Water and Carbon Cycle Flashcards
what are systems composed of?
- inputs
- outputs
- stores
- flows
- boundaries
define inputs
where matter or energy is added to the system
define outputs
where matter or energy leaves the system
define stores
where matter or energy builds up in the system
define flows
where matter or energy moves in the system
define boundaries
limits to the system
what are open systems?
when systems receive inputs and transfer outputs of energy or matter
what are closed systems?
when energy inputs equal outputs
what is dynamic equilibrium in a system?
when inputs equal outputs despite changing conditions
what is positive feedback?
when a chain of events amplifies the impacts of the original event
what is negative feedback?
a chain of events that nullifies the impacts of the original event, leading to dynamic equilibrium
what are systems on a local scale?
open systems
what are systems on a global scale?
closed systems
how can water be lost in a local drainage basin system?
through evapotranspiration and runoff
how can water be gained in a local drainage basin system?
through precipitation
why is a local scale an open system?
the inputs and outputs are not balanced
define precipitation
any water that falls to the surface of the earth from the atmousphere
what are the three types of rainfall?
- convectional
- relief
- frontal
define convectional rainfall
due to heating by the sun, warm air rises, condenses at higher altitudes and falls as rain
define relief rainfall
warm air is forced upward by a barrier (mountains) casino g it to condense at higher altitudes and fall as rain
define frontal rainfall
warm air rises over cool air when two bodies off air at different temperatures meet because the warm air is less dense, so lighter. It condenses at higher altitudes and falls as rain
what is the main input?
precipitation
what are the two main types of output?
- evapotranspiration
- streamflow
define evapotranspiration
evaporation occurs when water is heated causing it to become gas and rise into the atmosphere. Transpiration occurs in plants when they respire through their leaves, releasing water they absorb through their roots, which then evaporate
define streamflow
all water that enters a drainage Bain will either leave through the atmosphere or through streams which drain the basin
what are the seven types of flows?
- infiltration
- percolation
- throughflow
- surface runoff
- groundwater flow
- streamflow
- stemflow
define infiltration
the process of water moving from above ground into the soil
define percolation
water moves from the ground or soil into porous rock or rock fractures
define throughflow
water moves through the soil and into streams or rivers . speed of the flow is dependant on the type of soil
define surface runoff
water flows above the ground
define groundwater flow
water moves through the rocks, which ensures that there is water in rivers even after a long period of dry weather
define streamflow
water that moves through established channels
define stemflow
flow of water that has been intercepted by plants or tress, down a stem, leaf, branch or other parts of a plant
what are the five stores?
- soil water
- groundwater
- river channel
- interception
- surface storage
define soil water
water stored in the soil which is utilised by plants
define groundwater
water that is stored in the pore spaces of rock
define river channel
water that is stored in a river
define interception
water intercepted by plants on their branches and leaves before reaching the ground
define surface storage
water stored in puddles, ponds, lakes, etc
what’s is the water table?
the upper level at which the pore spaces and fractures in the ground become saturated
what is the water balance?
the process of water storage and transfer in a drainage basin system
what formula does the water balance use?
Precipitation = total runoff + evapotranspiration +/- (change in) storage
what are the five impacts on the water cycle on a local scale?
- deforestation
- storm events
- seasonal changes
- agriculture
- urbanisation
how is the water cycle impacted on a local scale by deforestation?
- less interception by trees, more runoff
- soil no longer held together by roots - soil water storage decreases and there are fewer plants so transportation decreases
how is the water cycle impacted on a local scale by storm events?
large amounts of rainfall quickly saturate the ground to its field capacity. No more water can infiltrate the soil, increasing the surface runoff. Storm events are therefore less effective at recharging water stores than prolonged rainfall
how is the water cycle impacted on a local scale in spring (seasonal changes)?
more vegetation growth so more interception by vegetation
what are the four ways the water cycle impacted on a local scale by agriculture?
- pastoral farming
- arable farming
- hillside terracing
- irrigation
what are the two ways the water cycle impacted on a local scale by urbanisation?
- roads and buildings
- green roofs and Sustainable Urban Drainage Systems (SUDS)
what is the soil water budget?
shows the annual balance between inputs and outputs in the water cycle and their impact on soil water storage/availability
why is the water budget never the same each year?
due to varying conditions and the process is affected by how much rainfall/dry weather there is the previous year
what is the water budget dependant on?
type, death and permeability of the soil and bedrock
what is field capacity?
the maximum possible level of storage of water on the soil
what happens to rainfall when the field capacity is reached?
rainfall will not infiltrate the soil and is likely to cause flooding
how is the water cycle impacted on a local scale in summer (seasonal changes)?
less rain, so ground may be harder and more permeable encouraging surface runoff
how is the water cycle impacted on a local scale in autumn (seasonal changes)?
less vegetation growth, so less interception
how is the water cycle impacted on a local scale in winter (seasonal changes)?
frozen ground may be impermeable and encourage runoff. Snow discourages runoff and takes time to melt, slowing down water cycle process
how is does the soil water budget change in autumn?
greater input from precipitation than output from evapotranspiration as deciduous trees loose leaves and cool temperatures mean plants photosynthesis less. Soil moisture levels increase and a water surplus occurs
what are the four ways the water cycle impacted on a local scale by pastoral farming (agriculture)?
livestock trample the ground, reducing infiltration
what are the four ways the water cycle impacted on a local scale by arable farming (agriculture)?
ploughing increases infiltration by creating looser soil, which decreases surface runoff, but digging drainage basins increases surface runoff and streamflow
what are the four ways the water cycle impacted on a local scale by hillside terracing (agriculture)?
increases surface water storage and therefore decreases runoff
what are the four ways the water cycle impacted on a local scale by irrigation (agriculture)?
can lead to groundwater depletion
what are the two ways the water cycle impacted on a local scale by roads and buildings (urbanisation)?
they have impermeable surfaces and have drains which create impermeable surfaces that reduce infiltration but increase surface runoff, reducing ragtime and increasing flood risk
what are the two ways the water cycle impacted on a local scale by green roofs and Sustainable Urban Drainage Systems (urbanisation)?
they use grass and soil to reduce the amount of impermeable surfaces, and help reduce
how is does the soil water budget change in winter?
potential evapotranspiration from plants reaches a minimum due to cold temperatures and the precipitation continues to refill the soil water stores. Infiltration and percolation refill the water table
how is does the soil water budget change in spring?
plants start to grow and potential evapotranspiration increases as temperatures get higher and plants photosynthesis more. Still water surplus
how is does the soil water budget change in summer?
hot weather leads to utilisation of soil water as evapotranspiration peaks and rainfall is at a minimum. Output from evapotranspiration is greater than the input from precipitation so water stores are depleting. A water deficit may occur
what is the global water cycles largest store?
oceans
what percent of global water is in oceans?
97%
what percent of stores are freshwater?
2.5%
what percent of freshwater is glaciers, ice caps and ice sheets?
69%
what percent of freshwater is groundwater?
30%
what four areas can water be stored in?
- hydrosphere
- lithosphere
- cryosphere
- atmosphere
define hydrosphere as a water store
any liquid water
define lithosphere as a water store
water stored in the crust and upper mantle
define cryosphere as a water store
any water that is frozen
define atmosphere as a water store
water vapour
what are aquifers?
underground water stores
how long can shallow groundwater aquifers store water for?
200 years
how long can deep fossil aquifers store water for?
10,000 years
when were deeper fossil aquifers formed?
during wetter climatic periods
how long can glaciers store water?
20-100 years
how long can lakes store water that are fed by glaciers?
50-100 years
how long do seasonal snow cover and rivers store water for?
2-6 months
how long does soil water store water for?
1-2 months
what is the main factor that determines cloud formation and rainfall?
the global atmospheric circulation model
what are the five natural processes that cause the water cycle to change over time?
- seasonal changes
- storm events
- droughts
- El Nino and La Nina
- cryospheric processes
how has the water cycle changed over time from seasonal changes?
- less precipitation, more evapotranspiration in summer
- reduced flows in water cycle in winter as water is stored in ice
- reduced interception in winter, when deciduous trees lose their leaves
- increased evapotranspiration in summer, deciduous trees have leaves and higher temperatures
how has the water cycle changed over time from storm events?
sudden increase in rainfall leads to flooding and replenishment of some water stores. Unlikely to cause long term change
how has the water cycle changed over time from droughts?
causes major stores to be depleted and the activity of flows acting within the water cycle to decrease, may become more common from climate change
how has the water cycle changed over time from el Nino and la Nina?
- el nino effect occurs every 2-7 years causing warm temperatures in predictable ways
- la Nina effect occurs every 2-7 years causing cooler temperatures in predictable ways
- climate change will increase the probability of more el ninos in the future
how has the water cycle changed over time from cryospheric processes?
- glaciers and icecaps used to store significant proportions of freshwater through accumulation
- glaciers are shrinking so sea levels rise
- if all glaciers and icecaps melt sea levels would rise 60 meters
what are the three human processes that cause the water cycle to change over time?
- farming practices
- land use change
- water abstraction
how has the water cycle changed over time from farming practices?
- ploughing breaks the surface increasing infiltration
- arable farming increases interception and evapotranspiration
- pastoral farming compacts soil reducing infiltration and increasing runoff
- irrigation removes water from local rivers
how has the water cycle changed over time from land use change?
- deforestation reduces interception, evapotranspiration but infiltration increase
- construction reduces infiltration and evapotranspiration, but increases runoff
how has the water cycle changed over time from water abstraction?
- reduces volume of water in surface stores
- water abstraction increases in dry season
- human abstraction from aquifers as an output to meet water demands is often greater than inputs to the aquifer, leading to a decline in global long term water stores
what will cause the greatest changes to the water cycle?
the combination of human activity and natural variation
what is the low pressure zone at the equator called?
inter tropical convergence zone
what is the intertropical convergence zone?
a narrow zone near the equator where northern and southern air masses converge, typically producing low atmospheric pressure
what is a flood hydrograph used to represent?
rainfall for the drainage basin of a river and the discharge of the same river
what are the key components of a flood hydrograph?
- discharge
- rising limb
- falling limb
- lag time
- baseflow
- stormflow
- bankfull discharge
what is the discharge of a flood hydro-graph?
the volume of water passing through a cross sectional point of the river at any one point in time. Made up of the base flow and stormflow
what is the rising limb of a flood hydro-graph?
the line on the graph that represents the discharge increasing
what is the falling limb of a flood hydro-graph?
the line on the graph that represents the discharge decreasing
what is the lag time of a flood hydro-graph?
the time between peak rainfall and peak discharge
what is the base flow of a flood hydro-graph?
the level of groundwater flow
what is the stormflow of a flood hydro-graph?
comprised of overland flow and throughflow
what is the bankful discharge of a flood hydro-graph?
the maximum capacity of the river. If discharge exceeds this then the river will burst its banks and be in flood
what is a flashy hydrograph?
short lag time and high peak discharge, most likely to occur during a storm event, with favourable drainage basin characteristics
what is subdued hydrograph?
long lag time and low peak discharge
what are the features of a flashy hydrograph?
- short lag time
- steep rising and falling limb
- higher flood risk
- high peak discharge
what are the features of a subdued hydrograph?
- long lag time
- gradually rising and falling limb
- lower flood risk
- low peak discharge
what are the nine natural causes of a flashy hydrograph?
- high rainfall intensity
- antecedent rainfall
- impermeable underlying geology
- high drainage density
- small basin
- circular basin
- low temperatures
- precipitation type
- vegetation cover
how does high rainfall intensity cause a flashy hydrograph?
higher discharge potential from the river and more likely for soil to reach its field capacity, increasing surface run off and decreasing lag time
how does antecedent rainfall cause a flashy hydrograph?
increased surface runoff as ground is saturated and soil has reached its field capacity
how does impermeable underlying geology cause a flashy hydrograph?
decreased percolation and therefore greater levels of throughflow
how does high drainage density cause a flashy hydrograph?
many tributaries to main river, increasing speed of drainage and decreasing the lag time
how does small basin cause a flashy hydrograph?
rainfall reaches the central river more rapidly, decreasing the lag time
how does circular basin cause a flashy hydrograph?
rainfall reaches the central river more rapidly, decreasing the lag time
how does low temperatures cause a flashy hydrograph?
less evapotranspiration, so greater peak discharge
how does precipitation type cause a flashy hydrograph?
snow or hail takes time to melt before moving towards the river, so rainfall increases the flooding risk
how does vegetation cover cause a flashy hydrograph?
forested areas intercept more rainfall, decreasing the flood risk but exposed areas will transfer water to the river more rapidly, decreasing the lag time
what are the three human causes of the flashy hydrograph?
- urbanisation
- pastoral farming
- deforestation
how does urbanisation cause a flashy hydrograph?
more impermeable surfaces, so runoff increased and surface storage and infiltration are reduced
how does pastoral farming cause a flashy hydrograph?
ground trampled so less interception and more surface runoff
how does deforestation cause a flashy hydrograph?
less interception by trees, so water reaches the ground and river more quickly. More surface runoff and greater flood risk
on a local scale, what do transfers in the carbon cycle do?
act to drive and cause changes in the carbon cycle over time
what do the transfers in the carbon cycle do?
drive and cause changes in the carbon cycle overtime
what are the eight transfers in the carbon cycle?
- photosynthesis
- respiration
- combustion
- decomposition
- diffusion
- weathering and erosion
- burial and compaction
- carbon sequestration
how is photosynthesis a transfer in the carbon cycle?
living organisms convert carbon dioxide from the atmosphere and water from the soil, into oxygen and glucose using light energy. Photosynthesis helps to maintain the balance between oxygen and CO2 in the atmosphere
how is respiration a transfer in the carbon cycle?
when plants and animals convert oxygen and glucose into energy which then produces the waste products of water and CO2
how is combustion a transfer in the carbon cycle?
when fossil fuels and organic matter are burnt, they emit CO2 into the atmosphere, that was previously locked inside of them.
how is decomposition a transfer in the carbon cycle?
when living organisms die they are broken down by decomposers which respire, returning CO2 into the atmosphere
how is diffusion a transfer in the carbon cycle?
the oceans can absorb CO2 from the atmosphere, which has increased ocean acidity by 30%.
how are weathering and erosion transfers in the carbon cycle?
rocks are eroded on land or broken down by carbonation weathering, which occurs when CO2 in the air mixes with rainwater to create carbonic acid which aids erosion of rocks. Carbon moved through water cycle and enters the oceans
how are burial and compaction transfers in the carbon cycle?
when shelled marine organisms die, their shell fragments fall to the ocean floor, become compacted to form limestone. Organic matter is compacted over time to form fossil fuel deposits
how is carbon sequestration a transfer in the carbon cycle?
transfer of carbon from the atmosphere to other stores and can be natural and artificial. A plant sequesters carbon when it photosynthesises and stores the carbon.
what are the advantages of carbon Capture and Storage (CCS)?
- fitted to existing coal power stations
- captures 90% of CO2 produced
- demand for CO2, transport systems already exist
- potential to capture half of the worlds CO2 emissions
what are the disadvantages of carbon Capture and Storage (CCS)?
- high cost
- increases energy demand
- may not be space to fit to existing power stations
- increases fossil fuel usage
what is a sere?
a stage of a vegetation succession and can relate to specific environments
when does a vegetation succession occur?
when a plant community develops and becomes more complex over time
in what environment does the carbon cycle function in?
a lithosere environment
what is achieved in the climatic climax?
environmental equilibrium is achieved
what is the final stage of the sere?
the climatic climax
what happens when a sere reaches a climatic climax?
the ecosystem is fully developed and stable and will not change dramatically as the equilibrium will counteract any change
what are the four environments that relate to the seres?
- lithosere
- halosere
- psammosere
- hydrosere
what is the lithosere environment?
bare rock
what is the halosere environment?
salty environment
what is the psammosere environment?
sand coastal environment
what is the hydrosere environment?
freshwater environment
define carbon sink
any store which takes in more carbon than it emits
define carbon source
any store that emits more carbon than it stores
what are the main six carbon stores?
-marine sediment and sedimentary rock
-oceans
-fossil fuel deposits
-soil organic matter
atmosphere
terrestrial plants
what is the biggest carbon store?
marine sediments and sedimentary rocks
give some facts about marine sediments and sedimentary rock as a carbon store
- in the lithosphere
- long term store
- 66,000 - 100,000 million billion metric tons of carbon
give some facts about oceans as a carbon store
- in the hydosphere
- dynamic store
- 38,000 billion metric tons of carbon
give some facts about fossil fuel deposits as a carbon store
- in the lithosphere
- long term store, but currently dynamic
- 4000 billion metric tons of carbon
give some facts about soil organic matter as a carbon store
- in the lithosphere
- mid term store
- 1500 billion metric tons of carbon
give some facts about the atmosphere as a carbon store
- dynamic store
- 750 billion metric tons of carbon
- increased 40% since industrial revolution
give some facts about terrestrial plants as a carbon store
- in the biosphere
- mid term store, but very dynamic
- 560 billion metric tons of carbon
where are oceans largest?
in the Southern Hemisphere
where are forests declining?
tropical areas in the southern hemisphere
where are the forests growing?
northern hemisphere
why have non tropical forests seen an increase in carbon sequestration in recent years?
because of the conversion of agricultural land and plantations to new forest
what are the two natural processes which have caused changes to the carbon cycle over time?
- wildfires
- volcanic activity
how have wildfires changed the carbon cycle?
CO2 is transferred from biosphere to atmosphere through burning
how has volcanic activity changed the carbon cycle?
carbon stored within the earth is released during eruptions. They can influence the carbon cycle by reducing photosynthesis rates, which also effects the water cycle
what are the three human impacts that have caused changes to the carbon cycle over time?
- fossil fuel use
- deforestation
- farming practice
how has fossil fuel use changed the carbon cycle?
combustion transfers CO2 to the atmosphere
how has deforestation changed the carbon cycle?
releases carbon stored in plants and interrupting the forest carbon cycle
how have farming practices changed the carbon cycle?
arable farming releases CO2, ploughing can release CO2 from soil and machinery release CO2
what are fluxes?
changes to the magnitude of carbon stores
what is the carbon budget?
the balance between carbon inputs and outputs to a store at any scale or the balance of exchanges between the four carbon stores
what is the enhanced greenhouse effect?
the process that is currently causing global warming as abnormally high levels of greenhouse gases
define radiative forcing?
the difference between incoming solar radiation absorbed by the earth and the energy radiated back out into space
what are the four causes of the enhanced greenhouse effect?
- land use change
- fertilisers
- deforestation
- urbanisation
how does land use change cause the enhanced green house effect?
-70% of deforestation is for cattle ranching, which produce methane
land use change accounts for how much carbon release annually?
a tenth
how does fertilisers cause the enhanced green house effect?
methane emissions increase due to increased productivity due to higher CO2 levels
how does deforestation cause the enhanced green house effect?
the cycle is interrupted and the land is used for other purposes, which the reduces carbon sequestration and it becomes a carbon source
deforestation accounts for how much of all global greenhouse emissions?
about 20%
how does urbanisation cause the enhanced green effect?
cement releases carbon dioxide during production
what is rewilding?
populated or managed human areas are being reduced or replaced by wildlife
what are the impacts of the carbon cycle on tropical rainforests?
- high rates of photosynthesis and respiration leads to greater humidity, cloud cover and precipitation
- deforestation reduces photo synthesis and respiration, reducing humidity, cloud cover and decreasing precipitation
what are the impacts of the carbon cycle on oceans?
- warmer oceans cause more plankton growth, so more chemical production, which causes clouds to form
- warm oceans store less CO2, warmer weather lessens oceans as carbon sinks
what are systems made up of?
- stores
- flows
- boundaries
- inputs
- outputs
what are inputs?
when matter or energy is added to the system
what are outputs?
when matter or energy leaves the system
what are stores?
where matter or energy builds up
what are flows?
when matter or energy moves from one flow to another
what are boundaries?
the limits of a system
what are open systems?
Both energy and matter can enter and leave an open system
-there are inputs and outputs of both
what are closed systems?
- matter can’t leave or enter a closed system, it can only cycle between stores
- energy can enter and leave a closed system and can be input or output
when is a system in equilibrium?
if the inputs and outputs of a system are balanced
-if there is no overall change to the system
what can cause a system to change and establish a new dynamic equilibrium?
large, long term changes to the balance of inputs and outputs
what changes trigger positive or negative feedback?
changes to dynamic equilibrium
what does positive feedback do?
positive feedback mechanisms amplify the change in the inputs or outputs
how does a system respond to positive feedback?
increasing the effects of the change, moving the system even further from its previous state
what does negative feedback do?
negative feedback mechanisms counteract the change in the inputs or outputs
how does a system respond to negative feedback?
decreasing the effects of the change, keeping the system closer to its previous state
how can the earth be seen as a closed system?
- energy is input from the sun and output to space
- but matter is not input or output to space
what are the 5 subsystems of the earths system?
- cryosphere
- lithosphere
- biosphere
- hydrosphere
- atmosphere
what is the cryosphere?
all the parts of the earths system where its cold enough for water to freeze
what is the lithosphere?
the outermost part of the earth
-includes the crust and the upper parts of the mantle
what is the biosphere?
the part of the earths system where living things are found
-includes plants, animals, bacteria, etc
what is the hydrosphere?
all the water on earth
- it may be in liquid form, solid form or gas form
- it can be saline (salty) or fresh
what is the atmosphere?
the layer of gas between the earths surface and space, held in place by gravity
what are the earths subsystems interlinked by?
the cycles and processes that keep the earth system as a whole running as normal
can changes in one of earths subsume affect another?
yes
does matter and energy move between the subsystems?
yes
how does matter and energy move between the earths subsystems?
the output of one cycle is the input of the next then the output of that cycle is the input of the next
what is the name of earths system?
a cascading system
why is earth a cascading system?
the way that matter and energy move from one subsystem to the next
how much water is in the hydrosphere?
1.4 sextillion litres
what percentage of water is fresh?
3%
what percentage of the earths fresh water is in the cryosphere?
69%
what percentage of the earths fresh water is groundwater?
30%
what percentage of earths freshwater is liquid freshwater on the earths surface (rivers, lakes, etc)?
0.3%
what percentage of earths freshwater is stored as water vapour in the atmosphere?
0.04%
why is there only a small amount of water on the planet that can be used by humans?
water must be physically and economically accessible for humans to be able to use it
what does water have to do too coil or melt?
gain energy
what does water have to do too condense or freeze?
lose energy
what is the global hydrological cycle?
a closed system, where water is continuously cycled between different stores
what does the magnitude of each store depend on?
the amount of water flowing between them
when does evaporation occur?
when liquid water changes state into a gas, becoming water vapour
what does evaporation do to the amount of water stored in the atmosphere?
increases the amount of water
what happens to the amount of evaporation if there is lots of solar radiation and a large supply of water and warm, dry air?
the amount of evaporation will be high
what happens to the amount of evaporation if there is not much solar radiation, little available liquid watering cool air that is nearly saturated?
evaporation will be low
what is condensation?
when water vapour changes state to become a liquid
when does condensation occur?
when air containing water vapour cools to its dew point
what is a dew point?
the temperature at which water changes from a liquid to a gas
what does the magnitude of condensation flow depend on?
the amount of water vapour in the atmosphere and temperature
what is the main flow of water from the atmosphere to the ground?
precipitation
when do clouds form?
when warm air cools down
how are clouds formed?
warm air cools down, causing the water vapour in it to condense into water droplets which gather as clouds
when do droplets from clouds fall as precipitation?
when the droplets get big enough
what are the three things that cause warm air to cool, leading to precipitation?
- other air masses
- topography
- convection
how does topography cause precipitation?
when warm air meets mountains, its forced to rise, causing it to cool
what does precipitation caused by topography result in?
orographic precipitation
how does convection cause precipitation?
when the sun heats up the ground, moisture on the ground evaporates and rises up in a column of warm air. As it gets higher, it cools
what does precipitation caused by convection result in?
convective precipitation
how do other air masses cause precipitation?
warm air is less dense than cool air. As a result when warm air meets cool air, the warm air is forced up above the cool air. It cools down as it rises
what does precipitation caused by other air masses result in?
frontal precipitation
can water droplets caused by condensation form clouds on their own?
no, they are too small
what must there be, as well as condensation, to form clouds?
there have to be tiny particles of other substances (dust or soot)
why must there be other substances than just condensation for a cloud to form?
to act as cloud condensation nuclei
-they give water a surface to condense on
do cryospheric processes change the amount of water stored as ice in the cryosphere?
yes
during periods of global cold, are inputs or outputs greater into the cryosphere?
inputs are greater
why are inputs into the cryosphere greater than outputs in periods of global cold?
- water is transferred to it as snow
- less of it is transferred away due to melting
during periods of warmer global temperatures, what happens to the magnitude of the cryosphere store?
the magnitude of the cryosphere store reduces
why does the magnitude of cryosphere stores reduce in warmer temperatures?
losses due to melting are larger than the inputs of snow
what is a rivers drainage basin?
the area surrounding the river where the rain falling on the land flows into that river
what is the boundaries ry of a river basin?
the watershed
what can a river drainage basin also be called?
river catchment
are drainage basins open or closed systems?
open
how does water come into a drainage basin system?
as precipiation
how does water leave from a drainage basin system?
via evaporation, transpiration and river discharge
what is precipitation?
rain, snow, hail, dew and frost
what is interception?
when some precipitation lands on vegetation or other structures (buildings), before it reaches the soil
where does interception cause a significant store of water?
wooded areas
why is interception storage only temporary?
the collected water evaporate quickly, or fall through the leaves as through-fall
what is vegetation storage?
water that’s been taken up by plants
-all the water contained in plants at any one time
what is surface storage?
water in puddles, ponds and lakes
what is soil storage?
moisture in the soil
what is groundwater storage?
water stored in the ground, either in the soil or in the rocks
what is the water table?
the top layer of the zone of saturation
what is the zone of saturation?
the zone the zone of soil or rock where all the pores in the sailor rock are full of water
what are aquifers?
porous rocks that hold water
what is channel storage?
the water held in a river or Chanel stream
what is infiltration?
water soaking into the soil
what are infiltration rates influenced by?
- soil type
- soil structure
- how much waters already in the soil
what is overland flow?
water flowing over the land
-it can flow over the who surface or in little channels
why does overland flow happen?
rain is falling onto the ground faster than infiltration can happen
what is through fall?
water dripping from leaf to another
what its stem flow?
water running down a plant stem or a tree trunk
what is through flow?
water moving slowly downhill through soil
where is through flow faster?
in ‘pipes’ (things like cracks in the soil or animal burrows)
what is percolation?
water seeping down through soil into the water table
what is groundwater flow?
water flowing slowly below the water table through permeable rock
where can groundwater flow be faster?
through rocks that are highly permeable with lots of joints
what is base flow?
groundwater flow that feeds into rivers through river banks and river beds
what is interflow?
water flowing downhill through permeable rock above the water table
what is channel flow?
the water flowing in the river or stream itself
what is channel flow also called?
the rivers discharge
what is the output from drainage basins?
water
what are the four ways water leaves from a drainage basin?
- evaporation
- transpiration
- evapotranspiration
- river flow or river discharge
what is evaporation?
water turning into water vapour
what is transpiration?
evaporation from within leaves
-plants and trees take up water through their roots and transport it to their leaves where it evaporates into the atmosphere
what is evapotranspiration?
the process of evaporation and transpiration together
what is potential evapotranspiration?
the amount of water that could be lost by evapotranspiration
what is actual evapotranspiration?
what actually happens
what is river discharge?
the volume of water that flows in a river per second
what is river discharge measured in?
cubic metres per second (m^3/s)
why do high levels of runoff increase the discharge of a river?
more water makes it into a river, increasing its volume
what are hydrography?
graphs of river discharge over time
what do hydographs show?
how the volume of water flowing at a certain point in a river changes over a period of time
what do flood hydrography show?
river discharge around the time of a storm event
what is peak discharge?
the highest point on the graph, when river discharge is at its greatest
what is lag time?
the delay between peak rainfall and peak discharge
why is there a delay between peak rainfall and peak discharge?
it takes time for the rainwater to flow into the river
why can a shorter lag time increase peak discharge?
more water reaches the river during a shorter period of time
what is rising limb?
the part of the graph up to peak discharge
-the river discharge increases as rainwater flows into the river
what is falling limb?
the part of the graph after peak discharge
why is discharge decreasing in the falling limb?
less water is flowing into the river
what does a shallow falling limb show?
water is flowing in from stores long after its stopped raining
what 4 factors does the amount of runoff and shape of the hydrography depend on?
- size of drainage basin
- shape of drainage basin
- ground steepness
- rock and soil type
how does the size of the drainage basin affect the amount of runoff and the shape of the hydrograph?
- larger drainage basins catch more precipitation, so they have a higher peak discharge than smaller basins
- smaller basins generally have shorter lag times because precipitation has less distance to travel, so it reaches the main channel more quickly
how does the shape of the drainage basin affect the amount of runoff and the shape of the hydrograph?
-circular basins are more likely to have a flashy hydrograph than long, narrow basins
what is a feedback loop?
a type of chemical Chain where one process leads to another process, leading to another process and so on
what are the two types of feedback loops?
positive and negative
what is negative feedback?
the process that occurs is counteracted by an opposing process, causing the effects to cancel each other out and nothing to change
what is positive feedback?
a process occurs which causes another process to occur, which started a chain reaction that heightens the first process
what happens in positive feedback of wild fires?
more likely in hotter and drier climates created by global warming, which release large amounts of CO2 into the atmosphere which increases the warming effect
what happens in negative feedback of increased photosynthesising rising global temperatures?
allows vegetation to grow in new areas. New vegetation absorbs CO2 from the atmosphere, decreasing the warming effect
what is a moorland?
an expanse of waterlogged, acidic soil and peat
how does waterlogged ground reduce plant growth?
stops oxygen from permeating
why are many moorlands no longer submerged?
they have been drained by large channels
why are drained moorlands often converted into highly productive farmland or plantations in tropical areas?
due to their fertile soil
how has draining the moorlands increased flood risk?
- surface storage is reduced by draining the moorland
- streamflow is increased by digging the drainage ditches
how does ground steepness affect the amount of runoff and the shape of the hydrograph?
water flows more quickly down hill in steep sided drainage basin, shortening lag time and meaning water has less time to infiltrate the soil, so runoff is higher
how does rock and soil type affect the amount of runoff and the shape of the hydrograph?
impermeable rocks and soils don’t store water or let water infiltrate, increasing surface runoff. peak discharge increases as more water reaches the river in a shorter period of time
what are the two physical factors for variations in the water cycle?
-storms and precipitation
seasonal changes and vegetation
how do storms and precipitation cause variations in the water cycle?
- intense storm surges generate more precipitation and greater peak discharge
- larger input of water causes flows to increase in size
- some flows may not be able to occur rapidly enough for the size of the input, increasing runoff
