Oceans
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Table of Contents
Introduction
Countering The Effects of High Seas
Hurricanes
Beach Protection
New Protection Methods
Conclusion
References
Introduction
Coastline changes due to weather and human intervention represent a major concern for coastal planners all over the world. Coastline changes, not only has an effect on citizens who own property by the seaside, it also has a major effect on our business here at McDuff. While beaches may be vacation spots for some, their disappearance through erosion a great loss of business for our company. The purpose of this report is to inform our coastal planners and stakeholders of ways to prevent coastal erosion in the Caribbean.
Shorelines are areas of continuous change. Natural forces of wind and water interact with the land and cause shifts between water and land. These shifts between water and land have been taking place for centuries but it has become a major issue in the Caribbean islands since tourism became the major industry in the 1970s. Despite being a major value here at McDuff, beaches have not been perceived as areas needing management, protection and funding.
Environmental awareness has been growing slowly due to the numerous hurricanes that have past through the region. These dramatic events bring home to everyone the importance and vulnerability of the regions beaches. This report will give information regarding: countering the effects of high seas, hurricanes, structures for beach protection, and new protection methods. This report provides information on these situations and offers ways to protect the beaches in the future.
Countering The Effects of High Seas
Waves, tides and ocean currents are among the several natural forces that cause beach changes. One cause of considerable beach erosion is swell waves. Swell waves are seas that have moved out and away from the area in which they were formed. Because of their different wave lengths and wave speeds, waves move outward from the windy areas where they formed, and separate into groups of waves with distinct wave periods. In the Caribbean, swell waves are usually caused by intense mid-latitude storms in the North Atlantic Ocean, which travel thousands of kilometers south affecting the west, north and east coasts of the islands in the winter months from October to April (
Figure 1: Effects of Accretion (Komar, 1976)
During the summer months, when the seas are calmer and the waves smaller, beaches tend to build up. This process is known as accretion (
Hurricanes
Extreme events such as hurricanes are the major cause of shoreline changes in the Caribbean. Many hurricanes originate as tropical waves off the west coast of Africa and travel across the Atlantic Ocean gaining strength from the warm ocean waters (
Scale # Category
Sustained Winds MPH
Damage
Examples
74-95
Minimal
Florence (1988) LA, Charley (1988) NC,
96-110
Moderate
Kate 1985, Bob 1991,
111-130
Extensive
Alicia 1983 TX, 1938 New England,
131-155
Extreme
Andrew 1992 FL, Hugo 1989 NC
Catastrophic
Camille 1969 MS, Labor Day Hurricane 1935 Fl Keys
Figure 2: Hurricane Categories (
Scientists that have studied hurricane weather patterns say that hurricane generation in the North Atlantic Ocean occurs in 20-25 year alternating cycles of activity and relative in activity. The evidence indicates that we have now entered an active hurricane cycle, which is expected to continue for the next two decades. The years 1995 and 1996 were especially active, 1995 registering as the second-most active year on record with nineteen named storms (
Figure 3: Beach Erosion (
Even in active hurricane cycles there can be years with below average hurricane activity. Tropical storms and hurricanes generate waves that move out of the immediate vicinity of the hurricane to affect other islands as swell waves. Considerable damage may occur to beach systems as a result of high seas, raised water level, high winds and heavy rain fall. Hurricane waves erode the