West Africa Dataset of Impervious Surface Change (WADISC) from 2001 – 2020

Rapid urbanization in most African countries is increasing impervious surfaces, including building roofs, glass, concrete, asphalt, and paved roads. However, regionally consistent urban data are lacking to support large-scale research and assessment of impervious surface expansion and its impacts on urban heat islands, hydrology and flood risk, infectious disease risk, cropland and biodiversity loss, habitat fragmentation, and carbon sequestration. The West Africa Dataset of Impervious Surface Change (WADISC) uses all available Landsat data to map urban change in Ghana, Togo, Benin, and Nigeria. The approach combines machine learning algorithm with LandTrendr time series analysis to generate annual maps of urban impervious surface cover from 2001 - 2020. The overall mean absolute error was less than 6% cover and the root mean squared error was less than 10% cover, giving us confidence that the predictions can effectively distinguish areas with high versus low impervious cover. We further classified the impervious cover into developed (pixel value is greater than 20%) and undeveloped (pixel value is less than or equal to 20%) with 93% overall accuracy and approximately similar producer (79%) and user (80%) accuracies in developed areas. WADISC is available in two forms: 1) continuous impervious cover with values ranging from 0% – 100% and 2) Developed area classification with pixel values of 1 and 0, representing the presence and absence of developed area. These data can support consistent city, national and regional assessments and research on urbanization and its impacts.WADISC_Impervious.zip contains GeoTIFF files with continuous impervious cover data from 2001-2020.WADISC_Developed.zip contains GeoTIFF files with classified developed area data from 2001-2020.