Coastal progradation in response to the recent sea level rise: a case study of El Grine coast, Gulf of Gabes (Southeaste
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ORIGINAL PAPER
Coastal progradation in response to the recent sea level rise: a case study of El Grine coast, Gulf of Gabes (Southeastern Tunisia) Maher Gzam & Mohamed Moncef Serbaji & Mohamed Ouaja & Younes Jedoui
Received: 2 August 2012 / Accepted: 12 October 2012 # Saudi Society for Geosciences 2012
Abstract Over the last 30 years El Grine coast recorded significant morphological changes leading to the shoreline progradation. Diachronic coastal evolution, through a set of satellite images data, supported by sedimentologic analysis of five sand cores have been applied to elucidate tidal flat reaction following the recent sea level rise. We found that an emerging sandy barrier and salt marsh domain were shaped by the local hydro-sedimentary processes. The marine sediments, mobilised by wave and tide currents, have been the sole sedimentary source. Recent sandy accumulations, occurred around 1987, have been able to balance a recent sea level rise. While during a mid-Holocene period, El Grine coast was governed by net erosion tendency inducing cliff recession. Keywords Sandy barrier . Salt marsh . Forced regression . Progradation . Gulf of Gabes . Tunisia
Introduction Recording geological data show that global average sea level has risen at an average rate of about 0.5 mm/year over the last M. Gzam (*) : M. Ouaja : Y. Jedoui U.R. Applied Hydrosciences 06/UR/10-03, Higher Institute of Water Sciences and Techniques, University of Gabes, Cité Erryadh, 6072 Gabes, Tunisia e-mail: [email protected] M. Ouaja e-mail: [email protected] Y. Jedoui e-mail: [email protected] M. M. Serbaji National School of Engineers of Sfax, University of Sfax, Soukra, 3038 Sfax, Tunisia e-mail: [email protected]
5 000 years and at an average rate of 0.1 to 0.2 mm/year over the last 3,000 years (Zerbini et al. 1996; Lambeck and Bard 2000; Lambeck et al. 2004; Lambeck 2004). The local relative sea level change along the coastal of Tunisia and Libya has increased about 0.5 m since the last 2,000 years (Anzidei et al. 2011). Based on tide gauge data, the rate of global average sea level rise during the twentieth century (1961–2003) is in the range 1 to 2 mm/year (Church et al. 2001). For the period 1993 to 2003, the estimated rate of sea level rise has accelerated of about 3.1 mm/year (IPCC 2007; Cazenave et al. 2008). Few geoarchaeological researches have yet been accomplished on the Gulf of Gabes where archaeological sites of Punic–Roman age are found at 40 cm below mean sea level, (Oueslati 2004). Otherwise, Masmoudi (2010) affirmed that barrier coasts system of Jerba Island are governed by relative sea level change where recent sandy accumulations are contemporaneous with the actual tendency of risen sea level. For the period 1990–2025, major climatic scenarios project an elevation of sea level, along Mediterranean coast, in the range of 3 to 14 cm (IPCC 2007). This paper is focused on the possible changes on Tunisian coast morphology, especially on the southeastern portion of the Gulf of Gabes (Fig. 1) where w
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