AQA Carbon & Water Cycles

a system

an assemblage of interrelated parts that work together. a series of stores and components and have flows between them

cascading system

outputs from one system becomes the input for the adjacent system

interception

raindrops fall on vegetation, preventing it from reaching the soil & river

leaf drip

water from leaves to soil

capillary uptake

water on roots

stem flow

water reaches the ground by flowing down trunks or stems or by dropping off leaves

infiltration

the passage of water vertically into the soil. in filtration cannot occur if soil is saturated

Percolation

a vertical movement of water from above the water table to below the water table. of the bedrock is impermeable, no percolation can occur

surface runoff (overland flow)

occurs during heavy rainfall when the ground is saturated or if surfaces are impermeable. rate except for in urban areas

through flow

water flows laterally through the soil to channel, mainly along "pipes" caused by animal activity or growth of plant roots

ground water flow

water moves laterally at a very slow rate. it transfers water to the river through their bed and banks long after a rainfall event

hydrostatic pressure

water goes up to river defying gravity

channel flow

precipitation directly entering the river channel

lithosphere

all rocks/ soils/ ground water stores found on the earth underground

Hydroshpere

all water stored on the earth. mostly found in ocean and seas, rivers and lakes. can also be found as underground water stores (aquafers)

96.5% of water is salt water

2.5% is fresh water

atmosphere

all water held in the atmosphere held as water vapour e.g. clouds

the atmosphere contains 12,900km3 of water as vapour - only 0.4% of earths total

crysphere

all ice stored on earth. mostly in Antarctica, Greenland, Canada, Russia, tops of mountains , sea ice, permafrost, ice caps, ice sheets, alpine glaciers

porous soils

holds very little water but allows the transfer of water

clay soils

store a huge amount of water but allows very little transfer

store residence time

the amount of water in a store divided by the rate of addition of water to the store or the rate of loss from it

fusion

the substance changes from a solid to liquid

evaporation

the substance changes from a liquid into a vapour

condensation

substance changes from a vapour to a liquid

evaporation rates depend on:

• amount of solar energy

• availability of water

• humidity in the air

dew point

the temperature at which water vapour in the air turns into liquid water

cryospheric processes

• ice is a large store of water - over time has fluctuated lots

• in the short term snow accumulates and adds to the mass of the glacier or ice sheet. annual changes in cryosphere change between winter & summer

orographic (relief rainfall)

air rises over mountains: cools & condenses

convection rainfall

air heats and rises. when air rises it cools and condenses. most common on the equator. often causes heavy rainfall

frontal rainfall

when warm and cold air meets. warm air forced over cold air, rises and condenses

drainage basin

the area of land drained by a river and it's tributaries. it includes water found on the surface and soil near surface geology. an open system/ cascading system

water balance/ budget

within a drainage basin the balance between inputs & outputs

rivers regime

discharge levels rise and fall in a river, often showing an annual pattern

water balance equation

precipitation(P) = discharge(Q) + evapotranspiration(E) +/- changes in storage

hydrograph equation

discharge = cross sectional areas × velocity in m3/s / cumecs

lag time

the time difference between the peak if the rain storm and the peak flow of the river.

a longer lag time = less prone to flood

features of a drainge basin

• source

• confluence

• tributary

• river channel

• mouth

• water shed

water balance

within a drainage basin the balance between inputs & outputs

run off variation and hydrographs

river flow is studied by measuring discharge (volume of water passing a measurement point in a given time). this is measured by using gauging stations

a flashy hydrograph

short lag time, high peak, steep rising and falling limbs

a subdued hydrograph

long lag time, low peak, gently rising and falling limbs

short lag time

• saturated soil

• lots of tributaries (high drainage density)

-lots of intense rainfall

-urbanisation

-impermeable surfaces

-agriculture

-steep soil angles

-deforestation

long lag time

-unsaturated soil

-no/little tributaries

-little rainfall

-small drainage basin

-permeable soils

-lots of vegetation

-rural

accumulation

inputs to a glacial system due to snow fall

ablation

output of a glacial system due to melting

sublimation

ice changing directly into water vapour

physical factors affecting hydrographs

-drainage basin density and size

-drainage basin relief/slope

-drainage basin shape

-geology

-vegetation

-saturation level by antecedent rainfall

human factors affecting hydrographs

-deforestation

-afforestation

-urban growth

-agriculture

-water abstraction

freshwater vs salt water %

oceans - 97%

freshwater 3%

freshwater storage %

rivers and ice caps - 69%

groundwater - 30%

surface/other freshwater - 1%

processes involved within the transfers of carbon

-photosynthesis

-respiration

-decomposition

-combustion

-burial and compaction

positive feedback example

increase in temperature ->increase in oceanic temperature -> dissolved co2 released from warmer oceanic -> increase in co2 -> further atmospheric warming

cloud formation

visible masses of water droplets or ice crystals held in the atmosphere. form when:

-air is saturated either bc it has cooled below the dew point or evaporation means the air has reached its maximum water holding capacity

-condensation nuclei are present

how does the process of evaporation and condensation relate to the formation of clouds

water evaporates from the surface of the earth and condenses around the nuclei to form visible water droplets

how does the process of evaporation and condensation relate to the formation of rainfall

water evaporates into the atmosphere, condensation occurs when air temperature reaches its dew point or due to adiabatic cooling

how does temperature affect evapotranspiration

warmer temperatures lead to higher rates of evapotranspiration as warm air can hold more water vapour

how does wind affect evapotranspiration

evapotranspiration increases as wind moves humid air away and the air does not become saturated as quickly.

how does humidity affect evapotranspiration

the more humid it is, the lower the evapotranspiration as the air becomes saturated quickly

name the flows of the drainage basin system and state a factor that will affect the rate of flow

stem flow - vegetation cover

precipitation - air humidity

evaporation - temperature

evapotranspiration - wind

percolation - soil moisture

groundwater flow - vegetation cover

river flow - precipitation

overland flow - ground saturation

infiltration - amount of vegetation cover

explain the term water balance

water balance is when there is a long-term balance between inputs and outputs of water in the drainage basin system

list the factors that lend to variations between different river regimes

climate - temperature, precipitation

drainage basin characteristics - gradient, geology, drainage basin size, shape, density and land use

what are the major pools/stores of carbon

lithosphere