Coastal flooding (Katrina) casestudy

Coastal flooding - Hurricane Katrina



What is a tropical cyclone?
A tropical cyclone is composed of a system of thunderstorms that shows a cyclonic rotation around a central core or eye.

What causes the flood in New Orleans- winds , produce a storm surge over the ocean which led to flooding in coastal areas.

Low atmospheric pressure by cyclones reduces pressure of the sea causing it to rise( storm surge)

Strong offshore winds force water to higher levels along the coast causing waves to move inland.
Due to this and high rainfall which may be unable to drain into the sea,

Tsunami-are huge ocean waves caused when water is displace due to plate movement  due to landslides volcanic eruption.When in sea waves have low height but as they approach the shore the waves become slower due t friction causing the wave height to increase.

Human activity may cause this 

management of rivers eg  dams may trap sediment causing less deposition at the rivers mouth to form deltas as this happens due to sediment starvation deltas shrinks proving less protection for high tides.

Building on coastal low lands has restricted sediment supply to protective beaches

Responses

There was much criticism of the authorities for their handling of the disaster. Although many people were evacuated, it was a slow process and the poorest and most vulnerable were left behind.

$50 billion in aid was given by the government.

The UK government sent food aid during the early stages of the recovery process.

• Katrina was a category 4 storm.
• Storm surges reached over 6 metres in height.
• New Orleans was one of the worst affected areas because it lies below sea level and is protected by levees. These protect it from the Mississippi River and Lake Ponchartrain. The levee defences were unable to cope with the strength of Katrina, and water flooded into the city.
• Despite an evacuation order, many of the poorest people remained in the city.
• People sought refuge in the Superdome stadium. Conditions were unhygienic, and there was a shortage of food and water. Looting was commonplace throughout the city. Tension was high and many felt vulnerable and unsafe.
• 1 million people were made homeless and about 1,200 people drowned in the floods.
• Oil facilities were damaged and as a result petrol prices rose in the UK and USA.
• The storm damages Mississippi delta causing erosion of deposited material.

Economic- it cost the US 105 billion dollars.