Final answer:
Man-made structures, such as breakwaters, jetties, and seawalls, can affect the movement of sand and change erosion or deposition in the dynamic zone of beaches.
Step-by-step explanation:
Man-made structures, such as breakwaters, jetties, and seawalls, can significantly affect the movement of sand and change the erosion or deposition of sand in the dynamic zone of beaches. These structures act as barriers that alter the natural movement of sand caused by waves and currents.
For example, breakwaters are structures built parallel or perpendicular to the coastline to break the force of waves. They create calmer areas behind them, resulting in deposition of sand. Seawalls are vertical structures built along the shoreline to protect coastal areas from erosion. However, they can lead to accelerated erosion in front of them due to increased wave energy.
Jetties are structures that extend into the sea from the coast to control sediment movement in harbor entrances. They trap sand on one side, causing erosion on the other side. These structures can have both positive and negative impacts on the movement of sand, erosion, and deposition, depending on their design, location, and the natural processes they interact with.