Test Area B

Comparing data obtained for profiles C1–C5 highlights the following trends: A slight restriction of the backshore as well as partial increases and decreases of the backshore and foreshore slopes, which resulted in an overall increase of the total beach slopes along C1 and C2 from 2019 to 2021 and their substantial stability along C3–C5. In addition, berm heights alternately increased or decreased. Finally, all profiles showed some dune front retreat, between 0.4 and 2.1 m.

Figure 9 illustrates the short-term evolution of beach profiles P6 and C4 from 2019 to 2021. These profiles, indicated by Rosskopf et al. (2018) [21] as profiles P1 and P2, respectively, have already been under study for two decades and were surveyed in 2001, 2010, and 2016. Hence, they are taken as a reference for the overall evolution of the beach–dune systems in the test areas in the last two decades.

In particular, profile P6 well illustrates the persistence of the substantial stability of the beach–dune system in test area A, without any setback of the dune front and only slight morpho-topographic changes in the backshore; it is therefore consistent with its previous evolution.

Profile C4, on the other hand, well represents the overall evolution of test area B, which has been affected by progressive shoreline and dune front retreat, while the backshore width has remained relatively stable (Table 5), consistent with what we observed from 2001 onwards.

**Figure 9.** Representative beach profiles (C4 and P6) and panoramic views of test areas A and B.

*4.3. Long- to Short-Term Shoreline Changes in the Test Areas and Related Erosion Indexes*

The long- to short-term shoreline changes calculated for the beach profiles surveyed in the test areas, which were based on shoreline data referring to 1954, 2004, 2016, 2019, 2020, and 2021, provide the following data (Figure 10 and Tables 6 and 7).

Concerning the long-term evolution of test area A (the period of 1954–2016, Figure 10), the balance is clearly positive, as also evidenced by the average annual shoreline rates at around 1 m/y reconstructed for profiles P1–P7 (Table 6), and which is consistent with the evolution of S3 (Table 4). A minimum value of 1 has been attributed to the erosion indexes E1 of profiles P1–P7.

**Figure 10.** Annual shoreline change rates calculated for the beach profiles surveyed in the study areas for the periods 1954–2016, 2004–2016, 2016–2019, 2016–2020, and 2016–2021.



Regarding the long-term evolution of test area B (Figure 10), the obtained data document its substantial stability (C4-C5) as well as a slight trend to progradation (C1-C3), with the erosion indexes (E1, Table 6) also assuming a minimum value of 1 in this case.

Considering then period of 2004–2016 (Figure 10), data show clear differences between the two test areas. The Petacciato area continues to exhibit a substantial stability, with all profiles being characterized by an erosion index of 1 (E2, Table 6). The Campomarino area (C1–C5), however, is characterized by erosion indexes ranging from 1 to the maximum value of 4 (E2, Table 6), highlighting its general destabilization and a significant trend toward erosion in the southern sector of B (C4–C5). These data are in agreement with those previously illustrated (Section 4.1, Figure 3) with regard to the stability conditions of segment S3 and the negative shoreline trend of the northernmost portion of segment S9 during the period of 2004–2016.


**Table 7.** NSM and LLR values calculated for profiles P1–P7 and C1–C5 for the periods 2016–2019, 2016–2020, and 2016–2021; related erosion indexes E2019, E2020, and E2021; absolute shoreline variations (Net Shoreline Measurement) for the period of 2019–2021 (NSM 2019–2021).

Regarding the period of 2016–2021 (Table 7), our data for test area A confirm conditions of substantial stability as well as a slight trend toward shoreline progradation; for test area B, however, there is a slight to moderate trend toward shoreline retreat (Figure 10 and Table 7).

Considering the periods 2016–2019, 2016–2020, and 2019–2021 in detail, data obtained for test area A (Table 7) show that 2016–2019 was the most positive period, while the last three years (period 2019–2021) were characterized by a slight negative shoreline trend, with values between −0.5 m (P6) and −7.6 (P2) (NSM, Table 7). This negative shoreline trend, however, did not have any influence on the erosion index levels for profiles P1–P7, which remained equal to 1.

Conversely, the data calculated for test area B for the period of 2016–2019 (Table 7) show that this period was the most negative one, as it was characterized overall by the worst values for annual shoreline retreat rates (LRR up to −5.3 m/y, see C3) and by prevalent erosion indexes of 3 and 4 (E2019, Table 7). Some amelioration in time is evidenced by profiles C1 and C4, whose erosion indexes decreased from 3 and 4 to 2 and 3, respectively, when considering the general period of 2016–2021 (Table 7).

Overall, these data highlight opposite trends for the two test areas. A slight trend toward destabilization for A, but without any effect on erosion indexes E2021; a slight trend toward recovery for B, with some positive influence on erosion indexes E2021. These trends appear to be clearly related to the increase of erosion along A and the decrease of erosion along B (see NSM values, Table 7) during the most recent period of 2019–2021.
