Coastal Defence Case Study (Cambridge (CIE) IGCSE Geography) : Revision Note

Causes of coastal erosion in Nassau County, Florida

Background

• Nassau County is located in northeast Florida, along the Atlantic Ocean

• It includes Amelia Island, a popular tourist destination known for its beaches, dunes, and historic towns like Fernandina Beach

• This area has experienced growing concerns about coastal erosion due to both natural processes and human activity

Causes

• Coastal erosion in Nassau County happens when wind, waves, and storms remove sand and sediment from beaches and dunes. The main causes are:

Tropical storms and hurricanes

• Storms like Hurricane Matthew (2016) and Hurricane Irma (2017) caused severe beach erosion and flooding

• These storms bring storm surges, high waves, and strong winds that wash away sand and damage dunes

Sea level rise

• Sea levels are rising due to global warming, causing more frequent high tide flooding and making erosion worse

• The sea level along Florida’s coast has risen by about 8 inches (20 cm) since 1950 and is expected to rise much more in coming decades

Human activity

• Construction of seawalls, roads, and buildings interrupts natural sand movement

• In some areas, removing coastal vegetation and sand mining have weakened dunes and left the beach more exposed to erosion

Impacts of coastal erosion in Nassau County, Florida

• Coastal erosion in Nassau County has affects the local economy, housing, infrastructure, ecosystems, and public safety

• Some of the most significant impacts been on Amelia Island and Fernandina Beach

AWAITING IMAGE

Nassau County's critically eroded beaches

Property damage

• Homes, roads, and buildings close to the beach are at risk of collapsing or flooding. Insurance costs have increased

  • Amelia Island, especially areas like South Fletcher Avenue, is highly exposed to beach erosion

  • Homes along this beachfront have been left just metres from the ocean after storms washed away the sand dunes that once protected them

  • After Hurricane Matthew (2016), several oceanfront homes experienced flooding and structural damage

  • Emergency sandbags and dune fencing had to be installed to protect houses from further damage

  • Erosion has lowered property values and led to higher insurance premiums due to increased risk of flooding and storm surge

Loss of tourist beaches

• Tourism is a major part of the economy and erosion has reduced beach size, affecting local businesses

  • Fernandina Beach, a popular tourist spot, has seen a narrowing of beaches, particularly near Main Beach Park and North Beach Park

  • Beachfront space for sunbathing, walking, and recreation is shrinking, especially during high tides and after storms

  • This has a direct impact on tourism, which is one of the main sources of income for Nassau County with fewer visitors, there is less income for local hotels, restaurants, and shops

Damage to roads and public infrastructure

• Erosion threatens highways and utility lines near the shore

  • The South Fletcher Avenue corridor, a major coastal road, has been undermined by waves, with sections repeatedly needing repairs

  • During Hurricane Irma (2017), parts of Ocean Avenue were temporarily closed due to flooding and roadbed erosion

  • Stormwater systems near the beach often fail due to excess sand and debris, increasing urban flood risk

Habitat loss

• Dunes and beaches support wildlife like sea turtles, shorebirds, and dune grasses

• Dunes along Amelia Island are essential habitats for:

  • Sea turtles (especially loggerhead turtles), which nest along the beach each year

  • Shorebirds such as plovers and terns

  • Dune vegetation like sea oats, which hold sand in place

• Erosion has led to:

  • Destruction of turtle nesting sites, decreasing nesting success

  • Collapse of vegetated dunes, which act as natural wind and wave buffers

  • Loss of biodiversity, as some species struggle to survive in changing conditions

Increased flooding and storm impact

• Without wide beaches and strong dunes, Nassau County becomes more vulnerable to:

  • Storm surges (a rise in sea level caused by hurricanes)

  • Saltwater intrusion into freshwater areas

  • Flooding of homes, parks, and infrastructure even during regular high tides (a phenomenon called 'sunny day flooding')

• For example: During Hurricane Dorian (2019), even though the storm didn’t make landfall, storm surge flooded parts of the Egans Creek Greenway and low-lying neighbourhoods near Atlantic Avenue

Cost of recovery and maintenance

• Each beach nourishment project in Nassau County can cost between $10 million and $20 million

• Maintaining infrastructure like revetments, sand fencing, and emergency dunes adds to public spending

• Local, state, and federal governments frequently share the economic burden, which means that long-term erosion increases the financial pressure on communities

Strategies used to manage coastal erosion in Nassau County, Florida

• The approach in Nassau County focuses on balancing development with natural protection

• Over $20 million has been spent on erosion control and beach restoration in Nassau County over the last 10 years

• Sea turtle nesting areas on Amelia Island have been protected through dune fencing and vegetation planting

• After Hurricane Matthew (2016), Fernandina Beach lost over 50 feet of sand, leading to urgent restoration projects

• Over 15,000 sea oats were planted in a single season as part of a community dune restoration project

Hard engineering techniques

Seawalls and revetments

• Built along the coast to block wave energy

  • For example a rock revetment was installed near Fernandina Beach after Hurricane Matthew to protect roads and homes

  • A concrete seawall was constructed along South Fletcher Avenue in Fernandina Beach to protect homes and a section of the road that was under threat after Hurricane Matthew (2016)

  • However, although the wall reduced erosion in that area it has led to increased erosion further down the beach, a process known as 'coastal squeeze'

• Revetments have been installed in front of public beach access points near Sadler Road and Seaside Park

  • These were added after dune failure during Hurricane Irma (2017)

  • They are visually more natural than seawalls but still require regular maintenance and can be dangerous for swimmers

Groynes

• Wooden or stone barriers built at right angles to the shore to trap sand moving along the beach

• Help widen beaches in one area but may cause erosion further along the coast

  • Old wooden groynes still exist on some parts of Amelia Island’s northern beaches

  • Although rarely used in new projects today, these older groynes helped maintain beach width for many decades

  • However, they often led to erosion on the down-drift side where sand was no longer transported naturally

Soft engineering and sustainable management

Beach nourishment

• Involves adding sand to the beach from another location

  • In 2020, a major beach nourishment project on Amelia Island added 700,000 cubic yards of sand to restore dunes and widen the beach

  • Benefits: This project widened the beach, improved turtle nesting habitats, and provided a natural buffer against storms

  • Looks natural, supports wildlife, and protects property

  • Cost: Sand was dredged from offshore and transported to shore

  • Over $10 million, but seen as a long-term investment

Dune restoration

• Planting sea oats and native grasses to stabilise dunes

• Helps absorb wave energy and acts as a natural buffer during storms

  • Community groups like Keep Nassau Beautiful have planted over 15,000 sea oats near North Beach Park and American Beach since 2019

  • The county has also installed fencing and boardwalks to protect newly formed dunes from foot traffic

• Fencing off dunes to prevent trampling by tourists

• Sand fences are simple wooden slat fences placed in a zigzag pattern to trap sand and help dune formation

  • Seaside Park and Main Beach use sand fencing, especially after storms, to aid in the beach's natural rebuilding.

  • Combined with sea oat planting, this helps create stronger, wider dunes

Managed retreat

• In some areas, officials are choosing to move buildings back from the beach over time

• This reduces future risk and allows the coast to change naturally

  • Emerging practice in Nassau County:

    • While no large-scale retreat projects have been completed yet, development restrictions near Egans Creek Greenway and dune buffer zones are early examples of planning to allow space for the shoreline to shift naturally in the future

Zoning and building regulations

• Nassau County has building setback laws, which stop developers from building too close to the shoreline

• New homes must be elevated on pilings to reduce flood risk

Community education and involvement

• Local organisations like Keep Nassau Beautiful teach residents about dune protection and organise coastal clean-ups and dune planting days

• Locals are encouraged to report erosion and storm damage

Managing tropical storms in Florida

• Florida is one of the most hurricane-prone states in the U.S., with a long history of tropical storms and hurricanes causing serious damage

• In response, Florida has adopted a wide range of engineering, ecological, and community-based strategies to manage these powerful natural events

• Florida’s location between the Atlantic Ocean and the Gulf of Mexico makes it vulnerable to hurricanes every year, especially between June and November

• Over 40% of U.S. hurricanes have made landfall in Florida

• Storms bring:

  • Strong winds (up to 150+ mph)

  • Heavy rainfall and flooding

  • Storm surge, which causes extreme coastal erosion and infrastructure damage

Traditional storm protection methods

• Florida has historically used hard engineering to protect its coastlines from tropical storm damage:

  • Seawalls in cities like Miami, St Augustine, and Naples protect urban areas from storm surges

  • Stormwater drainage systems and pumping stations are installed to quickly remove floodwaters

  • Building codes now require new structures in coastal zones to be elevated, wind-resistant, and built with hurricane straps

    • For example, after Hurricane Andrew (1992), one of the most destructive storms in Florida's history, the state completely overhauled its building code system, making it the strongest in the U.S. today

Sustainable storm management

• Recently, Florida has embraced nature-based solutions as part of sustainable storm management

• These are cost-effective, support biodiversity, and work with natural ecosystems to reduce damage

• Mangrove restoration (Everglades & Keys)

  • Mangroves reduce wind speed and storm surge, acting as a natural hurricane defence system

  • Each acre of mangroves can reduce property damage by up to $250,000 during a storm

  • Coral reef restoration (Southeast Florida Reef Tract)

    • Coral reefs act like underwater walls, breaking waves and protecting shorelines from surge

  • Dune and beach nourishment projects (Northeast Florida)

    • Rebuilding dunes and beaches with native vegetation and sand helps absorb storm energy and protect homes inland