The use of remote-sensing and the GIS for identifying areas suitable for building on a hilly urban site : the case of Yaounde (Cameroon). — Yaounde, the capital of Cameroon, is characterised by anarchical and precarious spatial expansion and is prone to flooding, erosion and landslides. To reduce the risks of natural disasters, the government needs to implement a development strategy consisting of redirecting urban development and resorbing pockets of urban anarchy (spontaneous districts and precarious housing). Policy-makers will first need to determine which areas are suitable for urban densification and which are not, based on criteria such as altitude, slope and distance from rivers and lakes. Satellite imaging and the GIS are ideally suited to such a task. By combining a wide variety of spatial data from different sources and on different scales, these tools provide concise information incorporating a large number of criteria.