Impact of rainfall variability

In Chad's Mayo Dallah region, rainfall oscillation is reflected in the frequency of extreme events (droughts and floods) that affect the water requirements for growing maize and groundnuts. This article analyzes the impact of rainfall variability on the productivity of these two crops in this terroir. Decadal and seasonal interannual rainfall variability is measured using rainfall data from 1990 to 2021. The standardized rainfall index (IPS), calculated from these data, was correlated with yields to establish relationships. Farmers' perceptions and the consequences of rainfall fluctuations were determined from a survey of 120 farmers. The results show a trend towards rainfall stability, but with wide disparities. The SPI showed values ranging from -1.71 to +2.89. These are equivalent not only to years of severe drought (2004, 2005 and 2009), but also to severe wet periods corresponding to years of flooding (1991, 1994, 2012 and 2020).