Grain-size characteristics of seafloor sediment and transport pattern in the Caspian Sea (Nowshahr and Babolsar coasts)

The aim of the current study is to determine the equilibrium beach profiles of the coasts of Babolsar and Nowshahr in the southern Caspian Sea. Using depth field data collected from two beaches in the period from 2018 to 2019, seasonal beach profiles and equilibrium beach profiles of the study area were extracted. To investigate the type and transfer of bed sediments, samples were collected from depths of 0.5, 1.5, 3 and 5 meters and were transferred to the laboratory for granulation. The results show the predominant type of sediments in Babolsar and Nowshahr are fine sand with an average of 82.39% and 82.12%, respectively. Also, the percentage of fine-grained sediments, including very fine sand and silt have increased from nearshore to offshore. In the west-east, the median diameter of sediment and the profile slope decreased, from there, the erosion and deposition rate in the two regions has changed. In the western regions, the diameter of beach sediments is more than in the eastern regions due to strong sea currents and relatively coarse-grained sediments from the rivers of western Mazandaran, as well as human activities.