ABSTRACT:

In this study, the nourishment needs of an eroding island beach (Eresos, Lesvos) are assessed through the collection/analysis of beach morphological, sedimentary and wind time-series (2009–2011) and wave hindcasting. 8 different beach nourishment scenarios have been investigated, in terms of scheme cost and life span. The results showed that the most cost-effective scheme involves beach nourishment with coarse-sized material sediment (median grain size of 2 mm), which is slightly coarser than the resident beach sediment. Finally, the early evolution of the beach profiles following nourishment has been studied through 1-D morphodynamic modeling under the present sea level and wave conditions and under increased sea levels.

INTRODUCTION

Climatic change and anthropogenic forcing form the main factors of beach erosion, i.e. the retreat/inundation of the low-lying coasts built on unconsolidated sediments. The most potent ‘climatic’ drivers of beach erosion are considered to be:

  • the accelerated sea level rise-(ASLR) (IPCC, 2007) and

  • changes in the intensity and frequency of extreme events such as storm surges, storms and hurricanes (e.g. Richardson et al., 2009; Ruggiero et al., 2010). Recent IPCC forecasts (IPCC, 2007) suggest that the mean sea level in 2100 will be 0.09 – 0.78 m higher than that of the period 1980–1999, while more recent studies suggest a sea level rise of over 1 m in 2100 (Rahmstorf, 2007; Grinsted et al., 2010). In addition, anthropogenic forcing, such as reduction of the fluvial sediment supply from the coastal drainage basins due to the construction of dams and the abstraction of riverine sediments (e.g. Velegrakis et al., 2008), is likely to put additional stress on beaches. Most of the Greek beaches are particularly vulnerable to long- and short-term sea level increases, as they are both sediment-starved and confined-in-length (‘pocket beaches’) and highly developed.

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