Coastal erosion

Coastal Erosion

The process of breaking down and carrying away materials by the sea.

Deposition

The process where material carried by the sea is deposited or left behind on the coast.

Swash and Backwash

Swash is when a wave washes up onto the shoreline, while backwash is when the water retreats back into the sea.

Destructive Waves

High-energy waves that lead to coastal erosion due to their strong backwash.

Constructive Waves

Low-energy waves that result in the build-up of material on the shoreline.

Longshore Drift

Movement of beach material along the coast due to prevailing winds and swell.

Sand Dune Anatomy

Landward aeolian processes depositing loose sediment as sand dunes.

Dune Profiling

Using a clinometer and tape measure to draw a profile of sand dunes for coastal management.

Wind Speed

Measured using an anemometer to record the speed of the wind.

Wind Direction

Recorded using a compass to determine the direction of the wind.

Vegetation Species

Identifying dominant plants in different locations without damaging them.

Functions of Vegetation on Dunes

Stabilizing sand, reducing erosion, sheltering other plants, and increasing soil nutrients.

Coastal Vegetation

Planting native species like Mat Rush, Coastal Banksia, and Coastal Tea Tree to increase biodiversity, stabilize dunes, and provide habitat for various species.

Human Activities Impact

Unrestricted access, recreational activities, and sand removal for construction purposes led to vegetation loss and dune destabilization in the past.

Strategies for Dune Preservation

Designated pathways, informative signage, and restricted access by Northern Beaches Council to protect dune vegetation.

Coastal Erosion Factors

Residential development on primary dune at Collaroy Beach makes it more vulnerable compared to Long Reef or Narrabeen Beach.

Sea Walls Impact

Sea walls reflect backwash energy, leading to increased erosion and negative sand budget in the long term.

Coastal Erosion Risks

Surf lifesaving clubs, houses, cafes, restaurants, car parks, and apartment blocks are at risk from coastal erosion.

Piled Foundations

Building foundations extending below dunes' movement area for stability, with high construction costs.

Beach Scraping

Tractor leveling after storms for temporary beach stabilization, speeding up natural processes.

Relocation

Dismantling and rebuilding at-risk buildings elsewhere, maintaining character but incurring significant costs.

Repurchase (Acquisition)

Purchasing high-risk land, demolishing buildings, and redeveloping for public use, compensating landowners.

Sand Nourishment

Importing sand to replenish lost beach sand, a natural protection method but temporary and costly.

Vertical Sea Wall

Hard, vertical structure protecting assets but causing increased erosion elsewhere.

Curved Sea Wall

Engineered to dissipate wave energy, protecting assets with less impact on erosion compared to vertical walls.

Mounded Sea Wall

Sloping sea wall of porous material to absorb wave energy, effective and visually appealing but still costly.

Evaluating Erosion Events

Historic events at Collaroy, management strategies like repurchase, mounded sea walls, and coastal vegetation.

Collaroy Sea Wall Case Study

Construction details, costs, controversies, opinions for and against, effectiveness, and alternative strategies.

Glossary Terms

Definitions of coastal terms like accretion, backwash, berm, coastal processes, constructive waves, and erosion escarpment.

Coastal Erosion

The gradual wearing away of land by natural forces, accelerated by human activities and climate change, leading to the loss of coastal areas.

Development Pressure

The increased urbanization and modification of natural coastal areas due to human activities like construction and infrastructure development.

Climate Impact

The effects of climate change on coastal environments, including rising sea levels, increased storm intensity, and extreme weather events that stress coastal areas.

Erosion Control Measures

Strategies such as seawalls, groynes, and other interventions designed to protect shorelines from erosion.

Beach Nourishment

Adding sand to eroded beaches to replenish them and maintain their profile.

Dune Stabilization

Techniques like planting vegetation and constructing fences to stabilize sand dunes and reduce erosion.

Integrated Coastal Zone Management (ICZM)

A holistic approach considering environmental, social, and economic factors in coastal management.

Climate Adaptation Strategies

Measures to adapt infrastructure and policies to address the impacts of climate change on coastal areas.

Goals of Management

Objectives including protecting property, preserving natural landscapes, and enhancing resilience to erosion and climate impacts.

Effectiveness of Management Practices

Evaluation of strategies like erosion control measures, beach nourishment, dune stabilization, ICZM, and climate adaptation in coastal management.