ELSS SG1 Flashcards
What are three reasons water is important for people?
Economic activity e.g. farming, Chemical reactions in the body and the circulation of oxygen and nutrients, Growth and reproduction
What are three reasons water is important for flora?
Photosynthesis (to make glucose and starches to grow), Transport nutrients from the soil, Metabolic function
What are three reasons water is important for fauna?
Chemical reactions in the body and the circulation of oxygen and nutrients, Cooling systems (evaporate cooling), Respiration
What are three reasons water is important for climate?
Clouds reflect 1/5 of incoming solar radiation and lower surface temperatures, Water vapour absorbs long-wave radiation helping maintain average global temperatures, Precipitation
Is the global water system a closed or open system?
Closed - transfers energy but not matter between the sun and earth
Define Stores or Stocks
The total amount of material of interest held within a part of the system
What are stocks expressed in?
Units of mass
What are stores measured in?
Thousands of cubic kilometres
What are the five global stores of water?
Lithosphere, Biosphere, Hydrosphere, Cryosphere, Atmosphere
Define Lithosphere
The rigid outer part of the earth, consisting of the crust and upper mantle. It is divided into tectonic plates
Define Biosphere
The space at the Earth’s surface and within the atmosphere occupied by living organisms
Define Hydrosphere
All the waters on the Earth’s surface e.g. lakes and seas
Define Cryosphere
The frozen part of the Earth’s surface e.g. ice caps, permafrost, glaciers
Define Atmosphere
The envelope of gases surrounding the planet
What % of water is stores on land (e.g. in ice, groundwater, soils, biosphere etc.)?
3%
What % of water is stored in the atmosphere?
0.1%
What % of water is stored in oceans?
97%
What % of water is stored in polar ice and glaciers?
2%
How long is water stored in oceans?
3,600 years
How long is water stored in ice?
15,000 years
How long is water stored in soil?
2-50 weeks
What % of freshwater is stored in rocks below the ground surface as underground reservoirs called aquifers?
20%
Where is most water vapour distributed?
Around the equator (between 15 degrees N and S) there is 55-770mm of water vapour
Why is there more water vapour at the equator?
Rays are more concentrated around the equator due to curvature so the climate is warmer = more water evaporates so the air has more water vapour (is more humid)
Define Drainage Basin
The area of land drained by a river
Define Confluence
Where two rivers meet
Define Tributary
Small river flowing into a larger river
Define River Source
Where the river starts
Define Watershed
Boundary between two drainage basins
Why is a river drainage basin an open system?
Water enters (precipitation) and leaves (evaporation/flows to sea) the drainage basin and won’t return
Define Precipitation
Any form of moisture falling from the sky e.g. rain, snow, sleet, fog
When does precipitation occur?
When water vapour cools to its dew point and condenses into water droplets. Precipitation only occurs when the droplets coalesce into larger ones. When they get large and heavy enough to overcome the uplift of the air, the droplets leave the cloud as precipitation
Define Flows
Physical mechanisms that drive the flux of material between stores
What is flows measured in?
Thousands of cubic kilometres/year
Define Flux
A measurement of the rate of flow of material between stores
Define Channel Precipitation
10% of precipitation falls directly into the river channel, before flowing out to the ocean
Define Interception
Precipitation is stopped from reaching the ground by vegetation
Define Stemflow
Water runs along branches and down the trunk of a tree
Define Throughfall
Water drips off leaves to the ground
Define Interception Loss
Water that is intercepted by plant surfaces and is later evaporated or absorbed by the plant. It never reaches the ground
What are four factors affecting interception loss?
Interception storage capacity, Wind Speed, Vegetation type, Tree species
How does interception storage capacity affect interception loss?
Before the onset of rain, the plant surfaces are dry so increasing the interception storage capacity. In prolonged rain interception storage capacity is reduced due to more stemflow and throughfall which could reduce the overall amount of interception loss which can happen
How does wind speed affect interception loss?
Turbulence increases with wind speed, causing more throughfall and therefore reducing interception loss
How does vegetation type affect interception loss?
Trees have the highest interception storage capacity due to their large surface area so interception losses will be higher compared to grasses and crops
Hoe does tree species affect interception loss?
Interception losses are greater for coniferous trees (evergreens e.g. conifers) than broadleaved deciduous trees. This is because coniferous trees all year round and water adheres to the spaces between the needles
Define Infiltration
The downward movement of water into the soil
Define Percolation
Movement of soil water into underlying permeable rock
What is the fastest flow of water?
Overland flow
What is the slowest flow of water?
Groundwater flow
What five factors affect infiltration?
High infiltration capacity, Saturation of soils, Arable land in winter, Coniferous trees, Rock type
Define Discharge
The volume of water passing a given point in a given time
What is discharge measured in?
Cubic meters per second (CUMECS)
What two ways does water leave the drainage basin and enter the atmosphere?
Evaporation and Transpiration
Define Evaporation
Water changes state from a liquid to water vapour due to heat
Define Transpiration
Loss of water from vegetation stomata via evaporation
What four factors affect transpiration?
Temperature, Wind speed, Water availability to plants, Seasons
Define Water Balance
The balance between the inputs and outputs of a drainage basin
Precipitation (P) =
Evaporation (E) + Streamflow (Q) +/- Storage
Define Water Surplus
Precipitation is greater than evapotranspiration and streamflow, creating saturated soil
Define Water Deficit
Precipitation is less than evapotranspiration and streamflow, creating dry soil
