Rising Sea Level Essays - Coastal Geography, Coastal Engineering

Rising Sea Level Rising Sea Level Rising sea levels have been disturbing geographers and geologists for some time now. Scientists are constantly trying to prevent the effects rising waters are causing, which mainly includes beach and island erosion. So far, their attempts with man-made development on beaches along the eastern coast of America have only made things worse. "Up and down the U.S. coast, public money is subsidizing private property on islands made of sand, the stuff on which, as the Bible says, only fools build" (Ackerman 7). In recent years there has been a trend towards living on the barrier islands of America's Atlantic Coast. High rise condominiums, numerous shops, and several businesses have been built to sustain large populations on these islands and continue to be built. As a result, this vital chain of islands that lies between the ocean and the mainland are at risk. While interfering with the natural configuration of these islands, human construction has advanced the rate of beach erosion, thus leaving the mainland with no barriers during times of high surf. This effect has also led to costly, unnatural ways to preserve the barrier islands. Saving these islands in their natural state by curbing human encroachment will both protect mainland populations from high surf and save a considerable amount of federal money. The barrier islands are a chain of islands, stretching from New York to southern Texas, that have served as a critical barrier from the Atlantic Ocean for well over the past 4,500 years (Ackerman 23). These islands however are not as stable as those who live on them would like it to be. Beaches, and in fact whole islands, are constantly eroded as they are subjected to varying winds, currents and changing sea levels. Along Florida's East Coast, roughly 368 miles, the average shoreline change is retreating 22cm per year. Under natural conditions, native vegetation and shifting sands constantly replace or withhold sand on the islands (16). Unfortunately for the inhabitants of the barrier islands, this is a geological behavior which can only continue if the islands remain in a natural state. In recent years humans on these shorelines and islands have been responding to the naturally changing conditions, through the use of man made structures such as seawalls, groins, and sand replenishment, in an effort to save beachfront property from erosion. Obstructing the natural shifts of the islands, says Orrin Pilkey of Duke University who has studied these islands for thirty years, will cause them to, "be lost forever" (16-17). Attempting to hold beaches in place with the use of seawalls, groins, and sand replenishment may seem like a good solution in theory, but in practice they probe ineffective. One of the most common methods of attempting to hold barrier island beaches in place is through the use of sea walls, which are costly and ineffective. Seawalls are typically cement walls constructed parallel to the seashore in an effort to block waves from coming over the beach and into property. However, seawalls tend to withhold sand behind the wall during times of high surf and the natural tendency of the beach to respond to waves is disturbed (Kaufman 207). The structures commonly fail from undermining or erosion by waves breaking over their tops. Under normal conditions sand would be spread out by outgoing currents, which in turn would lower the slope of the beach and cause the waves to break gradually. With seawalls in place, sand remains stationary while waves erode the beach as wave energy is deflected against sand not protected by the seawall (208). In addition to advancing the erosion rate of the sand and inhibiting the beaches' natural tendencies, seawalls have become quite costly to maintain. For example, in New York $120 million was paid by the federal government to sustain and replenish seawall installations as of 1996, and repairs continue to be made (Dixon 231). Clearly, this method is both costly and ineffective. Another commonly used method of stopping erosion is the placement of groins, which are also ineffective. Groins are pilings of rocks that extend into the ocean and perpendicular to the shore. Like seawalls, the primary purpose of a groin is to trap sand, but in longshore currents rather than sand deposits already on the beach. Contrary to their intended purpose, these structures trap sand on the side facing a longshore current and leave the opposite side without sand (Kaufman 207). Over time, the side not facing longshore currents erodes and the initial problem reoccurs. Once again, after the unsuccessful use of groins, money and resources must be spent to restore the beach.