Determination of set-back lines on eroding coasts. Example of the beaches of the Gulf of Lions (French Mediterranean Coast)

Abstract

The study presented here describes a method for defining set-back lines along eroding coasts. The method (a mathematical model) combines the long-term shoreline retreat trend with short-term shoreline erosion (during storms). Simulations are carried out for 2030 and compared with the beach width to determine whether the shoreline is likely to shift onshore. The mathematical model is applied to the Frontignan and Carnon beaches (south of France). Both sites possess hard engineering coastal structures and downdrift erosion on the natural beaches. The set-back lines indicate that beaches with groynes are generally wide enough to resist shoreline retreat, while the downdrift "natural" beaches are not. We discuss the possible utilisation of set-back line estimations.

The Mediterranean Coast of Andalusia (Spain): Medium-Term Evolution and Impacts of Coastal Structures

“…Commonly, the development of erosion processes in down-drift areas was prevented with the progressive emplacement of new structures generating the so called "domino" effect [81]. This process, frequently observed along the Mediterranean coast [31,34,38,80], translates and amplifies erosion processes in down-drift areas. An example was the construction of the port of Almerimar ( Figure 5) in 1978; according to [59], it caused the down-drift disappearance of 20,000 m 2 of beach surface.…”

“…Additionally, quantification of erosion rates in the studied area is very important because shoreline retreat takes place over a human time-scale. Consequently, the recorded data can be used to determine safe construction setbacks, to evaluate the efficiency of coastal protection structures, and to elaborate coastal erosion management and land use plans [22,37,38].…”

Sea-Level Rise and Shoreline Changes Along an Open Sandy Coast: Case Study of Gulf of Taranto, Italy

“…In recent years, the behavior of the Mediterranean coasts in relation to shoreline migration, as a consequence of the changes in the local sedimentary budget (e.g., [1][2][3][4][5]), and to the sea-level rise (e.g., [6][7][8][9][10]), has been of great interest. Currently, the sea-level change observed along the coasts depends on the sum of eustatic, steric, isostatic, and tectonic factors [11,12].…”

The impact of temperate reefs on 34 years of shoreline and vegetation line stability at Yanchep, southwestern Australia and implications for coastal setback

“…Least-squares, linear regression was used to provide historical trends of shoreline change. This is a popular method used to determine coastal setback (e.g., Sabatier et al, 1997), in part, because it is easy to understand and perform (Crowell et al, 1999), and because usually shoreline data sets do not have a statistically significant sample size/length to enable using non-linear models for extrapolation (Fenster et al, 1993).…”