## 4 Results
### Inner Shelf Morphology  
The digital terrain model of the inner shelf and of the inland area of the Sinis Peninsula was obtained by merging the MBES data, the SBES data and the lidar data ([[http://webgis2.regione.sardegena.it/catalogdati/card.jsp?uuid=R_SARDEG:BFPNM](http://webgis2.regione.sardegena.it/catalogdati/card.jsp?uuid=R_SARDEG:BFPNM)]([http://webgis2.regione.sardegena.it/catalogdati/card.jsp?uuid=R_SARDEG:BFPNM](http://webgis2.regione.sardegena.it/catalogdati/card.jsp?uuid=R_SARDEG:BFPNM)), accessed on 29 November 2019) (Figure 9a). The MBES data allow a more detailed description of the morphology of the sea floor, whereas the SBES were used to highlight the main morphological features of the shoreface of the studied system. Figure 9 showed that the northern sector of Sinis Peninsula is characterized by a series of barriers, longshore oriented and located between the depths of 21 m and 9 m.  
The DTM analysis revealed a first series of submerged barriers located between 20 m and 16 m (B1 Figure 9a,b). The foot of deeper barrier is located at a depth of 21 m, and the crest of the shallow barrier is located at 13.8 m (Figure 9a,b). The orientation of this barrier is NW-SE and the length is about 2 km. A more shallow barrier (B2 in Figure 9a,b) runs parallel to the shoreline for about 3 km from the north of Mari Ermi down to the north of Is Arutas. The foot of the barrier is located at a depth of 13.5 m, whereas the crest is at a depth of 9 m in the sector fronting Mari Ermi, and is located at 12.5m in depth in the sector fronting the north of Is Arutas. The DTM analysis highlighted that Is Arutas beach lies between two headlands that limit its longshore accommodation space (Figure 9a,e). This morphology is also present in the deeper area (about 25 m depth, Figure 9f) and is also evident in the backbeach where an incised valley characterizes the inland area beyond the Is Arutas beach (Figure 9a). Figure 8: (**a**) The cross correlation of volumetric changes (m\({}^{3}\) m\({}^{-1}\)) for the side profiles (northern and southern) on Mari Ermi beach; (**b**) Is Arutas beach; and (**c**) Maimoi beach. The inner shelf area of Maimoi beach is characterized by a profile that becomes steeper in the more inland area due to a wide transgressive dune field which lies on rocky bedrock. The inner shelf of Maimoi beach, beyond the depth of 10 m, is more flat compared to the inner shelf fronting the Is Arutas and Mari Ermi beaches (Figure 9a,d). The inland area, which may be flooded in consequence of the SLR, was evaluated by using the scenario provided by [PERSON] et al. (2017) [55]. The authors provide several maps of inundation for the Italian coastal plains. In particular, this study highlighted the maximum level of inundation following the Rahmstoff [56] and the IPCC 2013 scenarios [57]. Along the studied area the SLR was estimated as about 1.34 m for 2100 as the worst scenario [55]. This level was used to depict the line of the maximum ingression of the sea along Sinis Peninsula (cyan line in Figure 9). Figure 9 shows that a very limited inundation will occur along the Sinis coastline. However, the barrier crest and berm crest on the Mari Ermi and Is Arutas beaches, respectively, will not be inundated by SLR (Figure 9b,c), whereas along Mamoni a limited shoreline retreat may occur. Figure 9: (**a**) The digital terrain model obtained by the merging of the MBES data, SBES data and lidar Data. Lidar data are available from ([[http://webigis2.regione.sardegna.it/catalogodati/card.jsp?uuid=R_SARDEG:BFPNM](http://webigis2.regione.sardegna.it/catalogodati/card.jsp?uuid=R_SARDEG:BFPNM)]([http://webigis2.regione.sardegna.it/catalogodati/card.jsp?uuid=R_SARDEG:BFPNM](http://webigis2.regione.sardegna.it/catalogodati/card.jsp?uuid=R_SARDEG:BFPNM)), accessed on 29 November 2019), in green, the boundaries of the dune field along the studied area; in cyan, the foresee of the maximum level of the sea, as reported by [PERSON] et al., 2017 [55].