Topic 5 - Water Cycle And Insecurity: EQ2

Question 1

What is a drought?

Answer 1

An extended period of deficient rainfall relative to the statistical multi average for a region

Question 2

What’s famine drought?

Answer 2

Food deficit

Question 3

What’s agricultural drought?

Answer 3

Soil moisture deficit

Question 4

What’s hydrological drought?

Answer 4

Stream flow deficit

Question 5

What’s meteorological drought?

Answer 5

Rainfall deficit

Question 6

What are the 4 physical reasons for drought?

Answer 6

Global atmospheric circulation
Failing of the ITCZ
Blocking high pressures
El Niño Southern Oscillation (ENSO)

Question 7

How does global atmosphere circulation cause drought?

Answer 7

The subtropical high pressure zone is created where air that has risen at the equator has cooled and so sinks to form a belt of high air pressure and hot, dry conditions. It has low annual rainfall and is usually areas which are mostly deserts or grasslands due to limited moisture

Question 8

How does the failing of the ITCZ cause droughts ?

Answer 8

The ITCZ causes air to rise due to intense solar heating, leading to high ocean evaporation and alternating wet and dry seasons. In summer, it shifts north, increasing rainfall in regions like West Africa and South Asia. In winter, it moves south, affecting areas in South America and Central Africa.

Question 9

How can blocking high-pressure cause droughts?

Answer 9

Blocking high pressures disrupt air movement, creating stable conditions with clear skies and reduced cloud formation. They block low-pressure systems, potentially causing weeks or months of drought in mid-latitude regions like the UK. Persistent anticyclones can make it worse

Question 10

How does El Niño Southern Oscillation (ENSO) cause droughts?

Answer 10

ENSO disrupts global weather by shifting the ITCZ and altering atmospheric circulation. El Niño warms Pacific waters every 2-7 years, moving the jet stream south and east, causing floods and droughts. La Niña cools Pacific waters, raising the jet stream and bringing Arctic-like conditions.

Question 11

What is the case study for 5.4?

Answer 11

Sahel (2012/2013)

Question 12

What are the human causes of drought in the Sahel?

Answer 12

Over grazing by tribes
Deforestation for fuelwood
Increasing population
Wars
Increase in farming
Soil damage

Question 13

Why do humans have an impact in Sahel?

Answer 13

Humans act as a positive feedback loop and enhancing its impact due to social economic conditions

Question 14

What is resilience?

Answer 14

Is the capacity of an ecosystem to drought. It is the ecosystem ability to persist in its present state despite having a deficit of water

Question 15

What is a wetland?

Answer 15

An area of marsh, fern, peatland saturated with water permanent or seasonally. This might be static-water , flowing, fresh or salt

Question 16

Why are wetland important?

Answer 16

Provide vital habitats to many types of plants and animals, many of which are useful to humans.
Humans depend on wetland for recreational activities such as hunting, bird watching, fishing

Question 17

How do droughts affect wetlands?

Answer 17

Droughts have a big impact on wetland ecosystems and this can cause loss of habitats and as soil moisture is reduced they can be soil erosion and organic soils may oxidise recent carbon into the atmosphere.
Affect food web

Question 18

Why are forests important?

Answer 18

they have ecological function such as the carbon storage, nutrient cycle, water and air purification, and maintenance of wildlife habitat, so your preservation and species habitat. They are also good for timber, food, fuel, and bio products

Question 19

How do droughts affect forests?

Answer 19

the dryer warmer conditions lead to vegetation drying out and becoming more flammable. This makes them not very resilient as it would be hard to stop the fire once they started in the forest

Question 20

What are the meteorological causes of floods?

Answer 20

Jet stream and low pressure weather
Monsoon (India)
Ice melt (Siberia)

Question 21

How does Jet stream and low pressure weather cause floods?

Answer 21

Sometimes high pressure blocks the jet stream and continually delivers low pressure after low pressure to one area as there is high pressure either side

Question 22

How does the monsoon in India cause floods?

Answer 22

The monsoon brings heavy rain over a short period of time due to moist winds condenses into rain and causes continuous rainfall

Question 23

How does ice melt in Siberia cause floods?

Answer 23

Siberian snow melt in the spring causes extensive flooding across interiors of Asia such as the River Ob. There is a quick transformation from winter to spring, frozen ground meaning no infiltration means rapid level increase

Question 24

What is the case study for 5.5?

Answer 24

Cumbria floods in 2015

Question 25

what were the (physical primary) meteorological causes of the Cumbria floods in 2015

Answer 25

Position of Jet stream and low Low pressure system Orographic rainfall Antecedent conditions and rainfall intensity Historic flooding

Question 26

How did historic flooding events cause floods?

Answer 26

Storm Desmond brought 847 billion litres of rainfall over Cumbria

Question 27

How did the jet stream cause floods

Answer 27

It was over Columbia at the time of the rainfall and cause atmospheric river and focus on Columbia

Question 28

How does low pressure system cause floods

Answer 28

There was also a low pressure system over Columbia and this creates precipitation due to clouds

Question 29

How does orographic rainfall cause floods?

Answer 29

Cambria is in a mountainous area so this means orographic rainfall will be there and this happens frequently

Question 30

How does antecedent conditions cause floods

Answer 30

The rain occurred over a short period and just before that they had a storm a week before. High level of discharge

Question 31

What were the secondary physical causes of flooding in Cumbria?

Answer 31

The rock type was mostly impermeable Steep slopes of mountain means water travelled faster to rivers Ground was already saturated so water went straight to river

Question 32

What were the secondary human causes of Cumbria floods

Answer 32

More roads and impermeable rocks so more pressure on drains and made them overflow Deforestation, overgrazing Sheep farming means it’s hard for afforestation Bad flood defences

Question 33

Worst social impacts of the flood

Answer 33

The united biscuits factory which is the city’s biggest employer closed for weeks so many had to go with no work 3000 homes were flooded in 2005 and over 5200 in 2015

Question 34

Economic impacts of the flood

Answer 34

the cost of the flooding was over £270m in 2009 and £400-500m in 2015 house prices fell in flood risk areas

Question 35

Environmental impacts of the flood (Cumbria)

Answer 35

rivers were filled with debris and contaminated with sewage and pollutants The saturated grounds led to landslides

Question 36

Use worksheet for more data on the floods

Answer 36

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Question 37

How does climate change have an impact on the hydrological system

Answer 37

Increasing anthropogenic greenhouse gas emissions Increasing heat trapped in the atmosphere (enhanced global warming) Increasing average air temperatures and sea surface temperatures

Question 38

Hydrological variables that climate change has an affect on?

Answer 38

Precipitation input Soil moisture Evaporation Permafrost Snow Ice

Question 39

How is the hydrological cycle changing in California?

Answer 39

Increased droughts 3 times as many wildfires than normal in 2014 Forecasts of mega-droughts lasting 30 years

Question 40

How is the hydrological cycle changing in The Sahel?

Answer 40

Decline of rainfall of up to 40% between 1950 and 1990 Rains are failing due to ITCZ

Question 41

What is re-greening?

Answer 41

Covering land with grass and trees, making it healthy again

Question 42

What are the benefits of re-greening?

Answer 42

Natural regeneration of water-retaining shrubs and trees Low cost reforesting Use of water-harvesting techniques e.g. Demi-lunes

Question 43

Why is there uncertainty about future flooding?

Answer 43

We don’t know exactly where it will get hotter (and by how much)

Question 44

How would climate change lead to more floods?

Answer 44

For every 1 degree of temperature rise, the amount of moisture that can be held in the atmosphere rises by 7% Creates potential for heavier precipitation and floods

Question 45

What are some human influences on droughts?

Answer 45

Land use change Rising population Poor farming Normal variability

Question 46

What are some sources of uncertainty when discussing future climate change projections?

Answer 46

Complexity of climate systems (teleconnections) Natural short term oscillations - e.g. ENSO cycles Biogechemical positive and feedback mechanisms Incomplete set of data (not collected in all locations)

Question 47

How could water uncertainty lead to famine?

Answer 47

Not being able to adapt to different conditions may cause a famine Additionally, people don’t know whether they need to adopt new strategies or not