Water Lesson 9: Human Cause of Drought

Question 1

Name 3 human causes of drought

Answer 1

Over-abstraction
Building reservoirs and waterways
Changing land use

Question 2

% of Australia affected by drought each year?

Answer 2

30%

Question 3

When do most droughts occur in Australia?

Answer 3

Closely linked to El Nino

Question 4

Causes of drought in Australia?

Answer 4

Record low rainfall
Hot temperatures

Question 5

What is Day Zero?

Answer 5

Major dams and rivers will no longer be able to supply drinking water to people and agriculture

Question 6

Other impacts of drought in Australia?

Answer 6

Land becomes orange/red
Windstorms
Decline in agriculture - crops and livestock
Loss of jobs - particularly farmers
Loss of communities

Question 7

Define wetland

Answer 7

An area of marsh, fen, peatland and water, where natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt

Question 8

How do wetlands act as temporary water stores?

Answer 8

Mitigate river floods downstream, protect land from destructive erosion and recharge aquifers

Question 9

How do wetlands maintain water quality?

Answer 9

Wetlands act like giant water filters by trapping and recycling nutrients, as well as pollutants

Question 10

Other reasons wetlands are important?

Answer 10

-Very high biological productivity and support a very diverse food web, proving nursery areas for fish and refuges for migrating birds.
-For humans they are of huge benefit as both a resource and service

Question 11

Drought impacts on wetlands?

Answer 11

-Lack of precipitation leads to areas of open water shrinking or drying up
-Extended drying leads to soil erosion as soil moisture is reduced, leading to a reduced ability to store water
-Organic soils may oxidise, releasing carbon
-Some flora and fauna species could be eliminating, creating gaps in the food web in which other species can establish themselves
-Concentrations of dissolved nutrients and pollutants may increase

Question 12

Drought impacts on rainforests

Answer 12

-Trees become stressed, leading to foliage loss, impairing growth and increased accumulation of pests and diseases
-Younger trees die, reducing the canopy cover
-This reduces humidity, water vapour and therefore rainfall
-Dying vegetation and surface tree litter can easily catch fire

Question 13

When was the Big Dry in Australia?

Answer 13

1996-2012

Question 14

% of water provided to agricultural outputs by Murray-Darling Basin?

Answer 14

50%

Question 15

% of low run-off reservoirs fell to what?

Answer 15

40%

Question 16

Which city in Australia was most vulnerable due to what % of drinking water coming from the Murray river?

Answer 16

Adelaide, South Australia
40% of water

Question 17

Location of Pantanal wetlands?

Answer 17

Brazil in the Upper Paraguay river basin, South America

Question 18

Size of Pantanal wetlands in Brazil?

Answer 18

140 000 km2

Question 19

Why is the Pantanal wetland so important?

Answer 19

Aquatic and bird wildlife makes it a significant freshwater ecosystem

Question 20

When is seasonal rainfall in the Pantanal?

Answer 20

November and April

Question 21

% of Pantanal covered with flooding during rainfall seasons?

Answer 21

80%

Question 22

% of floodwater retained in Pantanal even in dry years?

Answer 22

60%

Question 23

Where and when was the Pantanal drought?

Answer 23

Savannah grassland (furthest point from rivers)
2014/15

Question 24

Effects of drought on the Pantanal?

Answer 24

-Increased tree mortality, which in turn reduced habitats for wild animals
-Wildfires became a major threat, caused by cattle ranchers deliberately setting old grass on fire during the dry season to clear vegetation left un-grazed by their cattle - spread out of control

Question 25

How long do living trees take to recover from a period of drought?

Answer 25

2-4 years

Question 26

What species had lower resilience to drought?

Answer 26

Pines which use water at a higher rate

Question 27

Where are the Pinon Pines?

Answer 27

Four Corners region of south-west USA

Question 28

When did drought occur in the Pinon Pines?

Answer 28

200-2003

Question 29

Cause of decline in Pinon Pines?

Answer 29

Severe drought and high temps

Question 30

What did the Pinon Pines become more susceptible to as a result of the ht dry conditions?

Answer 30

Pine bark beetle attacks

Question 31

% of pine die-off in some regions?

Answer 31

90%