Natural Resources: Land Resources (Unit 5) Flashcards
True or False: Beach erosion and shifting shorelines are more prevalent today than in the past
True
What is beach erosion and how does it occur?
Beach erosion occurs when sand is removed from the beach and deposited in deeper waters offshore.
What are the three causes of beach erosion?
Human activity, ocean currents, and storm waves
How do ocean currents and storm waves cause beach erosion? What are sandbars? How long does it take for sand from sandbars to return back to the shore?
The movement of waves and ocean currents removes sand from beaches. As waves crash against the shore, the current removes and carries the sand out to deeper waters. When a storm occurs, the waves grow bigger and stronger. These storm waves deposit a lot of sand in large, offshore sandbars. It can take weeks and even months before this sand returns to the beach.
Ocean Current Definition
Human activity can cause and sometimes accelerate erosion. Building close to the coast can have an effect on beaches and speed up erosion. Sand dunes, which separate low-lying beaches from higher grounds, can be damaged during the building process. These dunes help to prevent water from going too far inland. If the dunes are damaged, water is able to flow inland, causing shorelines to change.
How can human activity accelerate and cause beach erosion? How does building close to the coast accelerate erosion?
Human activity can cause and sometimes accelerate erosion. Building close to the coast can have an effect on beaches and speed up erosion. Sand dunes, which separate low-lying beaches from higher grounds, can be damaged during the building process. These dunes help to prevent water from going too far inland. If the dunes are damaged, water is able to flow inland, causing shorelines to change.
True or False: Because of erosion, beaches have become narrower and the elevation lower. Less sand simply means less beach.
True
What does it mean when a shoreline shifts?
It moves inland
True or False: In places that are uninhabited, shifting shorelines mean beaches are created farther inland
True
Remember: News reports indicate that beach erosion from Hurricane Irma has severely impacted Miami Beach, Florida. It has been determined that one-third of the sand on Miami Beach was lost due to huge storm waves produced by Hurricane Irma. Since then, beach erosion continues to worsen due to severe weather. The width of the beach has narrowed greatly. The erosion has caused cliffs to form along the shore. The shoreline is moving inland, causing a concern for public safety and private properties. The city is working to bring in more sand as part of a $1.5 million emergency project to restore Miami Beach.
News reports indicate that beach erosion from Hurricane Irma has severely impacted Miami Beach, Florida. It has been determined that one-third of the sand on Miami Beach was lost due to huge storm waves produced by Hurricane Irma. Since then, beach erosion continues to worsen due to severe weather. The width of the beach has narrowed greatly. The erosion has caused cliffs to form along the shore. The shoreline is moving inland, causing a concern for public safety and private properties. The city is working to bring in more sand as part of a $1.5 million emergency project to restore Miami Beach.
Is beach erosion a worldwide problem? What does beach erosion impact?
Beach erosion is a worldwide problem. Beach erosion causes shorelines to move inland or shift, impacting both the surrounding environment and human activity.
Beach Erosion Definition
The movement of sand and sediment from off the shore to deeper waters
What do many beach management strategies include? What are the various hard structures used in these strategies?
Many beach erosion management strategies involve building hard structures to protect sand and sediment loss on beaches. These structures include, but are not limited to, the following: jetties, groins, seawalls, and coconut coir logs.
What are jetties and groins? What do they protect the shoreline from? How do they compare in size? Although viable, what problems do they pose, especially on the downdrift side? What must be done to combat erosion by jetties?
Jetties and groins are hard structures built perpendicular to the shoreline. They both protect from erosion caused by waves and current. Groins tend to be smaller, shorter structures, whereas jetties can reach farther out into the ocean. While both are viable management options, they can actually cause some erosion in places as sand piles up on the updrift side of the structure, resulting in less sand on the downdrift side. Erosion caused by jetties can be severe with unintended consequences for beaches on the downdrift side of the jetty. Because of this, multiple jetties have to be built to help reduce this effect.
What are seawalls? What do they protect the land from? What happens when a wave crashes into a seawall? What additional protection compensates for the seawall’s expensive installment?
Seawalls are structures built at the water’s edge or slightly inland. They protect the land from rising tides as well as from strong waves or tsunamis. As a wave crashes into a seawall, the energy of the wave is reduced, causing it to pick up and erode less sand. While seawalls can be expensive to install, they have an additional benefit of flood protection.
What are coconut coir logs, and where are they placed? What are they used for? What are their properties? What is the negative of this hard structure beach erosion management strategy?
Coconut coir logs are placed along shorelines to help reduce beach erosion. They are round logs made of coconut fibers. They are biodegradable, safe for surrounding wildlife, and can help to stabilize the area long enough for natural seagrass to establish a strong root structure. However, this can take time to allow for growth of plant life and may not have immediate results.
What are vegetation management and beach nourishment known as, in terms of beach management strategies? What do they involve doing?
Vegetation management and beach nourishment, also known as soft alternative strategies, involve relocating materials to the beach and just offshore to help fight erosion.
What is beach nourishment? What does it accomplish? When is beach nourishment preferred over hard-structures? How is the cost of beach nourishment a negative? How about its longevity?
Beach nourishment involves adding sand and sediment to a beach. Unlike structures that help to keep existing sand and sediment on the shores, beach nourishment replaces what has been lost. It helps to create new natural environments, rebuild sand dunes, and protect sediment volume during sea level rise. In some areas, beach nourishment is the preferred method over hard structures for fighting erosion when the threat of flood or sea level rise is not prevalent. However, beach nourishment is a very expensive strategy. It requires the pumping or trucking of sand onto beaches. In some cases, this can cost millions of dollars. It is also not a long-term solution to the problem of erosion.
How is vegetation management similar to beach nourishment? What is vegetation management? What does it work to do? How does vegetation aid in less erosion?
Vegetation management is similar to beach nourishment in that they both bring materials to the shore and beach to help fight erosion. Vegetation management works to maintain and bring in plant life around shorelines to help trap more sand and sediment and keep it on the beach. The thicker and larger the vegetation, the more sand and sediment build up over time.
True or False: Beach erosion is mainly a natural occurrence. While it is nearly impossible to prevent, finding ways to manage beach erosion is a vital task that coastal cities worldwide are undertaking.
True
Review: What are the various materials groins can be made out of? What do they do? What are their negatives? What are multiple groins in one area known as?
Groins are steel, concrete, stone, or wood barriers. They are built perpendicular to the shoreline to slow the movement of sediment along the shore. Sand builds up on the updrift side of a groin. However, erosion can occur on the downdrift side. Multiple groins are known as a groin field.
Review: What are jetties? What materials can jetties be made out of? What do jetties protect and keep open? What is its negative?
Jetties are long, narrow structures built perpendicular to the shoreline. They are made of stone, steel, or concrete. Jetties protect inlets from currents and tides while keeping the channel open for navigation. A buildup of sand occurs on the updrift side. However, erosion on the downdrift side can be severe.
What are breakwaters? What materials can they be made of? Where are they built? What is their purpose? How do breakwaters help ships in harbors?
Breakwaters are rock or concrete structures that are built parallel or at an angle to the shore. Their primary purpose is to protect the coast or harbor from the waves and reduce erosion on the shoreline. Breakwaters create calm water, which facilitates safe passage into the harbor for ships.
Review: Seawalls are concrete, stone, wood, or steel structures built along the coastline. They have a stepped, sloped, or curved face. They prevent or limit erosion by directing waves back to the ocean. Seawalls also provide coastal flood protection and, if maintained, can last a long time.
Seawalls are concrete, stone, wood, or steel structures built along the coastline. They have a stepped, sloped, or curved face. They prevent or limit erosion by directing waves back to the ocean. Seawalls also provide coastal flood protection and, if maintained, can last a long time.