摘要
Due to its abundant rainfall, the city of Libreville, which concentrates more than half of Gabon’s population, is frequently confronted with the impacts of natural disasters such as floods and landslides. This study attempts to identify the complex relationships between the dynamics of land use and the role of rainfall in the occurrence of landslides. On the one hand, it uses statistics on landslides compiled from information taken from general news bulletins and, on the other, daily rainfall data obtained from the National Meteorological Department. The study revealed that the Libreville East sector, dominated by Mount Nkol Ogoum, one of Libreville’s most prominent landforms, is affected by a land-use dynamic in which human settlement has been progressing for some thirty years, to the detriment of the original vegetation which, among other things, helped to stabilise the soil on the hillsides and the marshy areas at the foot of the slopes. The result is not only an uncontrolled occupation of the land, but also a major landslide every two years in this part of the city, causing significant loss of life and property. However, an analysis of the time series shows little rainfall variability, marked in particular by a predominance of negative anomalies, and the occurrence of a few exceptional daily rainfall peaks. Similarly, the period from 20 October to 20 November, which receives the most rainfall, also appears to be the most conducive to landslides.
Due to its abundant rainfall, the city of Libreville, which concentrates more than half of Gabon’s population, is frequently confronted with the impacts of natural disasters such as floods and landslides. This study attempts to identify the complex relationships between the dynamics of land use and the role of rainfall in the occurrence of landslides. On the one hand, it uses statistics on landslides compiled from information taken from general news bulletins and, on the other, daily rainfall data obtained from the National Meteorological Department. The study revealed that the Libreville East sector, dominated by Mount Nkol Ogoum, one of Libreville’s most prominent landforms, is affected by a land-use dynamic in which human settlement has been progressing for some thirty years, to the detriment of the original vegetation which, among other things, helped to stabilise the soil on the hillsides and the marshy areas at the foot of the slopes. The result is not only an uncontrolled occupation of the land, but also a major landslide every two years in this part of the city, causing significant loss of life and property. However, an analysis of the time series shows little rainfall variability, marked in particular by a predominance of negative anomalies, and the occurrence of a few exceptional daily rainfall peaks. Similarly, the period from 20 October to 20 November, which receives the most rainfall, also appears to be the most conducive to landslides.
