Analysis of the Dynamics of Hydroclimatic Extremes in Urban Areas: The Case of Grand Nokoué in Benin, West Africa

Abstract

With accelerating urbanization; the frequency and magnitude of extreme weather events have increased rapidly. This study aims to examine how these land use changes influence hydroclimatic extremes in the region, to better understand the complex interactions between natural and anthropogenic factors that shape local climate. The study’s results revealed that precipitation trends increased significantly (tau = 0.25 and p-value = 0.04), as did night-time temperatures (tau = 0.41 and p-value = 0.001), between 1991 and 2020. However, daytime temperatures show a non-significant downward trend (tau = -0.14 and p-value = 0.30). Landsat 8 data show that the development of impervious surfaces affects surface temperature regulating factors (vegetation, water bodies and bare soil). Pearson correlation revealed that flooding and diurnal and nocturnal heat waves were the main hydroclimatic hazards likely to be influenced by urbanization. Extremes calculated at the 99th percentile showed statistically highly significant increasing return values (all p less than 0.001) over periods of 2, 5, 10, 50 and 100 years.