Starter

Person A – Describe how a waterfall is formed.

In pairs

Person B – Describe how meanders and Ox Bow Lakes

are formed.

Do you know what happened here?

http://www.youtube.com/watch?v=ewTVKR_ZFhU

The causes and frequency of flood events.

Aim of the lesson:-

To find out why floods occur and how often they can happen.

By the end of this lesson you

should be able to:-Knowledge

• To know why floods occur.

Understanding

• To understand the different causes of flooding and how they can be grouped into physical and human.

Skill

• To be able to annotate photographs effectively and complete graph work.

Floods occur when a river bursts its banks if it is carrying so much water that it cannot be confined

in its usual course.

Usually big floods occur less often and less severe floods

occur more frequently.

The effects of flooding

The frequency of flood events in the

UK

Are we getting more and more floods in the UK?

Flooding appears to becoming an increasingly frequent event. In 1607, a great flood affected Devon, Somerset and South Wales. Major floods however were infrequent in the UK. In March 1947, major floods did occur, affecting many areas of southern, central and north eastern England, including York, Tewkesbury, Shrewsbury, Sheffield, Nottingham and London, following the rapid melting of snow. The combined effects of storm surge and high tides, contributed to the floods of January 1953 that hit the east coast including Suffolk, Essex and Kent, when huge waves washed away sea defences and 307 people died. In 1968, another great flood affected counties in south east England.

After this time, there is little mention of major floods until relatively recently, when they have regularly made the headlines. Since 1998, floods have been an almost annual occurrence.

Most people agree that the frequency of damaging floods in the UK is increasing

Why??

Some blame climate change for more extreme weather events

Others blame planners for allowing houses to be built on flood plains

Weather experts point out that weather across the British Isles is highly variable; wet summers (like 2008 & 2009) happen when frontal depressions hit the UK by tracking further south than normal.

Flooding 2012

http://www.youtube.com/watch?v=MLqVQoL4JmE

Other flood events in the UK

Morpeth floods 2008In early September the River

Wansbeck, which flows through the town centre, could take no more after a wet summer, & a

particularly wet August was followed by more than the whole of September's rain

falling within 48 hours.

Morpeth, Northumberland 2008

The heavy, persistent rain came from an active area of low pressure, which spent the weekend over

north-east England, moving only a little.

Yorkshire Floods in 2007

The summer floods of 2007 affecting south & east YorkshireA prolonged period of wet weather, much higher than average rainfall, & concentrated periods of heavy rainfall, all of which precipitated the very serious local flood events. A year later, many of the affected households had still not fully recovered.

3 marks

There may be reference to what flooding is – that rivers flood when they burst their banks.

Allow 1 for this, but emphasis should be on underlying causes such as building towns on floodplains and creating an impermeable surface so that water cannot infiltrate and thus flows quickly over surface to river, reducing lag time.

There should be recognition of the factor from the information and this then needs using to explain the sequence of events that cause flooding. May refer to only one cause or two or more.

And the marks scheme says . . .

3 marks

Homework

Learn your key

words for next

lesson.