Since the construction of a harbour, Port de l'Amitie, an important importation gate for Nouakchott in 1987, the previous coast dynamic equilibrium had been destroyed and thus a significant littoral geomorphological change has occurred, which has produced a severe degradation of the littoral and urban environment. Our research is focused on this coastal environmental change monitoring and its potential evolution estimation by remote sensing techniques using multi-temporal SPOT images and Markov chain analysis. The objectives of this study are to understand coastline evolution particularities, measure geomorphological change rates, evaluate life-span of the harbour, produce useful data for the government to control the environment degradation and provide reference for the future similar coastal engineering. According to our research, the north beach of the harbour has extended by 0.92km2 (91.6ha) from 1989 to 2001 and the accretion will probably reach its maximum limit in about 13.4 ± 0.5 years (in 2014-2015) and the harbour will arrive at the end of service. The south sandbar has been eroded by 1.34km2 (134ha) and the coastline has landward retreated at the maximum by 362m. Another 0.91km2 of land will be nibbled by seawater in the next 10 years. This erosion has caused several times inundation into the suburb and urban areas, provoking a deterioration of the urban environment.