The Causes and Effects of Drought

LO: To understand the causes of anti-cyclonic weather and the global distribution of droughts.

Starter Activity:Write down all the ways in which we

use water every day.Which ones could

you not do without?Which ones are

easier to cut down on?

What is a drought?• Look at the pictures and come up with a

definition of your own.

A lack or of for an unusually

period of , involving less than the

usual over 3 months

A lack or shortage of water for an unusually long period of time, involving 50% less than the usual rainfall over 3 months

A good definition for drought

A drought is

A reduction in precipitation over an extendedperiod of time. (lack of rainfall)

‘Effective precipitation’

The difference between actual precipitation andevapo-transpiration.

What’s different about a drought compared to a hurricane, earthquake or volcano?

(apart from the obvious!)

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec0

50

100

150

200

250

300

350

400

450

500Rainfall in Southern Spain

Months

Rain

fall

or e

vapo

tran

spir

ation

in m

mEvapotranspirationRainfall Q: Explain which months Spain is at risk

of severe drought.

Droughts. So where do you think?

Where do the droughts occur?

Arid Semi Arid

http://drought.mssl.ucl.ac.uk/drought.html?map=%2Fwww%2Fdrought%2Fweb_pages%2Fdrought.map&program=%2Fcgi-bin%2Fmapserv&root=%2Fwww%2Fdrought2%2F&map_web_imagepath=%2Ftmp%2F&map_web_imageurl=%2Ftmp%2F&map_web_template=%2Fdrought.html

Some areas are more at risk than others...

Arid + High Density = High Risk

Use the atlas to gather population density data and then write a description of the distribution of droughts globally considering the potential risk to the areas below. (Arid + High Density = High Risk)

Arid Semi Arid

North America

South America

Africa

Asia

Oceania

How might these factors affect the severity of a drought?

Mix and match

• Complete the sheet to show all the different factors that affect the severity of drought.

• Extension question: how might the effects of drought be different in an LEDC and an MEDC?