The article discusses how wave-induced stresses control sediment transport on beaches. By conducting experiments, researchers found that beach slope and sediment size affect longshore sediment transport. They discovered that total longshore transport increases with steeper beach slopes, but only slightly with larger sediment sizes. The maximum rate of sediment flow also increases with both beach slope and sediment size. These findings suggest that the slope of the beach and the size of the sediment play a significant role in determining how sediment moves along the shore.