deficits within hydrological cycle

• What are the four types of drought mentioned in the study material?

  Meteorological, hydrological, agricultural, and socio-economic drought
• How is drought defined in meteorological terms?

  Drought is defined as a shortfall or deficiency of water over an extended period, usually at least a season.
• What characterizes hydrological drought?

  Hydrological drought is characterized by reduced stream flow, lowered groundwater levels, and reduced water stores.
• What is agricultural drought?

  Agricultural drought occurs when agricultural activity is greatly impacted by drought.
• What are the potential consequences of agricultural drought?

  It can lead to food shortages, famine, and starvation, which is referred to as socio-economic drought.
• What are the physical causes of meteorological drought?

  • Complex interactions between atmosphere, oceans, cryosphere, biosphere, and land
  • Ranges from short-term localized precipitation deficits to longer-term trends related to climate change
  • Sea surface temperature anomalies are important causal factors
• What is the El Niño Southern Oscillation (ENSO)?

  ENSO is a climate pattern that involves temperature anomalies in the Pacific, which can trigger droughts.
• What happens to trade winds during a non-El Niño year?

  In a non-El Niño year, trade winds blow from east to west along the equator.
• What occurs during an El Niño event regarding ocean currents?

  The trade wind pattern is disrupted, which affects ocean currents and replaces cool water along the coast of Peru with warmer water.
• How often do El Niño events typically occur?

  El Niño events usually occur every 3-7 years.
• What is La Niña and how does it relate to El Niño?

  La Niña events may follow an El Niño event and involve the build-up of cooler-than-usual subsurface water in the tropical Pacific.
• What is desertification and where does it typically occur?

  Desertification is the process by which productive land gradually changes into a desert-like landscape, usually in semi-arid areas on the edges of existing deserts.
• What are the natural causes of desertification in the Sahel region?

  Natural causes include changing rainfall patterns, vegetation stress, and soil erosion.
• How does human activity contribute to desertification in the Sahel?

  Human activities such as over-abstraction of water, population growth, overgrazing, overcultivation, and deforestation enhance the impacts of drought.
• What is the impact of civil wars on the Sahel region's agricultural situation?

  Civil wars have led to the destruction of crops, livestock, and homes, worsening the situation.
• What percentage of Australia is affected by serious or severe rainfall deficiency?

  Up to 30% of Australia is affected by serious or severe rainfall deficiency.
• What was the 'Big Dry' of 2006 in Australia?

  The 'Big Dry' of 2006 was assessed as a 1-in-1000 year event associated with longer-term climate change.
• What measures has Australia taken to manage drought and prevent desertification?

  • Careful management of water resources
  • Sorting out competing demands of irrigation and urban dwellers
  • Large-scale recycling of grey water
  • Constructing desalination plants
  • Devising new water conservation strategies
• What is ecological resilience?

  Ecological resilience is the capacity of an ecosystem to withstand and recover from natural events or human disturbances.
• What functions do wetlands perform?

  • Act as temporary water stores
  • Recharge aquifers
  • Filter pollutants
  • Provide nurseries for fish
  • Serve as feeding sites for migrating birds
• How does drought impact wetlands?

  Drought leads to less precipitation, reduced interception, infiltration, and percolation, causing water tables to fall and increasing evaporation.
• What is the major challenge to the survival of wetlands?

  The major challenge remains artificial damage to wetlands.
• What impacts do forests have on the hydrological cycle?

  • Responsible for much interception
  • Reduced infiltration and overland flow
  • High levels of transpiration
• How does drought threaten forests?

  Drought threatens forests by causing physiological damage and increasing susceptibility to diseases, leading to increased tree mortality.
• What is the concern regarding increased tree mortality in tropical rainforests?

  Increased tree mortality in tropical rainforests raises concerns about the impact on carbon storage.
• Why is it important to ensure ecological resilience in ecosystems?

  • To withstand and recover from natural events
  • To prevent overstretching by human activities
  • To maintain the hydrological cycle