5.4 Deficits within the hydrological cycle result from physical processes but can have significant impacts

Question 1

Meteorological drought -

Answer 1

Shortfalls in precipitation as a result of short - term variability or longer term trends, increasing the duration of dry periods.

The precipitation deficiency is usually combined with high temperatures, winds and strong sun.

Question 2

Agricultural drought -

Answer 2

Some farming practices such as over grazing can onset the causes of agricultural drought leading to a lack of soil moisture and soil water availability. Effects of plant growth and biomass.

Question 3

Hydrological drought -

Answer 3

Associated with reduced stream flow and groundwater because of reduced rates of precipitation and high rates of evaporation. Can result in decreased water supplies for urban areas as there is reduced access for storage of lakes which lead to marked salinisation and poorer water quality.

Question 4

Affects of hydrological drought in Northen-East Brazil -

Answer 4

Rural areas. Where there are no rivers and they depend on seasonal rainfall for reservoirs and ponds leaves many rural dwellers with little access to water leading to the decrease of water quality and resulting in ill health and water insecurity.

Question 5

Famine drought -

Answer 5

All these 3 types of drought cause famine drought, leads to widespread failure of agricultural systems, food shortages with economic and environmental impacts. Malnutrition effects.

Question 6

ENSO cycle affects on the demanding population -

Answer 6

As populations grow and become wealthier their demand for water also increases, while this occurs there can be natural variability in a climate which can cause a temporary decline in supply with no replenished stores this can be brought about by an ENSO cycles.

Question 7

What does ENSO stand for?

Answer 7

El Niño - southern Oscilation

Question 8

ENSO 1. Changes of water

Answer 8

Conditions of an El Niño event when cooler water for example along the coast of Peru is replaced by warmer water, at the same time the warmer of Australia and Indonesia further west is replaced by cooler water.

Question 9

How often for El Niño events?

Answer 9

Occur every 3-7 and last for about 18 months

Question 10

El Nino 2. The effects of changing water -

Answer 10

This can trigger very dry conditions throughout the world, usually in the second year especially in South East Asia, in India El Nino always leads to a relatively weak monsoon rain.

Question 11

El Nino Events 1-3 -

Answer 11

1. Trade winds die in the Western Pacific
2. May even be a reverse of direction of flow
3. The piled up water in the west moves back east, leading to a 30cm rise in Peru

Question 12

El Nino Events 4-6

Answer 12

4. The region of rising air moves east with the associated convectional uplift.
5. Therefore the eastern Pacific ocean becomes 6-8 degrees warmer, breaks the food chain.
6. Conditions are calmer across the whole Pacific

Question 13

La Nina Events 1-4 -

Answer 13

1. Extremely strong trade winds
2. The trade winds push warm water westwards
3. Low pressure develops with strong convectional uplift as the warm water heats the atmosphere, leads to heavy rainfall in south east Asia
4. Results in strong high pressure and extreme drought and can be a problem in the already semi- arid environments in Chile and Peru

Question 14

Human Influences on drought - Sahel region

Answer 14

Human factors do not necessarily cause drought but act like positive feedback loop making it worse, for example the drought impacts were increased by socio-economic impacts due to worsening degradation of deforestation and overgrazing. Also rural populations have increased for example the population had double every 20-30 years. So population had outstripped food production in those years and agriculture was mainly rainfed making the drought worse for agricultural benefits. This doesn’t help in certain seasons due to 85% of their annual rainfall coming in the summer months.

Question 15

Desertification -

Answer 15

Land degradation in semi-arid dry areas resulting from various factors including human activities.

Question 16

Human influences - Increase in livestock for example

Answer 16

In some areas livestock numbers have increased by 40% therefore this has led to overgrazing, this destroys the protective areas of lands including plants and results in soil erosion. The vegetation cannot re-establish itself

Question 17

Human population Sahel region due to the population the demand is more -

Answer 17

Required increased wood for cooking, heating and building especially in urban areas. The act of vegetation removal leads As more and more trees get cut down, evaporation levels are disrupted, drying up the moisture in the air and throwing off the balance of the water cycle.

Question 18

What is a Wetland?

Answer 18

Multitudes of different landscape types with water static or naturally flowing can be natural or artificial.

Question 19

Impacts of drought on ecology (Wetlands) - Impacts on the water store -

Answer 19

They act as water stores thus protecting the land and mitigating river floods and protecting land from destructive erosion.

Therefore, limited precipitation will lead to less interception and infiltration rates and percolation to the groundwater stores. This therefore makes them less functionable and effect food webs and biodiversity from potential increased competition with the evaporation rates still increasing.

Question 20

El Niño with its conditions it brings -

Answer 20

El Niño cab triggers very dry conditions throughout the world usually in the second year, especially in South East Asia like India, like India it always leads to weak monsoon rains.