Long Beach Island Case Study
Beach Erosion on Long Beach Island and the Grand Strand
Earth 111
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Abstract
Long Beach Island is a barrier island located approximately one mile off of the southern coast of New Jersey. The island in some areas is only a half-mile wide, with some areas, which are even narrower. Therefore, coastal erosion and flooding are both major concerns for the residents. Most of the island’s eighteen miles of beaches have experienced significant damage from erosion in recent decades. The damage is not only threatening the multimillion dollar homes in the area, but others also believe that the island will eventually become one with the Atlantic Ocean. However, in 2005 the Army Corps of Engineers began work on a $75 million dollar project to build a dune the length of the island. To analyze the severity of beach erosion on Long Beach Island, the following report compares the conditions to the Grand Strand off the coast of South Carolina. Both areas are experiencing many negative factors, which are contributing to the deterioration of the sandy beaches. The conclusion points to the fact that however short-term beach replenishment may be; it is the most viable option to solve the current devastation of beach erosion. …show more content…
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Beach Erosion on Long Beach Island and the Grand Strand
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Beach Erosion: a Rising Problem
The coastline is constantly changing due beach erosion, which is caused by a multitude of factors. Beaches are temporary features of land because sand is constantly removed and added to and from them. Except near tidal entrances, sand transport is controlled primarily by wind wave action, and by wind generated currents. Waves can move sand both onshore and offshore, and also in the alongshore direction. (Sorensen, pg. 2). The U.S. Environmental Protection Agency estimates that between 80 and 90 percent of the sandy beaches along America’s coastlines have been eroding for decades. In the most basic terms, beaches erode because the supply of sand cannot keep up with the loss of sand to the sea. This depletion of sandy beaches is what defines beach erosion.
Climate Change
The main cause of beach erosion is climate change, which causes the sea level to rise. Significant rise in sea level accelerates beach erosion and can be the start to erosion in areas that were not predisposed to it. The leading cause of erosion from sea level rise is simply the fact that higher water level allows wave and current erosion processes to reach further up beaches and results in deposition on the near shore bottom (See Figure A). In addition, at higher sea level, waves can become closer to the shore before breaking, which increases erosion. The deeper water also decreases wave fraction, which increases the capacity for alongshore, transport. A rise in sea level can also be the cause of a change in the source sediments. This becomes problematic because it decreases river transport to the sea because the mouth is flooded. Climate change is a major factor of beach erosion because it not only causes sea levels to rise, but it also increases the severity and frequency of storms. America’s foremost beach expert Dr. Stephen Leatherman states, “While sea level rise sets the conditions for landward displacement of the shore, coastal storms supply the energy to do the ‘geologic work’ by moving the sand off and along the beach” (Scentific American).
Figure A: Demonstrates how sea level rise causes beach erosion.
Source: Google Images
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Long Beach Island, New Jersey
Long Beach Island is a barrier island located approximately one mile off the southern coast of New Jersey. Most of the island is only a half-mile wide, however some areas are even narrower. Therefore, coastal erosion and flooding are both major concerns for the residents. Most of the island’s eighteen miles of beaches have experienced significant damage from erosion in recent decades. Especially with the recent devastation of Hurricane Sandy, beach erosion and the damage, which comes along with it, is a huge concern to this area. The damage is not only threatening the multimillion dollar homes in the area, but others also believe that the island will eventually become one with the Atlantic Ocean.
Beach Replenishment
In the beginning of the year 2012, the U.S. Army Corps of Engineers began a 16 million dollar project to replenish the beaches of Long Beach Island. “What we try to do is build a wider beach with large dunes. The dunes are the protective feature,” says Keith Watson, project manager for the U.S. Army Corps of Engineers. This particular project stretches just over a mile long. More than a million cubic yards of sand will be pumped up from the ocean floor and placed on the beach (NJ Today). They have been working on this project since 2005, and have already spent 75 million dollars. The beach replenishment project has created intense controversy amongst the residents and homeowners on the island for many reasons.
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South Carolina’s Grand Strand
The nearly continuous series of sandy beaches in northeastern South Carolina is commonly known as the "Grand Strand". This segment of coast extends 62 miles along the central and southern portions of Long Bay, a large bay that lies between Cape Fear, North Carolina and Cape Romain, South Carolina. The Grand Strand is made up of barrier islands and mainland-attached beaches. Beaches in the region receive little or no sediment from rivers due to the fact that sediment is trapped upstream behind dams or in the estuary before it reaches the coast. This area of South Carolina is experiencing similar coastal change as Long Beach Island. The USGS conducted a study on the Grand Strand in South Carolina, which due to similarities, can be used to help understand the sediment budget and ocean processes in Long Beach Island.
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Sediment Budget and Coastal Processes
As sediment shifts continuously along shorelines, it proves to be a challenge in the prediction of beach behavior. An annual sediment budget is a beneficial approach to manage coastal resources. A sediment budget measures the sediment, which is moved in and out of, or is stored within a beach (See Figure B). In a perfect world, annual loses in sediment are offset by annual gains, and the beach remains stable. However, evidenced by the coastal changes in both Long Beach Island, and along the Grand Strand, an imbalance in the sediment budget can lead to an unstable shoreline. A sediment budget works like a bank account, when more is deposited than removed, the sediment budget has a surplus and the beach grows seaward. On the other hand, when the sediment removed exceeds the deposits, the sediment budget is in a deficit and the beach retreats landward. In addition, coastal erosion occurs when waves and current remove sediment faster than it can be replaced. In Long Beach Island, where the initial balance of the sediment budget is in a deficit, and more sediment is removed, significant changes in the shape and area of the beach can occur (USGS).
Figure B: Diagram showing the components of a conceptual long-term sediment budget for the Grand Strand region. Numbered arrows indicate the general direction of sediment movement.
Source: USGS
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Sediment Sources
Sediment in a beach system comes from four main sources; erosion of upland rivers, longshore transport from adjacent coastal compartments, and erosion of older beaches and shore face deposits. All of these deposits from each source create the input of sediment onto a beach.
Sediment Delivered by Rivers
In the Grand Strand in South Carolina, fluvial input to the coastal system is limited to areas at the northern and southern boundaries of Long Bay. Dams on the rivers leading to the other bays in the area block the movement of sediment. Most of the sediment that does make it downstream is trapped in the Winyah Bay before it can reach the coast. Extensive deposits of mud are dredged routinely to maintain shipping channels in the upper parts of both the Winyah Bay and the Cape Fear River estuary. The limited amount of fluvial sediment that is transported beyond the estuaries is incorporated into the shoal complexes offshore of both Cape Fear and Cape Romain (USGS). In Long Beach Island, sediment delivered by rivers comes from the Toms River, Metedeconk River, and Forked River. These rivers empty through small estuaries along the inner shore into the Barnegat Bay, which is a small arm of the Atlantic Ocean. Sediment is carried through these rivers and estuaries, however is not deposited directly onto the shoreline, similar to the situation described above in the Grand Strand. This is due to the fact that the sediment must travel through the Barnegat Inlet to reach around to the eastern shore of Long Beach Island (Stockton College).
Sediment Delivered by Longshore Transport
In the Grand Strand, evidence suggests that little or no sediment is exchanged around the capes that separate Long Bay from coastal compartments to the north and south.
At the entrance of the Winyah Bay, there is extensive southerly spit growth, which indicated a dominance of longshore transport to the south. This is very similar to the conditions in Long Beach Island as well. The sediment transport rate along the coast of Long Beach Island is 38,250 m3/yr to the south. This southward longshore transport is due to the gradual change in the shoreline configuration (Van Gaalen, pg. 28).
Erosion of Beach and Shoreface
Deposits
Beach and shoreface erosion also have a contribution to the sediment of beaches, and can be measured by analyzing beach-profile geometries and historical erosion rates. In the Grand Strand of South Carolina, the beach-profile is measured by first dividing the coast into 950 segments that measure 330 feet wide. Each segment is assigned a beach profile and is translated landward according to the long-term erosion rate for that segment of beach (See Figure ___). It is assumed that the translated profile maintains a constant shape over long-term years and decades. However, slight variations due occur over the short term, months or years. The difference between the translated and existing profile in each segment is calculated to represent the volume of sediment derived by this migration. To calculate the annualized average for the region, all of the volumes for each segment are added together. Based on the analysis in the entire Grand Strand, an average of 136,027 yd3/yr of sediment have been released in the year the study was completed, 2008 (USGS). In comparison, Long Beach Island released an average of 216,084 yd3/yr in the year 2009 (Stockton College). This demonstrates that Long Beach Island is decorating at even a faster rate than the Grand Strand. Long Beach Island beaches are losing a significant amount of sediment due to erosion of beaches and shoreface deposits.
Figure C: Diagrams showing how volumes were calculated for sediment eroded from beach and shoreface deposits for the Grand Strand.
Source: USGS
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Conclusion
Sandy beaches represent a public resource that is vitally important to the economic and environmental health of coastal communities. Sandy beaches along the coast of New Jersey and South Carolina, in Long Beach Island, and the Grand Strand, respectively, have been eroded at epic rates. And it seems that it is not stopping or slowing any time soon. Direct and indirect effects of shoreline migration will increase due to anticipated climate change and accelerated rates of sea-level rise. A rise in sea level can cause beach erosion not only from direct changes to the budget of the beach but also due to decreasing the amount of sediment supply from rivers, and also by increasing the severity of storms. The depletion of the sediment budget, and increase of longshore transport in both Long Beach Island and the Grand Strand serve as indicators that erosion is only going to progress in deteriorating these beaches.
Beach Replenishment: a Solution
Beach replenishment which is the process of dredging sand up from under the ocean offshore, and depositing it on vanishing beaches, is the preferred method of erosion control. However, experience shows that nearly all replenished beaches have a limited lifespan; so repeated additions of new sediment are constantly required. The long-term need for beach replenishment in the Grand Strand region and on Long Beach Island will require improved projections of coastal-erosion rates and identification of new sediment sources. There is not one clear answer to the solution of beach erosion in both of these areas. However, beach replenishment seems to be the most viable and practical option at this time to slow the erosion, which is depleting our beloved beaches.
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Works Cited
"Beach Replenishment Underway at Long Beach Island." NJ Today. N.p., 2012. Web.
17 Dec. 2012. <http://www.njtvonline.org/njtoday/video/beach-replenishment-underway-at-long-beach-island/)>.
"Coastal Change Along the Shore of Northeastern South Carolina: The South Carolina
Coastal Erosion Study." USGS OFR 2008-1206. U.S. Geological Survey, 2008. Web. 20 Nov. 2012. <http://pubs.usgs.gov/of/2008/1206/html/processes2.html>.
"New Jersey Coastal Composition." New Jersey Geological History. Coastal Research
Center: Stockton College, 2009. Web. 17 Nov. 2012.
Sorensen, Robert M., Richard N. Weisman, and Gerard P. Lennon. "Chapter 6: Control of Erosion, Inundation, and Salinity Intrusion Caused by Sea Level Rise." Erosion, Inundation, and Salinity Intrustion. N.p.: n.p., n.d. N. pag. Print.
Van Gaalen, John F. "Longshore Sediment Transport from Northern Maine to Tampa
Bay, Florida: A Comparison of Longshore Field Studies to Relative Potential Sediment Transport Rates Derived from Wave Information Study Hindcast Data." Graduate School Theses and Dissertations. University of South Florida, 1 Jan. 2004. Web. 4 Dec. 2012.
"What Causes Beach Erosion." Scientific American, 2012. Web. 13 Dec. 2012
Earth 111
-------------------------------------------------
Abstract
Long Beach Island is a barrier island located approximately one mile off of the southern coast of New Jersey. The island in some areas is only a half-mile wide, with some areas, which are even narrower. Therefore, coastal erosion and flooding are both major concerns for the residents. Most of the island’s eighteen miles of beaches have experienced significant damage from erosion in recent decades. The damage is not only threatening the multimillion dollar homes in the area, but others also believe that the island will eventually become one with the Atlantic Ocean. However, in 2005 the Army Corps of Engineers began work on a $75 million dollar project to build a dune the length of the island. To analyze the severity of beach erosion on Long Beach Island, the following report compares the conditions to the Grand Strand off the coast of South Carolina. Both areas are experiencing many negative factors, which are contributing to the deterioration of the sandy beaches. The conclusion points to the fact that however short-term beach replenishment may be; it is the most viable option to solve the current devastation of beach erosion. …show more content…
-------------------------------------------------
Beach Erosion on Long Beach Island and the Grand Strand
-------------------------------------------------
Beach Erosion: a Rising Problem
The coastline is constantly changing due beach erosion, which is caused by a multitude of factors. Beaches are temporary features of land because sand is constantly removed and added to and from them. Except near tidal entrances, sand transport is controlled primarily by wind wave action, and by wind generated currents. Waves can move sand both onshore and offshore, and also in the alongshore direction. (Sorensen, pg. 2). The U.S. Environmental Protection Agency estimates that between 80 and 90 percent of the sandy beaches along America’s coastlines have been eroding for decades. In the most basic terms, beaches erode because the supply of sand cannot keep up with the loss of sand to the sea. This depletion of sandy beaches is what defines beach erosion.
Climate Change
The main cause of beach erosion is climate change, which causes the sea level to rise. Significant rise in sea level accelerates beach erosion and can be the start to erosion in areas that were not predisposed to it. The leading cause of erosion from sea level rise is simply the fact that higher water level allows wave and current erosion processes to reach further up beaches and results in deposition on the near shore bottom (See Figure A). In addition, at higher sea level, waves can become closer to the shore before breaking, which increases erosion. The deeper water also decreases wave fraction, which increases the capacity for alongshore, transport. A rise in sea level can also be the cause of a change in the source sediments. This becomes problematic because it decreases river transport to the sea because the mouth is flooded. Climate change is a major factor of beach erosion because it not only causes sea levels to rise, but it also increases the severity and frequency of storms. America’s foremost beach expert Dr. Stephen Leatherman states, “While sea level rise sets the conditions for landward displacement of the shore, coastal storms supply the energy to do the ‘geologic work’ by moving the sand off and along the beach” (Scentific American).
Figure A: Demonstrates how sea level rise causes beach erosion.
Source: Google Images
-------------------------------------------------
Long Beach Island, New Jersey
Long Beach Island is a barrier island located approximately one mile off the southern coast of New Jersey. Most of the island is only a half-mile wide, however some areas are even narrower. Therefore, coastal erosion and flooding are both major concerns for the residents. Most of the island’s eighteen miles of beaches have experienced significant damage from erosion in recent decades. Especially with the recent devastation of Hurricane Sandy, beach erosion and the damage, which comes along with it, is a huge concern to this area. The damage is not only threatening the multimillion dollar homes in the area, but others also believe that the island will eventually become one with the Atlantic Ocean.
Beach Replenishment
In the beginning of the year 2012, the U.S. Army Corps of Engineers began a 16 million dollar project to replenish the beaches of Long Beach Island. “What we try to do is build a wider beach with large dunes. The dunes are the protective feature,” says Keith Watson, project manager for the U.S. Army Corps of Engineers. This particular project stretches just over a mile long. More than a million cubic yards of sand will be pumped up from the ocean floor and placed on the beach (NJ Today). They have been working on this project since 2005, and have already spent 75 million dollars. The beach replenishment project has created intense controversy amongst the residents and homeowners on the island for many reasons.
-------------------------------------------------
South Carolina’s Grand Strand
The nearly continuous series of sandy beaches in northeastern South Carolina is commonly known as the "Grand Strand". This segment of coast extends 62 miles along the central and southern portions of Long Bay, a large bay that lies between Cape Fear, North Carolina and Cape Romain, South Carolina. The Grand Strand is made up of barrier islands and mainland-attached beaches. Beaches in the region receive little or no sediment from rivers due to the fact that sediment is trapped upstream behind dams or in the estuary before it reaches the coast. This area of South Carolina is experiencing similar coastal change as Long Beach Island. The USGS conducted a study on the Grand Strand in South Carolina, which due to similarities, can be used to help understand the sediment budget and ocean processes in Long Beach Island.
-------------------------------------------------
Sediment Budget and Coastal Processes
As sediment shifts continuously along shorelines, it proves to be a challenge in the prediction of beach behavior. An annual sediment budget is a beneficial approach to manage coastal resources. A sediment budget measures the sediment, which is moved in and out of, or is stored within a beach (See Figure B). In a perfect world, annual loses in sediment are offset by annual gains, and the beach remains stable. However, evidenced by the coastal changes in both Long Beach Island, and along the Grand Strand, an imbalance in the sediment budget can lead to an unstable shoreline. A sediment budget works like a bank account, when more is deposited than removed, the sediment budget has a surplus and the beach grows seaward. On the other hand, when the sediment removed exceeds the deposits, the sediment budget is in a deficit and the beach retreats landward. In addition, coastal erosion occurs when waves and current remove sediment faster than it can be replaced. In Long Beach Island, where the initial balance of the sediment budget is in a deficit, and more sediment is removed, significant changes in the shape and area of the beach can occur (USGS).
Figure B: Diagram showing the components of a conceptual long-term sediment budget for the Grand Strand region. Numbered arrows indicate the general direction of sediment movement.
Source: USGS
-------------------------------------------------
-------------------------------------------------
-------------------------------------------------
Sediment Sources
Sediment in a beach system comes from four main sources; erosion of upland rivers, longshore transport from adjacent coastal compartments, and erosion of older beaches and shore face deposits. All of these deposits from each source create the input of sediment onto a beach.
Sediment Delivered by Rivers
In the Grand Strand in South Carolina, fluvial input to the coastal system is limited to areas at the northern and southern boundaries of Long Bay. Dams on the rivers leading to the other bays in the area block the movement of sediment. Most of the sediment that does make it downstream is trapped in the Winyah Bay before it can reach the coast. Extensive deposits of mud are dredged routinely to maintain shipping channels in the upper parts of both the Winyah Bay and the Cape Fear River estuary. The limited amount of fluvial sediment that is transported beyond the estuaries is incorporated into the shoal complexes offshore of both Cape Fear and Cape Romain (USGS). In Long Beach Island, sediment delivered by rivers comes from the Toms River, Metedeconk River, and Forked River. These rivers empty through small estuaries along the inner shore into the Barnegat Bay, which is a small arm of the Atlantic Ocean. Sediment is carried through these rivers and estuaries, however is not deposited directly onto the shoreline, similar to the situation described above in the Grand Strand. This is due to the fact that the sediment must travel through the Barnegat Inlet to reach around to the eastern shore of Long Beach Island (Stockton College).
Sediment Delivered by Longshore Transport
In the Grand Strand, evidence suggests that little or no sediment is exchanged around the capes that separate Long Bay from coastal compartments to the north and south.
At the entrance of the Winyah Bay, there is extensive southerly spit growth, which indicated a dominance of longshore transport to the south. This is very similar to the conditions in Long Beach Island as well. The sediment transport rate along the coast of Long Beach Island is 38,250 m3/yr to the south. This southward longshore transport is due to the gradual change in the shoreline configuration (Van Gaalen, pg. 28).
Erosion of Beach and Shoreface
Deposits
Beach and shoreface erosion also have a contribution to the sediment of beaches, and can be measured by analyzing beach-profile geometries and historical erosion rates. In the Grand Strand of South Carolina, the beach-profile is measured by first dividing the coast into 950 segments that measure 330 feet wide. Each segment is assigned a beach profile and is translated landward according to the long-term erosion rate for that segment of beach (See Figure ___). It is assumed that the translated profile maintains a constant shape over long-term years and decades. However, slight variations due occur over the short term, months or years. The difference between the translated and existing profile in each segment is calculated to represent the volume of sediment derived by this migration. To calculate the annualized average for the region, all of the volumes for each segment are added together. Based on the analysis in the entire Grand Strand, an average of 136,027 yd3/yr of sediment have been released in the year the study was completed, 2008 (USGS). In comparison, Long Beach Island released an average of 216,084 yd3/yr in the year 2009 (Stockton College). This demonstrates that Long Beach Island is decorating at even a faster rate than the Grand Strand. Long Beach Island beaches are losing a significant amount of sediment due to erosion of beaches and shoreface deposits.
Figure C: Diagrams showing how volumes were calculated for sediment eroded from beach and shoreface deposits for the Grand Strand.
Source: USGS
-------------------------------------------------
Conclusion
Sandy beaches represent a public resource that is vitally important to the economic and environmental health of coastal communities. Sandy beaches along the coast of New Jersey and South Carolina, in Long Beach Island, and the Grand Strand, respectively, have been eroded at epic rates. And it seems that it is not stopping or slowing any time soon. Direct and indirect effects of shoreline migration will increase due to anticipated climate change and accelerated rates of sea-level rise. A rise in sea level can cause beach erosion not only from direct changes to the budget of the beach but also due to decreasing the amount of sediment supply from rivers, and also by increasing the severity of storms. The depletion of the sediment budget, and increase of longshore transport in both Long Beach Island and the Grand Strand serve as indicators that erosion is only going to progress in deteriorating these beaches.
Beach Replenishment: a Solution
Beach replenishment which is the process of dredging sand up from under the ocean offshore, and depositing it on vanishing beaches, is the preferred method of erosion control. However, experience shows that nearly all replenished beaches have a limited lifespan; so repeated additions of new sediment are constantly required. The long-term need for beach replenishment in the Grand Strand region and on Long Beach Island will require improved projections of coastal-erosion rates and identification of new sediment sources. There is not one clear answer to the solution of beach erosion in both of these areas. However, beach replenishment seems to be the most viable and practical option at this time to slow the erosion, which is depleting our beloved beaches.
-------------------------------------------------
Works Cited
"Beach Replenishment Underway at Long Beach Island." NJ Today. N.p., 2012. Web.
17 Dec. 2012. <http://www.njtvonline.org/njtoday/video/beach-replenishment-underway-at-long-beach-island/)>.
"Coastal Change Along the Shore of Northeastern South Carolina: The South Carolina
Coastal Erosion Study." USGS OFR 2008-1206. U.S. Geological Survey, 2008. Web. 20 Nov. 2012. <http://pubs.usgs.gov/of/2008/1206/html/processes2.html>.
"New Jersey Coastal Composition." New Jersey Geological History. Coastal Research
Center: Stockton College, 2009. Web. 17 Nov. 2012.
Sorensen, Robert M., Richard N. Weisman, and Gerard P. Lennon. "Chapter 6: Control of Erosion, Inundation, and Salinity Intrusion Caused by Sea Level Rise." Erosion, Inundation, and Salinity Intrustion. N.p.: n.p., n.d. N. pag. Print.
Van Gaalen, John F. "Longshore Sediment Transport from Northern Maine to Tampa
Bay, Florida: A Comparison of Longshore Field Studies to Relative Potential Sediment Transport Rates Derived from Wave Information Study Hindcast Data." Graduate School Theses and Dissertations. University of South Florida, 1 Jan. 2004. Web. 4 Dec. 2012.
"What Causes Beach Erosion." Scientific American, 2012. Web. 13 Dec. 2012