Earth's life support systems

• What is the primary function of the hydrological cycle?

  It supports life on Earth.
• How does the hydrological cycle operate?

  It circulates water between various stores.
• What drives the global hydrological cycle?

  Solar energy and gravitational potential energy.
• What is the first step in the hydrological cycle?

  Evaporation of water from the ocean.
• What happens to moisture after evaporation?

  It is transported and returns as precipitation.
• What is runoff in the hydrological cycle?

  Water that remains on the surface and flows.
• Where is the majority of Earth's water stored?

  In saline oceans.
• What is a water budget?

  The balance between water inputs and outputs.
• What is the significance of residence times in water stores?

  They indicate how long water is stored.
• What is a drainage basin?

  An area of land drained by a river.
• What are the key processes in the hydrological cycle?

  • Interception: Precipitation intercepted by vegetation.
  • Infiltration: Water soaking into soil and rocks.
  • Throughflow: Water flowing within the soil.
  • Percolation: Water moving through soil to groundwater.
• What are the outputs of the hydrological cycle?

  Evaporation, transpiration, and channel flow.

  
• How does climate affect the hydrological cycle?

  It determines temperature and precipitation patterns.
• What is the impact of urbanization on the hydrological cycle?

  It increases impermeable surfaces, reducing groundwater.
• What is a storm hydrograph?

  A graph showing river discharge over time.

  
• What causes droughts?

  Long periods of below-average precipitation.
• What is El Niño?

  A weather pattern causing drought in Australia.
• What is La Niña?

  An intensification of Walker's cell affecting rainfall.
• What happened in southern Australia in 2006?

  It experienced extremely low rainfall.
• How does human activity contribute to drought risks?

  By over-abstraction of water resources.
• What are the impacts of drought on ecosystems?

  Loss of wetlands and forest stress.
• What can surpluses in the hydrological cycle lead to?

  Flooding with disastrous impacts.
• What are meteorological causes of flooding?

  Intense storms and prolonged rainfall.
• How does urbanization affect flood risk?

  It increases impermeable surfaces and runoff.
• What was the cost of the Carlisle flooding in 2005?

  Over £400 million.
• What is the impact of climate change on the hydrological cycle?

  It alters precipitation and evaporation rates.
• What is water stress?

  When each person has below 1700 m³ of water.
• What is the difference between water stress and water scarcity?

  Water scarcity threatens food production.
• What is a physical cause of water insecurity?

  Climate variability and saltwater encroachment.
• How does over-abstraction affect water resources?

  It reduces water supply and causes salinization.
• What is the impact of agricultural pollution on water sources?

  It can wash fertilizers into lakes and rivers.
• What is industrial water pollution?

  Contamination from chemicals used in industry.
• What is water stress defined as?

  Below 1700 m$^3$ of water per person
• How is water scarcity defined?

  Freshwater shortages threaten food production
• What are physical causes of water insecurity?

  Climate variability and salt water encroachment
• What happens during salt water encroachment?

  Drinking water becomes contaminated with salinity
• What are the human causes of water insecurity?

  • Over abstraction from rivers and groundwater
  • Water contamination from agriculture
  • Industrial water pollution
• What was a consequence of over abstraction during the Green Revolution in Punjab?

  Salinization and reduced food production
• What can cause water contamination from agriculture?

  Use of fertilizers and pesticides
• What conflict arose in Kerala regarding water use?

  Locals accused Coca-Cola of stealing water