How Underwater Bathymetry Affects Your Surfing and Choice for Your Next Wave
Surfers may overlook this concept, but the sport of surfing relies heavily upon science. Surfers use science when designing boards (shape, material) to obtain optimal hydrodynamic properties, and many surfers look to science in the form of weather forecasts for predicting where the best surf will break, but one overlooked area of study – bathymetry – explains wave physics in a way that gives surfers new insight on what coasts and water features make for the best waves. This article will explain bathymetry and how surfers benefit from it.
What is bathymetry?
The National Oceanic and Atmospheric Administration defines bathymetry as “the study of ‘beds’ or ‘floors’ of water bodies including the ocean, rivers, streams, and lakes.” Bathymetry helps to describe marine biology, ocean currents, and prepare cities for tsunamis, but, for surfers, it provides more information on how to decide the next surf.
IMAGE CREDIT: NOAA – http://oceanservice.noaa.gov/
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How does bathymetry explain wave physics?
The topography of the ocean floor or a river bed forces water currents to flow differently. In the ocean, when the trough of a wave moves over an incline of land underwater, the wave peak crashes into the trough and causes the wave to break. In rivers, the edges of waves roll with the river banks, allowing waves to move for miles with seamlessly endless energy. Rivers also present standing waves whereby water currents crash against underwater rocks and surfaces and provide a continuously breaking, unmoving wave. Each of these cases present surfers with new spots to consider that the sport forgot.
What are some examples bathymetry and surfing?
Hawaiian Waves
The coasts of Hawaii make for great surfing renown around the world. These surfing conditions develop from the natural inclines of the volcanic peaks underwater rising to the coasts of the islands. When waves move towards the Hawaiian islands, the front of the wave begins to rise with the land and slow down, but the back of the wave still moves forward at the same speed. The back of the wave keeps gaining more energy and more water as the front holds it back. This process continues until the back of the wave peaks and crashes over the front. It provides Hawaii with large waves close to the coastline and some of the best surfing in the world.
Sunset Beach, Oahu Bathymetry . IMAGE CREDIT: Surfline.com http://bit.ly/1RfHyfJ
READ MORE: MECHANICS OF SUNSET BEACH by Sean Collins for Surfline.com
Californian Waves
California offers different kind of surfing because its coast sits on top of the boundary between the Pacific and North American tectonic plates. Many Californians attribute this to numerous earthquakes, but it also produces interesting land features underwater. The numerous valleys and peaks affect how waves behave.
Ever wonder by Blacks Beach breaks so distinctly without a reef or point?
Black’s Beach Bathymetry. IMAGE CREDIT: http://earthguide.ucsd.edu/
Valleys
The underwater valleys near California provide different wave features than those at Hawaii. When a wave moves into a valley, the center part of the wave falls into the valley while the rest of it moves over a flat surface. The part of the wave that falls into the valley draws the wave forward. Because the trough has sunk to fill the valley, the peak has less potential to break. The banks of valleys produce some great waves, but inside the valley, some waves might not break until right at the shore.
Peaks
The underwater peaks on California’s coast make waves behave differently. These peaks act as barriers for waves and cause them to crash and break before normally expected. Peaks also pull the waves towards one another so that they crash into themselves. Peaks create extremely choppy water and definitely make surfing harsh in those conditions.
River Waves
Rivers have different dynamics when compared to ocean waves. Rivers produce greater effects from tides and underwater obstructions, but this also leads to some different and intriguing surfing conditions. People surf rivers all over the world including in Europe, the Amazon, and North America.
Tidal Bores
Depending on what has attracted a surfer to the sport, river surfing might offer new challenges or appreciation for the skills involved. On rivers, some surfers have ridden waves for over 10 miles. At the Petitcodiac River in Canada, two Californians, JJ Wessels and Colin Whitbread, set the North American record of 18 miles. The Petitcodiac River experiences effects called tidal bore. These waves form during the tides when water gets focused from large, wide areas into small, narrow passages and then crashes along the banks. These waves can travel for several miles and leave surfers with a great thrill.
Standing Waves
Other rivers, like the Snake River near Jackson Hole, Wyoming, create standing waves. This type of wave occurs from rock formations under the river that cause the water to back up and churn, producing a continuous, stationary wave. It resembles a process similar to how rapids form but results in waves that resemble typical ocean waves. Surfers have visited the Jackson Hole location since the 1970’s and have named the annual wave the “Lunch Counter”. Surfers enjoy these waves because they feel like surfing large, ocean waves but never end.
Bathymetry paints a picture for surfers to use when deciding their next trip to find the best wave. Surfers can use publicly available maps to decide if they would like to try surfing in ocean environments similar to Hawaii or California, or they might want to try hopping on a tidal bore or standing wave. Surfers benefit tremendously from knowing the underwater topography of their favorite surfing spots, so they can find others similar or different to them and appreciate the wide variety of options available in surfing.
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