APPLICATION OF REMOTE SENSING AND GIS IN COASTAL EROSION MAPPING IN CAPE CAMEROON

Cape Cameroon is a small, insular territory bordering the northern shore of the Wouri estuary in Cameroon. It is located in the 6th district of the city of Douala (1 907 479 inhabitants (BUCREP, 2010)), with Manoka as its capital. It is occupied by 2654 inhabitants. This territory is occupied mainly by a Nigerian ethnic group, and the Cameroonian sovereignty has been fighting in this Cameroonian territory since the 1998-2008 conflict with Nigeria on the Bakassi peninsula.Coastal erosion is very intense and affects populations and ecosystems.

Sustainable development is a particular challenge in this insular territory because the population is confronted with important coastal erosion phenomena and that cannot migrate inland because of the Mabé swamp Natural Reserve. Since the beginning of the 2000s, coastal erosion has removed houses, infrastructures and a large part of the Mabé Reserve.

This contribution aims to mobilize remote sensing and GIS tools and data to (1) map the different sequences of the coastline retreat in Cape Cameroon and highlight the main factors, and (2) map the mangrove degradation due to the inland motion of the anthropic pressure, and (3) make projection for future of this territory. For modeling the coastal kinematics, the mapping is based on the Digital Shoreline Analysis System (DSAS) model, developed by Thieler et al. (2009). We used supervised classifications of Landsat images from the 1975, 1986, 2000 and 2018 with 30-meter resolution according to the maximum likelihood algorithm. We could thus assess the land use change and extract shorelines.
Furthermore we use field observations, the testimonies of the people who lived for a long time along the shore to access if (1) erosion occurs continuously or during extreme events and if (2) mangrove degradation is linked to coastal erosion.

Between 1986 and 2014, earth losses are estimated at more than 103 ha. Mangroves recorded a considerable degradation that the rate is estimate of 13.68%. The improved quantification of coastal erosion (in terms of soil area loss), the human occupation and land degradation through time and its possible future evolution allow to address the specific challenge of closed restricted territories occupied by growing poor and marginalized population, and the long-term sustainability of a natural reserve in such environment.