Drought Flashcards
What is a drought?
A prolonged period of abnormally low rainfall leading to a shortage of water.
What are some impacts of drought?
-water shortages
-damage to agriculture
-economic losses
-impacts on ecosystems
-increased food prices.
Why are droughts difficult to predict?
They are slow-onset hazards, and it can take a long time for the effects of low rainfall to become apparent.
What is the difference between a meteorological and a hydrological drought?
A meteorological drought is defined by a lack of precipitation.
A hydrological drought refers to low water levels in rivers, lakes, and groundwater stores.
What is a short-term drought often caused by?
A precipitation deficit, often due to changes in the frequency of frontal precipitation or high-pressure systems (anticyclones).
How can climate change affect drought frequency?
Climate change can alter ocean temperatures and weather patterns, leading to more frequent and severe droughts. It can also shorten the recovery time between droughts.
What is the El Niño-Southern Oscillation (ENSO) cycle?
A natural cycle of changes in ocean temperatures and atmospheric pressure in the Pacific Ocean that can affect global weather patterns, including drought.
What are the typical conditions during an El Niño event?
Warmer waters in the central and eastern Pacific, weaker trade winds, and often drier conditions in the western Pacific (e.g., Australia).
What are the typical conditions during a La Niña event?
Cooler waters in the central and eastern Pacific, stronger trade winds, and often drier conditions in the eastern Pacific.
How does El Niño/La Niña relate to drought?
El Niño events can increase the risk of drought in some regions, while La Niña events can increase the risk of drought in other regions.
How can human activity increase the risk of droughts?
By increasing demand for water beyond natural replenishment rates (over-abstraction), diverting water for human use, and potentially through contributing to climate change.
What is over-abstraction of groundwater?
Extracting water from an aquifer at a faster rate than it is recharged, leading to depletion.
How did the 2006-2007 Millennium Drought affect Australia’s Murray-Darling Basin?
80% of Adelaide was in severe danger of running out of water as its source was the River Murray.
Climate change will reduce rainfall and a growing population will cause water prices to rise by 5-10 times.
The Murray Basin produces 50% of Australia’s food, so the drought pitted town against farmers’ needs.
What factors contributed to the Millennium Drought in Australia?
Naturally low rainfall, El Niño events, high temperatures (potentially linked to climate change), and over-abstraction of groundwater.
What is ecological resilience?
The ability of an ecosystem to survive and recover from a disturbance, such as a drought.
Why are wetlands particularly vulnerable to drought?
They are sensitive to water level changes and have limited resilience. Drought can lead to vegetation dieback, reduced habitat, and decreased water purification.
How does drought affect aquatic life in wetlands?
As water levels drop, algae concentration increases, reducing oxygen levels and potentially harming or killing aquatic organisms.
How are forests affected by drought?
Tree growth slows, young trees are vulnerable, and dieback can occur. This increases the risk of land exposure, higher temperatures, and wind erosion.
How did the Millennium Drought affect rice production in Australia?
Rice yields fell dramatically due to water shortages, dropping to only 2% of pre-drought levels.
What were the reasons for drought in the Sahel region?
Almost all rainfall is concentrated in the summer. There is annual variability due to unusually warm sea temperatures weakening the West African monsoon. Human activities.
Why is the impact of drought more severe in the Sahel region?
People are more marginalised and therefore more vulnerable. They have less ability to influence policies.
High population growth and slow health and education services development leave them unable to cope.
They face cyclical drought, preventing them from coping with long-term effects.
