Recent rainfall trends between 1990 and 2020: Contrasting characteristics between two climate zones in Burkina Faso (West Africa)

Abstract

The northern region (municipality of Samba) and the southwestern region (municipality of Gaoua) are agricultural production areas, which are however dependent on rain-fall. Therefore, knowledge of rainfall characteristics is essential for good agricultural planning. Thus, the objective of this study is to analyse the recent evolution of rainfall between 1990 and 2020 in Burkina Faso. To this end, monthly rainfall data were acquired from the National Meteorological Agency of Burkina Faso. Statistical methods for detecting breaks in time series, standardised rainfall indices, rainfall extremes and rainfall concentration were applied to the data collected. The study shows that annual rainfall totals are increasing between 1990 and 2020, but are marked by alternating wet and dry periods. Moreover, precipitation is more concentrated in a few months (July, August, September) in the northern region since the rainfall concentration index (RCI) is ? 25% between 1990 and 2020, and precipitation is more spread over several months (May, June, July, August, September, October) in the southwestern region, since the RCI oscillates between 18.13% and 19.09%, except for the decade 2000-2010 when the RCI is 20.3%. Therefore, the northern region is exposed to extreme precipitation (increase in total wet days (precipitation ?1 mm) (JP), frequency of intense rainfall (P95(day), intensity of rainy days (SDII (mm/day), maximum daily precipitation (PXJA (mm)) more than the southwestern region (decrease in frequency of intense rainfall, maximum daily precipitation). It is therefore imperative for the national authorities to initiate resilience actions in favour of farmers in the northern region.