Unit 1B - Hot Deserts - Desertification

Question 1

Desertification definition?

Answer 1

Process by which land becomes drier and degraded

Question 2

3 human causes of desertification?

Answer 2

Population growth - collect more firewood so loss of forrest cover (deforestation), leaving soil exposed
Overgrazing - animals grazed at higher stocks, eating more food in area, leading to soil erosion
Over cultivation + soil erosion - land farmed more intensively, nutrients taken out of soil and remove natural vegetation

Question 3

Name of area that is at very high risk of desertification? How many people faced hunger and what was required to combat this in 2014?

Answer 3

Sahel region (Sahara Desert)
20 million faced hunger and required $2billion in food aid

Question 4

What problem does too much irrigation cause? Definition of this?

Answer 4

Salinisation - when water in soils evaporates, drawing salts to the surface

Question 5

3 physical causes of desertification?

Answer 5

Climate change - hotter and rainfall less reliable meaning salinisation
Drought - lead to water shortages
Flash flood - can take away top soil (soil erosion)

Question 6

Soil erosion definition?

Answer 6

When soil left bare, unprotected soil is blown away by wind or washed away by rain

Question 7

Over-cultivation definition?

Answer 7

Exhausting soil by over-cropping in same land so all nutrients in soil used up

Question 8

Overgrazing definition?

Answer 8

Grazing too many livestock for too long on land, so it is unable to recover its vegetation

Question 9

Cycle of desertification? 7 stages

Answer 9

1. Amount of natural vegetation decreases
2. Exposed soil and increased soil erosion
3. Sun bakes soil and it cracks
4. More evaporation and increased surface runoff (salinisation)
5. Soil often washed way through soil erosion
6. Soil is degraded, losing fertility and structure
7. Drought, less plant able to grow
   Repeat

Question 10

How many people died in Sahel drought of 1968 to 73?

Answer 10

250,000 died