MORPHOSEDIMENTARY BEHAVIOR OF THE DELTAIC FRINGE IN COMPARISON TO THERELATIVE SEA-LEVEL RISE ON THE RHONE DELTA

For the first time, mareographic data obtained by the 'Compagnie du Sa lin du Midi' have been used to estimate the relative sea-level rise (R SLR) in the Rhone delta. The results were compared with the data obtai ned in the Marseille region which is known to be a tectonically stable zone, at least, on the secular time scale. The magnitude of relative sea-level rise is equal to 2.1 mm/ year, from which 1 mm/year could be attributed to subsidence. The morphosedimentary behaviour of the delt aic fringe has been analyzed in order to see if the amount of sediment input is sufficient to allow the wetlands to continue to exist with R SLR. The horizontal variations (erosion and progradation) have been qu antified from land surface changes obtained by shoreline variation ana lysis. The vertical accretion is measured using isotopic dating (Cs-13 7). It appears that the eastern part of the mouth of the Rhone is char acterized by high sediment input, sufficient enough to offset the rece nt rise of sea level. The western part remains vulnerable due to the l ack of sediment in this area. Copyright (C) 1996 Elsevier Science Ltd