Progradation and retrogradation of the Medjerda delta during the 20th century (Tunisia, western Mediterranean)
| Autor: | Gil Mahé, Abderraouf Hzami, Laurent Dezileau, Oula Amrouni, Saâdi Abdeljaouad, Thouraya Ben Moussa |
|---|---|
| Přispěvatelé: | Université de Tunis El Manar (UTM), Institut National des Sciences et Technologies de la Mer [Salammbô] (INSTM), Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Hydrosciences Montpellier (HSM), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Delta
Progradation 010504 meteorology & atmospheric sciences 137Cs (210)pb(ex) [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Silt Retrogradation 010502 geochemistry & geophysics 01 natural sciences Paleontology (CS)-C-137 14. Life underwater [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology 210Pbex Gulf of Tunis 0105 earth and related environmental sciences Shore Global and Planetary Change geography geography.geographical_feature_category River delta Radiometric dating Human management 13. Climate action [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy Facies General Earth and Planetary Sciences Geology |
| Zdroj: | Comptes Rendus Géoscience Comptes Rendus Géoscience, Elsevier, 2019, 351 (4), pp.340-350. ⟨10.1016/j.crte.2018.10.004⟩ |
| Popis: | The aim of this study is the reconstitution of the recent morpho-sedimentary evolution of the Medjerda River delta. We examine the spatio-temporal evolution of the Medjerda shoreline between 1936 and 2016 using satellite images, complemented by sedimentological and geochemical analyses and (210)Pbex and (137) Cs radiometric data. The general tendency of the shoreline evolution shows an increasing progradation (300 +/- 12 m) between 1936 and 2016. Yet the mesoscale Net Shoreline Movement position (NSM) and the End Point Rate (EPR) reveal an erosion pattern estimated to be -20 m +/- 0.15 m/yr during the period 1988-1999. The sedimentological analyses reveal four main lithostratigraphic units. The fine sand substratum layer (Md = 0.08 mm) decreases toward clay and silt facies (Md < 0.063 mm), rich in continental plant debris. The geochemical results reveal gradual incoming of the terrigenous component instead of marine deposits. The Cs-137/(210) Pbex radiometric dating confirms the functioning of the new river flow by the 1950s with the highest sedimentation rate being 3.3 cm/yr. Our results show that the Sidi-Salem dam impoundment (1981) led to a dramatic reduction of sediment discharge, a decrease of the grain size with nearly no more sand reaching the coast, and the shoreline retreat. |
| Databáze: | OpenAIRE |
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