Morpho-bathymétric 4D Study of Cap Lopez, Gabon

The oil terminal of the Cap Lopez in Gabon is situated on the extremity of a sandy arrow which is subject to strong sedimentary mobility phenomena’s. To understand the hydrodynamic system of the site, a 4D morpho-bathymetric study is conducted since 1958. The difficulty of this study is mainly due to the lack of homogeneity in terms of precision and wedging of the data. The old data (1958 to 2003) consists of sounding maps acquired with mono-beam echo-sounders. From 2004, digital data were acquired with mono-beam echo-sounders (2004 to 2008) then with multi-beam echo-sounders. Besides the diversity of the operated tools, the quality of the surveys and their precision are variable depending on the weather conditions, the calibration processes and the validation of the data during the acquisition. After data homogenization and selection, a 4D analysis was conducted using GIS tool in order to compare all the bathymetric surveys but also the shoreline evolution. A quantitative and qualitative analysis of the evolutions of the site is produced. The objectives of this regular follow-up are to better understand the sedimentary processes and to delineate the potential geohazard zones to anticipate slope failures.