B.3.2 Coastal Erosion and Flooding Management Strategies Notes

Coastal Erosion and Sediment Supply: A Chain Reaction

What is Coastal Erosion?

1. Coastal erosion occurs when waves, currents, and tides wear away land along the coast.
2. This process is driven by natural forces like wind and water, but human activities - such as construction, deforestation, and damming rivers - can accelerate it.
3. The eroded material, often sand or sediment, is transported by water and deposited elsewhere along the coast or in marine environments.

Sediment Supply and Downstream Ecosystems

1. Sediment is essential for maintaining coastal and marine ecosystems.
2. It replenishes beaches, supports the growth of mangroves and salt marshes, and provides habitats for marine organisms.
3. When coastal erosion reduces or redirects sediment supply, it can trigger a cascade of effects downstream.

The Domino Effect on Ecosystems

When sediment supply is reduced:

1. Beaches may shrink, increasing vulnerability to storm surges and flooding.
2. Coral reefs and seagrass beds, which rely on sediment for nutrients, may degrade.
3. Mangroves and salt marshes, which act as natural barriers against coastal erosion, may fail to regenerate, further accelerating erosion.

Coastal Management Strategies Are Used to Manage Risks

1. Coastal areas face significant risks from erosion, flooding, and rising sea levels.
2. To manage these risks, a combination of engineering and adaptive strategies is used.

Cliff Line Stabilization

Hard Engineering Controls Natural Processes

1. Examples of these include:
   1. Seawalls: Tall, curved walls reflect wave energy back to the sea, protecting cliffs and land behind them.
   2. Groynes: These structures extend perpendicular to the shore, trapping sand and reducing erosion by interrupting longshore drift.
   3. Rock Armoring (Riprap): Large boulders placed at the base of cliffs absorb wave energy, reducing its impact on the coastline.

Example

Holderness Coast, UK

• Seawalls and groynes protect towns like Hornsea, but they also cause erosion further down the coast by disrupting sediment flow.

Soft Engineering: Working with Nature

1. Soft engineering strategies enhance natural defenses rather than relying on artificial structures. Examples include:
   1. Beach Nourishment: Sand is added to eroded beaches to restore their size and protect the coastline.
   2. Dune Stabilization: Planting vegetation on dunes helps anchor the sand, reducing erosion and providing a buffer against storms.

Managed Retreat: Letting Nature Take Its Course

1. Managed retreat is a coastal management strategy that involves allowing certain areas to flood or erode naturally, often to restore ecosystems like wetlands or salt marshes.
2. These natural buffers absorb wave energy, reduce flooding, and support biodiversity.

Case study

Holderness Coast, UK

1. The Holderness Coast is one of Europe’s fastest-eroding coastlines, losing up to 2 meters of land per year.
2. This erosion is driven by its soft geology (boulder clay) and powerful wave action from the North Sea.

Issues and Stakeholders

1. Local Residents: Demand hard engineering solutions like seawalls to protect homes and property.
2. Environmentalists: Advocate for managed retreat to allow natural processes and restore ecosystems.
3. Tourism Businesses: Support strategies that preserve beaches, which are vital for the local economy.

Strategies Implemented

1. Hard Engineering: Seawalls and groynes protect towns like Hornsea and Withernsea but cause erosion further down the coast.
2. Soft Engineering: Beach nourishment maintains tourist beaches but requires regular replenishment.
3. Managed Retreat: Areas like Spurn Head have been allowed to erode naturally, creating valuable habitats.

Coastal Management Strategies: Effectiveness and Trade-offs

1. Coastal management is a critical aspect of geography, particularly in the context of sustainable development.
2. It involves balancing the need to protect coastlines from natural and human-induced threats with the imperative to preserve ecosystems and support local communities.

Economic Costs: Infrastructure and Enforcement

Infrastructure Investments

1. Infrastructure projects, such as seawalls, artificial reefs, and coastal dams, are widely used to protect coastlines and manage ocean resources.
2. While these structures can be effective, they come with high upfront costs and ongoing maintenance expenses.

Enforcement Mechanisms

1. Beyond physical infrastructure, effective coastal management often requires enforcement of regulations, such as fishing quotas, pollution controls, and protected area boundaries.
2. These enforcement mechanisms involve costs related to personnel, technology (e.g., satellite monitoring), and legal systems.

Environmental Benefits: Habitat Preservation and Pollution Reduction

Habitat Preservation

1. Coastal management strategies can protect critical habitats, such as mangroves, coral reefs, and wetlands, which serve as natural buffers against storms and erosion.
2. These habitats also provide breeding grounds for marine species and support local livelihoods.

Biodiversity Conservation

1. Artificial reefs and marine protected areas (MPAs) are examples of strategies that enhance biodiversity.
2. By creating safe spaces for marine life, these interventions can help restore overfished populations and maintain ecological balance.

Pollution Reduction

1. Coastal management can also address pollution through measures such as wastewater treatment plants and stricter regulations on industrial discharge.
2. Reducing pollution not only benefits marine ecosystems but also improves water quality for human use.

Challenges: Balancing Economic Development with Conservation Goals

1. The most significant challenge in coastal management is finding a balance between economic development and environmental conservation.
2. This often involves difficult trade-offs, as the goals of these two priorities can conflict.

Competing Interests

1. Coastal areas are often hubs of economic activity, including tourism, fishing, and industrial development.
2. While these activities generate income and employment, they can also lead to habitat destruction, overfishing, and pollution.

Unintended Consequences

1. Even well-intentioned management strategies can have unintended consequences.
2. For example, seawalls may protect one area from erosion but accelerate it in adjacent regions.
3. Similarly, restricting fishing in one area may lead to overfishing elsewhere.

Limited Resources

1. LEDCs often face additional challenges due to limited financial and technical resources.
2. This can make it difficult to implement and enforce effective coastal management strategies, even when the need is urgent.

Evaluating Effectiveness and Trade-offs

1. To assess the effectiveness of a coastal management strategy, it’s essential to consider both its short-term and long-term impacts.
2. This involves weighing the economic costs against the environmental benefits and examining how well the strategy addresses the challenges of sustainable development.

Key Questions for Evaluation

1. Economic Viability: Are the costs of the strategy justified by its benefits? Can the strategy be maintained over the long term?
2. Environmental Impact: Does the strategy effectively preserve habitats, conserve biodiversity, and reduce pollution? Are there any unintended negative consequences?
3. Social Equity: Does the strategy benefit all stakeholders, including local communities, or does it disproportionately favor certain groups?
4. Adaptability: Can the strategy be adjusted to respond to changing conditions, such as rising sea levels or shifting economic priorities?

Reflection and Broader Implications

1. Coastal management strategies must balance immediate needs with long-term sustainability.
2. Hard engineering provides short-term protection but can have negative impacts on the environment and neighboring areas.
3. Soft engineering and managed retreat offer more sustainable solutions but require careful planning and stakeholder cooperation.