Posted by admin | 12.19.2012 | Marine Science
You can huff and puff but you can’t blow me down!
Have you ever been to the beach on a windy day? If so, then you’ve had that raw sandblasted sensation once or twice after a visit to your closest coast. As sand whips down the waterline you may feel more like your traversing the Sahara Desert than a tourist vacationing on the seashore. This is actually a very important part of beach building. Swift winds relocate sand into the dune bed, essentially building up this protective zone.
The fact is beaches, and more specifically dunes, are in a constant state of change. A major energy convergence occurs at the beach-line as waves, wind, and earth abruptly meet. Beaches are endlessly growing, shrinking, and shifting, depending on the location and time of year. Add in the occasional tropical storm, longshore current, and the daily tide and it’s a wonder we have them at all.
When left to their own devices beaches are naturally able to sustain themselves. You may have heard discussion on the negative aspects of beach erosion but, in fact, beaches are the product of erosion. Composed of eroded sediment, shells, and minerals they breakdown and rebuild continuously. Over millions of years beaches have naturally relocated thousands of miles from where they now stand. Coastlines have been changing and adjusting since this planets birth, only in the past few centuries when man-made structures became threatened has this normal migration become a “problem”.
Jetties, seawalls, and beach renourishment are all processes used to “keep the beach where it is” so that the luxurious condos, waterfront houses, and pricey resorts don’t fall into the sea. Unfortunately these measures are extremely expensive and only work short-term. These solid structures inhibit this natural cycles of sand movement. The coastline will always move, with or without manmade structural support. Building a house on barrier island is like building a house on an airport conveyer belt and then acting surprised when your house falls down.
Though wave energy is responsible for shaping most of the beach, dunes are more the product of wind and an essential part of regulating and maintaining a beaches structure. Dunes are held in place by highly adapted vegetation and the dune face is a very harsh environment. Extreme temperatures, strong winds, and salt spray make the dune a particularly tough place to survive for most plants. However there are a few species, such as the sea oat, that can bear the cruel climate. These plants are responsible for dune building because they trap windblown sand and their root systems provide stabilization near the surface.
Beaches and dune systems offer a large amount of protection for coastal communities by absorbing the energy of the ocean as it migrates to shore. However the effectiveness of this protection directly correlates to the areas ability to naturally reform and shift. Humans attempt to control these natural processes unsuccessfully and each year millions if not billions is spent repairing and rebuilding permanent structures along ocean’s edge ( i.e. Hurricane Sandy).
No matter what precautions, measures, or action plans me make anything built adjacent to the ocean will eventually be reclaimed by the water and the sand as sea level continues to rise. We can either learn from this historical movement, or find ourselves twisting in the sandy wind.