Net Sediment Transport Paths based on Grain-Size Trend Analysis and Monitoring of the Southern Marche Region Coast: the Sentina Beach Case Study (Italy, Central Adriatic Coast)

In many studies of coastal management, it is essential to have a reasonable estimate of sediment transport. Several models, both with deterministic mathematical framework and datadriven one, were built by numerous researchers to predict bed material transport. In this works, therefore, the GSTA method will be applied to an irregular distribution of samples to obtain a sediment transport model characteristic of the Sentina beach, located in the municipality of San Benedetto del Tronto at the southern boundary of the Marche Region. The results will be compared with those obtained from the application of the standard Gao & Collins (1992) method and with some modifications. General transport paths in the whole study area, without uncovered areas, were obtained through a regular grid of points. A two cells circulation system was highlighted as a result of a sea storm from 95°-105°N. To this purpose morphological surveys of the whole beach, both emerged and submerged, were performed in the period 2012-2015. Particularly were carried out: seabed bathymetric surveys, reliefs of the beach profiles and shoreline position in different periods, sampling and grain size analysis of sediments taken both in the emerged and submerged beach. The monitoring testified that the Sentina beach is affected by strong erosion phenomena: in the last years most of the seaward surface (about 23.000 m2 for a trend of 4,3 m/year and a volume equal to 135.000 m3) of the beach has disappeared (period 2012-2015) and the landward border has constantly retreated at the expense of the existing lagoons environment. In this way a general set back of the whole beach environment was happened.