Landslides in Africa: the Emerging Trends of Slope Catastrophes and the Factors Driving Instability in the Continent

Abstract

While landslides and associated hazards in Africa are not new, the current trend of slope failure events leading to enormous loss of lives and property certainly is novel. Not only have the dimensions and frequency of landslides increased, uncommon types of debris flow, debris-rock avalanche and a complex mix of others have emerged. From Sierra Leone to DR Congo, to Uganda, to Nigeria the signature of disaster bears close resemblance. Evidences available to the author suggest an increasing trend of landslide catastrophes that may extend to terrains where landslides are rare, and other zones across the west, south and central Africa where the markers of instability are present but unknown. The areas of future failures may include Conakry Guinea, Lokoja Nigeria and several other areas bearing the marks of instability. Increase in rainfall intensity (probably due to global warming) as well as destabilisation of slopes by activities related to urbanisation may be regarded as the primary drivers of instability patterns in the continent. However, the present research discovered that secondary effects of landslides such as blocked drainage and channels (by sediments derived from slope movements and from domestic and industrial wastes), diversion of river courses, and inertness of environmental laws are also significant factors driving landscape evolution, slope movements and increasing the probability of people dying by other forms of natural disasters in Africa. This paper proposes that landslide management strategies taking into consideration the impact of blocked drainage may offer better outcomes.