Assessment of Drought Event, its Trend and Teleconnected Factors Over Burundi, Central East Africa

Abstract

\n This study assessed the drought events across Burundi for 37 years ranging from 1981 to 2017. The drought assessment was conducted using the Standardized Precipitation Index (SPI) at 1, 3, 6 and 12-month time scales. The Mann Kendall and Modified Mann Kendall trend tests and Sen’s slope statistic tests were used to analyse the spatiotemporal drought trend. The overall analysis of SPI-3, SPI-6 and SPI-12 outputs revealed that the Northern part of Burundi was the most threatened by dry events, and more than 80% of the extremely and severely dry events occurred within the period 1993–2000. The drought magnitude varied highly in the short rains season (SOND) than during the long rains season (MAM) specifically during the 1990s decade. The cumulative frequency of extremely dry events was very high in the North with 5.2%, 6.1% and 7.4 % at 3, 6 and 12-month time scales respectively. Likewise, the northern part experienced both short, medium and long dry periods, thus 88 consecutive dry months within only 8 years. The North and East regions exhibited a positive increasing trend over annual and seasonal time scales at both 3, 6, and 12 months of SPI analysis while the mountainous region and the South experienced a significant decreasing trend. The first abrupt point issued by forward and backward sequential statistics occurred in 1990, the year corresponding to the beginning of the driest period. Dry years are associated with circulation anomalies over the Indian Ocean and La Nina events.