The Water Cycle Flashcards
Blue water
Water stored in rivers, lakes and groundwater in liquid form. The visible part of the hydrological cycle
Green water
Water stored in soil and vegetation. The invisible part of the hydrological cycle
Precipitation
The movement of water in any form from the atmosphere to the ground
Evaporation
The change in state of water from a liquid to a gas
Residence time
The average times a water molecule will spend in a reservoir or store
Fossil water
Ancient, deep groundwater from former pluvial (wetter) periods
Transpiration
The diffusion of water from vegetation into the atmosphere, involving a change in state from gas to liquid
Groundwater flow
The slow transfer of percolated water underground through pervious or porous rock
Catchment
The area of land drained by a river and its tributaries
Watershed
The highland which divided and separates water flowing into different rivers e.g. Tyne and Wear
Condensation
The change in state from a gas to a liquid, such as when water vapour changes into water droplets
Dew point
The temperature at which dew forms; it is a measure of atmospheric moisture
Convectional rainfall
Often associated with intense thunderstorms, which occur widely in areas with ground heating such as the Tropics and continental interiors
Cyclonic rainfall
A period of sustained, moderately intensive rain; it is associated with the passage of depressions
Orographic rainfall
Concentrated on the windward slopes and summits of mountains
Interception loss
Water which is retained by plant surfaces and later evaporated or absorbed by the vegetation and transpired. When the rain is light, for example, drizzle, or of short duration, much of the water will reach the ground and will be recycled by this process
E.g. standing under and tree and won’t get wet because of this
Throughfall
Period where rainfall persists or is relatively intense, and the water drops from the leaves, twigs, needles etc.
Stem flow
When water trickles along twigs and branches then down the trunk
Infiltration
The movement of water from the ground suface into the soil
Infiltration capacity
The maximum rate at which rain can be absorbed by soil
Surface run-off
The movement of water that is unconfined by a channel across the surface of the ground. Also known as overland flow
Throughflow
The lateral transfer of water down slope through the soil via natural pipes and percolines
Percolines
Lines of concentrated water flow between soil horizons to the river channel
Percolation
The transfer of water from the surface of the rock into the bedrock beneath
Saturated overland flow
The upward movement of the water table into the evaporation zone
Albedo
A measure of the proportion of the incoming solar radiation that is reflected by the surface back into the atmosphere and space
Evapotranspiration
The combined effect of evaporation and transpiration
Channel flow
The flow of water in streams or rivers
Channel storage
The storage of water in streams or rivers
Potential evapotranspiration (PEVT)
The water loss that would occur if there was an unlimited supply of water in the soil for use by vegetation
Deforestation
The cutting down and removal of all or most trees in a forested area
Afforestation
The planting of trees in an area that has not be forested in recent times
River regime
The annual variation in discharge or flow of a river at a particular point or gauging station, usually measured in cumecs
Rising limb
The part of a storm hydrograph in which the discharge starts to rise
Peak discharge
The time when the river reaches its highest flow
Lag time
The time interval between peak rainfall and peak discharge
Falling or recessional limb
The part of a storm hydrograph in which the discharge starts to decrease
Base flow
The normal, day-to-day discharge of the river
Meteorological drought
Shortfalls in precipitation as a result of short term variability within the long term average overall, many semi-arid places e.g. the Sahel
Recent years have shown a downward trend in rainfall totals and the duration and predictability of the rainy season
Agricultural Drought
MD leads to a lack of soil moisture and soil water availability, knock on effect on plant growth and reduces biomass
Hydrological drought
Reduced stream flow and groundwater levels, decrease because of reduced inputs from precipitation and continued high rates of evaporation
Results in reduced storage in lakes and reservoirs often with marked salinisation and decreased water quality
Famine drought
A humanitarian crisis with widespread shortages as agricultural systems fail and food supplies are short. Leads to economic, social and environmental impacts
Teleconnection
Refers to climate anomalies which relate to each other at large distances
Desertification
Land degradation in arid, semi-arid and dry sub-humid regions resulting in various factors, including climatic variations and human activity
Wetland
An area of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt
Groundwater flooding
Flooding that occurs as the ground has become saturated from prolonged heavy rainfall
Surface water flooding
Intense rainfall has insufficient time to infiltrate soil so flows overland
Flash flooding
A flood with an exceptionally short lag time - often minutes or hours
Urbanisation
The increase in the number of people living in towns and cities compared to the number of people living in the countryside
Jökulhlaup
A type of glacial outburst flood that occurs when the dam containing a glacial lake fails
Eutrophication
Excessive richness of nutrients in a lake or other body of water, frequently due to run-off from farming land, which causes dense growth of plant life and death of animal life from a lack of oxygen
Morbidity
A state of ill health
Players
Individuals, groups or organisations with an involvement or interest in a particular issue
Fracking
Hydraulic fracking or oil/gas well simulation is a new technique in which rock is fractured by pressurised liquid
Virtual water
The hidden flow of water when food or other commodities are traded
Green revolution
The use of high yield varieties (HYVs) of crops along with the use of agrochemicals and irrigation to increase yields and improve food supplies; begun in the 1960s
Structural adjustment programmes
Neo-liberal policies promoted by the WB and IMF to help developing countries to overcome their debt problems, These are now superseded by poverty reduction strategy papers (PRSPs) as for many countries SAPs resulted in unacceptable hardship and little progress with solutions to debts
NIMBYism
‘not in my backyard’ - people protesting about developments which they see as detrimental to their own neighbourhood
Top down
Large scale capital intensive development schemes, usually government run
Bottom up
Small scale development schemes, usually ran by local groups
Grey water
Refers to waste bath, sink or washing water. It can be recycled, resulting in savings in water usage
Hydroponics
The method of growing plants using mineral nutrient solutions without soil
Intergrated water resource management (IWRM)
The process which promotes the coordinated development and management of water, land-related resources in order to maximise economic and social welfare in an equitable manner without compromising the sustainability of vital eco-systems
Factors controlling how precipitation reacts on reaching the land surface
Basin wide factors
Relief Geology Climate Land use Vegetation Drainage density
Over-abstraction
Abstracting too much water from groundwater can lead to rivers drying up during low rainfall
Inputs to the hydro cycle
Precipitation
Outputs of the hydro cycle
Evaporation, transpiration and stream flow
Drainage basin stores
A 'black box', unknown due to a number of factors Throughput controlled by: Relief Geology Water quantity Available energy
The Inter-tropical Convergence Zone
The biggest flux, transporting water from oceans to land
Steep angle of the sun at the Tropics intensifies radiation so there is higher evaporation
Vapour is transferred towards the ITCZ
Where air rises and cools due to convectional current, and form clouds
Antecedent moisture
Water from one storm that has not been drained away before more rain arrives
Aquifer
An underground reservoir most commonly formed in rocks such as chalk and sandstone
Closed system
Where there are no inputs or outputs of matter from an external source - i.e. where inputs and outputs are outbalanced
Complex river regimes
Where larger rivers cross several different relief and climatic zones and therefore experience the effects of different seasonal climatic events. Human factors can also contribute e.g. damming rivers for energy or irrigation
Cryosphere
The frozen part of the Earth’s hydrological system
Discharge
The volume of water passing a certain point in the channel over a certain amount of time
Drainage density
Describes whether a river has many or few tributaries. Dense drainage networks have many tributaries and carry water more effectively
El Niño
A situation occurring every 3-8 years where the pressure systems and weather patterns are reversed
El Niño Southern Oscillation (ENSO)
The change in air pressure between a normal year and an El Niño year
Flux
The movement of water between stores
Gravitational Potential Energy
The ways in which water accelerates under gravity, thus transporting it to rivers and eventually to the sea
Jet stream
A band of fast-moving air which determines the direction of weather systems and their speed of movement
La Niña
When the normal pressure systems and weather patterns intensify and low pressure over the western Pacific becomes lower, and high pressure over the eastern Pacific becomes higher
An exaggeration of normal
Leeching
Loss of nutrients from the soil through infiltration
Mega-drought
A period of unusually low rainfall, lasting for decades or longer
Negative feedback
When a change tends to reinforce a system, leading to stability
Rain shadow effect
When orographic rainfall has occurred over an upland area, the area on the lee side of the hills will receive less rain because the air descends, warms and becomes drier
Storm hydrographs
A graph showing how a river responds to a particular storm
It displays both rainfall and discharge
Sustainable Drainage Systems (SuDS)
Techniques such as permeable pavements and infiltration basins which reduce surface runoff produced from rainfall
Thermohaline circulation
The flow of warm and cold water that circulates around the world’s oceans
Throughput
The quantity of water that flows through a system or store
Water budget
The difference between inputs and outputs in a given area
Water insecurity
The state where present and future supplies of water cannot be guaranteed, caused by water scarcity and water stress
Water poverty index (WPI)
Measures how far a community or country meets all the criteria for; the availability of water resources, access to water, handling capacity, use of water and the ability to sustain nature and ecosystems
Water scarcity
There is less than 1000m3 of water available per person per year. An inbalance between demand and supply of water, classified as physical scarcity (insufficient water to meet demands) or economic scarcity (people can’t afford water even when it’s available)
Water stress
There is less than 1700m3 of water available per person per year. If a country’s water consumption exceeds 10% of its renewable fresh water supply, including difficulties in obtaining new quantities of water, as well as poor water quality restricting usage
World Water Gap
The idea that in many parts of the world there is not enough water to meet the demand whereas wealthy countries are consuming greater and greater quantities of water
Walker cell
The circulation of air whereby upper atmospheric air moves eastward and surface air moves west across the pacific, causes the trade winds which control El Niño/La Niña
