B.1.3 Hurricanes and Their Impacts on Coastal Margins Notes

Understanding Storm Systems and Coastal Impacts

1. Imagine standing on a beach, watching the ocean churn as dark clouds gather overhead.
2. The air feels heavy, and the wind picks up speed.
3. This is the beginning of a storm system, a powerful force of nature that can reshape coastlines and disrupt lives.

How Storm Systems Form

1. Warm Ocean Water: The ocean surface must be at least 26°C to provide the heat energy needed for evaporation and ocean water has to be similarly warm to a depth of 50-70 meters.
2. Rising Air and Low Pressure: As warm, moist air rises, it cools and condenses into clouds, releasing latent heat. This heat causes more air to rise, creating a low-pressure area at the surface.
3. Coriolis Effect: The Earth’s rotation causes the rising air to spin, forming the characteristic spiraling winds of a storm system.
4. Air and Water Circulation: The cooled off air descends along the edges of the system and rushes towards the center to equalize the air pressure - this causes extreme winds. At the same time the water held in clouds starts to fall - this causes extreme precipitation.
5. Sustained Energy: The storm continues to grow as long as it remains over warm water and away from land, where friction and cooler temperatures weaken it.

Where Do Storm Systems Occur?

1. Tropical Regions: Storm systems form between 5° and 30° latitude in both hemispheres, where ocean temperatures are warm enough.
2. Major Ocean Basins where tropical storms carry three different regional names:

• Atlantic Ocean: Hurricanes often impact the Caribbean, Gulf of Mexico, and the eastern United States.
• Pacific Ocean: Typhoons affect Southeast Asia, Japan, and the western Pacific islands.
• Indian Ocean: Cyclones impact countries like India, Bangladesh, and Madagascar.

Physical Impacts of Storm Systems

1. Storm Surges

• A storm surge is a rise in sea level caused by strong winds, pushing water toward the shore.
• These surges can flood coastal areas, causing significant damage.

2. Coastal Flooding

• Heavy rainfall from storm systems can overwhelm drainage systems, leading to widespread flooding.
• This flooding can contaminate freshwater supplies and damage homes and infrastructure.

3. Erosion

• Powerful waves and currents erode beaches, cliffs, and dunes, reshaping coastlines.
• This erosion can destroy habitats and make coastal areas more vulnerable to future storms.

4. Infrastructure Damage

• High winds and flooding can destroy buildings, roads, bridges, and power lines, disrupting communities for months or even years.

Case study

Hurricane Katrina (2005, USA)

1. Location: Gulf Coast of the United States, primarily affecting Louisiana and Mississippi.
2. Storm Surge: Reached up to 8.5 meters, flooding 80% of New Orleans.
3. Response: Criticized for delays in federal aid and inadequate evacuation plans.

Environmental Impacts

1. Coastal Erosion: The storm eroded beaches and barrier islands, leaving the coastline more exposed.
2. Wetland Loss: Over 560 square kilometers of wetlands were destroyed, reducing natural flood protection.
3. Habitat Destruction: Critical habitats for wildlife, such as marshes and forests, were severely damaged.

Social Impacts

1. Loss of Life: Over 1,800 people died due to flooding and storm-related incidents.
2. Displacement: Hundreds of thousands were forced to evacuate, with many unable to return home for months or years.

Economic Impacts

1. Cost of Damage: Katrina caused an estimated $125 billion in damages, making it one of the costliest storms in U.S. history.
2. Business Losses: Flooding in New Orleans disrupted the economy, with many businesses closing permanently.

Why Understanding Storm Systems Matters

1. Predicting Impacts: By studying storm systems, scientists can improve forecasting models, giving communities more time to prepare.
2. Mitigating Damage: Understanding the physical impacts helps planners design better infrastructure and coastal defenses.
3. Adapting to Climate Change: As ocean temperatures rise, storms are becoming more intense, making it crucial to adapt to these changing conditions.