In 1948, the colonial authorities began to build a strip of filao on Dakar’s northern coastline to stem the advance of sand dunes and protect the inter-dune basins (Niayes), the site of important market-garden produc...In 1948, the colonial authorities began to build a strip of filao on Dakar’s northern coastline to stem the advance of sand dunes and protect the inter-dune basins (Niayes), the site of important market-garden production. Today, the dynamics of the filao strip in the Dakar region tend to take on significant proportions under the impetus of natural and anthropogenic factors that threaten its sustainability. It is in this context that this study attempts to analyze the relationship between the dynamics of the land-use units of the filao strip and the natural and anthropogenic factors at the origin of its modification. The diachronic study of Landsat Multispectral Scanner System (1978), Thematic Mapper (1990), Enhance Thematic Mapper Plus (2006) and Operational Land Imager (2020) satellite images through the directed pixel-oriented classification method, cartographic information systems and qualitative surveys have been applied. The results based on the analysis of the data obtained show that both natural and anthropogenic factors are at the root of the profound changes observed in the filao strip. They reveal that the average annual progression rates of the open filao strip and the built-up area exceed 100%, and that the closed filao strip classes regressed by −16.2%, the sand dunes by −62.9% and the beach by −18.2% between 1978 and 2020. In short, the study shows that the landscape of the Niayes zone is marked by anthropization, leading to the degradation of the filao strip and natural ecosystems. The shrinking surface area of the increasingly anthropized closed filao strip represents a threat to its future.展开更多
文摘In 1948, the colonial authorities began to build a strip of filao on Dakar’s northern coastline to stem the advance of sand dunes and protect the inter-dune basins (Niayes), the site of important market-garden production. Today, the dynamics of the filao strip in the Dakar region tend to take on significant proportions under the impetus of natural and anthropogenic factors that threaten its sustainability. It is in this context that this study attempts to analyze the relationship between the dynamics of the land-use units of the filao strip and the natural and anthropogenic factors at the origin of its modification. The diachronic study of Landsat Multispectral Scanner System (1978), Thematic Mapper (1990), Enhance Thematic Mapper Plus (2006) and Operational Land Imager (2020) satellite images through the directed pixel-oriented classification method, cartographic information systems and qualitative surveys have been applied. The results based on the analysis of the data obtained show that both natural and anthropogenic factors are at the root of the profound changes observed in the filao strip. They reveal that the average annual progression rates of the open filao strip and the built-up area exceed 100%, and that the closed filao strip classes regressed by −16.2%, the sand dunes by −62.9% and the beach by −18.2% between 1978 and 2020. In short, the study shows that the landscape of the Niayes zone is marked by anthropization, leading to the degradation of the filao strip and natural ecosystems. The shrinking surface area of the increasingly anthropized closed filao strip represents a threat to its future.
