Measurements of Longshore and Cross-shore Sediments in a Littoral Cell

Abstract

Field observation on spatial and temporal variation of shoreline positions along a 16 km-long sandy beach forming a littoral cell was conducted with four X-band radars in year 2010. Half of the coast is protected by jetties,locally known as Headlands,and the rest is close to natural state exposed to the ocean. Hourly shoreline position variations at the Headland were decomposed with Empirical Orthogonal Function analysis into non-synchronizing and synchronizing modes. Non-synchronizing modes are the most prevailing constituent,having opposite signs on both sides of the Headland. These are due to trapping of the longshore sediment at the Headland,and showed a moderate correlation with longshore wave energy flux and migration speeds of coastal features observed at the research pier which locates in the natural section.