Agroclimatic drought and vulnerability of rainfed cereal growing in the high plateaux of Sétif and Bordj Bou Arreridj

Abstract

The regions of Sétif and Bordj Bou Arreridj are currently experiencing worrying droughts, with major implications for the rainfed cereal-growing sector. This phenomenon is closely linked to climate change and the increased water requirements of this crop, requiring appropriate intervention. With this in mind, an assessment of drought trends was carried out over an 80-year period (1940-2021) on a monthly basis, from September to June. The trends identified make it possible to distinguish climatic drought from agroclimatic drought, using predefined criteria such as rainfall thresholds, number of rainy days, intensity and duration of rainfall. These criteria are essential for assessing the vulnerability of crop development. The results, summarised over three distinct periods (1940-1970, 1970-2000 and 2000-2021), highlight significant variations from one period to another, from one month to another and from one region to another. An increase in monthly drought intensity and duration is observed between the first and second periods.  On the other hand, the third period shows less pronounced droughts, in correlation with the cumulative rainfall received, particularly from November to March (2002/2003 and 2003/2004). The drought conditions, summarised by principal component analysis, were used to simulate monthly risk indices (r). These indices, with values ranging from -0.8 to +0.7, express the degree of vulnerability of the crop, from sowing to harvesting, independently of the specific characteristics of the drought. They play an essential role in improving cereal production management in semi-arid environments, although other factors are also involved.