Determining flood zones using digital elevation model and geographic information systems: An example of bonoumin-palmeraie watershed (Cocody, Ivory Coast)

Every year, during the rainy season, the City of Abidjan is confronted with several natural disasters related to torrential rains. The resulting effect of this meteorological phenomenon is an extensive pluvial flooding which adversely impacts many areas of Abidjan including the affluent neighborhood of Cocody. Often, many parts of Cocody face extreme flood causing property damages and displacement of people. To circumscribe this issue and better develop action plans of response, this study aims at using digital elevation models (DEM) and geographic information systems (GIS) to determine flood areas identify the type of flood, and the risk factors in the Bonoumin-Palmeraie watershed, one of the most impacted neighborhoods in Abidjan. Digital elevation Models of the watershed reveal that only the areas of natural occurrence for runoffs are susceptible to be flooded. Furthermore, an analysis of ground occupation shows that these areas of natural runoffs are at time heavily inhabited and thus making them at risk of flooding. To reduce this risk of flooding in this watershed, improvements must be made in the infrastructure of the drainage system in order to efficiently evacuate rainwater.