Final answer:
Coastal structures such as jetties, groins, breakwaters, and seawalls each have different purposes in protecting shorelines. A breakwater with a specific opening width affects wave patterns, offering protection at particular angles inside a harbor where wave energy is dispersed due to diffraction.
Step-by-step explanation:
Jetties, groins, breakwaters, and seawalls are all structures built along coastlines to protect against erosion and storm damage, but they differ in form and function.
- Jetties are structures that extend from the shore into the ocean and are primarily built to protect the entrance of harbors and ports by keeping navigation channels free of sediments.
- Groins are shorter structures, often built perpendicular to the shore, to reduce beach erosion by interrupting the flow of sediment along the beach.
- Breakwaters are constructed parallel to the shoreline but detached from it, creating a calm zone to protect anchorages or harbor entrances from wave action.
- Seawalls are solid walls built onshore, right at the edge of the coastline, to defend land from the force of incoming waves.
In the case of wave behavior related to a breakwater with a 50.0-m-wide opening and ocean waves with a 20.0-m wavelength approaching straight on, we can apply principles of wave diffraction. When waves pass through a narrow opening relative to their wavelength, they bend or spread out in a semicircular pattern. This diffraction can create protected areas at certain angles where wave intensity is greatly reduced. The boats inside the harbor are most protected at angles where diffraction causes the wave energy to dissipate rather than directly hit.