Cet article examine les facteurs de production des risques dits « naturels » dans les grandes villes du Cameroun. D’une approche historique, il ressort que l’établissement d’agglomérations dans des sites d’aménagement difficile est à la base du problème. Le manque de ressources ainsi que la forte croissance démographique qui caractérisent les pays les moins avancés (PMA) en général et le Cameroun en particulier sont du point de vue anthropique les causes de la forte sensibilité aux risques naturels. Il se pose aussi le problème de l’ambiguïté du système foncier qui n’aide pas à la maîtrise de l’espace. L’incapacité des autorités et de la protection civile à gérer l’espace urbain consolide la vulnérabilité. Les changements climatiques diminuent la perception et l’acceptation des risques par les populations et augmentent leur fréquence.
This study is based on analysis of rainfall data from 1951-2010 collected at the climatic station of Bamenda. We also use the results of a questionnaire survey applied to 172 households in at-risk neighborhoods. The inventory of some cases of flooding that occurred in the city of Bamenda was done through focus groups. The appreciation of the socio-economic and demographic environment is based on surveys among Cameroonian Households by the National Institute of Statistics (NIS) and General Census of Population and Housing. Statistical examination revealed that annual rainfall in the city of Bamenda experienced a break in 1958. This break buckled the wettest decade of the series. After three decades of worsening, rainfall is experiencing rising since early 1990. The average profile of the annual distribution of rainfall shows a concentration of over 53% in 03 months (July, August and September). During these three months, the rivers of the city know their flood flows and populations in the valleys are affected. The analysis of the annual number of rainy days shows a downward trend and an increase of extreme rainfall event frequency (≥50mm in 24h). It is also apparent that more and more years are experiencing erratic distribution of their precipitation. Then, the perception of people is significantly reduced. Subsistence activities are also affected and development is facing new subtleties. In conclusion, the rainfall experienced strong variability in the city of Bamenda. This situation reinforces the risk of flooding by increasing flood water and increasing the vulnerability of populations.
Abstract. Le système Chari-Logone est principal cours d'eau drainant l'Extrême-Nord du Cameroun. À l'image des autres parties du bassin versant de ce cours d'eau, cette région a connu plusieurs inondations catastrophiques. Cet article examine la dynamique des extrêmes hydrologiques du Logone et du Chari à travers les stations de Bongor et N'Djamena en prenant en compte le contexte des changements climatiques et l'occurrence des risques hydro-climatiques. Les analyses portent essentiellement sur les données journalières maximum (Qmax) et minimum (Qmin) sur la période 1960–2015. Les logiciels XLStat et ChronoStat ont permis de calculer un ensemble d'indices. Il en ressort que les Qmax présentent une rupture en 1971 aux deux stations marquant la fin de la période humide. Les Qmin de Bongor ont connu deux ruptures successives en 1994 et en 2007. Les Qmin de N'Djamena par contre ont connu une rupture en 1986. Le coefficient de tarissement est globalement faible (0,020/jour en moyenne). L'occurrence des inondations catastrophiques est très contrastée, car seulement 30 % s'inscrivent dans les années excédentaires. Cela témoigne du rôle important que jouent les autres facteurs de construction du risque comme la pédologie, la pluviométrie et la vulnérabilité socioéconomique.
Mining practices in Cameroon began since the colonial period. The artisanal mining sector before independence contributed to 11–20 % of GDP. From 2000, the rich potential of the Cameroonian subsoil attract many foreign investors with over 600 research and mining permits already granted during the last decade. But, Cameroonian forests also have a long history from the colonial period to the pre-sent. However, mining activities in forest environments are governed by two different legal frameworks, including mining code i.e. Law No. 001 of 16 April 2001 organizing the mining industry and Law No. 94-01 of 20 January 1994 governing forests, wildlife and fisheries. Therefore, in the absence of detailed studies of these laws, there are conflicts of interests, rights and obligations that overlap, requiring research needs and taking appropriate decisions. The objective of this research in the Lom and Djérem division is to study, apart from the proliferation of mining li-censes and actors, the dilemma as well as the impact of the extension of mining activities on the degradation of forest cover. Using geospatial tools through multi-temporal and multisensor satellite images (Landsat from 1976 to 2015, IKONOS, GEOEYE, Google Earth) coupled with field investigations; we mapped the dynamic of different forms of land use (mining permits, FMU and protected areas of permanent forest estate) and highlighted paradoxically the conflict of land use. We came to the conclusion that the rhythm of issuing mining permits and authorizations in this forestall zone is so fast that one can wonder whether we still find a patch of forest within 50 years.
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