InSAR monitoring of ground motions impacts for in-situ sea level measurement: The example of Dakar (Senegal)

Tide gauges are a unique source of information on past sea level changes over the 20^th century. However, these instruments can be affected by local ground motions, which are often poorly known. Here, InSAR can provide valuable information to understand the ground deformation context at city scale. In this study, we evaluate ground motion velocities from 13 interferograms of 10 Envisat images. Within the precision limitations of the technique, our results suggest that the city of Dakar displays relatively uniform ground motions, except in the harbor. Further investigation is necessary to examine the particular case of a recent tide gauge, which could be affected by a moderate subsidence with respect to the permanent GPS station of Dakar.