Geography (9635) | Coastal management

Welcome to Coastal Management!

Hi Geographers! This chapter is where we move from studying how coasts work naturally (systems and processes) to tackling the big question: How do we protect our homes and infrastructure from the powerful sea?

Coastal areas are some of the most populated and economically important places on Earth, but they are constantly threatened by erosion and flooding. Learning about coastal management is essential because it explores the difficult choices humans must make when dealing with dynamic natural environments.

Ready to jump in? Let's figure out how we manage the mighty ocean!

Coastal Risks: Why Intervention is Needed

Human intervention in coastal landscapes is necessary because the natural processes (like marine erosion and rising sea levels) pose significant risks to people and property.

The two main risks we manage are:

• Coastal Erosion: The gradual or rapid removal of coastal material (cliffs, beaches), leading to loss of land and damage to structures.
• Coastal Flooding: When the sea level rises above normal (often due to storm surges or high tides), causing inundation of low-lying areas.

The fundamental conflict in coastal management is whether to work against nature using solid structures, or with nature using more flexible, environmentally friendly methods.

1. Traditional Approaches: Hard Engineering

Hard engineering involves building rigid, artificial structures designed to stop or resist natural coastal processes. These are usually expensive and have high environmental impacts.

Advantages and Disadvantages of Hard Engineering

• Advantages: Provides immediate and certain protection for high-value assets (cities, nuclear power plants). They are robust and long-lasting.
• Disadvantages: Very expensive to build and maintain, often visually unattractive (spoils the landscape), and can create problems further down the coast (the 'domino effect').

Key Hard Engineering Methods

1. Sea Walls

These are large concrete or rock structures built parallel to the shore at the foot of cliffs or at the top of a beach.

• Function: Acts as a vertical barrier to prevent high water and absorbs/reflects wave energy.
• Analogy: Think of a sea wall as a concrete shield.
• Drawbacks: The reflected wave energy often causes scouring (erosion) at the base of the wall, and they are incredibly expensive.

2. Groynes

Wooden or rock barriers built at right angles (perpendicular) to the coast, designed to trap sediment moving via longshore drift.

• Function: They build up the beach on the updrift side, which provides a natural buffer against waves.
• Analogy: Groynes are like speed bumps for the sand flow.
• Drawbacks: The downside is the downdrift side (the area further along the coast) is starved of sediment, often leading to increased erosion there. This is known as terminal groyne syndrome.

3. Rock Armour (or Rip-Rap)

Large piles of boulders placed at the foot of cliffs or edges of the coast.

• Function: The gaps between the rocks allow water to filter through, dissipating wave energy rather than reflecting it.
• Drawbacks: Can look messy and foreign to the environment, and sourcing the rock can be costly.

4. Gabions

Wire mesh cages filled with rocks, typically placed along the back of a beach or cliff foot.

• Function: A cheap, temporary form of rock armour. They dissipate wave energy.
• Drawbacks: They rust easily, are unattractive, and have a relatively short lifespan.

Key Takeaway for Hard Engineering: It works well locally but often just transfers the erosion problem elsewhere. It is usually disruptive to the natural coastal system.

2. Traditional Approaches: Soft Engineering

Soft engineering attempts to work with natural processes, using natural materials and focusing on enhancing the coast’s existing defenses (like beaches and dunes). These are often more aesthetically pleasing and sustainable.

Advantages and Disadvantages of Soft Engineering

• Advantages: Less impact on the landscape, often cheaper than hard engineering, creates natural habitats, and is more sustainable as it maintains the natural system.
• Disadvantages: Not suitable for high-energy coasts or areas with very rapid erosion; requires continuous maintenance; protection is temporary and less robust during severe storm events.

Key Soft Engineering Methods

1. Beach Nourishment (or Replenishment)

The process of importing sand or shingle from elsewhere (usually offshore) and adding it to an existing beach.

• Function: Increases the height and width of the beach, making it a better buffer against wave energy and reducing the distance waves can travel inland.
• Did you know? The sand used must be of a similar size to the existing beach material, otherwise, the waves will quickly remove it!

2. Dune Stabilisation

Protecting and improving sand dunes by planting vegetation (like Marram grass) or installing fences/boards to restrict human access.

• Function: The roots of the plants bind the sand together, preventing wind erosion and providing a natural barrier against storm waves.
• Common Mistake to Avoid: Dunes are only effective barriers if they remain healthy and intact. Trampling by tourists is a major threat.

3. Managed Retreat (or Coastal Realignment)

This is a strategy where coastal defenses are deliberately breached or removed, allowing the sea to flood low-value land (like farmland) behind the original defenses.

• Function: The newly flooded land becomes a saltmarsh or tidal flat, which acts as a powerful natural defense, absorbing wave energy before it reaches structures further inland.
• Context: This is only used when the economic value of the land being flooded is lower than the cost of maintaining the defense.
• Example: The abandonment of sea walls in the Blackwater Estuary, Essex, UK, has successfully created new saltmarsh habitats.

Key Takeaway for Soft Engineering: This approach is more sustainable and environmentally friendly, but it requires space (e.g., for saltmarshes) and is vulnerable to extreme events.

3. Sustainable Coastal Management

As geographers, we know that coastal systems are interconnected. Traditional, short-term solutions focusing only on one small area are increasingly unsustainable. Modern approaches demand holistic, long-term planning.

The Integrated Approach

Sustainable coastal management relies on two key linked frameworks:

1. Shoreline Management Plans (SMPs)

An SMP is a non-statutory (not legally binding, but generally followed) plan covering a specific length of the coast, setting out a strategy for coastal defense over the next 20 to 100 years. They assess risks and outline the preferred policy for each section of the coast.

There are four main policy options considered in an SMP:

1. Hold the Line (HTL): Maintain existing coastal defenses (usually hard engineering). This is typical for high-value towns or essential infrastructure.
2. Advance the Line (ATL): Build new defenses further out to sea (very rare and expensive).
3. Managed Realignment (MR): Allow the shoreline to move naturally, sometimes involving creating new natural defenses inland (Soft Engineering).
4. No Active Intervention (NAI): Doing nothing; allowing natural processes to continue without human interference. This is chosen for low-value, remote areas.

Memory Aid: Remember the policies by thinking of the acronym HAMA (Hold, Advance, Managed, No Active).

2. Integrated Coastal Zone Management (ICZM)

ICZM is the overarching, holistic philosophy that guides modern coastal planning. It aims to integrate all sectors (economic, environmental, social) and all stakeholders (fishermen, farmers, government, tourists) into the decision-making process.

• Scope: ICZM looks at the entire coastal zone, from several kilometres inland to the territorial waters offshore.
• Key Goal: To achieve sustainable development—meeting the needs of the present population without compromising the ability of future generations to meet their own needs.

This involves balancing conflicting needs, such as:

• Need for tourism development vs. Need for habitat protection (e.g., sand dunes).
• Need for flood protection vs. Need to maintain natural sediment flow.

Step-by-Step ICZM Planning:

1. Information Gathering: Collect data on erosion rates, sea level rise predictions, land values, and ecological importance.
2. Stakeholder Consultation: Talk to everyone who uses the coast to understand their needs and concerns.
3. Develop SMPs: Create regional plans (like the SMPs) that apply the four HAMA policies to specific coastal sections.
4. Monitoring and Adaptation: Continuously check if the strategies are working and adjust plans as conditions (like climate change) evolve.

Key Takeaway for Sustainable Management: ICZM and SMPs force us to think regionally and long-term, moving beyond local fixes to holistic sustainability, even if it means sacrificing some land through managed retreat.