Archive for the ‘Erosion’ Category
Erosion impacts coastlines locally and globally
A wartime ‘pill box’ in Suffolk, UK succumbs to coastal erosion. The WWII bunker held back the Third Reich, but it was no match for coastal erosion.
Photo Courtesy, Barry Hughes
Last week scientists from around the world descended on South Carolina’s, Myrtle Beach to discuss coastal erosion. Scientific American reports the impetus of the event was a study conducted by the US Geological Survey (USGS) and the South Carolina Sea Grant Consortium. In the study researchers researchers looked at whether or not South Carolina should begin re-sanding portions of its receding beaches. The results of the study were presented to the scientists as part of the International Geological Program Annual Conference.
The study showed that South Carolina’s coastline is receding at a rate of up to thirty centimeters (11.8 inches) per year. While losing a foot of coastline into the ocean doesn’t seem overly concerning; the long term effects are staggering. On average South Carolina can expect to lose almost one hundred feet of coastline over the next century.
This is certainly not an isolated phenomenon. Coastlines all over the world recede each year. Oceanography in the 21st Century, an online text book reports that, “Average erosion rates are 6 feet per year along the Gulf [of Mexico] and 2 to 3 feet per year along the Atlantic.”
According to the National Oceanic and Atmospheric Administration (NOAA), “17 percent of the contiguous U.S. land area [the coast] is home to more than half of the nation’s population.” Meaning receding coastlines have the potential to affect a huge number of Americans. And, Scientific American sites the U.S. Environmental Protection Agency’s estimate “that between 80 and 90 percent of the sandy beaches along America’s coastlines have been eroding for decades.”
Yet, coastal erosion remains invisible to most beach goers. This may be a result of how beach erosion occurs. Research indicates that it is almost never the case that a beach will consistently loses a foot or two of soil each year. Rather a portion of coastline will remain relatively stable for forty or fifty years. Then all the ‘deferred’ erosion will take place over a short period of time.
Oceanography in the 21st Century says, “Beach erosion is episodic. Most erosion occurs over a short period, sometimes in hours during a hurricane such as Katrina, sometimes during a season as in California during an El Niño event [as is this winter].”
Photos before and after Hurricane Katrina illustrate rapid coastal erosion in Louisiana.
Photo Courtesy, USGS
This has special significance here, the home of The Surf Check blog, in San Luis Obispo, Calf. Nearby homes worth millions of dollars are built atop bluffs overlooking Shell Beach. The owners build these beautiful homes with the expectation that the home and the land will be there forever. But, given the episodic nature of erosion, based on averages how long can they really expect that bluff to be there? How permanent are their homes and investments with the onset of El Niño conditions this winter?
