Droughts

Question 1

What is a drought?

Answer 1

An area drier than normal conditions— a prolonged period of abnormally low rainfall, leading to a shortage of water.

Question 2

What are the main differences between an arid environment and a drought?,

Answer 2

Arid environment
-permanent low rainfall
-10-250mm per year
-high pressure conditions
- mostly found where Hadley cells and ferrel cells meet
Droughts
-temporary low precipitation <0.2mm
-(in the Uk) drought is 15 consecutive days without rainfall
-global
-high pressure as well

Question 3

State the 3 human causes to droughts

Answer 3

Dams, déforestation and agriculture

Question 4

What are dams?

Answer 4

They are large structures built on rivers to act as flood defences, so create reservoirs as stores for water, to use in industry / agriculture and recreation.

Question 5

What do dams produce?

Answer 5

Hydro-electrical power

Question 6

Why do dams contribute to drought formations?

Answer 6

By storing large amounts of water upstream, the amount of water further down is reduced significantly if the water is not continuously flowing. This leaves areas in drought as the water levels have dropped.

Question 7

What is deforestation?

Answer 7

The permanent removal of widespread trees in a location for constructional or resource purposes.

Question 8

How does deforestation contribute to droughts forming?

Answer 8

Removing trees reduces less absorption of CO² leads to an increase in greenhouse gas emissions, influencing climate change / global warming. Without transpiration, the water cycle is disrupted hindering the processes: condensation + precipitation. Therefore, less rainfall occurs as there aren’t photosynthesising plants.

Question 9

What are impacts of drought on agriculture

Answer 9

Low crop yields, crop failures and loss of livestock.

Question 10

How does agricultural irrigation cause droughts?

Answer 10

Ways of irrigation, such as pumping from wetter areas, rivers or groundwater sources contributed to a lack of water in that area over time. This leads to lowered water supplies increasing droughts and worsening its effects.

Question 11

State the two natural causes of droughts.

Answer 11

Meteorological and hydrological causes

Question 12

What is the cause to droughts — meteorological?

Answer 12

when the amount of precipitation received in a specific area is less than the average

Question 13

Why is an area like the Sahara not in a drought?

Answer 13

The conditions are normal for that climate, precipitation levels etc.

Question 14

What are three defects to meteorological droughts?

Answer 14

Circulation levels vary which cause disruptions.
Changes in normal weather patterns can lead to climate change.
Atmospheric and oceanic circulation systems disrupted.

Question 15

What causes changes to oceanic / atmospheric circulation?

Answer 15

Warmer temperatures than usual

Question 16

What do jet streams divert?

Answer 16

Weather systems like rainy seasons.

Question 17

What is the cause to droughts — hydrological?

Answer 17

This is when reduced precipitation impacts water supply, e.g there is decreased streamflow, soil moisture, reservoir, lake levels, and groundwater supplies.

Question 18

State the differences between meteorological and hydrological drought causes.

Answer 18

Meteorological
- occurs before hydrological
-this is a lacking of rain
-lack of rain affects photosynthesis, food growth etc
Hydrological
-occurs resultant to the shortage in rain
-lack of rain affects a hydrological store of water.
-less obvious effects

Question 19

What happens to the water cycle when there is a drought?

Answer 19

the flow of streams and rivers declines, water levels in lakes and reservoirs fall, and the depth to water in wells increases

Question 20

Why does water monitoring take months to see changes with hydrological droughts?

Answer 20

The effects are prolongedly seen afterwards due to various reasons - lack of management or supervision in an area of flowing water, levels of water are not documented.

Question 21

Why does water in rivers and other flowing sources become harder to access with hydrological droughts?

Answer 21

The water begins to enter permeable rocks and soil as there is a lack of precipitation (meteorological droughts). This means that river levels drop and an over-dependance on groundwater / reservoir sources is developed.