Spatiotemporal dynamics and drivers of agricultural droughts in the agroecological zones of Cameroon

Abstract

Droughts are some of the most devastating natural extreme events in sub-Saharan with enormous economic impacts on agrarian economies such as Cameroon. However, knowledge and information on their dynamics and drivers in the five agroecological zones (AEZs) of Cameroon is very scanty leading to poor planning and management. Therefore, this study aimed to characterize agricultural droughts based on soil moisture, explored trends and drivers of scale 3 standardized soil moisture index in the five AEZs of Cameroon at high spatial and temporal resolutions for the period 1990–2022. Results show a predominance of moderate to severe droughts in most parts of the MF AEZ, a general increase in the percent of drought area (PDA) in the last four years averaging at 48% and, a significant increase in droughts for over 65% of the country at 5% level of significance. The observed droughts were found to be significantly internally associated with precipitation, evapotranspiration, vapor pressure deficit and minimum temperature but majorly driven by evapotranspiration, precipitation and vapor pressure deficit with a 52% coefficient of determination. This relationship was well aligned with the first Empirical Orthogonal Function (EOF) mode that for 34.1% explained variance. Externally, the second EOF mode (21% explained variance) was associated with atmosphere-oceanic teleconnections including Atlantic Meridional Mode, Tropical North Atlantic Index, El-NINO Standardized Precipitation Index and Atlantic Multi-decadal Oscillation Index. While as, the third EOF (9.7% explained variance) corresponded to both precipitation and ENSOs. The results of this study not only inform effective drought planning and management but also help in boosting the forecasting capacity of the Cameroonian climate and water management agencies for agricultural droughts with a good lead time.