Coastal morphology changes in the southern Mediterranean Basin: the case of the Hammamet fringe (Gulf of Hammamet, NE-Tunisia)

Morphology changes along the Hammamet fringe (South Rive of the Mediterranean) were studied based on coastline evolution during the period 1956-2010 using topographic maps (1956 and 1985), aerial photographs (2010) and satellite images (2020). Coastline evolution rates are calculated using Arc GIS software's extension Digital Shoreline Analysis System (DSAS). The study was completed by grain-size analysis of superficial sediments collected from different depths (0, 2, 5, 7 and 10 m) in July 2020. Results show a coastline retreat of 0.33 to 2.5 +/- 0.25 m/year essentially, during 1956-1985, and an accretion (1.1 to 9.32 +/- 0.13 m/year) upstream of the leisure harbour (Marina). From 2010 to 2020, recent evolution indicates an accretion around the exoreic rivers of El Mrezga, Batene, and Moussa and upstream of the cited harbour. Erosion is observed along the coastline of Hammamet North (1.64 to 10.5 +/- 1.53 m/year). The existence of rocky beaches proves it, the loss of an important quantity of sediments, and the change of grain-size characteristic of sediments (Mz) from fine sands to Medium and coarse sands. These results can be explained by changes in hydrodynamic parameters (waves, currents horizontal ellipsis ) and the acceleration of Sea Level Rise in the Mediterranean due to recent climate change.

Automated summary

This study examines the morphology changes along the Hammamet fringe in the Mediterranean Sea. Results indicate a retreat of the coastline during 1956-1985 and an accretion upstream of the leisure harbour. From 2010 to 2020, there was an accretion around the exoreic rivers and upstream of the harbour, along with erosion along the Hammamet North coastline. The changes in sediment characteristics can be attributed to alterations in hydrodynamic parameters and sea level rise due to climate change.