Dynamique sédimentaire de la flèche sableuse de Kalaat Andalous (Delta de la Medjerda, Tunisie, Méditerranée)

Abstract

As a part of the MOSBIOCLIM institutional research program of the LR02INSTM04, a multi-approaches study has been undertaken to monitor the multi-temporal morphodynamic evolution of the coastal sandy spit of Kalâat Andalous (Western bay of the Gulf of Tunis, Tunisia). The methodology is based on the monitoring the spatial evolution of the shoreline position from 1882 to 2016 in order to describe the rapid sandy barrier creation and the migration of the coastal lagoon sandy barriers. The reduction of the Medjerda River yields due to the displacement of the historic natural course (Foum El Oued) southward and the built up of dams on the watershed plain explain the alarming retreat of the shoreline with an average rate of EPR (End Point Rate) of -15.95 m ±0.17 /yr and the creation of the sandy spit by spatial redistribution of sediment under the coastal drift current. The long-term spatial observation was completed by the nearshore bathymetric surveys of the sandy spit in 2019. The crescentic inner sandbar morphology is a response to the wave-dominated swells during marine storms which would also contribute to its reduced sediment balance.