Slide 13 of 21
Notes:
- Bathymetric Considerations - underwater topographic features have a strong influence on the behavioral characteristics of waves and the resulting surf conditions.
- Underwater Canyons - If a canyon runs right up to the coast, the surf zone will be relatively calm due to increased water depth.
- Underwater Ridges - the opposite reaction of a canyon. As the wave train rides over the ridge, the interaction with the bottom causes the wave on either side to refract towards the ridge (focal point).
- Sandbars - cause waves to crest.
- Offshore Islands - refraction can cause waves to swing in behind the islands preventing their use as a safe shelter.
- Coral reefs - act as a barrier between the open ocean and the lagoon of most volcanic islands. At low tide the reef may be shallow or exposed, preventing landing craft from reaching the intended beach.
- Manmade Obstructions - reefs, jetties, sunken ships can increase surf conditions as well as pose a hazard to boat operations.
