Water Cycle and Water Insecurity - All Flashcards
What type of system is the global hydrological cycle and what drives it?
A closed system driven by solar energy (evaporation) and gravitational potential energy (precipitation and runoff).
Name the major water stores and rank them by size.
Oceans (96.5%) > Cryosphere > Groundwater > Surface Water > Atmosphere > Biosphere.
What is the water budget and how does it limit water availability?
The global water budget refers to how water is distributed/stored. Limited availability due to residence times (e.g., fossil water) and non-renewable stores like cryosphere losses.
What is a drainage basin and is it a closed or open system?
It’s an open system with inputs (precipitation), flows (interception, infiltration, percolation etc.), and outputs (evapotranspiration, runoff).
Name 3 physical factors that influence drainage basin flows.
Climate, soil type, and geology (e.g. permeable = more infiltration).
How does deforestation in Amazonia affect the water cycle?
Reduces interception and evapotranspiration → increases runoff → alters groundwater recharge and local climate patterns.
What is a water budget and what does it show?
The balance between precipitation and evapotranspiration, influencing soil moisture and water availability.
Give examples of climate types and their water budgets.
Tropical: High rainfall, surplus.
Temperate: Seasonal variation.
Polar: Low evapotranspiration, water locked in cryosphere.
Define a river regime and name 3 examples
The annual variation in river discharge.
Amazon: Equatorial, constant high flow.
Yukon: Arctic, summer peak from snowmelt.
Indus: Monsoonal, flow drops when glacial sources reduce.
What physical and human factors shape a storm hydrograph?
Basin shape, slope, soil, geology, vegetation cover (physical);
urbanisation, land use, deforestation (human).
What are the two main types of drought?
Meteorological (lack of precipitation)
Hydrological (reduced flow in rivers/groundwater).
How does ENSO contribute to droughts?
El Niño suppresses rainfall in places like Australia, increasing drought risk.
Example of human impact worsening drought?
Sahel – overgrazing and deforestation reduced soil moisture retention → desertification.
How does drought impact ecosystems?
Wetland drying, reduced biodiversity, forest stress → e.g. Okavango Delta in Botswana.
Name 4 meteorological causes of flooding.
Flash flooding from intense storms
snowmelt
monsoons
prolonged rainfall.
How do humans exacerbate flood risk?
Urbanisation, deforestation, hard engineering (e.g., levees), mismanaged rivers
Case study of UK flood event?
UK 2007 floods – 13 deaths, £3bn in damages, caused by prolonged rainfall and overwhelmed drainage.
How does climate change affect the water cycle?
Alters precipitation patterns, evaporation rates, increases flood/drought risk.
What stores and flows are affected by climate change?
Shrinking glaciers, reduced snowpack, permafrost melt, declining lake levels.
What’s the synoptic risk tied to climate change?
Uncertainty
In water supply planning; harder to predict floods and droughts (links to development, food security, migration).
Define water stress and water scarcity.
Stress: <1700 m³/person/year;
Scarcity: <1000 m³/person/year.
Physical causes of water insecurity?
Climate variability, saltwater intrusion, seasonality of rainfall
Human causes of water insecurity?
Over-abstraction, contamination (e.g., agricultural runoff, industrial discharge).
What is ‘virtual water’?
Water embedded in production of goods – increases global water dependency.
What’s the difference between physical and economic water scarcity?
Physical: not enough water.
Economic: lack of infrastructure to access available water.
Why does water pricing vary globally?
Supply vs demand, privatisation, subsidies. Example: USA vs Sub-Saharan Africa.
How can water insecurity cause conflict?
Transboundary tensions (e.g., Nile Basin, Mekong River) over shared rivers, competing uses (irrigation vs hydropower).
Name 3 hard engineering solutions for water supply
Water transfers (e.g., China SNWTP)
Mega dams (e.g., Three Gorges)
Desalination plants (e.g., UAE).
Pros & cons of hard engineering?
Pros: Large-scale supply.
Cons: High cost, environmental damage, displacement.
Give 2 sustainable water management strategies.
Smart irrigation (e.g., drip systems),
Recycling/reuse (e.g., Singapore’s NEWater).
What is Integrated Water Resource Management (IWRM)?
Holistic planning to balance water use among stakeholders.
Example: Colorado River Compact, UNECE Water Convention.
