Vertical ground motion and historical sea-level records in Dakar (Senegal) Vertical ground motion and historical sea-level records in Dakar (Senegal)

Abstract : With growing concerns regarding future impacts of sea-level in major coastal cities, the most accurate information is required regarding local sea-level changes with respect to the coast. Besides global and regional sea-level changes, local coastal vertical ground motions can substantially contribute to local changes in sea-level. In some cases, such ground motions can also limit the usefulness of tide-gauge records, which are a unique source of information to evaluate global sea-level changes before the altimetry era. Using satellite synthetic aperture radar interferometry, this study aims at characterizing vertical coastal ground motion in Dakar (Senegal), where a unique century-long record in Africa has been rediscovered. Given the limited number of available images, we use a stacking procedure to compute ground motion velocities in the line of sight over 1992–2010. Despite a complex geology and a rapid population growth and development, we show that the city as a whole is unaffected by differential ground motions larger than 1 mm year −1. Only the northern part of the harbor displays subsidence patterns after 2000, probably as a consequence of land reclamation works. However, these ground motions do not affect the historical tide gauge. Our results highlight the value of the historical sea-level records of Dakar, which cover a 100 year time-span in a tropical oceanic region of Africa, where little data are available for past sea-level reconstructions.
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Environmental Research Letters, IOP Publishing, 2015, 10, 084016 (11 p.). 〈10.1088/1748-9326/10/8/084016〉
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Soumis le : lundi 24 août 2015 - 10:35:01
Dernière modification le : mercredi 19 septembre 2018 - 01:36:14

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Gonéri Le Cozannet, Daniel Raucoules, Guy Wöppelmann, Manuel Garcin, Sylvestre Da Sylva, et al.. Vertical ground motion and historical sea-level records in Dakar (Senegal) Vertical ground motion and historical sea-level records in Dakar (Senegal). Environmental Research Letters, IOP Publishing, 2015, 10, 084016 (11 p.). 〈10.1088/1748-9326/10/8/084016〉. 〈hal-01186059〉

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