Mud bank migration from remote sensing and bathymetric data : The example of the Kourou River Estuary, French Guina, South America

In French Guiana, the coastal mud banks dynamics, specially the intertidal part, have been largely studied while the subtidal expansion suffers a lack of knowledge. The subtidal area requires significant study in order to understand the complete processes of mud bank migration. The aim of this short paper is to compare the mud bank migration in the subtidal area combining remote sensing data and in-situ measurement. The determination of the delimitation of the subtidal part is realized with remotely sensed data using waves attenuation as a proxy of the subtidal part location. Waves are dampened by fluid mud at proximity of the subtidal area, and are highly detectable on SPOT images. The regular bathymetric survey of the Kourou harbor channel offers a detailed situation of fluid mud arrival along the channel and so on the subtidal migration of the mud bank. Fresh mud arrival in the Kourou channel induce significant depth addition, more precisely the mud lens, important dredging effort in the navigation channel is organized to allow the passage of ships. Therefore, it is observed that the passage of mud bank contributes differently along the channel with a more pronounced arrival of fluid mud in the offshore part of the navigation channel between 2003 and 2009 while the onshore channel were silting-up by the trailing edge of the mud bank from 2010. Combining both the mud bank position from remote sensing images analyses and mud lens surveys allow the determination of the localization of a mud bank along the Kourou coast for 10years