Sand bar behavior in a mixed sediment environment

The Adriatic coastline is characterized by complex nearshore systems, which include beaches punctuated by rivers with nearby harbors. We investigate a representative nearshore system in Senigallia, Marche, Italy, which consists of a mixed sediment beach and the Misa River, rich in clays and silt. Previous analysis, based on infrequent bathymetric surveys and 4 years of wave observations, has made the case that medium term sand bar behavior is driven by bar growth and onshore migration during Scirocco conditions (low waves, east southeasterly winds) and bar destruction and offshore migration during Bora conditions(large waves, north northeasterly winds). We aim to test this hypothesis at shorter timescales by improving temporal resolution using a newly installed long term coastal monitoring station. We also aim to examine the effect of river discharge events on sandbar behavior. A video monitoring station consisting of four color cameras was installed on a pole 25 m above mean sea level in July 2015. The station records hourly imagery during daylight hours at 2Hz. We will describe preliminary analysis of summer and fall data including the presence of multiple sand bars, migration of a rip channel and beach terrace, and the influx of suspended cohesive sediment to the beach following discharge events from the Misa River. Figure 1. Example time exposure image showing the sediment laden Misa River and white foam patches associated with wave breaking over the sand bar on the beach.