Landslides: Causes, Consequences and Mitigation techniques
With the heavy rains Cameroon is recently experiencing, landslide slides and floods have become very common in most regions of Cameroon. These catastrophes have destroyed numerous properties and even claimed lives. Landslide, also called landslip, is the movement downslope of a mass of rock, debris, earth, or soil (soil being a mixture of earth and debris). Landslides occur when gravitational and other types of shear stresses within a slope exceed the shear strength (resistance to shearing) of the materials that form the slope.
In the southwest region of Cameroon, mainly in the Lebialem division, landslide series have been occurring for some years now: On July 2003, a landslide occurred in the southern part of Cameroon, particularly in the district of Wabane, Lebialem Division, in 400 kms of the capital Yaoundé. 20 deaths, many injured and at least 100 people made homeless were reported by national authorities. On August 2017, a landslide occurred in the village of Essouala in the Lebialem division in Southern Cameroon. A man is reported missing and significant material damage on private property. Some classrooms and farming plantations were totally engulfed by the landslide.
On September 2017, a landslide occurred in the Nkah Njequinie quaters of Fontem subdivision (lebialem division) resulting to extensive damage to property and death of 2 people. On August 2020, the landslide which originated from the Mbeisep forest in Lebialem, led to lots of material damages including market garden crops in hectares of farm land, one building and over 5000 trees planted in 2 riparian forests under the framework of MBI South West.
According to Zogning et al. 2007, the landslides and mudflows observed in Cameroon are of different types and vary from one place to another depending on the causes and factors in operation. Two major groups of causes and factors can be distinguished: Remote causes responsible for the vulnerability of the physical milieu (topography, geology)
Immediate causes or opportunistic factors (excess rainfall and mudflows generation, rainfall deficit, total annual rainfall, maximum daily rainfall, frequency in terms of the number of days of rainfall, the impact of rainfall deficits on the evolution of mass movements, seismic activities, mechanical erosion by mudflows, human action).
To mitigate the landslide in Cameroon, a comprehensive National Landslide Hazards Mitigation Strategy involving a wide range of scientific, planning, and policy tools to address various aspects of the problem to effectively reduce losses from landslides and other ground failures is to be developed.
