EQ2 Flashcards
Has an objective decision about the definition of dought been decided upon?
No. Most places define it as a prolonged period where below-average rainfall occurs. UN definition.
Give some drought vunerability statistics:
- 38% of the world has exposure to drought on som level.
- This equated to 70% of the population.
What is different about socio-economic drought compared to the other types of drought?
It has a temporal and spatial difference means it has different demand.
What is the ITCZ?
- A belt of low atmospheric pressure around the equator.
- There is high evaporation.
- However, this may differ in some regions due to the level of humidity shifting.
How do blocked anticyclones cause drought?
- Depression movement moved from West to East because of coriolis force.
- However, anticyclone conditions block these movements.
- UK experienced below-average rainfall in 2010-2012 due to these conditions. (MET Office)
What are ENSO cycles?
- Hot water in west Pacific leads to spread over the pacific due to failing trade winds.
This causes a cooler environment in places such as Australia.
What human activities increase drought risk?
- Birmingham Uni researchers suggest drought should not be considered a natural hazard.
- Changing land use
- deforestation
CASE STUDY: The Sahel
Semi-arid. (Not equitorial)
Affecting 11 countries.
2002 study suggested drought due to air pollution.
2005 study suggests anthropogenic influence. Temp was 2 degrees higher due to El Nino events.
Other features such as overgrazing may have contributed towards desertification.
Case Study: Australia Millenium drought (1997-2009)
12.4% lower than 20th century mean in this period.
2002-3 and 2006-7 El Nino events contributed to this. This is seen to account for 80% of the declined rainfall in Australia.
How is drought affecting the Wetands of the UK?
Environmental agency state that when water is taken from these regions, they can dry up or shrink.
Concentration of pollution and nutrients can harm wildlife, such as the moorhen which needs open water to live in this habitat.
Areas which are more able to fluctuate will be able to support species.
What is the impact of drought on forests?
2015 research from 1,300 different sies showedd it takes trees an average of two years to overcome and recover from drought.
CASE STUDY: Four corners Pinon Pines
Pines are very vulnerable to drought. They become vulnerable to bark beetle attacks. In some areas, 90% of trees died.
How much of the world is affected by freshwater land flooding?
1/3.
What are the meteorological causes of flooding?
Prolonged precipitation causes flash floods.
Sardinia floods of 2013 killed 18 and cost $1.4 billion.
Fast Snowmelt can also cause flooding.
What human action can increase flooding?
Hard engineering strategies also impact this.
Deforestation and urbanisation.
