water cycle

• natural systems


  stores or components- where matter or energy builds up

  flows or transfers- where matter or energy moves from one store to another

  boundaries- limits of the system

  
  

  open system- matter and energy can leave or enter, drainage system

  closed system- matter cant leave, only move between stores, whereas energy can leave or enter, carbon cycle (limit of matter)
• drainage basin as open system example


  open systems as energy from the sun enters, and can leave

  water is input as precipitation and output as river discharge into the sea.

  drainage basin as the catchment area

  the boundary of the drainage basin is the watershed- any precipitation falling beyond the watershed enters a different drainage basin

  storage of drainage basin- interception, vegetation, surface and soil storage, groundwater and channel storage.

  flows- inflation, through flow, stem flow, runoff

  outputs- evapotranspiratiom, transpiration, evapotranspiration, river discharge.
• positive feedback loops


  cycles are normally balanced (dynamic equilibrium) positive means amplifying the change in outputs and inputs. meaning the system moves even further from its original state. increasing effects taking it further from the dynamic equilibrium

  example- albedo effect, as temperature rises, more ice is melted, dark water exposed to sunlight and more sunlight is then absorbed rather than reflected, increasing temperature and more water melted
• negative feedback loops


  counteracts change in the feedback loops, keeps system closer to original state.

  example- CO2 example- lots of co2 emitted, more in atmosphere, plants grow so more co2 is absorbed and stored, then removing it from the environment again.
• soil moisture definitons


  soil water budget- annual budget between inputs and outputs in the soil, changing over the years.

  soil moisture surplus- precipitation is higher than potential evapotranspiration, all the pore spaces have been filled and reached maximum capacity so floods occur

  soil moisture defecit- happens at warmest temperatures, plants have used all the moisture so its in surplus. draughting course, plants must adapt.

  soil moisture recharge- towards winter, precipitation exceeds potential evapotranspiration the groundwater starts to recharge and fill up
• physical changes to the water cycle


  storms/ intense rainfall- excess amount of water, precipitation exceeds evapotranspiration, leading to soil moisture surplus, ground and soil water pores fill up. large input, leading to surface runoff and flooding in which water cannot infiltrate (2007 uk floods)

  seasonal changes- usually more input of precipitation during the winter and more output of evapotranspiration in summer. if the soil gets too baked, infiltration cannot occur leading to overland flow, however if the soil is too saturated, also cannot infiltrate.

  drought- reduced water stores in lakes and rivers, lack in vegetation so less transpiration, infiltration and interception. become more reliant on groundwater stores which are finite.
• human changes to the water cycle


  land use change- urbanisation means more of the ground is more impermeable, meaning less water can infiltrate, leading to overland flows and surface runoff.

  deforestation- less interception and transpiration, water reaches the river quicker, increasing surface runoff, mire flashy hydrographs.

  farming practices- ploughing breaks up the soil, meaning more water can infiltrate and crops increase interception rates. livestock tramples and compacts soil, making it impermeable, pastoral farming also decreases the crop yield, animals such as pigs. groundwater is also extracted for irrigation.
• factors of hydrographs


  flashy hydrographs- small basin, large drainage density, impermable rock (urbanisation) steep slopes (faster runoff) saturated soil (reached soil moisture surplus) heavy rainfall, deforestation

  subdued hydrograph- large basin with a small drainage density, afforestation, gentle relief, drier soil with light rain conditions

  antecendent conditions- conditions prior to rainfall events.
• carbon stores


  Places where carbon accumulates for a period of time such as rocks and plant matter. mainly in permafrost in the cyrosphere.
• effects of a Yellowstone eruption

  90% of people within a 1,000k radius of the volcano would be killed. global temperature would decrease by 10-12 degrees for 10 years as a result of the 2,000 million tonnes of sulphur dioxide released into the atmosphere.
• human impacts of carbon cycle


  urbanisation- 60% of the global population expected to live in urban areas by 2030. high rates of emissions from transport, agriculture and domestic use. deforestation in urban areas, deforestation in this area, greater outputs of carbon emissions.

  deforestation- emissions from the land use change account for 30% of global emissions, 13 million hectares of forest cut down annually, in cases such as logging, less trees to absorb and extract carbon.

  fossil fuels- burning fossil fuels, releases the carbon locked in the lithosphere, contributing highly to the enhanced greenhouse effect. CO2 has risen by 80ppm in the past 50 years, accounting to 90% of human emissions. CO2 dominated by China, USA and India, enhanced since industrial revolution.
• physical impacts of the carbon cycle


  farming practices- ploughing exposes the soil to the atmosphere, leading to decomposition and the release of carbon. machinery runs off fossil fuels and finite resources, such as petrol which release co2. growing rice in rice paddies releases a lot of methane, as world population increases there is more food production so more co2.

  largest carbon store is in the lithosphere, 100,000,000 pg

  largest transfers- plant respiration, photosynthesis and ocean uptake

  
  

  wildfires- rapidly transfer biomass to the environment, loss of vegetation means less carbon is removed. in the long-term cleared land means more vegetation can be planted so plant growth can be renewed.

  volcanic activity- carbon which is stored within the magma or the earth, majority enters the atmosphere through co2. now much less emitted through volcanoes as more comes from human activities.
• types of carbon cycles


  slow carbon cycle- the long-term storage of carbon, for example marine shellfish dying and becoming compacted along the ocean floor.

  fast carbon cycle- the transfer of carbon between atmosphere and oceans,
• condenstation in the water cycle


  occurs when water vapour changes state to become a liquid. when air containing water vapour cools to itsdew point 100% humidity, (temperature for change) eg. temperatures fall at nightie to the heat being lost to space.water can either stay in the atmosphere or change to a different subsystem, when dew is formed it decreases the amount of water stored in the atnosphere.magnitude of condensation depends on volume of water and temperature.example- if there is lots of water vapour and there is a rapid drop in temperature condensation will be very high.
• types of rainfall and the causes


  other air masses- warm air is less dense than cool air, as a result when warm air meets the cool air, warm air is forced above the cool air, cooling down as it rises leading to frontal precipitation

  topography- when the warm air reaches high mountainous areas, its forced to rise and then it will cool causing orographic precipitation

  convectional- 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, resulting in convective precipitation.
• cloud formation and precipitation


  clouds form when the warm air cools down, causing the water vapour to condense into water droplets, gathering as clouds, as they get even larger they fall as precipitation.

  water droplets caused by condenstation are too small to form clouds on their own, they must have particles of other substances to form cloud condensation nuclei, giving the water a surface to condense on. encouraging clouds to form, rather than moist air dispersing

  
  

  affected by seasonality (more in winter than summer) and by location (more at tropics than at the poles)
• cryospheric processes on the water cycle


  such as accumulation and ablation affect the change of how much water is stored as ice within the cyrosphere, the balance depends on temperature.

  during cold periods, inputs are greater than outputs, as more water is transferred to snow, and less is lost through melting, opposite in warm spells

  the earth is emerging from a glacial period (warming now) as there's still a large volume of sea ice in the artic and antarctic.

  variations of cryosphere change over timescales, takes thousands of years.
• ocean uptake on carbon


  co2 is directly dissolved from the atmosphere into the ocean. it is also transferred to the ocean when it is taken up by organisms that live in them (plankton) as temp rises phytoplankton cannot adapt, so they die releasing carbon onto the sea floor.

  carbon is also transferred from the ocean to the atmosphere when carbon-rich water from deep in the ocean reaches the surface and releases co2.

  the increase in co2 levels, then increases the acidity within the oceans which then absorbs more co2, having adverse effects on marine life.
• organisms on carbon uptake


  respiration- transfers carbon from living organisms to the atmosphere. plants and animals break down glucose for energy releasing co2 in the process. plants absorb co2 to emit oxygen

  decomposition- transfers carbon from dead biomass to the atmosphere and the soil. after death, bacteria and fungi break organisms down meaning co2 and methane are released. some carbon is then released into the humus layer.
• impacts of climate change


  changing patterns of precipitation, wetter areas get wetter, drier areas get drier causing water shortages and even food insecurity, as agriculture decreases- leading to conflicts in areas.

  extreme weather events- expected to get more frequent and affect more areas as they get hotter. LICs will be most negatively affected as they cannot mitigate or respond to events.

  sea levels rise- increasing flood in coastal areas.

  plankton levels decline as temperature increases, having effect on marine food chain.
• humans influence on the carbon cycle


  40% more co2 in the atmosphere than 1750.

  individual mitigation- choose to use more fuel efficient cars, install their homes so they are more energy efficient

  regional/national- governments increase the availability of renewable sources rather than fossil fuels. afforestation and restoring the degraded forests so they can increase carbon uptake in the biosphere. improving public transport, encouraging people to use it. CCS

  global- countries can work together through international treaties to control the amount of emissions released, within a set limit (Paris agreements, 2015) international carbon trading schemes, limit on what they can produce and can be rewarded if they release even less than that.
• features on dynamic equilburim on water cycle


  tendency towards a natural state of balance

  can be upset by dramatic changes such as extreme events or seasonal changes

  water cycle is a closed system

  human acuity can sway the cycle
• impacts of long term global warming on water cycle


  warmer temperatures, so more evaporation, more water transferred from groundwater stores to atmosphere. water moves faster through stores

  less in cyrosphere, more in hydrosphere/atmosphere, currently 69% in cryosphere
• sequestration- slow carbon cycle


  carbon from atmosphere can be captured in sedimentary rocks. eg fossils compacting carbon when compacted

  carbon in fossil fuels is sequestered until we release it through combustion.
• natural process causing change to carbon cycle


  wildfires, volcanoes

  volcanoes release sulphur dioxide which reduces global temperature

  wildfires are detrimental, release co2 though combustion but also destroy vast vegetative areas, releasing more carbon and not being able to uptake anymore
• phytoplankton - warmer oceans impact on oceans


  co2 is disolved into the oceans, phytoplankton use co2 to photosynthesis. too much co2 in oceans, changes the acidity having adverse affects on marine life

  if oceans become too warm, from carbon phytoplankton die, releasing carbon onto the sea floor, as well as less co2 being used for photosynethsis.

  also warmer oceans cannot dissolve as much co2.
• carbon budget


  the difference between the inputs and outputs,

  example off inputs- volcanoes, burning fossil fuels, respiration and outputs- phytosynethis, sequestration and phytoplankton

  the dependance relies on if inputs outweigh outputs= carbon sink, absorbs more carbon than it releases

  or carbon source= outputs outweigh inputs.

  inputs = extracting carbon from atmosphere.
• feedback loops in water cycle


  positive- albedo affect, warmer temperatures mean more melting of sea ice, in which less rays are relefected but rather absorbed by water then increasing melting and temp

  
  

  negative- cloud cover, warmer temperatures, so more evapotranspiration, more water returned to the atmosphere as cloud cover, reflecting the sun rays, meaning temp drops
• feedback loops in carbon cycle


  positive- phytoplankton

  more co2 increases temp and acidity of oceans, phytoplankton cannot adapt, therefore they die and decompose releasing even more co2 into the oceans

  
  

  negative- photosynthesis

  more co2, means plants can do more photosynthesis, in which they extract more co2 from the atmosphere, counteracting change.
• weathering


  transfers carbon from the atmosphere to hydrosphere and biosphere.

  atmospheric carbon joins with water vapour and falls as acid rain.

  
  

  when acid rain falls on the rocks, a chemical reaction occurs which dissolves into the rocks, forming with water to form calcium carbonate- creates sea shells.