Cities in tropical Africa are growing rapidly and are spreading over large areas. Settlements are developing on floodable land, aided by rainfall deficits. Since the 2000's, these cities have been experiencing perpetual flooding due to increased rainfall in the region. Located at 12° 0' 44'' and 12° 6' 30'' North latitude and 15° 1' 59'' and 15° 9' 47'' East longitude, the 9th district of N'Djamena does not escape this situation, since it experiences recurrent flooding. This contribution aims to highlight the deficit in policies to produce building land in urban areas. The method is based on the exploitation of various sources of information including demographic, climatic, hydrological, and field observations. This has made it possible to understand that population growth is accompanied by anarchic expansion of the city, the most well-known characteristics of which are the illegal acquisition of building land and settlement on marginal land thanks to the multiplication of dry years during the period from 1980 to 2000. With the return of the wet years, the 9th district experiences cyclical flooding. As a result, the dwellings located in the depressions are flooded or collapse. The damage caused is enormous. The public authority has erected a dike to protect the inhabited areas. Similarly, the inhabitants take measures to build dikes around the houses during floods to prevent them from collapsing. Canals are dug to drain away rainwater. Households in the most vulnerable areas take refuge in the district's schools. Thus, land practices are the main source of uncontrolled expansion. The public authorities are partly responsible for this anarchism because land control through urban planning and the official production of building lots is the only means capable of dissuading illegal developers. To remedy this situation, it is sufficient to promote the official production of building lots, to control anarchic installations in the urban perimeter, to improve the protective dike of the district and to set up rainwater drainage networks in flood-prone areas.

Keywords : N'Djamena, 9th District, Urban Growth and Flooding