Water and carbon cycle

• Inputs


  Water enters as rain
• Outputs


  Evaporation, or when the river meets the sea.
• Stores


  Soil or vegetation
• Flows


  Run off, infiltration.
• Positive feedback, water cycle

  -When the effect of an action is amplified.

  1) Temp rises

  2) Ice covering the cold part of the earth melts due to higher temperatures.

  3) Less ice cover so less of the suns energy is reflecting.

  4) Less of the sun energy is being reflected so more is being absorbed by earth.

  5) Temp rises.
• Negative feedback, carbon cycle

  - When the effects of an action are nullified.

  1) Large amounts of co2 emitted.

  2) Co2 in atmosphere increases.

  3) More Co2 means more plant growth.

  4) Plants remove co2 and store from the atmosphere.

  5) Amount of co2 in the atmosphere reduces.
• Positive feedback, carbon cycle

  1) Increased temp due to climate change

  2) Causes melting of permafrost.

  3) Trapped greenhouse gases are released.

  4) Enhancing the greenhouse effect.

  5) Temps rise further.
• Cyrosphere


  - All parts of the earth where it is cold enough to freeze. eg. Glacial landscapes.
• Lithosphere


  - Outermost parts of the earth including the crust and the upper parts of the mantle.
• Bioshphere


  Includes all living things in the earth.
• Hydrosphere


  Where all water on earth is found, may be in liquid form (rivers and lakes), Ice form (cryosphere), or in water vapour in the atmosphere.
• Distribution of water


  - 69% is frozen in cryosphere.

  - 30% is groundwater in the lithosphere.

  - 0.04% is stored as water vapour in the atmosphere.
• Evaporation


  - Occurs when liquid water changes state to gas, water vapour. It gains energy from solar radiation.

  - Evaporation increases the amount of water stores in the atmosphere.

  - The MAGNITUDE of the evaporation varies by location and season, if there is lots of SOLAR RADIATION, a large amount of water, warm and dry air, higher evaporation rates.

  - If there is NOT MUCH solar radiation, little available liquid and cool air that is already nearly saturated, evaporation will be low.
• Condensation


  1) Occurs when water vapour changes state to become a liquid- it loses energy to the surroundings

  It happens when air containing water vapour cools to its dew point.

  2) Water droplets can stay in the atmosphere or flow to other subsystems.

  3) The magnitude of the condensation flow depends on the amount of water vapour in the atmosphere and the temperature. eg, if there is lots of water vapour and there is a large drop in temp, condensation will be high.
• Cloud formation and precipitation

  1) Clouds form when warm air cools down, causing the water vapour in it to condense into water droplets. which gather as clouds, when the water droplets get big enough they fall as precipitation.

  2) Cloud formation varies seasonally eg. In the UK there's normally more rainfall in winter than in summer) and by location (eg. precipitation is generally higher in the tropics than at the poles.)
• Cyrospheric Processes


  1) Cyrospheric processes such as accumulation and ablation, change the amount of water stored as ice in the cryosphere. The balance of accumulation of accumulation and ablation varies with the temperature.

  2) During glacial periods, inputs in the cryosphere are greater than outputs - water is transferred to snow, and less water is transferred away due to melting. During global warmer periods, the magnitude of the cryosphere reduces as losses due to melting are larger than inputs of snow.
• Precipitation - Input


  Mainly rain, but also includes snow, hail, dew and frost.
• Storage


  1) Channel storage - Water stored in streams or rivers.

  2) Interception storage - any rain intercepted by vegetation or other structures, only temporary before the water is evaporated or reaches the soil as through flow.

  3) Surface storage - Puddles, lakes and ponds.

  4) Vegetation storage - Taken up and contained by plants.

  5) Groundwater storage - Water stored in the ground, either in rocks or the soil.
• Flows


  1) Infiltration = Water soaking into the soil, influenced by the soil type, soil structure and how saturated the soil already is.

  2) Stemflow = Water running down a plant stem or tree trunk.

  3) Overland flow = Water running horizontally over the lands surface, because rate of precipitation is faster than rate of infiltration.

  4) Throughflow = Water moving slowly horizontally through the soil, it occurs faster when there is cracks in the soil or animal burrows.
• Outputs


  1) Evaporation = water changing state into water vapour

  2) 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.

  3) River discharge.
• The water balance


  - Shows the balance between inputs and outputs, and affects how much water is stored in a drainage basin.

  1) In WET SEASONS, precipitation exceeds evapotranspiration, causing a water surplus, The ground stores then fill with water so there is more surface runoff and so higher river discharge, so river levels rise.

  2) In DRIER SEASONS, evapotranspiration exceeds precipitation causing a deficit, the ground stores are depleted as some of the water is used (plants and humans), and some flows into river channels but isn't replaced by precipitation. The ground stores are recharged in the next wet season (Autumn).
• Hydrographs


  - Show a rivers discharge over a given period of time.
• River discharge


  The volume of water that passes a certain point at a certain time. Increased runoff results in increased discharge because more water makes it into the river, increasing its volume.
• Draw and label a hydrograph

  1) peak discharge - Highest point on the graph, when river discharge is at its greatest.

  2) Lag time - The delay between the peak rainfall and peak discharge. This delay happens because it takes time for the rainwater to flow into the river. A SHORTER lag time can increase peak discharge because more water reaches the river during a shorter period of time.

  3) Rising limb - River discharge increasing as rainwater flows into the river.

  4) Falling limb - Discharge is decreasing because less water is flowing into the river.

  
• Factors affecting runoff and hydrographic shape:

  1) Size of drainage basin - The larger the drainage basin is, the more precipitation it catches, so they have a higher peak discharge than smaller basins. Smaller basing generally have shorter lag times, because they have less distance to travel, so reaches the main channel more quick.

  2) Ground steepness - Water flows more quickly downhill in steep sided drainage basins, shortening lag times, as soil has less time to infiltrate and do run off is higher.

  3) Soil and rock type - Impermeable rocks and soils don't store water or let water infiltrate. Increased surface runoff. Peak discharge also increases as more water reaches the river in a shorter period.
• Physical factors affecting the water cycle: Storms and precipitation:

  - Intense storms generate more precipitation and greater peak discharges than light rain showers.

  - The larger input of water causes flows, eg. runoff, and stores eg. groundwater to increase in size.

  - Some flows eg. Infiltration, may not be able to occur rapidly enough for the size of input, increasing runoff.
• Physical factors affecting the water cycle: Seasonal changes and vegetation

  - The size of inputs, flows and stores in the water cycle varies with the seasons (eg. the UK, summer is normally drier than winter)

  - During the winter, temp can drop to below 0 degrees, causing water to freeze. This can reduce the flows through drainage basins, while the store of frozen water grows. when the temp increases again, flows through drainage basins can be much larger as the ice melts.

  - Most plants show seasonal variation. Vegetation intercepts precipitation and slows its movement to the river channel. Interception is its highest when there's lots of vegetation and deciduous trees have they're leaves.

  - The more vegetation there is in a drainage basin, the more water is lost, (through transpiration and evaporation directly from the vegetation) before it reaches the river channel, reducing runoff and peak discharge.
• Human activities affecting the water cycle: Farming practices


  1) Ploughing can break up the soil and so more water can infiltrate, reducing the amount of runoff.

  2) Livestock eg, cattle, trample and compact the ground, decreasing infiltration and increasing runoff.

  3) Irrigation - Can increase runoff if some of the water can't infiltrate. Groundwater or river levels can fall if water is extracted for irrigation.

  4) Crops increase interception and infiltration. Evapotranspiration also increases which can increase rainfall.
• Human activities affecting the water cycle: Land use change

  1) Deforestation - Reduces the amount of water that Is intercepted by vegetation, increasing the amount that reaches the surface. In forested areas, dead plant material on the forest floor helps to hold the water allowing it to infiltrate the soil rather than run off.

  2) Construction of new buildings and roads creates an impermeable layer over the land, preventing infiltration. Increases runoff, causing water to run through the system much more quickly and increasing flood risk.
• Water abstraction


  - More water Is abstracted to meet demand in areas where population density is high. Reduces amount of water in stores.

  - During dry seasons, even more water is extracted from stores, for consumption and irrigation, so stores are depleted further.
• Lithosphere (Carbon cycle)


  - Over 99.9% of Carbon on the earth is stored in sedimentary rocks such as limestone.

  - 0.004% is stored in fossil fuels such as coal and oil, in the lithosphere.
• Hydrosphere carbon cycle


  - Co2 is dissolved in rivers, lakes and oceans.

  - The oceans are the second largest carbon store on earth. The majority of carbon here is found deep in the ocean in the form of dissolved inorganic carbon.

  - A small amount is found at the ocean surface where it is exchanged with the environment.
• atmosphere (carbon cycle)


  - Carbon is stored as CO2, contains about 0.001% of earth's carbon.
• Biosphere carbon cycle


  - Stored in the tissues of living organisms. Transferred to the soil when living organisms die and decay.
• Cryosphere (carbon cycle)


  - Stores less than 0.001% of the Earth's carbon, most of the carbon in the cryosphere is in the soil in areas of permafrost, where decomposing plants and animals have frozen into the ground.
• Flows in the carbon cycle: Photosynthesis


  - Transfers carbon stores in the atmosphere to biomass, plants and phytoplankton use energy from the sun to change CO2, and water into glucose and oxygen. Co2 passed through the food chain and released through decomposition and respiration.
• Flows in the carbon cycle: Respiration:


  - Transfers carbon from living organisms to the atmosphere. Plants and animals break down glucose for energy, releasing Co2 in the process.
• Flows in the carbon cycle: Combustion:


  - Transfers carbon stored in living, dead or decomposed biomass into the atmosphere by burning.
• Flows in the carbon cycle: Decomposition

  - Transfers carbon from dead biomass to the atmosphere and soil.

  - After death, bacteria and fungi break organisms down. Co2 and methane are released.

  - Some carbon is transferred to the soil in the form of humus.
• Flows in the carbon cycle: Sequestration:

  - Carbon from the atmosphere can be sequestered (captured and held) in sedimentary rocks or as fossil fuels. Rocks and fossil fuels form over millions of years when dead animal and plant material in the ocean falls to the floor and is compacted.

  - Carbon in fossil fuels in sequestered until we burn them.