Coastal Erosion is a huge problem today and is causing our beaches to get smaller and smaller every year. Coastal erosion is also causing the coast lines to recede and therefore taking away space for which people build on. Even though coastal erosion causes issues it is also the effect of something, Humans! Nature has a way of keeping the world in balance, it creates things such as barrier islands and sand dunes to help protect against costal erosion. However, humans play a big part in messing up that balance by creating man-made structures that actually increase the damage of coastal erosion rather than preventing it.
Some of these structures such as groins, jetties, breakwaters and seawalls, when used properly can help. Unfortunately, in most cases they are used improperly and cause more damage than they do to help. With this being said, there needs to be laws or guidelines put in place to implement the proper use of these structures to reduce the effects they have on coastal erosion. Groins are man-made structures designed to trap sand as it is moved down the beach by the longshore drift. As the longshore drift current reaches the groin it is forced to not only slow down but also change direction.
As stated by Carla Montgomery, a professor Emerita at the Northern Illinois University, in her book Environmental Geology Ninth Edition, the shoreline eventually ends up changing due to the change in velocity and flow of the current, which is caused by the use of groins (160). Although groins trap sand on one side, the erosion they cause on the other side, makes them detrimental to a beach environment. Homeowners who build groins on their beachfront properties in attempt to protect their beach, actually causes erosion of their neighbor’s property on the down drift side of the groin.
Montgomery also exclaims, this build up of sand on one side and extreme erosion on the other side, causes the beach to become a scalloped shape instead straight like it is supposed to be (160). Some states have even outlawed the construction of groins due to the effects they have on coastal erosion. Similar to groins there are structures called jetties. These structures are extended into a body of water to influence the current or tide to protect a harbor. However, jetties have the same effects as groins do with coastal erosion.
An example of this is shown in the article “Development of Downdrift Erosion” by Per Bruun. Bruun explains that there was an inlet constructed in Port St. Lucie, by this inlet a jetty was also constructed to help prevent erosion. However, this jetty did indeed stop the erosion on the south side. Over a course of 33 years the beach area showed a build up of about 0. 7 km/year. The north side showed something completely different. Over a course of just 16 years the beach had eroded at about 1. 5 km/year (1247). This absolutely shows how detrimental jetties can be to the beach environment.
Another issue presented by man is something called breakwaters. These are structures built in the water to create areas of slack water or calm water between the breakwater and the coast. Montgomery asserts, breakwaters prevent nearby unprotected sections of the beach from receiving fresh supplies of sediments and they may gradually shrink due to the naturally occurring erosion process of longshore drift (161). Although breakwaters do allow for sediment deposition in the slack water behind them, they also cause erosion in front of them.
The waves crashing in the structures cause the water to force back in the opposite direct causing a turbulence in front of them. This over time, pulls the sand sediments away from the structure leaving it vulnerable to storms that can then easily destroy them. Lastly there are the seawalls. Now these are the same thing as breakwaters the only difference is that seawalls are built on land. Homeowners with beachfront property build these seawalls in front of their property to prevent erosion of their land. Bruun exclaims, the force of the waves crashing into the structures will pull the sand in front of the structure away.
Therefore, the water does not have time to slow down or stop and deposit the sediments already in the water, thus causing a double negative and causing an even more extreme amount of erosion (1253). Eventually the seawalls will need to be replaced and when they are they will need to be placed back further than they were originally, and the process of erosion will start over again. Some states have outlawed the use of some man-made structures because they see negative effects they have on an already eroding shoreline.
It is true however, that if used correctly and sparingly they can be affective in helping to reduce coastal erosion. This is reason why there needs to be laws or guidelines put in place to implement the proper use of these structures to reduce the effects they have on coastal erosion.
Bruun, Per. “The Development of Downdrift Erosion. ” Journal of Coastal Research 11. 4 (1995): 1242-1257. JSTOR. Web. 27. Nov. 2012. Montgomery, Carla W. Environmental Geology. 9th ed. New York: McGraw-Hill, 2011. Print.