Analysis of rainfall dynamics in the three main cities of northern Cameroon.

The northern zone of Cameroon, which depends mainly on agriculture, is considered one of the most vulnerable regions in the country to climate change. Few studies based on field data have examined the changes in climatic conditions that affect agriculture. This research focuses on fluctuations in precipitation that determine dry and wet seasons. From 1973 to 2020, data were collected from weather stations located in three major cities in northern Cameroon: Ngaoundere, Garoua and Maroua. Data were tested for homogeneity using the Pettitt and Buishand tests. Trends were analyzed using the Mann-Kendall test, Sen's slope estimator and the regression line, while drought severity was assessed using the standardized rainfall index method. These data homogeneity tests were performed using two statistical tools, SPSS and XLSTA software. According to Pettitt's test, rainfall increased by 29.6% in Ngaoundere from 1997 to 2020 compared to the previous years of 1973-1996; in Garoua, rainfall increased by 36.2% from 1988 to 2020 compared to the previous years of 1973-1987. However, from 1973 to 2020, the average rainfall in Maroua remained stable at approximately 716.5 mm, with a decreasing trend according to the Mann-Kendall test. In conclusion, this study shows that rainfall has increased significantly in the cities of Ngaoundere and Garoua, making these areas favorable for seasonal and market gardening. However, in Maroua, caution is advised, as rainfall is reportedly decreasing in this locality, increasing the risk of food insecurity. A credible climate warning system must be implemented on a large scale to guide farmers.