MAPPING DEFORESTATION IN THE DEPARTMENT OF ALIBORI (NORTHERN BENIN) USING SATELLITE IMAGERY SPOT

Abstract

In the department of Alibori, cotton production, essentially extensive and transhumant cattle breeding, logging, Sahelian climatic influences, and urbanization are all factors that accelerate deforestation. The objective of this research is to assess deforestation in the department of Alibori using satellite imagery. Planimetric data from the 2005 and 2015 SPOT 5 and 7 images, provided by the spatial observation of tropical forests (OSFACO) project, were interpreted and analyzed. Digital processing of the satellite images was carried out using QGIS 2.18.2 software, in particular the Train Random Forest Image Classifier module contained in the Orfeo ToolBox. Ground control was carried out through 852 GPS points. The average accuracy of the land cover maps was approximately 96 %. The results revealed a decline in natural vegetation types in favor of mosaics of fields and fallow land. Gallery forests, dry forests, woodlands, and wooded and shrubby savannas were converted into mosaics of fields and fallow land, as well as settlements. Surrounding villages were more affected by deforestation than protected areas, which occupy nearly 45 % of the department's surface area. The rate of deforestation throughout the department was 1.83 %. The rate was 3.10 % in village areas and 0.70 % in protected areas. Thus, 14.96 % of the department's total surface area was affected by deforestation, including more than 20.45 % of village areas and only 7.40 % of protected areas. In addition, 2.66 % of the department was affected by degradation; 1.40 % was naturally restored, and only 0.35 % was improved. Restoring these degraded areas is necessary in the department of Alibori, which constitutes Benin's cotton belt.