Expansion urbaine incontrôlée et exposition aux mouvements de masse dans la commune de Yaoundé 6

Abstract

The phenomena of landslides are recurrent in Cameroonian cities. For several decades we remember the one in Bafoussam - Gouache in October 2019 and the one in Yaounde - Damas in November 2022. This work attempts to explain the conditions of uncontrolled urban expansion, one of the consequences of which is exposure to mass movements. The site chosen is that of Yaoundé 6, which is not only located in a very hilly area but also experiences a massive influx of people in search of housing construction. The work is based on the hypothesis that the anarchic occupation of steep slopes exposes vulnerable populations to mass movements. Analyses based on surveys, fieldwork and cartographic processing reveal several findings. Thus in 1987 the area of the Council presents a rate of built-up areas estimated at 44%. It rose to 46% in 2001 and 66% in 2002, jointly the green spaces which represented 54% of the surface in 1987, went down to 33% in 2001 and only 8% in 2022. Of the sample of households surveyed in Akok-ndoé, Mendong and Mewoulou respectively, 65% are located on uneven slopes (values between 12% and 20%) and 27% on very uneven slopes (values between 20% and 30%). In the above-mentioned target districts, a survey of 1052 houses was carried out with a GPS in the steepest sectors. The count leads to the following findings: 54% of the houses were built without any landslide prevention measures. 24% had concrete retaining walls and 21% had piles of used bags and tires. Thus, only less than ¼ of the houses are built in conformity with the urban planning norms since the other means such as sandbags, tires or stabilization of the slope by vegetation are only very random measures.