Spatial and temporal variation of drought patterns over East Africa

<p>Understanding historical patterns of changes in drought is essential for drought adaptation and mitigation.<br>While the negative impacts of drought over east Africa have attracted increasing attention,<br>a comprehensive and long-term spatiotemporal assessment of drought is still lacking. Here, we provided<br>a comprehensive spatiotemporal drought pattern analysis during the period of 1964–2015 over<br>the GHA. The Standardised Precipitation-Evapotranspiration Index (SPEI) at various timescales (1 month<br>(SPEI-01), 3 month (SPEI-03), 6 month (SPEI-06), and 12 month (SPEI-12)) was used to investigate drought<br>patterns on a monthly, seasonal, and interannual basis. The results showed that despite regional differences,<br>an overall increasing tendency of the drought was observed across the GHA over the past 52 yr, with trends of<br>change of -0.0017 yr<sup>-1</sup>, -0.0036 yr<sup>-1</sup>, -0.0031 yr<sup>-1</sup>, and -0.0023 yr<sup>-1</sup> for SPEI-01, SPEI-03, SPEI-06, and<br>SPEI-12, respectively. Droughts were more frequent, persistent, and intense in Sudan and Tanzania, while<br>more severe droughts were found in Somalia, Ethiopia, and Kenya. Droughts occurred frequently before<br>the 1990 s, and then became intermittent with large-scale impacts occurred during 1973–1974, 1984–<br>1985, and 2010–2011. A turning point was also detected in 1989, with the SPEI showing a statistically significant<br>downward trend during 1964–1989 and a non-statistically significant downward trend from 1990<br>to 2015. Seasonally, droughts exhibited an increasing trend in winter, spring, and summer, but a decreasing<br>trend in autumn. The research findings have significant implications for drought adaptation and mitigation<br>strategies through identifying the hotspot regions over east Africa at various timescales. Area-specific<br>efforts are required to alleviate environmental and societal vulnerabilities to drought events.</p>