Coastal Erosion and Shoreline Stability

This mindmap explores how coastal erosion affects shoreline stability, considering natural and anthropogenic factors, and potential mitigation strategies.

Defining Shoreline Stability

Shoreline stability refers to the ability of a coastline to maintain its position and form over time. A stable shoreline experiences minimal erosion or accretion, while an unstable shoreline undergoes significant changes (Ozturk & Maraş, 2024). Shoreline stability is crucial for coastal communities, ecosystems, and infrastructure.

Natural Factors Influencing Coastal Erosion

These factors contribute to the natural dynamics of shorelines, sometimes leading to instability.

Hydrodynamics

• Waves: Wave action is a primary driver of coastal erosion. Wave energy erodes and transports sediment, altering the shoreline (D’Anna et al., 2023).
• Tides: Tidal currents can also erode and transport sediment, especially in areas with large tidal ranges (Ozturk & Maraş, 2024).
• Storms: Storm surges and large waves associated with storms can cause significant and rapid coastal erosion (Dietz et al., 2018).

Geological Factors

• Lithology: The type of rock or sediment that makes up the coastline influences its erodibility. Sandy and unconsolidated sediments are more vulnerable to erosion than hard rock (Guerrera et al., 2021).
• Geomorphology: The shape and features of the coastline, such as headlands, bays, and beaches, affect how waves and currents interact with the shore (Castillo et al., 2023). Straight beaches are more prone to erosion (Castillo et al., 2023).
• Tectonics and Subsidence: Tectonic activity and subsidence can cause relative sea-level rise, increasing coastal erosion (Guerrera et al., 2021).

Sea Level Rise

• Global Warming: Rising sea levels due to global warming exacerbate coastal erosion by inundating low-lying areas and increasing wave energy reaching the shore (Ozturk & Maraş, 2024).

Other Natural Factors

• Vegetation: The presence of coastal vegetation, such as mangroves and salt marshes, can help stabilize shorelines by trapping sediment and reducing wave energy (Herbert et al., 2018).
• Sediment Supply: A decrease in sediment supply from rivers or other sources can lead to coastal erosion (Ozturk & Maraş, 2024).

Anthropogenic Factors Influencing Coastal Erosion

Human activities can significantly alter coastal processes and increase erosion rates.

Coastal Development

• Construction: Building structures such as ports, marinas, and seawalls can disrupt natural sediment transport and increase erosion in adjacent areas (Ozturk & Maraş, 2024).
• Hard Structures: Coastal protection structures, while intended to protect the shoreline, can sometimes exacerbate erosion by reflecting wave energy and preventing natural beach recovery (Ozturk & Maraş, 2024).

River Regulation

• Dams: Dams trap sediment upstream, reducing the amount of sediment reaching the coast and leading to erosion (Castillo et al., 2023).

Other Anthropogenic Factors

• Sand Mining: Removing sand from beaches or nearshore areas for construction or other purposes directly contributes to coastal erosion (Castillo et al., 2023).
• Vegetation Removal: Clearing coastal vegetation for development or agriculture removes a natural buffer against erosion (Ozturk & Maraş, 2024).
• Boat wakes: Increased boating activity can induce biological stress and morphological changes along the coastline, leading to shoreline and habitat erosion (Herbert et al., 2018).

Effects of Coastal Erosion on Shoreline Stability

Coastal erosion directly impacts shoreline stability by causing:

• Shoreline Retreat: The landward movement of the shoreline, resulting in loss of land and habitats (Dietz et al., 2018).
• Beach Narrowing: Reduction in the width of beaches, decreasing their ability to protect the coastline from wave action (Castillo et al., 2023).
• Habitat Loss: Destruction of coastal habitats such as salt marshes, mangroves, and dunes, which provide important ecosystem services (Herbert et al., 2018).
• Increased Vulnerability to Storms: Eroded shorelines are more vulnerable to damage from storms and storm surges (Castillo et al., 2023).
• Infrastructure Damage: Erosion can damage or destroy coastal infrastructure, such as roads, buildings, and pipelines (Ozturk & Maraş, 2024).

Mitigation and Management Strategies

Various strategies can be employed to mitigate coastal erosion and enhance shoreline stability.

Hard Engineering

• Seawalls: Structures built parallel to the shoreline to protect against wave action. However, they can reflect wave energy and exacerbate erosion in adjacent areas (Ozturk & Maraş, 2024).
• Breakwaters: Offshore structures designed to reduce wave energy reaching the shoreline. They can be effective but can also alter sediment transport patterns (Dietz et al., 2018).
• Groins: Structures built perpendicular to the shoreline to trap sediment and widen beaches. They can be effective in trapping sediment but can also cause erosion downdrift (Ozturk & Maraş, 2024).

Soft Engineering

• Beach Nourishment: Adding sand to eroded beaches to widen them and provide a buffer against wave action (Dietz et al., 2018).
• Dune Stabilization: Planting vegetation on dunes to stabilize them and prevent erosion (Castillo et al., 2023).
• Living Shorelines: Using natural materials, such as vegetation and oyster reefs, to stabilize shorelines and provide habitat (Herbert et al., 2018).

Management Strategies

• Coastal Zone Management: Implementing policies and regulations to manage coastal development and protect natural resources (Ozturk & Maraş, 2024).
• Managed Retreat: Relocating infrastructure and development away from eroding shorelines (Ozturk & Maraş, 2024).
• Sediment Management: Managing sediment supply from rivers and other sources to ensure adequate sediment reaching the coast (Castillo et al., 2023).

Case Studies

• Samsun, Turkey: Construction of a small fishing port led to significant coastal erosion, highlighting the importance of proper planning and precautions (Ozturk & Maraş, 2024).
• Bay Champagne, Louisiana (USA): Hurricanes are a major driver of coastal erosion, with shoreline retreat rates increasing significantly during periods of high storm activity (Dietz et al., 2018). Beach re-nourishment projects can temporarily reverse shoreline retreat (Dietz et al., 2018).
• Coast of Togo (Bight of Benin, West Africa Margin): Geological vulnerability and oceanographic variations contribute to coastal erosion (Guerrera et al., 2021).
• Yellow River, Yangtze River and Mekong River Subaqueous Deltas: Comparative analysis of erosion-deposition causes in different delta types (Li et al., 2022).
• Chimkurgan reservoir: Water level changes in reservoir basin affect coastal erosion (Arifjanov et al., 2023).