Comparative Analysis of Characteristics of Drought over Some West Africa Regions Based On Selected Drought Assessment Indices

Abstract

Prolonged absence of moisture exacerbates drought and assessment indices such as Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) are critical tools. Therefore, the objective of this paper was to evaluate the comparative characteristics of drought over West Africa using SPI and SPEI. The data used in this work was established on four monthly time scales of 3, 6, 12, and 24 and covered a period between 1979 and 2021 (42 years) at five regions in Hyper-Arid region, Sahelian region, Sudano region, Dry-Sub-humid region, Moist-Sub-humid region. The data was further analyzed and the characteristics of the drought were assessed. Data obtained revealed that there were some differences between SPI and SPEI in regional drought characteristics. Most of the regions considered experienced extreme drought in 1982. The result also revealed that more droughts were experienced in the eighties than in the nineties. Likewise some regions experienced severe drought in 2021 due to increase in drought intensity in the year 2021 as recorded by SPI and SPEI. Therefore it is vital for frequent assessment of meteorological drought characteristics in West Africa using recent data in order to explore its impact because climate change prediction can cause places that are currently experiencing mild or moderate drought to become more severe in the future, and the total impact of drought in West Africa will increase.  This study could also assist water resource planners to better understand the drought events.