Water Cycle

systems approach

systems approach/ system = a set of interrelated components working together towards a process

flow/ transfer = when matter or energy moves from one store to another

  • eg. stemflow, infiltration, percolation, throughflow, throughfall groundwater flow, evapotranspiration, transpiration, evaporation, condensation, overland flow, runoff and channel flow

input = where matter/energy is added to a system

  • eg. precipitation

store/component = where energy or matter builds up

  • eg. interception, soil water, surface storage, groundwater. soil storage

matter= any physical substance involved in a system

  1. eg. transpiration, evaporation and channel flow

output = where matter or energy leaves a system

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open system = energy and matter can be transferred into the surrounding environment. eg. drainage basin (sun enters and leaves a system.) water is an input and output as river discharge.

closed system = energy is transferred into the surrounding environment, matter is not. the matter is cycled within the stores. eg carbon cycle. energy is input but the amount of carbon stays the same.

isolated system = no interactions, no input/ output not found in nature (a lab experiment)

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dynamic equillibrium

dynamic equilibrium = inputs and outputs are in balance. dynamic involves the subtle changes available

positive feedback = effects of an action are amplified or multiplied and creates multiple knock on effects eg. global temperatures rise, increased sea temperatures, co2 released by warmer oceans, more co2 in atmosphere

negative feedback = the effects are nullified, return to its original state. eg. increase in atmospheric co2, plant growth, reduces atmospheric co2.

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global distribution

The hydrosphere encompasses all forms of water, including liquid, solid, and gas.

atmosphere = layer of gas between the earth’s surface and space held in place by gravity.

biosphere = living things are found

The hydrosphere (also known as the lithosphere) is the earth's outermost layer. crust plates in the upper part of the mantle.

these systems form a CASCADING system. energy and matter is passed along the chain from one and another. they are interlinked.

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SYSTEMS TERM- WATER CYCLEdefinition}}(drainage basin)}}}}water example}}}}(woodland)carbon cycle example}}
inputmatter or energy is added to a system}}precipitation}}}}precipitation with dissolved co2.}}
outputmatter or energy leaves a system}}river discharge}}}}dissolved carbon with runoff}}
energypower or driving force}}heat with changes in state of water}}}}glucose via photosynthesis}}
stores/componentsenergy or matter builds up}}puddles, ground storage. stem storage}}}}trees, soils, plants, rocks (biosphere)}}
flows/transferslinks or relationships between stores}}infiltration, groundwater flow, runoff,}}}}burning, absorbtion}}
positive feedbackevents that amplify and increase change.}}rising sea levels, due to thermal expansion and melting of freshwater ice, can increase the rate of calving. increase in melting, sea levels rise further.}}}}increased temperatures due to climate change cause permafrost melting, trapped greenhouse gases are released, raising temperatures}}
negative feedbackevents that decrease the change, brings it back towards the original state}}increased surface temperatures lead to more evaporation from ocean, more clouds reflect the sun, which leads to cooling.}}}}co2 leads to warmer temperatures, with more plant growth, photosynthesis increases removing co2 from air, counteracting rise in temp.}}
dynamic equillibriumwhere the state of balance is equal, yet constantly changing within the system.

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where is earth’s water?

global water:

hydrospheric/ oceanic water = 96.5%

other saline water = 0.9%

freshwater = 2.5%

  • glaciers and icecaps = 68.7%
  • ground water 30.1%
  • surface/other freshwater 1.2%
    • ground ice and permafrost = 69%
    • lakes = 20.9%
    • soil moisture = 3.8%
    • swamps, marshes = 2.6%
    • rivers = 0.49%
    • living things = 0.26 %
    • atmosphere = 3%

hydrosphere

fresh water = cryoshphere/ lithosphere/ atmosphere

oceanic water = cryosphere.

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biosphere water = consists of all water stored in biomass, vegetation such as trees, trees store water in branches.

cryosphere = sea ice, alpine, permafrost, ice sheets, ice caps

lithosphere = ground water, soil water, biological water, surface water, rivers, lakes, wetlands.

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Water Processes

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evaporation and condensation:

evaporation = water changes from liquid to gas.

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alongside evaporation there is transpiration = the process by which moisture is lost through stomata.

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condensation (and cloud formation) = air cools it holds less water vapour. it will become less saturated, and will be converted into liquid water. energy is released in an exothermic reaction. there needs to be something for the molecules to condense on. they are condensation nuclei (smoke salt or dust) but can be cold surfaces

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cloud formation:

insolation provides heat energy. earths surface is heated. an updraft is called thermal torms. warmer air pocket rises. (this is called convection)

as it rises it will begin to expand tue to lower pressure and it cools. the cooling is called adiabatic cooling

the thermal will continue to rise until it reaches the saturation point. condensation occurs, and at the dew point, clouds form.

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sublimation and deposition:

sublimation = a direct change of state from solid to gas

deposition = change to state from gas to solid. eg. formation of ice via water vapour

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melting and freezing:

melting = a change of state from solid to liquid

freezing = a change of state from liquid to solid.

processexplainationtemperaturehumiditysunlightwindsaltitudewaterfactors that affect
condensationgas to liquidcold, inputs increase--decreases with solar radiationdecreases with winds (high presure)
}}evaporation}}}}liquid to gas}}}}warm, inputs increase}}}}increases with dry air}}}}increases with solar radiation}}}}increases with winds}}}}increases if there is a large supply of water}}amount of solour energy, availability of water, humidity in the air
freezingliquid to solidcold, imputs increasedecreases with solar radiationdecreases with windsfreezing point increases with altitude-increases if there is a large supply of water
meltingsolid to liquidwarm, inputs increaseincreases with solar radiationincreases with winds
}}sublimation}}}}solid to gas}}}}warm, inputs increase}}}}increases with dry air}}}}increases with solar radiation}}}}increases with strong winds as their bring mild warm air}}}}increases with high altitudes because low pressure brings low temperatures}}
depositiongas to soliddecreases with solar radiation

low pressure brings low temperatures**

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atmospheric circulation model:

winds blow from high to low pressure. polar, ferrel and hadley cell

polar and ferrel cell: rising warm moist air, descending cool dry air.

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adiabatic rainfall = when air rises and expands in low pressure of the upper atmosphere

frontal effect = warmer air rises over cooler air

warm air is cooled and water vapor consenses, rainfall occurs

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precipitation = discharge + evapotranspiration +- changes in storage

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melting- solid to liquid

freezing- liquid to solid

→ ablation varies with temperature

→ when cold, inputs increase

→ earth emerging from glacial period, 21,000 years

evaporation- liquid to gas

→ gains energy from solar radiation

→ higher solar + more evaporation

→varies by location/season

→ high evaporation = warm, dry air

condensation- gas to liquid

→ loses energy

→ water droplets flow to other systems

→ decrease water store in atmosphere

→ varies by amount of water vapour + temperature

deposition- gas to solid

sublimation- solid to gas

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drainage basin:

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input = precipitation

storage = interception, soil water, surface storage, groundwater

flow = stemflow, infiltration, percolation, through flow, groundwater flow, transpiration, evaporation and channel flow

output = transpiration, evaporation and channel flow

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source

tributary

confluence

watershed

river catchment

mouth

delta

alluvial fan

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water balance graph

shows a long term relationship between inputs, outputs, stores within the drainage basin.

p = q + e + (s)

p = precipitation

q = runoff/discharge

e = evaporation

s = storage change

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there are seasonal changes.

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lag time = delay between peak rainfall and peak discharge as it takes time for water to flow in river

hydrograph = a graph showing how a river responds to a particular storm

peak rainfall = the part of a storm which records the greatest hourly rainfall

peak discharge = the part of the graph which records the greatest level of a river within the channel

rising limb = discharge increasing into the river

falling/receding limb = discharge is reducing, less water flowing into river

discharge line = volume of water in cumecs

bankfull discharge = river reaches the top of the channel, will begin to overflow and flood depending on river

baseflow = normal discharge of river fed by groundwater and throughflow. can change seasonally

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influences of runoff in a drainage basin:

natural

area/size of drainage basin

→ large drainage basins recieve more precipitation and therefore have larger runoff. larger size means longer lag time as water has a longer distance to travel to reach the main river

shape of drainage basin

→ produce a lower peak flow and longer lag time than a circular one of the same size

ground steepness/ slope

→ channel flow can be faster downa steep slop therefore steeper rising limb and shorter lag time

tributaries

→ the number of smaller streams or tributaries will determine how quickly an area of land will drain

rock type

→ permeable rocks mean rabid infiltration and little overland flow, therefore shallow rising limb

soil type

→ infiltration is generally greater on thick soil, although less porous soils act as impermeable layers. the more infiltration ccurs the longer lag time and shallower the rising limb

land use

→ urbanisation- concrete and tarmac form impermeable surfaces, creating a steep rising limb and shortening the lag time.

→ afforestation- intercepts precipitation creating a shallow rising limb and lengthening the leg time.

storms and precipitation

seasonal changes and vegetation

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transient and permanent characteristics

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human

SAD

→ ==s==oil drainage (farming practices)

ploughing causes more water to infiltrate, reducing runoff

crops increase infiltration and interception

livestock tramples ground, increasing runoff

irrigation increases runoff which makes groundwater levels fall

→ water ==a==bstraction

overabstraction causes droughts.

→ ==d==eforestation (land use change)

deforestation reduces interception by infiltration

infiltration decreases due to mumus content. soil is looser. removal of root systems shatter. there is nothing to hold soil cover.

construction creates impermeable layers, increasing runoff

water passes quicker, increasing flooding

water abstraction reduces water in stores.

Eden Basin Case Study

characteristics of Eden Basin that affets the water cycle

  1. rainfall is higher than natural average due to relief, mountains encourage orographic rainfall. weather coming in from irish sea and is difficult to predict.
  2. eden basin is relatively narrow which increases lag time. less of flashy flood. all rivers converge in carlisle which means all the water enters the city at the same time
  3. slopes within basin are steep. reduces lag time and increases peak discharge
  4. rock type- highest ground (west) is made up of igneous rock which is impermeable. infiltration is slow.
  5. most of basin is made from limestone and sandstone which is permeable. little surface run off.

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factorhow it affects flow / storesexplainationhow significant/important evidence
rainfallorographic (mountainous) rainfall that is higher than average for uk. lots of water, high river discharge.soils can become saturated with prolonged rainfall reducing infiltration and increasing overland flowhigh flood risk especially during winter when prolonged. higher in upland areas lower in lower course but high levels upstream affect areas downstream.average rainfall exceeds 2800mm on Halvellyn average anual rainfall for England and Wales is 920mm
stormseg. desmond 2015 record rainfall. 262mm in 38 hours in village of Shap.increases dischargedifficult to predict and increase flood risk.
geologyhigh grounds have impermeable igneous rock- so low infiltration and high surface runoff. reduces lag timemuch of basin = limestone and sandstone, permeable so infiltration quick and little surfact runoff increasing lag time, increased groundwaterhigh surface runoff in lower course which affects river downstream.
drainage basin shapelong and narrowdecreases lag time as shorter distanceincreases flood risk, flashy- floods quickly.
drainage densitylong and narrow. increases lag time as shorter distance.high flood risk in carlisl- largest settlement in basin so affects largest number of people
reliefsteep. reduces lag time and increases peak discharge as increases surface runoff and decreases infiltrationincreases flood risk, flashy floods quickly
land use (agriculture)more intense farming compacted soils. marching and livestock reduces infiltration and increases surface runoff, increases dischargeincreases flood risk. flashy floods quickly. 30% increase in cattle between 2000-2009
land use- urban areasrural areas increasees, increases impermeable surfaces, reduces infiltration and increases surface runoffbuilding on flooplains prevents infiltration in areas it naturallyincreases flood risk. flashy floods quickly.eden gate north of Carlisle. plans for garden village to s with 10,000 homes. building on floodplains and construction of flood defences increases flooding downstream
land use- deforestationopen grassland has less tree cover so less interception and increased runoffincreased flood risk. thousands of forest now removed

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revision:

what is an individual rainfall event?

  • a rainfall period separated by dry intervals of at least 4 hours

what is ablation?

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how can pores and fissures in soil be made larger and more frequent?

  • burrowing of worms and other ogranisms

biological weathering

chemical weathering

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