Geomorphological Constrains and the Occupation of Slopes Prone to Rockfall Risk in Mowo and Mokong Communities of the Mandara Mountains-Far North – Cameroon

Etame Sone Diabe; Jules Balna; Saïdou Bogno Daniel; Nnoko Maxwell Haggat Enongene

Etame Sone Diabe
Jules Balna
Saïdou Bogno Daniel
Nnoko Maxwell Haggat Enongene

Keywords: Natural hazard, Rockfall risk, Pressure on land, Mowo/Mokong of the Mandara Mountains, Far north Cameroon

Abstract

Nowadays, rockfall is a major concern as a natural lithospheric hazard. Since the return of migrants from major metropolis that began in the 1990s, pressure has increased on land hence; steep slopes have become new settlement and agricultural areas. This paper examines the geomorphological constrains and the occupation of slopes pruned to rockfall risk in the Mowo and Mokong localities of the Mandara mountains-Far North Cameroon. Using interviews, focus group discussions in both study sites, rockfall simulation on the slopes to determine Run-Out and Impact Distance of falling blocks and determining the vulnerability of the sample sites, as well as spatial analysis through remote sensing, results show that: the trajectory and travel distance of falling rock blocks depend on major parameters like velocity, kinetic energy, slope angle, position of rocks, weathering process, and rock mass. Also, more that 90% of the settlements and farmlands as well as electricity transmission lines and roads are found on along the trajectory of falling blocks. Also, more than 50% of the houses are constructed beyond the indicators of maximum run-out distance of falling rock blocks making them more vulnerable to this hazard. The impact intensity (Force) varies from 241,195.50 N to 754,055.46 N from very gentle slopes to steep slopes respectively and will crush everything on its way. Furthermore, more than 98.5% of the population under study do not see rockfall as a risk but as the manifestation of anger of their “gods” who protect them, solve their problems and who they worship, respect and pay allegiance to. Territorial planning policies should incorporate the respect of a maximum run out distance limit for construction on rockfall risks slopes to reduce their vulnerability to this hazard.

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