What is drought?

There are many definitions, but usually it is a period of time where there is much less than average rainfall.

What do you think factors affect drought in a country? Can you list some ideas?

What factors affect drought?

WealthPopulationTemperatureRainfallRun-off ratesLand use… these are found on p96 PTT

How does drought affect MEDC’s?

Fall in river levelsReduced water supplyHosepipe bansDamage housing foundationsFire risk Crop failureReduced water for industries (needed for

cooling in processing)

Can drought be controlled?

Reduce the causes of droughtCope with drought

Improve prediction, e.g. satellite warning. Provide food aid sooner, especially to small

scale farmers. Build large reservoirs and deeper wells.

Live with drought Improve farming methods, e.g. AGRHYMET Stop desertification.

English drought

http://search.bbc.co.uk/cgi-bin/search/results.pl?tab=av&q=uk%20drought&recipe=all&scope=all&edition=

Drought in the Sahel- LEDC case study

The Sahel is the narrow belt of semi-arid land on the edge of the Sahara desert in Africa.

Sahel literally means ‘edge of the desert’. It is famous for the

severe droughts it suffers.

The causes of the drought are quite unique

In rain years, the Sahel receives just enough to prevent the droughts from causing a disaster…

Position of the ITCZ on 21 June

Strong south-westerly rain-bearing winds

The causes of the drought are quite unique

But in drought years, the ITCZ doesn’t move as north as it should, due to global climatic patterns and this prevents the south-westerly winds bringing the usual rain.

Position of the ITCZ on 21 June

Weak south-westerly rain-bearing winds

Human causes of drought in the Sahel Desertification- is the spread of desert-like conditions in

arid or semi arid areas dues to human influence or climate change. It is very hard to get the land back to its original condition.

http://www.green.tv/unep_global_desertification_outlook

Overcultivation- when arable agriculture has taken the nutrients out of the soil and it is over-used. The soil then becomes useless, and dry and is easily eroded by wind or water

Overgrazing- when there are too many cattle for the land to support them. They eat all of the vegetation that protect the soil and so erosion occurs.

Annotate your spiral diagrams on p25 to show these causes.

What are the effects of drought in the sahel??

List as many as possible

Living with drought in the Sahel and preventing desertification

Build dams to improve water storage for dry periods.

Introduce new drought-resistant crops as in Nigeria

Build earth traps to prevent soil from being washed away

Start afforestation schemes (will increase interception and reduce overland flow, and prevent erosion

The best solutions are small scale, low cost of appropriate technology.

How can we reduce the effects of drought in MEDC’s and LEDC’s?

1) Reduce the costs of drought.

2) Cope with drought.

3) Live with drought.