为明确内蒙古地区不同时间尺度旱灾危险性分布特征,选取内蒙古地区1949—2018年SPEIbase v.2.6数据集,利用Theil-Sen趋势分析和Mann-Kendall检验法分析气象干旱时空演变特征,并基于干旱多年平均强度与加权综合评价模型,对研究区年、季节尺度的旱灾危险性进行了评价。结果表明：无论是年际变化还是在空间上,内蒙古年尺度和春、夏、秋3个季节尺度的气候整体呈显著干旱趋势;研究区以中等及以上等级的年尺度旱灾危险性为主,占总面积的71%。其中,高、极高危险性区域主要位于呼伦贝尔市和锡林郭勒盟东部;在春、夏两季,内蒙古干旱灾害危险性空间分布呈“北高南低”,高等级的危险性主要位于锡林郭勒草原和地处干旱区的阿拉善盟;秋、冬两季的高等级危险性区域显著减少,尤其是冬季,以东北地区的低、极低危险性为主要特征,与其干旱趋势变化特征较为一致。研究结果可为内蒙古地区干旱灾害风险管理提供参考依据。

In recent years, drought disasters have occurred frequently in Inner Mongolia, northern China, and losses caused by drought have increased year by year. Understanding the spatial and temporal characteristics of drought, and associated disaster-causing factors, are crucial for early-warning, prevention, and mitigation of future regional drought disasters. This study utilized the comprehensive SPEIbase v.2.6 dataset of precipitation and evapotranspiration from 1949 to 2018 for Inner Mongolia. The spatiotemporal characteristics of drought-related meteorological data were analyzed statistically using Theil-Sen trend analysis and the Mann-Kendall method. Based on the multi-year average intensity of droughts, a weighted comprehensive evaluation model was used to assess the drought hazard at annual and seasonal timescales. Results from Inner Mongolia show a significant downward trend in SPEI-12 (i.e., the SPE index calculated on a 12-month timescale), indicating that the climate of the study area experienced an increasing risk of drought with time. This trend of increasing frequency and degree of drought became particularly pronounced from the start of the 21^st century. For the three seasons of spring, summer, and autumn, the climate of the whole of Inner Mongolia shows a significant trend of increasing drought frequency. Data for winter do not show a significant drought trend on an interannual timescale. Spatially, winter data show increasing humidity in the east and a subtle trend of increasing drought in the west. In general, Inner Mongolia can be considered extremely prone to drought disasters: areas ranked with a drought hazard grade of medium and above account for 71% of the total area of the province. The principal areas of high and extremely high drought risk are located in the east of Hulun Buir City and Xilin Gol League. For spring and summer, the spatial distribution of drought hazards in Inner Mongolia shows a pattern of “high in the north and low in the south”. The high-grade hazards lie mainly in the Xilin Gol grassland and the Alxa League. In autumn and winter, the areas of high-grade hazard shrink significantly in size. In winter particularly, low- and extremely low-grade hazards of drought disaster are found in the northeast part of the study area, consistent with the spatial characteristics of the evolving drought trend. In summary, the results of this study can provide a scientific reference for drought disaster risk management in Inner Mongolia. The SPEI index, which integrates the sensitivity of demand for evapotranspiration, is shown to have good applicability in the study area. The SPEIbase v.2.6 dataset used in this study can remove the need for data collection and SPEI calculation, which improves efficiency. In the future, we will consider drought duration and other factors to optimize the model and enhance its predictive capabilities.