Water Scarcity (key terms) Flashcards
Blue water
Water that is stored in rivers, lakes, streams and groundwater (visible).
Cryosphere
Describes the set of all locations on Earth where water is found in solid form, including areas of snow, sea ice, glaciers, permafrost, ice sheets and icebergs.
Drainage basin
Area of land drained by a river and its tributaries. Separated by a watershed (area of highest land around it).
Ecosystem functioning
The biological, chemical and physical processes that take place within an ecosystem.
Ecosystem resilience
The capacity of an ecosystem recover from disturbance or withstand ongoing pressure.
Flux
The flow or flowing of a liquid.
Fossil water
Water contained in an undisturbed space (aquifer) for millennia or longer.
Green water
Water stored in soil and vegetation (invisible)
Saturated overland flow
Occurs when the soil becomes saturated, and any additional precipitation causes runoff.
Water stress
If a country’s water consumption exceeds 10% of its renewable freshwater supply (or less than 1700m^3 per person per year)
Physical water scarcity
When demand exceeds supply or when amount available falls to less than 1000m^3 per person per year.
Economic water scarcity
When clean water is unaffordable even if its available or it is too expensive for people to access the water
Absolute water scarcity
Renewable water supplies (from rivers, aquifers and lakes) become very low (less than 500m^3 per person per year). Leading to widespread restrictions.
Water insecurity
When present and future water supplies cannot be guaranteed.
Surplus
Precipitation is greater than potential evapo-transpiration and the soil water store is full so there is a surplus of soil moisture for plant use, runoff and recharging groundwater. Soil is at field capacity.
Utilisation
Potential evapo-transpiration increases and exceeds precipitation, so there is more water evaporating from the ground surface and being transpired by plants than is falling as rain. Water is also drawn up from the soil by capillary action. The water is gradually used up.
Deficit
The soil water has been used up by high rates of evapo-transpiration and low precipitation.
Recharge
This occurs when potential evapo-transpiration decreases so that it is lower then precipitation and the soil starts to fill up again.
Field capacity
The soil is now full of water and cannot hold anymore. Further rain could lead to surface runoff.
Potential evapo-transpiration
The amount of evapo-transpiration that occurs as a result of temperature and vegetation as long as there is water available.
