## 5 Discussion
Indeed, as observed on other gravel sandy beaches, most of the sediment transport may occur along the swash zone [7; 58]; hence, the related morphological changes on these two systems happened mainly along the beachface (Figure 4a,b). Maimoi beach is a sediment-abundant beach (sensu [18]), siliciclastic relict sediments were found only in the foreshore scrap, foreshore step and swash limit, while finer biogenic samples were found on the upper beach (the dune area) (Figure 3c) and the submergedbeach [40]. The presence of a large dune field, composed of fine and medium sand [40], highlighted that exchanges of sediments can occur between the submerged and emerged beach. As shown in Figures 4c and 5c, the morphological response to storms of Maimoi beach involves the whole profile (Figures 4c and 5c), leading to a transfer of sediment from the subaerial part of the beach towards the submerged beach during the period with the highest Ps (from November 2010 to March 2010). This process may suggest a certain reversibility of cross-shore processes with exchange of sediment between the submerged and emerged beach. Furthermore, the presence of headlands and outcrops can limit the longshore and cross-shore sediment transport and can promote beach rotation [2; 4; 16; 18; 59]. On Mari Ermi beach a rocky cape limits the beach in the north part (Figure 2a,d) and inhibits the sediment transfer towards the north. The barrier did not show relevant changes, only along the southern profile minor variability was found, this could be related to overwash. This sector was narrow and lower in height compared to the northern and central areas, and overwash may affect the barrier crest (Figures 4c and 5c). The gravel and coarse sandy beach barrier system has a good resistance to wave forcing and storms [10; 60]. Along Mari Ermi beach the presence of rocky outcrops a few meters seaward to the shoreline can inhibit the cross-shore sediment transport (Figure 2a). This could constrain the variability of the beach profile only on the subaerial beach. However, the cross correlation analysis of volumetric changes performed on the side profiles did no show statistical evidence of a beach rotation process (Figure 8a; R = 0.63; \(p\) > 0.05). On Is Arutas beach the headlands constrained the sediment to move within the embayment from the northern to the southern side of the beach and vice versa in relation to wave direction [3]. The volumetric changes (Figure 7b) and the evolution of the elevation of the beach profile (Figure 5b) highlighted that an erosion of the northern profile corresponds to an accretion of the southern profile, and vice versa. The beach rotation on Is Arutas is confirmed by the cross correlation analysis of the volumetric changes of the side profiles (Figure 8b) (R = \(-\)0.78; \(p\) < 0.05). This morphodynamic response is common on sandy and coarse-grained embayed beaches in several contexts around the world [4; 61; 62]. The occurrences of rocky outcrops a few meters seaward to the shoreline can inhibit the beach profile variability in the submerged area (Figure 4b). Maimoi beach is limited towards the south by a rocky headland that does not allow sediment transport towards the south. The effects of the headlands on this beach seem to be less evident than those in the northern beaches. Morphological changes occurred during the storm period, which involved the whole subaerial beach. These changes caused retreat of the shoreline and a generalized lowering in the beach level (Figures 5c and 7c). This process may be related to the cross-shore exchange of sediment, which can be responsible for the erosion (during autumn and winter) and accretion (during spring and summer) of the beach, rather than the longshore sediment transport occurring along the swash zone in the northern beaches. The sediments eroded during storms from each of the beach profiles may be deposed towards the submerged sector. During the fair conditions sediments can migrate onshore and rebuild the beach morphologies, leading also to shoreline accretion (Figure 5c).