The Northwestern Escarpment of the Ethiopian Rift Valley has been frequently affected by droughts for decades. The area is among the most drought-prone and chronically food-insecure parts of the country. The study areas that include the Raya Valley livelihood Zone (RVLZ), Alagie-Offla livelihood Zone (ALOFLZ), and Tsirare Catchment Livelihood Zones (TCLZ) are amongst the most vulnerable and badly affected livelihood zones in the Northwestern Escarpment of the Ethiopian Rift Valley. Hence, this study aimed to monitor the meteorological drought conditions of the three LZs from 1983 to 2016 using the Standardized Precipitation Evapotranspiration Index (SPEI) at three months’ time scale. Both monthly Climate Hazards Group InfraRed Precipitations with Station data (CHIRPS) and Enhancing National Climate Service (ENACTS) temperature data (1983–2016) at moderate spatial resolution (i.e. 4 km-by-4 km) were obtained from the National Meteorological Agency of Ethiopia. This study uncovers seasonally recurring droughts that vary in severity, frequencies, and durations within and between the livelihood zones. The results indicated that severe drought occurred in all livelihoods zone of the study area from years 1983 to 1991, while ALOFLZ and TCLZ have recorded relatively higher drought severity. From 1989 to 2016, the severity and frequency of droughts were increased during the Belg (small rain) season but decreased in Kiremt (summer). In most of the study years, there have been Belg or Kiremt or both drought seasons in the study areas. The severity and frequencies of Kiremt drought in this study were higher from 1983 to 1991, better 1993–1998, and mildly to moderate drought from 2000 to 2016. As the frequencies and persistence of mild drought have increased, the intensity and precipitation amount are too small to cultivate crops and forage growth. This problem needs special considerations on the current moisture harvesting system and afforestation practices to reduce natural and human-induced drought impacts. Studying drought with long recorded meteorological data from a large number and uniformly distributed meteorological grids in small scale livelihood zones had great implications to identify the real trends of spatiotemporal meteorological drought. This enabled the researchers to investigate the real drought frequencies, severity, and durations in small scale areas. The study will support to improve the existing drought monitoring system and to build resilience to drought at the household level. The finding also will have a significant contribution to early warning systems, particularly at district levels. Ended, it needs to consider solutions for short and long drought impacts. The agricultural sector should consider the long-cycle crop growth patterns to reduce crop failures and forage problems.

中文翻译：

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埃塞俄比亚裂谷西北悬崖的气象干旱：探测季节和空间趋势

数十年来，埃塞俄比亚裂谷的西北悬崖经常受到干旱的影响。该地区是该国最容易干旱和长期粮食不安全的地区之一。包括拉雅谷生计区（RVLZ），阿拉基-奥弗拉生计区（ALOFLZ）和锡拉雷集水区生计区（TCLZ）在内的研究区是埃塞俄比亚纵谷西北悬崖最脆弱，受影响最严重的生计区之一。 。因此，本研究旨在使用三个月的时间尺度上的标准化降水蒸散指数（SPEI）来监测1983年至2016年这三个LZ的气象干旱状况。从气象局的国家气象局获得的月度气候灾害组带站数据的红外降水（CHIRPS）和增强国家气候服务的温度数据（ENACTS）（1983–2016）均处于适当的空间分辨率（即4 km x 4 km）。埃塞俄比亚。这项研究揭示了季节性反复干旱，其生计区域内和生计区域之间的严重性，频率和持续时间各不相同。结果表明，从1983年到1991年，研究区域的所有生计地区都发生了严重的干旱，而ALOFLZ和TCLZ的干旱严重程度相对较高。从1989年到2016年，干旱的严重程度和发生频率在Belg（小雨）季节有所增加，而在Kiremt（夏季）有所减少。在大多数研究年中，研究区域都出现了贝尔格或基雷姆特旱灾或两个干旱季节。在这项研究中，基雷姆特干旱的严重程度和频率在1983年至1991年期间较高，1993年至1998年较好，在2000年至2016年期间为轻度至中度干旱。随着轻度干旱的频率和持续性增加，强度和降水量也随之增加小以种植农作物和饲料。对于当前的水分收集系统和绿化措施，需要特别考虑这一问题，以减少自然和人为造成的干旱影响。利用长期记录的，来自小规模生计区域的大量且均匀分布的气象网格的气象数据来研究干旱，对确定时空气象干旱的真实趋势具有重大意义。这使研究人员能够研究小规模地区的实际干旱频率，严重程度和持续时间。该研究将支持改善现有的干旱监测系统，并在家庭一级增强抗旱能力。这一发现还将对早期预警系统做出重大贡献，特别是在地区一级。最后，它需要考虑针对短期和长期干旱影响的解决方案。农业部门应考虑长期的作物生长方式，以减少作物歉收和饲草问题。