Water Flashcards
(42 cards)
What is an input?
Where matter or energy is added to the system
(Precipitation)
What is an output?
Where mater of energy leaves the system
(Evaporation, evapotranspiration and runoff)
What is a store?
Where matter or energy builds up in the system
(Lake, large body of water)
What is a flow?
Where matter or energy moves in the system
What is a boundary?
Limit to the system
(Watershed)
What is an open system?
When systems receive inputs and outputs of energy or matter.
What is a closed system?
Energy inputs equal outputs
What is dynamic equiliubrium?
When inputs and outputs are equal.
What is postive feedback?
When an event amplifies the impact of the original event.
What is negative feedback?
Event that nunifies the impact of the original event
Leads to dynamic equilibrium
Example of open systems
Local scale
Carbon and water cycle
BUT on a global scale they are closed systems
What are systems composed of?
Flows/transfers, inputs, outputs and stores/components
The water cycle
Local scale
Local drainage Basin
Water lost as an output (evapotranspitation/runoff), more can be gained as an input (precipitation).
Due to not being in equilibrium = open system.
The components of the water cycle drive/cause change over time.
Examples of Inputs
And different varieties
Precipitation:
Convectional: heat from sun = warm air rises and condenses at hight and falls as rain.
Relief: Warm air forced up by a barrier (mountain), = condense at hight and fall as rain.
Frontal: Warm air rises over cool air, different densities, condenses at hight ans falls as rain
Examples of outputs
Evapotranspiration: Evaporation & transpiration. Evap = water heated by sun, gas, rises into atmopsphere. Trans= in plants, respire through leaves, releasing water they absorb, evaporates due to heating by the sun.
Streamflow: All water that eneters a drainage basin either leaves through the atmosphere or through streams which drain the basin, (tributaries).
Examples of Flows
Infiltration, grass/crops allow quicker infiltration, but heavy rainfall greater than infilitration capacity causes overland overlfow.
Percolation: water moves from ground or soil into porous rocks/rock fracures. Percolation rate depends on amount of fractures present.
Throughflow: Water moves through soil and into streams or rivers- dependant on soil type.
Surface runoff (overland flow): water flows above the ground as sheetflow.
Groundwater flow: Water moves through rocks
Streamlow: water moves through establised channels
Stemflow: Flow of water intercpeted by plants or trees, down a stem, leaf, branch or other parts of the plant.
Examples of Stores
Soil water: utilised by plants
Groundwater: stored in the pore spaces of rock
River channel: stored in a river
Interception: water intercepted by plants on their branches and leaves before reaching the ground
Surface storage: water stored in puddles, ponds, lakes, etc.
What is the water table?
The upper level at which the pore spaces and fractures in the ground become saturated.
What is the water table used for?
Used by researchers to assess drought conditions, health of wetland systems, success of forest restoration programmes, etc.
What is the water balance?
And what formula does it use?
Used to express the porcess of water storage and transfer in a drainage basin.
FORMULA: Precipitation = total runoff + evapotranspiration +/- (change in) storage
The water balance of an area will change dependent on physical factors, especially during seasonal variations of temp and precipitation.
Changes to the water cycle
What is the water cycle impacted by?
On a local scale
Deforestation: less interception = surface runoff increase. Soil no longer held by roots = soil water storage decreases = fewer plants, transpiration decreases.
Storm events: Large volumes saturate the ground to its field of capacity. No more water can infiltrate the soil = more surface runoff. Less effective at recharging water is stored than in prolonged rainfall.
**Seasonal changes: **Spring- more veg = more interception
Summer: less rain, harder ground = impermeable = more surface runoff
*Autumn: *less veg, more rain
*Winter: *frozen ground may be impermuable = more surface runoff. Snow discourages runoff.
**Agriculture: **Pastoral farming = compressed soil = reducing infiltration. Arable (crops) = ploughing = increased infiltration by creating looser soil, decreases surface runoff.
Irrigation can lead to groundwater depletion.
Urbanisation: Roads/buildings = impermeable surfaces likely to have drains which creates impermuable surfaces = reduce infiltration but increase runoff, reduce lag-time and increase flood risk.
Green roofs and sustainable urban drainage systems use grass and soil to reduce of impermuable surfaces, help urban flooding.
What is the soil water budget?
Shows the annual balance between inputs and outputs in the water cycle and thir impact on soil water storage/availability.
What is the soil water budget affected by?
How much rainfall/dry weather there is.
Dependant on type, depth and permeability of the soil and bedrock.
What is the field capacity?
The maximum level of storage of water in the soil.
Once it is reached, any rainfall after this will not infiltrate the soil = likely to cause flooding.
