2.7: Causes of Drought are Complex

Match each of the definitions to the correct key term.

• Pastoral farming

• The rearing of sheep, cattle, pigs or any other animal on a farm.

• Drought

• An area of grassland which has a few shrubs and trees; it can be found in tropical areas.

• Irrigation

• People raising animals for their own food; they move around and have no fixed land.

• Savannah ecosystem

• A period of below-average precipitation resulting in prolonged shortages in water supply.

• Nomadic herdsman

• The artificial watering of land for farming.

Complete the paragraph below to show the difference between being an arid environment and an area in drought.

Areas suffering from drought can be in arid (​ (a)   ) environments but can also be in other climate regions. The main characteristic of a drought is the gradual ​ (b)   in available water, whereas arid environments ​ (c)   have low amounts of available water. Low precipitation in arid regions is because they are dominated by ​ (d)   pressure where air cannot rise, so condensation doesn't occur. As a result ​ (e)   don't form and so it doesn't rain.

• dry
• reduction
• high
• clouds
• always

Match each description to the correct cause of drought.

• Human - dams

• A reduced amount of water in rivers, lakes, reservoirs. Water levels drop below what’s normally expected because of less rainfall or because people are using more water.

• Hydrological

• This can help areas near rivers by providing electricity and water. But places further downstream might get less water, which can lead to drought.

• Human - agriculture

• When there isn’t enough water for crops to grow properly. It’s caused by less rainfall or if farming methods change (e.g. use of irrigation).

• Human - deforestation

• When an area gets much less rain than usual for a long time, leading to a shortage of water.

• Meteorological

• • Fewer trees means less CO² in the air, causing global warming, reducing rainfall in some areas.

  • Trees also help create rain. They release water into the air through transpiration, creating clouds and therefore rain. Fewer trees means less transpiration and therefore less rain.

Sort the statements into the correct order to explain why global atmospheric circulation makes some locations more vulnerable to drought than others.

• High pressure is created by the sinking air, resulting in clear skies/no rain.

• When it reaches approximately 30°N or S, the dry air sinks and warms.

• This gives reason for the location of many of the World's arid areas.

• Warm air rises at the Equator causing thunderstorms and a lack of moisture.

• The drier air then moves towards the mid-latitudes.

Fill in the gaps to explain a reason why some areas are likely to experience drought in the future.

Global ​ (a)   patterns are shifting. Jet streams are moving toward the poles, and the tropical zone has ​ (b)   since the 1970s. As a result, dry (​ (c)   ) areas are changing. Places that used to get more rain are getting ​ (d)   , leading to more ​droughts. For example, the Upper Colorado River Basin in the USA has had much less rain than normal and is now facing ​ (e)   .

• wind
• expanded
• arid
• drought
• less

Match each of the explanations to the correct ending to explain some of the human causes of drought.

• downstream resulting in possible drought

• Agricultural practices can cause drought. For example, irrigation can use too much water leaving below average levels in ...

• becoming warmer and drier.

• On a global scale, deforestation results in less CO2 being absorbed, causing global warming. This results in some areas ...

• resulting in less rainfall.

• Building a dam holds water back in a reservoir, resulting in less water ...

• water stores, such as lakes and rivers.

• On a regional scale, fewer trees results in less transpiration. Therefore, there's less water in the atmosphere...

Sort the reasons for why droughts are hazardous, into the correct category.

Groups:

(a) Social

,

(b) Economic

,

(c) Environmental

• Wild animals suffer from a lack of water.

• Migration away from affected areas.

• Soil becomes dry and cracked, and so no longer supports plants.

• Safety risks as fires and dust storms are more likely.

• Poorest are at risk of malnutrition due to an increase in food prices.

• Industries such as those building farming equipment, see a drop in income.

• Ill health caused by low supply or poor quality of water.

• Wildlife might migrate away from the area.

• Endangered species could become extinct.

• Industries, such as farming and forestry, unable to support jobs, leading to mass unemployment.

• Water companies have to spend large amounts on new supplies & pipe systems = higher bills.

• Habitats, particularly river habitats, are damaged or lost.

• Depression and anxiety over economic impacts.

Study Figure 8. Identify which one of the following countries has the largest arid environment.

• South Africa

• Ghana

• Angola

• Madagascar

Study Figure 5a. identify the amount of winter rainfall in 1995.

• 155mm

• 220mm

• 325mm

• 400mm

Study Figure 5a.

Calculate the range of winter rainfall.

Only write the answer (not the workings) so that the computer doesn't get confused marking it.

Mathematical Equivalence

ON