuan .The highest frequency of drought in autumn was occurred in Huan County ,the least frequency in Wudu City .The major draught disaster was the light drought in each re-gion ,the secondly drought disaster was the middle drought .During the 40 years ,the most frequency of drought was oc-curred in 1990 s ,but the least in 1980s .The trend of drought frequency in autumn has significantly decreased and in＆amp;nbsp;spring relatively increased since into 21st Century .The minimal influence risk by drought in whole growth season of win-ter wheat was the Huicheng Basin and Liangjiang River Basin with the maximal planting insurance rate as 92% to 93% ;The secondly was the Guan Mountain Areas with the planting insurance rate as 91% and less influence risk by drought ;The larger drought risk was in the Weihe River Basin and Weibei Arid Area with the planting insurance rate as 88% to 89% ;The minimal planting insurance rate was in Longdong Loess Plateau as 83% to 85% ,the winter wheat growth was suffered the maximal drought stress .