Welcome to Coastal Management!
In this chapter, we explore how humans interact with the coastline. Because so many people live near the sea, we often find ourselves in a "tug-of-war" with nature. We will look at why coasts flood, the arguments between different groups of people who use the coast, and the clever (and sometimes expensive) ways we try to protect the land from the power of the ocean.
1. Coastal Conflicts: The Great Tug-of-War
The coast is a busy place! Many different groups of people, known as stakeholders, want to use the same small strip of land. This leads to conflicts because what is good for one person might be bad for another.
Common Coastal Users
• Local Residents: Want to protect their homes from erosion and keep their views.
• Tourists: Want beautiful beaches, hotels, and easy access to the water.
• Environmentalists (Conservationists): Want to protect habitats like salt marshes and bird nesting sites.
• Developers: Want to build new apartments, shops, or industries to make a profit.
• Fishermen: Need clean water and access to docks and harbors.
Conservation vs. Development
This is the most common argument. Conservationists believe we should leave the coast in its natural state to protect ecosystems. Developers believe the coast should be used for economic growth (jobs and money). For example, building a massive hotel might provide 500 jobs (Development) but destroy a rare sand dune habitat (Conservation).
Quick Review: Conflict happens when different stakeholders have different priorities for the coast. It’s usually a balance between money and nature.
2. Coastal Flooding: Why does it happen?
Coastal flooding is a major hazard. There are three main causes you need to know for your exam:
1. Storm Surges: Imagine a "bulge" of water being pushed toward the land. This happens when there is very low atmospheric pressure (which allows the sea level to rise slightly) combined with strong winds blowing the water toward the shore. During a storm, the sea level can rise by several meters in just a few hours!
2. Tsunamis: These are giant waves caused by underwater earthquakes or landslides. They carry a massive amount of energy and can flood land miles away from the shore.
3. Climate Change: As the planet warms, two things happen: ice sheets melt, and the ocean water expands (thermal expansion). This leads to a gradual sea-level rise. What used to be a "once in a hundred years" flood might now happen every decade.
Did you know? A storm surge is like a temporary, extra-high tide that arrives with a big storm. It's often the surge, not the rain, that causes the most damage during a hurricane.
3. Prediction and Prevention
We can't always stop the water, but we can reduce the damage. Here is how:
• Forecasting: Using satellites and computer models to predict when a storm surge is coming. This gives people time to evacuate.
• Building Design: In flood-prone areas, houses can be built on stilts or have the ground floor used only for garages so that living areas stay dry.
• Planning: Governments can use zoning to stop people from building expensive homes in high-risk flood zones.
• Education: Teaching people what to do when a flood warning is issued (e.g., "Go to high ground") can save thousands of lives.
4. Management Strategies: Hard Engineering
Hard Engineering involves building large, man-made structures to "fight" the sea. These are usually expensive and look very artificial.
• Sea Walls: Massive concrete walls that reflect wave energy back to sea. Pros: Very effective. Cons: Very expensive and can look ugly.
• Groynes: Wooden or rock fences built at right angles to the beach. They trap sand moved by longshore drift. Pros: Creates a wide beach for tourists. Cons: Starves beaches further down the coast of sand.
• Rock Armour (Riprap): Large boulders piled at the foot of a cliff. The gaps between rocks soak up wave energy. Pros: Relatively cheap. Cons: Rocks often come from elsewhere and don't match local geology.
• Gabions: Wire cages filled with smaller rocks. Pros: Cheap and easy to build. Cons: Not very strong and the wire can rust away.
• Revetments: Sloping wooden or concrete structures that break up the force of the wave.
5. Management Strategies: Soft Engineering
Soft Engineering works with nature. It is usually cheaper, more sustainable, and looks more natural.
• Beach Replenishment: Adding fresh sand or shingle to a beach. Pros: Looks natural and helps tourism. Cons: It needs to be redone every few years as the sea washes it away.
• Cliff Regrading: Changing the angle of a cliff so it isn't so steep. This stops it from collapsing (slumping).
• Ecosystem Rehabilitation: Replanting mangroves or salt marshes. These plants act as a natural sponge and buffer against waves.
• Revegetation: Planting Marram Grass on sand dunes to stabilize them with their long roots.
• Managed Retreat: Allowing the sea to flood low-value land (like farmland). Pros: Creates new habitats and is very cheap. Cons: Farmers lose their land and may need compensation.
Memory Trick: Think of Hard engineering as "Armor" (heavy, metal/concrete, expensive) and Soft engineering as "Gardening" (plants, sand, working with nature).
6. Shoreline Management Plans (SMPs)
In the past, towns just built their own walls without thinking of their neighbors. Today, we use Shoreline Management Plans (SMPs). These plans look at a large stretch of coastline and decide on one of four "policies" for each section:
1. Hold the Line: Build defenses to keep the coast exactly where it is.
2. Advance the Line: Build new defenses out into the sea (very rare).
3. Managed Realignment (Retreat): Allow the shoreline to move inland naturally.
4. Do Nothing: Let nature take its course without any interference.
7. Case Studies: Coastal Management
For your exam, you need to be able to talk about coastal management in two different contexts. Don't worry if you haven't picked specific locations yet; your teacher will provide these, but here is what to look for:
Developed Country Example (e.g., UK or USA)
Focus on how they spend large amounts of money (\( £££ \)) on high-tech sea walls or complex SMPs. The conflict is often between wealthy homeowners and the government.
Developing or Emerging Country Example (e.g., Bangladesh or Vietnam)
Focus on sustainable methods. They often use more soft engineering, such as planting mangrove forests to protect against storm surges. The conflict here might be between shrimp farmers (who want to clear mangroves) and local villagers (who need them for protection).
Common Mistake to Avoid: Don't say that soft engineering is "bad" just because it isn't a concrete wall. In many cases, soft engineering like managed retreat is much smarter because it lasts longer and costs much less over time (\( Cost < Benefit \)).
Quick Summary Table
Hard Engineering: Sea walls, Groynes, Riprap, Gabions, Revetments. (Expensive, artificial, high-impact).
Soft Engineering: Beach replenishment, Managed retreat, Regrading, Revegetation. (Cheaper, natural, sustainable).
Causes of Floods: Storm surges, Tsunamis, Climate change.
Key Strategy: Shoreline Management Plans (SMPs).