Abstract:

Based on the drought disaster data of the Heng-Shao drought corridor from 1961 to 2018, the meteorological drought composite index (MCI) was used to study the drought monitoring and evaluation methods of the Heng-Shao drought corridor. The results are as follows: (1) During the peak period of crop water demand (from June to October), the drought events with weighted mean of regional MCI (DI) less than or equal to -0.5 and the process duration greater than or equal to 16 days were included in the statistics, and the three elements such as the extreme intensity, cumulative intensity and duration of DI index were the best factors for annual regional drought assessment. Furthermore, based on the three elements of DI index, the annual assessment index of regional drought (MCI_e) calculated by using the TOPSIS method was the best. (2) Based on the MCI_e index, the combined grading method of average value and standard deviation was used to obtain the threshold of regional drought degree for normal, drought, severe drought, and extreme drought years. It was found that the MCI_e index had a strong ability to assess extreme drought years and normal years in the Heng-Shao district, and had good assessment ability for 2019 and 2020. Furthermore, the extreme disaster year in 2013 was simulated, it was found that the MCI_e index could better capture the change of drought in the Heng-Shao drought corridor. Therefore, the MCI_e index could support the rapid assessment and early warning of drought in the Heng-Shao drought corridor to some extent.

Key words: the Heng-Shao drought corridor, MCI index, annual assessment index of regional drought, drought level threshold

摘要：

基于衡邵干旱走廊1961—2018年干旱灾情数据,利用气象干旱综合监测指数(MCI),对衡邵干旱走廊的干旱监测评估方法进行研究。结果表明:(1)在农作物需水高峰期(6—10月),满足区域MCI指数加权均值(DI指数)小于等于-0.5,且过程持续时间大于等于16 d的干旱事件纳入统计,计算DI指数的极端强度、累加强度、持续时间三要素用于区域干旱年度评估最优。基于DI指数三要素,采用TOPSIS法计算的区域干旱年度评估指数(MCI_e)最好。(2)对MCI_e序列采用平均值和标准差组合的分级方式,得出正常、干旱、大旱、特旱的干旱等级阈值,检验发现MCI_e指数对衡邵区特旱年和正常年有较强的评估能力,且2019年和2020年评估结果与实际相符;对2013年特旱年进行模拟,发现MCI_e指数能较好地拟合衡邵区干旱灾情变化,可以为衡邵区旱情快速评估和预警提供一定参考。

关键词: 衡邵干旱走廊, MCI指数, 区域干旱年度评估指数, 干旱等级阈值