![]() ![]() For these sections, this evolution results in greater sensitivity to erosion and breaching during severe storms, as was the case in April 1962 and during winter 1989-90. Thus, the proximal section shows very high retreat rates (1.35 m/yr) due to a sediment budget deficit, which can be explained by gravel migration towards the north-east section of the spit. Upon closer investigation, the rate of retreat and the main morphological changes proves to differ between the morphosedimentary units of the spit and illustrates cannibalization processes. The results obtained show that for the entire period (1930-2010), the mean migration rate was 1.1 m/yr. This trend is mainly due to a sediment supply deficit, which can be explained above all by sediment depletion on the continental shelf and, to a lesser extent, by anthropogenic activities, particularly gravel extraction. Long-term analysis of shoreline changes over the past decades highlights the mobility of the Sillon de Talbert, which is characterized by rapid landward retreat by rollover. ![]() A slow cannibalization processes began, dividing the spit into a source area at the proximal section, a transit zone in the median section and an accumulation zone at the distal section of the spit. A gradual change in its general direction towards a more driftaligned position promoted longshore sediment drift towards the distal end. Towards the mid-18th century, a breach that had formed in the north of the barrier resulted in its transformation into a trailing spit. The examination of early maps shows this barrier was attached to the Olone Islands until the end of the 17th century. The main morphological changes to the Sillon de Talbert have been studied since the 17th century, and were accurately quantified between 19, based on early marine maps, aerial photographs and topographic surveys recently conducted by DGPS. It partially protects the islands of the Bréhat Archipelago against coastal erosion and marine flooding of low-lying land. The Sillon de Talbert is the largest gravel barrier spit in Brittany and forms a swash-aligned formation exposed to swell that enters the English Channel from the west.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |