Journal des sciences de la Terre et du changement climatique

Abstrait

The Dynamics of the Coastal Land Scapes Over the Last Decades: Wind Drivers for Change Along the North Western Mauritanian Coast

Anne Littaye and Sidi Cheikh Quld Ahmed

The alterations of the coastline are a major concern for maritime countries. Mauritania is no exception. As one of the countries with the highest marine productivity in the world, it stimulates growth in infrastructure development and jobs with its marine resources exploitation. But, the marine erosion and submersion have never been more critical to the entire coast. Coastal developments are planned, despite these risks both in the north and in the south. What about the coastline dynamic over the last decades and are they the same all along the Mauritanian coastline? What are the consequences on the coastal landscapes? The chronology of the paleo shoreline has been extensively studied near the Arguin Gulf for a better understanding of the infill of this large sedimentary basin and the last marine invasion started during the Nouakchottian period. The current retrospective study gives details on recent dynamics over the last seven decades. It is based on remote sensing images coupled with statistical analyses of climate data. A focus has been chosen on the Arguin Bank Park, which has been protected since 1976, because such wild areas represent a preferred window to evaluate natural responses. It is also home to coastal ecosystems of primary interest such as eelgrass beds. Five patterns differ in the dynamics of coastal segments that are a continuing accretion, a stability or an erosion. In addition, the time scales of these analyses allow for the identification of the impulse response of the environment, in phase or lagged time. Two new lagoons are developing and one of which shows a colonization by an eelgrass meadow system. The flooding of several insular wetland has become increasingly frequent and raises various questions about the mangroves and changes in the attractiveness of birdlife, the park's main richness. The various coastal dynamics may be the consequence of the sedimentary balance driven by northeasterly winds and the coastal drift currents. While the future projection of this coastal area remains complex, a better understanding of the dynamics should help feed the Strategy for managing the Mauritania’s coastline as well as the management of the Park. The ecological approach of the climate impacts opens up new perspective based on equivalent ecological concept.