Short-Long term variations hydrological cycle.

Question 1

Define Drought.

Answer 1

Extended period (Season, year, several years) of deficient relative to the statistical multi year average for a region.

Question 2

What four catagories cause droughts?

Answer 2

Socio-economic drought, Hydrological drought, Agriculture drought, meteorological drought.

Question 3

Define Socio-economic drought.

And what causes it?

Answer 3

Occurs when water demand is higher than water avaliability. Can be caused by lack of precipitation or by human overuse of water sources.

Question 4

Define Hydrological drought.

And what causes it?

Answer 4

This happens when when the amount of surface area and subsurface water (rivers, groundwater ect.)is deficient. Caused by lack of precipitation.

Question 5

When do Hydrological droughts usually occur?

Answer 5

After meteorological and agricultural droughts.

Question 6

Define Agricultural drought.

And what causes it.

Answer 6

When there is not enough soil moisture to allow enough crops to grow. It is caused by precipitation shortages, changes in rates of evapotranspiration and reduced groundwater levels.

Question 7

Define Meteorological drought.

And what effects it.

Answer 7

When long-term precipitation is lower than normal. It changes for different regions as it is affected by the atmospheric conditions.

Question 8

Describe a normal Non-El Niño year.

Answer 8

1. Trade winds blow equator-wise and westwards across tropical pacific.
2. Winds blow towards warm water of western Pacific.
3. As water heats the atmosphere, convectional uplift occurs.
4. Trade wind pushes warm air westwards. Along the East coast of Peru, shallow position of thermoline allows winds to pull up water from below.
5. Cause upwelling of nutrient-rich cold water creating optimum fishing conditions.
6. The pressure of the trade winds results in sea levels in Australasiabeing 50cm higher than Peru, sea temperature being 8°C higher.
7. The Walker loop returns air.

Question 9

Describe an El-Niño year.

Answer 9

1. Trade winds in Western Pacific weaken and die.
2. May be a reverse direction of flow.
3. Piled-up water in West moves back east leading to Peru sea levels 30cm rise.
4. Region of rising air moves East with associated convectional uplift. Upper air disturbances distort the path of jet streams which can lead to teleconnections all around the world.
5. Eastern Pacific Ocean becomes 6-8°C warmer. The El Niño effect overiddes cold northbound Humboldt current, thus breaking the food chain. Lack of phtoplankton results in reduction in fish numbers, which in turn affects fish eating birds on the Galapagos Islands.
6. Conditions are calmer across the whole Pacific.

Question 10

Describe a La Niña year.

Answer 10

1. Extremerly strong trade winds.
2. Trade winds push warm water westwards giving a sea level up to 1m higher in Indonesia and the Philippines.
3. Low pressure develops with very strong convectional cuplft as very warm water heats the atmosphere. Leads to heavy rain in southeast Asia.
4. Increase in the equatorial undercurrent and very strong upwelling of cold water off Peru results in strong high pressure and extreme drought. This can be a major problem in the already semi-arid areas of Northern Chile and Peru.

Question 11

What were the 2014-16 El Niño’s impacts on Australia?

Answer 11

• Drying influence of event was contradicted by warm temperatures in Indian Ocean leading to above average rainfall in Western Australia, New South Wales and eastern Victoria.
• Spring 2015 it reversed and Indian Ocean started to help El Nino, meant limited crop growth, third driest spring ever.
• Lack of heavy rains in North and West meant reduced downtime for mining.
• Fewer clouds and less tropical rain contributed to most severe coral bleaching event for the Great Barrier Reef ever recorded.
• Heat and low rainfall brought Australian bushfire season in 2015-16, 125 fires recorded in Victoria and Tasmania during October.
• Dry conditions also started fires from dry lightning in January 2016, damaged Tasmanian world heritage area.

Question 12

What were the 2014-16 El Niño’s impacts on Africa?

Answer 12

• El Nino 2014-16 boosted 2015 short rains season from October-december. Increasign rainfall in east Africa.
• Multiple countries including, Lesotho, Swaziland and Zimbabwe declared national states of emergency.
• March 2016 Southern African Community declares a regional drought disaster.

Question 13

Tell the card about the Case study for Human influences on drought in the Sahel region of Africa. In regards to Sahel’s features that make in vulnerable to drought.

Answer 13

The Sahal region is a vast semi-arid region of the Southern edge if the Sahara. It goes from Mauritania to Eritrea and houses some of the poorest developing countries in the world.

• Sahel = drought sensitive as it occupies a transitional climate zone. In normal conditions mean annual rainfall is all concentrated in the Summer. Varies from 100mm on edge of Sahara to 800mm on Southern Margins.
• Annually, there is huge variability on the Saharan fringe. On tropical seas warm sea surface temperatures create strong convectional uplift. This weakens West African monsoons and contributes to the Sahel drought.

Question 14

Case study. What human influences increase drought in the Sahel region of Africa?

Answer 14

1999-2000 there was an Ethiopian > Enitrean drought and 10 million people needed famine assistance.

Drought’s impact was increased by socio-economic conditions like environmental degradation by overgrazing by Nomadic tribes. Also deforestation for feul wood and rural poverty.

Rural population density increased so population growth outstripped food production.

Etheopia and Enitrea were at war which blocked people’s access to food.

Question 15

Case Study. Drought in Australia. What are the two main types of drought in Australia?

Answer 15

• Serious deficiency - Rainfall totals within 10% of value’s record for at least 3 months.
• Severe deficiency - Rainfall totals within the lowest 5% of values on record for at least 3 months.

Question 16

Case study. Drought in Australia. How much of Australia is usually affected per year?

Answer 16

30% is usuallly affected per year.

Question 17

Case Study. Drought in Australia. Why is Australia so drought prone?

Answer 17

• Highly variable rainfall due to a climate dominated by sub-trophic high pressure belt of Southern hemisphere.
• Droughts vary considerably in severity and duration E.g.Big dry of 2006 covered most of Australia for several years.
• Most Australian droughts are linked to El Niño events. E.g. East coast drought of Southern Queensland from 2002-2003.
• Since 1970s theres been a shift in rainfall patterns in East areas where most people live.
• ‘Big dry’ is associated with longer - term climate change leading to a warmer, dryer climate for south- eastern Australia.

Question 18

Case study. Drought in Australia. What was the ‘Big dry’ of 2006?

Answer 18

• Affected over half of Australia’s farmlands, including Murray-Darling Basin which provided 50% of nation’s agricultural outputs. It lowered food, wool, wheat and meat exports as well as water, Which farmers needed for irrigated farming of rice, cotton and fruit.
• Australia’s city’s water supply schemes designed to resist low run-off fell to 40% capacity. Hit Adelaide in South Australia especially hard as it drew 40% of it’s drinking water from river Murray. In recent years because of over extractions no water has flown to the river Murray’s mouth.
• As Australia’s population increases more water is needed but many groundwater resources have been over-extracted from agriculture and industrial and urban usage.

Question 19

Case study. Drought in Australia. What are Australia’s future plans to tackle drought?

Answer 19

Future demands for water will exceed supply, so new schemes for desolation plans are,

• Large scale recycling of grey water and sewage, and water conservation must be developed.

Question 20

Define Wetland.

Answer 20

An area which is either permanently or seasonally saturated with water.

Question 21

What are the important features of Wetlands?

Answer 21

• Temporary stores in Hydrological cycle which can prevent flooding and build up groundwater stores.
• They support a food web for animals.
• They retain and recycle nutrients, which maintains water quality.
• They support the carbon cycle, prevent erosion and provide a range of goods and services.

Question 22

What are the impacts of droughts on wetlands?

Answer 22

• Areas of water dry up or shrink which can cause habitats to be damaged or lost.
• Soil moisture drops causing soil erosion to occur as more land is exposed.
• Food webs can change as certain species ore more or less resistant to drought. E.g. swallows and ducks are not very resistant.

Question 23

What is the RAMSAR convention?

Answer 23

The Ramsar convention on wetlands (1991) protects 1.7 million km² of wetland.

Question 24

Give an example of a wetland.

Answer 24

Southern Iraq

• Dams along the river Euphrates and Tigris have affected marshland.
• During Saddam Hussein’s reign drainage schemes were put in place to eliminate marsh arabs who lived there.
• It became desert but has begun to grow back recently as water has started to flow again.

Question 25

What are important functions of forests?

Answer 25

• Timber
• Regulation of hydrological processes
• Providing habitats
• Carbon sequestration (CO₂ being removed from the air in solid or liquid form)
• Food chains.

Question 26

What are impacts of drought on forests?

Answer 26

• Trees can take 2-4 years to recover from drought but some species are less resilient.
• Trees do not grow properly and can be more susceptible to pests and diseases.

Question 27

Give an example of drought affecting forests.

Answer 27

Four Corners, New Mexico, USA

• Severe drought from 2000-2003 in region killed large amount Pinon pine trees.
• These were very highly vulnerable to pine bark beetle attacks so in some areas 90% of pine bark beetles died out.
• This is an example of the many major ecosystem changes.

Question 28

On Synoptic weather charts, What is an occluded front and what is the weather like at them?

Answer 28

Occluded front - Combination of a cold and warm front.

Associated with patchy rain and low clouds.

Question 29

What is weather like at troughs? On synoptic weather charts?

Answer 29

Air is unstable, air it turbulent, rain showers

Question 30

On synoptic weather charts, what is weather like around warm and cold fronts?

Answer 30

Position depends on meteorological factors e.g. wind, direction and temperature.

On the fronts are increased amounts of cloud and rainfall.

Question 31

What do these symbols mean on synoptic weather charts? And what can you determine from them?

Answer 31

Red line with semi-circles - Warm front, the way the semi circle are facing is the direction of the front.

Blue line with triangles - Cold front, the way the triangles point is the direction of the front.

Question 32

What do H and L on synopic weather charts mean? And what do the numbers below them mean?

Answer 32

H - High pressure

L - Low pressure

Numbers are the units of air pressure in that area.

Question 33

What are the circular lines running across the whole map on synoptic weather charts?

What are features of them?

Answer 33

Contour lines

Show the air pressure at areas in the world.

Closer they are, steeper the gradient, stronger the winds tend to be.

Question 34

In what way do winds circle in different presure areas of wind on synoptic weather charts?

Answer 34

Winds circle clockwise in high pressure areas

Winds circle anti-clockwise in low pressure areas.

Question 35

What does warm and cold air follow on synoptic weather charts?

Answer 35

Warm air follows warm fronts

Cold air follows cold fronts

Question 36

What happens when faster cold fronts catch up to warm fronts on synoptic weather charts?

Answer 36

They create Occluded fronts.

Question 37

How are Occluded fronts represented on synoptic weather charts?

Answer 37

A purple line with sets of coupled purple triangles and semi-circles next to each other.

Question 38

What do you call air trapped between warm and cold fronts on synoptic weather charts?

Answer 38

Warm sectors.

Question 39

What do dots and crosses on synoptic weather charts represent?

Answer 39

Dots represent a developing front.

Crosses represent a weakening front.

Question 40

What do troughs represent on Synoptic weather charts? And what weather are they associated with?

Answer 40

Trophs represent where air is unstable.

Associated with areas of showers.

Question 41

Where do trophs not work on Synoptic weather charts?

Answer 41

Trophs don’t work on boundaries.