West Africa Coastal Vulnerability Mapping: Subset of JRC Map of Accessibility

The West Africa Coastal Vulnerability Mapping: Subset of JRC Map of Accessibility data set is a 30 arc-second raster of travel time to major cities in West Africa within 200 kilometers of the coast. Extensive literature shows that road networks and market accessibility play an important role in development and access to health care and other social services. Greater spatial isolation is assumed to produce higher vulnerability to climate stressors. Market accessibility is defined as the travel time to a location of interest using land (road/off road) or water (navigable river, lake, and ocean) based travel. A team at the Joint Research Centre (JRC) in Ispra, Italy, created a global raster of accessibility using a cost-distance algorithm which computes the "cost" (in Units of time) of traveling between two locations on a regular raster grid. The raster grid cells contain values which represent the cost required to travel across them, hence this raster grid is often termed a friction-surface. The friction-surface contains information on the transport network, and environmental and political factors that affect travel times between locations. Transport networks can include road and rail networks, navigable rivers, and shipping lanes. The locations of interest are termed targets, and in the case of this data set, the targets are cities with a population of 50,000 or greater in the year 2000.