安徽冬麦区4种干旱指数应用对比

Comparison and Application of Four Drought Indices in Winter Wheat Area in Anhui Province

干旱是安徽冬小麦生育期主要的农业气象灾害,对冬小麦生长发育及产量形成均产生重要的影响。利用安徽冬麦区36个气象站1960—2012年逐日气象资料,分别计算冬小麦生育期水分亏缺指数(CWDI)、综合气象干旱指数(CI)、标准化降水指数(SPI)及降水距平百分率(PA),并对上述指标的计算结果进行对比及适应性分析。结果表明:冬小麦生育期4种干旱指数得到的干旱日数时空分布趋势基本一致;SPI和PA指数计算相对简便、稳定,但由于没有考虑水分支出,易导致干旱程度跳跃发展,CI和CWDI指数考虑了最近的降水情况,同时考虑了水分的收支情况,能够较好的表征干旱过程发生发展机制及特征,尤其是CWDI考虑到生长季作物系数,能反映作物水分亏缺状况。通过干旱指数与冬小麦减产率的相关分析,进一步表明CWDI在安徽冬小麦生育期干旱监测评估中具有较好的适用性。

Droughts are the main agro-meteorological disasters during winter wheat growth periods, which seriously influence the growth and yields of winter wheat. Taking the winter wheat growing area of Anhui Province as an example, based on the daily meteorological data from 36 meteorological stations of the winter wheat area from 1960 to 2012, the Crop Water Deficit Index （CWDI）, Comprehensive meteorological drought Index （CI）, Standardized Precipitation Index （SPI） and Precipitation Anomaly percentage （PA） are calculated, and the four kinds of drought indices are compared and analyzed. The results show that PA and SPI are extremely consistent in crop growth season. The temporal-spatial distributions of drought days calculated by the four drought indices are consistent in winter wheat growth season in total. SPI and PA indices have excellent stability of computation. However, they do not consider the expenditure of water, so that they are easy to exaggerate the level of drought; CI and CWDI indices take both recent rainfall situation and water balance into account, and can better characterize droughts. Considering the crop coefficient, CWDI can reveal the status of crop water deficiency and drought events in winter wheat growing season especially. In addition, according to correlation analysis between yield reduction rate and four drought indices, CWDI has better applicability in the monitoring and evaluation of drought development of winter wheat in Anhui.