The article explores how seawalls affect sediment and waves at two coastal sites. The researchers studied the impact of seawalls on beach erosion and sediment movement. They found that seawalls can cause changes in beach profiles, increase sediment transport rates, and lead to sediment accumulation downstream. The study suggests that seawalls can alter wave patterns and currents, influencing sediment movement along the coast. These findings have implications for coastal management and designing breakwaters to prevent sediment buildup in harbors.