The implications of last decades sea level variations for coastal erosion: a review
Résumé
Shoreline erosion is a consequence of the coupled effects of waves and currents on coastal sediments, either available locally or provided by adjacent coastal sedimentary units. In the future, sea level rise due to anthropogenic climate change is expected to exacerbate coastal erosion, but the actual role of this ongoing process in present day's shoreline mobility is still debated. Starting from a review of papers previously published, we identified two barriers to a better understanding of the actual consequences of contemporary sea level rise in coastal erosion. First, actual sea levels along the coast are generally only known for a few areas where tide gauges are available, whereas subsidence or uplift is a common feature of many coastal areas. Secondly, there is a lack of well-established method for attributing shoreline mobility to a specific factor or to a combination of causes. At present, such methods range from field expertise, analysis of data to schematic or physical modeling. However, no model is presently able to represent accurately all processes accounting for coastal hydro-sedimentary processes. In spite of these limitations, this review highlights that sea level rise rates in the order of a few millimeters per year are generally not considered as a dominant cause for shoreline erosion. On the contrary, most studies attribute it to the effects of waves, storms, variations in sediment supply and human activities.