Floods: What are floods?

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What are Floods?

Floods : How Can Cities Prepare For Floods?2

‘Floods are overflows of large amounts of water onto land that is normally dry.’

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Have anyone of you experienced the Orchard Road

flooding in 2011/ flooding?

Do you think Yew Tee will be flooded?

Why is it important to learn about floods?

Number of events

Flood events in Singapore

1 Bukit Timah Canal overflowed on 19 November 2009

2 Orchard Road flooding 16 June 2010

3 Orchard Road flooding 23 December 2011

4 Western parts of Singapore 5 September 2013

Why is it important to learn about floods?

Describe the types of floods Coastal floods River floods Flash floods

Lesson Objective

Types of Floods

Coastal Floods River Floods Flash Floods

Coastal Floods Definition:

Coastal floods occur in areas along the coast (especially low-lying coastal land, such as river mouths)

Floods: How Can Cities Prepare For Floods?8

River floodsDefinition: River floods occur when water in the river rises and overflows its banks

Floods: How Can Cities Prepare For Floods?9 A cross-section of a river channel

River floodsRiver floods occur on the floodplain, which consists of the river and the low-lying land on either side of it

Levees: Raised banks on both sides of the river.

Floods: How Can Cities Prepare For Floods?10 A cross-section of a river channel

Flash floodsDefinition:

A flash flood can be recognised by its quick rise in water level. It can take place suddenly and lasts for a short period of time

Floods: How Can Cities Prepare For Floods?11

Flash Flood in Pakistan, July 2010

1. Great Tohoku Earthquake and Tsunami that hit Japan in 2011 caused a coastal flood in Miyako City

2. Mississippi River, USA 2011

3. Flash flood in Colorado, USA, September 2013

Video

Great Tohoku Earthquake and Tsunami 2011 Play video from the start to 1.08minutes.

1. From the video, what is Japan experiencing? Earthquakes and Tsunami.

2. What is the cause of the coastal flooding? Tsunami

3. How do we know if it is a coastal flooding? The tsunami is approaching the coast. We can observe that the ships and boats are drawn away by

the water.

Questions from worksheet 5.1A

River flood: Play video from the start to 0.13minutes, then start at 0.39minutes to the end(2.26).

The video shows an aerial view of the Mississippi river, the image was taken by Landsat 5 (satellite).

Show the outline of the river (in dotted lines) State what is the cause of the river flood. Observed the contrast between the non-flooded areas

and flooded areas. (Pause at 0.59, 1.22, 2.01, 2.05, 2.19)

Observed that the crops are being inundated.

Mississippi River, USA 2011

1. What causes river flooding? Heavy spring rains/heavy rainfall Snowmelt

2. How do we know if it is a river flood? The flood occurred along the Mississippi River. Water overflow out of the banks.

Questions from worksheet 5.1A

Flash flood: Play video from the start to 1.58 minutes.

Flash flood in Colorado, USA, September 2013

1. What weather is Colorado facing? (Circle the answer) Extreme weather – Wet or Dry. (Large or Small) amount of rain expected.

2. What is the cause the flash floods? Extreme weather/ Heavy rainfall

3. How do we know if it is a flash flood? (0.30minutes) Spike in the river gauge, in less than ____15_____ minutes,

__10___ feet of water slamming down.

Questions from worksheet 5.1A

Other possible causes for floods

Coastal Floods Other possible causes:

Intense storms such as tropical storms and tropical cyclones. Tropical cyclones are also known as typhoons and hurricanes.

Storm Surges Floods: How Can Cities Prepare For Floods?20

River floods Other possible

causes: Dam failure

Floods: How Can Cities Prepare For Floods?21

Flash floods Other possible causes:

Coastal and river floods

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Workbook Activity 5.1 Page 117 & 118

Describe the types of flood. Identify the flood type Give evidence

Practice Time!

Describe: means provide facts about the

distinctive features of an

item.

Types of Floods

Coastal Floods River Floods Flash Floods

Recap