Drought Variability and Cycles in Smallholder Farming Systems of the Sudano-Sahelian Region of Burkina Faso and Ghana

Rainfed smallholder farming systems in semi-arid tropical climates are highly vulnerable to drought, threatening food security and rural livelihoods. This study evaluates drought variability, severity, and temporal periodicity from 1981 to 2021 across representative Sudano-Sahelian locations in the Centre-Est and Centre-Sud regions of Burkina Faso and the Upper East Region of Ghana. Monthly precipitation and temperature data were used to calculate the Standardized Precipitation–Evapotranspiration Index (SPEI) at 1-, 3-, 6-, and 12-month timescales. Continuous Wavelet Transform (CWT) was applied to identify recurrent drought periodicities, while temporal trend analysis and spatial interpolation assessed spatiotemporal variability. Drought frequency (months with SPEI < −0.5) ranged from 6% to 35%, while the spatial frequency of prolonged drought episodes lasting at least four consecutive months ranged from 11% to 39%. Wavelet analysis revealed dominant drought cycles between 15 and 64 months, together with shorter intra-seasonal oscillations. Seasonal analysis showed that drought also occurs during the wet season, coinciding with critical crop growth stages. Wet-season drought occurrence was slightly higher than dry-season occurrence, highlighting the potential for moisture deficits during critical crop growth periods. Integrating multi-timescale drought monitoring with periodicity analysis into early-warning systems can strengthen drought preparedness and support climate-resilient agricultural management in semi-arid West Africa.