5.4A

Question 1

What are the courses of drought

Answer 1

The courses of drought, both meteorological and hydrological:
short-term precipitation deficit, longer term trends, and ENSO
cycles

Question 2

When does water stress occur

Answer 2

When water demand > available amount

Question 3

What does water stress lead to

Answer 3

• deterioration of fresh water resources
• in terms of quantity (aquifer over-exploitation, dry rivers, etc.)
• and quality (eutrophication, organic matter pollution, saline intrusion, etc.).

Question 4

Define meterological drought

Answer 4

shortfall or deficiency of water over an extended period, usually at least a season.
- long term precip is much lower than normal but depends on whether evapotranspiration is high

Question 5

define hydrological drought

Answer 5

0 reduced stream flow, lowered groundwater levels and reduced water stores.
- deficiencies in surafce and subsurface water
- starts with lack of rain but takes a while for that to affect water flow

Question 6

Normal conditions in pacific basin

Answer 6

• In a non-El niño year, the trade winds blow from east to west along the equator
• The air pushes the warm water westerwards
• Thermocline, upwelling,
• Warm, moist air rises, cools and condenses, forming rain clouds

Question 7

Conditions in pacific basin during an el nino event

Answer 7

• The trade wind pattern is disrupted - it may slacken or even reverse and this has a knock-on effect on the ocean currents
• Air circulation loop reversed

Question 8

What happens as a result of el nino

Answer 8

• cool water normally found along the coast of Peru is replaced by warmer wate
• area of warmer water further west, near Australia and Indonesia, is replaced by cooler water.

Question 9

How often does el nino occur and what is its duration

Answer 9

• every 3-7yrs
• last 18 months

Question 10

What is el nino

Answer 10

• El Nino is the change in water body patterns within the Southern hemisphere, leading to unusual weather conditions.

Question 11

What else does El nino trigger

Answer 11

ENSO can also trigger extremely dry conditions in areas South & South-East
Asia, Eastern Australia and North-East Brazil.
- In South Asia, ENSO can weaken the annual monsoon.

Question 12

Describe normal pacific basin conditions

Answer 12

• rising warm moist air gives heavy rainfall in west
• high altitude air flow west
• descending waring air gives dry conditions
• surface flow from trade winds blowing from east to west

Question 13

Describe el nino process

Answer 13

• high altitude air flow from east to west
• so rising air in the east gives heavy rainfall on pacific coast from peru to cali
• descending air warms to give dry conditions in west

Question 14

simplified types of drought

Answer 14

• Meteorological drought – when the 0 amount of precipitation received in a specific area is less than the average.
• Hydrological drought – when reduced precipitation impacts on water supply, eg there is decreased streamflow, soil moisture, reservoir and lake levels, and groundwater