EQ2 5.4 DEFICITS IN THE HYDROLOGICAL SYSTEM LEAD TO DROUGHT

Question 1

what are the 4 types of drought

Answer 1

meteorological, agricultural, hydrological, socio-economic

Question 2

meteorological drought

Answer 2

this type of drought presents a degree of dryness compared to what is considered to be normal precipitation levels for that area, climate and season.

Question 3

agricultural drought

Answer 3

when there is insufficient water for crops, leading to wilting or loss of crops without irrigation.

Question 4

hydrological drought

Answer 4

when the drainage basin suffers shortfalls such as reduced streamflow or an increase of river flow into the reservoirs.

Question 5

Socio-economic drought

Answer 5

when there is a demand for water to be used for social and economic purposes such as crop irrigation or when HEP exceeds water availability.

Question 6

drought

Answer 6

Drought happens when an area suffers from a water deficit. If rainfall falls well below average for a specific place then a deficit can happen.

Question 7

what are ENSO cycles

Answer 7

(El Niño Southern Oscillation) refer to the El Niño and La Niña changes in the Pacific Ocean.

Question 8

what happens in El Niño in south america

Answer 8

El Niño events happen every 3-5 years, where winds weaken across the South Pacific Ocean and reverse direction. Warm water moves to the South American coastline, where lower air pressure causes large increases in rainfall, promoting the potential for flooding.

Question 9

what happens in El Niño in Australasia

Answer 9

During El Niño, Australasia has cooler than normal ocean temperatures and is subject to high air pressure, resulting in little rainfall and an increased risk of drought.

Question 10

what happens in La Niña in Australia

Answer 10

During La Niña years, low air pressure descends on Southeast Asia and Australia leading to increased rainfall and risk of flooding.

Question 11

what happens in La Niña in south america

Answer 11

South America receives high air pressure, which leads to reduced rainfall and increased likelihood of drought.

Question 12

Short-term precipitation deficit

Answer 12

There can be a short-term precipitation deficit in places when the cycle that creates clouds is interrupted.
A water deficit may be experienced in areas that are used to low air pressure systems and have a change of weather front to experience a high air pressure system. The cool sinking air in high air pressure systems does not have the ability to form clouds and produce precipitation.

Question 13

what are the main human activities associated with drought

Answer 13

over-abstraction of surface water and aquifers

Question 14

Brazil over abstraction

Answer 14

In 2014-15 industries, farmers and domestic users in Brazil increasingly used groundwater, until the rivers began to run low.
Poor and rural communities suffered because they only had access to groundwater because of rivers running low.

Question 15

causes of over-abstraction in Brazil

Answer 15

Brazil’s government introduced a charge for drilling wells of around US$35,000- US$100,000.
Residents drilled illegally because they could not afford the charge, meaning the water abstracted was not monitored.
Hydrologists believe that the government’s official records of wells drilled in 2014 only represent a 1/3 of the total, as 70% of wells were illegal.

Question 16

problems with over abstraction in Brazil

Answer 16

The government’s well charge resulted in illegal drilling.
Illegal wells are shallower and so have not percolated deep into the bedrock. Water from illegal wells is less filtered by bedrock and may contain industrial and agricultural pollutants with higher levels of bacteria.
An increase in poor sanitation and water-borne diseases happens if the water is not filtered further.

Question 17

what does drought lead to

Answer 17

Drought leads to less water for the vegetation of an area. This can have devastating effects on an flora and fauna that interact in that ecosystem.

Question 18

Ecosystem functioning

Answer 18

the biological, chemical and physical processes that take place in an ecosystem.

Question 19

Ecosystem resilience

Answer 19

how capable the ecosystem is of surviving changing water levels.

Question 20

which areas are more resilient to drought

Answer 20

deserts and semi-arid areas

Question 21

the impact of drought on rainforests

Answer 21

Prolonged periods of drought lead to forest stress.
Younger trees die as a result of drought. This reduces the canopy cover.
Reduction of canopy cover leads to less interception and infiltration but also decreases evapotranspiration. This means water vapour and rainfall reduces.

Question 22

the impact of drought on forests

Answer 22

Forests that are exposed to tropical sunlight with dead vegetation and a mass of dry organic material can easily set alight.
Lightning storms and high winds can then turn a small fire into a wildfire.

Question 23

the impact of drought in the forests of Croatia

Answer 23

Croatia suffered from 2 ½ months of no rainfall during the summer of 2017. This lead to widespread drought and ultimately wildfires that were challenging to manage. Water-bombing planes were donated from nearby countries to control the flames.

Question 24

the impact of drought on wetlands

Answer 24

Drought increases the likelihood of tree mortality.
A decrease in vegetation reduces the habitat for both wild or farm animals. Birds and wetland vegetation respond to drought differently. Drought can change communities by eliminating species and having knock-on impacts on the rest of the food chain.
The likelihood of wildfire increases.

Question 25

the impact of drought on wetlands in Suffolk

Answer 25

In Minsmere, Suffolk, wetlands species such as snipe and thrush are impacted by the dry soil surface which is present during a drought.
The snipe and thrush are less able to penetrate the dry soil to reach the invertebrates they feed off.