Mapping and analyzing urban growth in West Africa

Abstract:

Africa has experienced the highest urban growth (~3.5% per year) in the developing world. West Africa in particular has seen significant urban growth mainly driven by the high natural population growth rate and the increasing percentage of population moving to urban areas. Urban growth in West Africa is expected to continue in decades to come. This study uses Landsat data at five different time steps (1970, 1980, 1990, 2000, and 2010) to map four cities from four different eco-regions of West Africa since the early 1970s. The selected four cities, Kumasi in Ghana, Abuja in Nigeria, Tahoua in Niger and Ouagadoughou in Burkina Faso, are some of the fastest growing cities in the region. We selected the cities in the following ecoregions: Eastern Guinean Forest, Guinean Forest-Savanna Mosaic, Sahelian Acacia Savanna and West Sudanian Savanna. We hypothesize that urban growth in West Africa is different compared to the other parts of the world primarily due to the dependency of about 60 percent of active labor force on subsistence agriculture in the region. As agriculture productivity is dependent on favorable climatic conditions (i.e., good rainfall, suitable temperature), any variability in climate impends the livelihood of subsistence farmers triggering the movements of more people towards the cities. Therefore, studying urban growth based on ecoregions help to better explain the urban development in West Africa. After mapping the urban areas, this study makes a comparative analysis of the temporal and spatial pattern of the urban growths across the ecoregions in West Africa.