Trend Analysis of Annual Precipitation in Southern Benin using Innovative Trend Analysis (ITA) Method

Aims: Most socio-economic activities depend on the climate. In the context of global climate change, it is crucial to understand how the climate is changing in a country like Benin in order to design effective adaptation responses. This study focused on analyzing the trend of annual precipitation totals in southern Benin.
Study Design: Graphical study.
Place and Duration of Study: Data for this study was collected by M´et´eo-B´enin agency, from 1922 to 2016 across six stations in southern Benin. The selected stations are those with less than ten percent missing data.
Methodology: The innovative trend analysis method (ITA) and the non-parametric Mann-Kendall test were applied to the data.
Results: The Mann-Kendall test shows that rainfall is stationary in all stations, while the ITA indicates that Adjohoun (slope = 0.792), Bopa (slope = 1.181), and Grand-Popo (slope = 0.734) are experiencing a relatively increasing trend, whereas Pobe (slope = -1.590) and Sakete (slope = -1.156) show a decreasing trend. By category, low totals have not shown any significant trend across the stations, while medium totals are relatively increasing in Adjohoun. As for high totals, they are decreasing at the stations of Abomey, Adjohoun, Grand-Popo, and Sakete, but increasing at Bopa.
Conclusion: The hidden trends revealed by the ITA are important for decision-making, particularly in agriculture and fishing, which are the main activities in the study area.