Water & carbon

• Systems approach


  A set of interrelated components that form a working unit
• Key components of a system

  • Flows
  • Inputs
  • Stores
  • Components
  • Matter
  • Output
• Open system


  Energy and matter can be transferred into the surrounding environment
• Closed system


  Energy is transferred into and beyond the system, but matter is only cycled between the stores
• Isolated system


  No interactions with anything outside of the system boundary
• Examples of systems


  • Drainage basin (open system)
  • Carbon cycle (closed system)
• Dynamic equilibrium


  Inputs and outputs in the system are in balance
• Positive feedback


  The effects of an action get amplified or multiplied by knock-on effects
• Negative feedback


  Nullifies the change and tries to restore equilibrium
• Earth system components


  • Hydrosphere
  • Atmosphere
  • Lithosphere
  • Biosphere
• Hydrosphere


  All water, liquid, solid and gas
• Atmosphere


  Layer of gas
• Biosphere


  Living things
• Lithosphere


  Outermost part of the Earth's crust
• 3% of water is fresh, 70% is frozen, 1% is surface water
• 50% of fresh water is in lakes, 40% in soil, 10% in other sources
• Evaporation


  1. Occurs when water changes from liquid to gas

  2. Depends on solar radiation, temperature, water supply, dry air
• Transpiration


  Process by which moisture is lost from plant leaves
• Cloud formation


  Unequal heating causes hot air to rise and cool, reaching saturation point and condensing
• Sublimation


  Direct change from solid to gas, bypassing the liquid stage
• Deposition


  Direct change from gas to solid, bypassing the liquid stage
• Winds blow from high to low pressure, curved by Coriolis force
• Atmospheric circulation cells


  • Polar cell
  • Hadley cell
  • Ferrel cell
• Drainage basin


  1. Area of land a river drains

  2. Includes soil water, groundwater, stemflow, overland flow, throughflow, percolation
• Water balance shows long-term average inputs, stores and outputs in a system
• Infiltration capacity


  • Can be compared to the rate of infiltration
• Inputs in the water cycle diagram

  • Precipitation
  • Interception
  • Groundwater
  • Soil water
  • Surface storage
• Flows in the water cycle diagram

  • Stemflow
  • Infiltration
  • Percolation
  • Throughflow
  • Groundwater flow
• Outputs in the water cycle diagram

  • Transpiration
  • Evaporation
  • Channel flow
• Water balance


  The long-term relationship between inputs, outputs and stores in a basin
• Calculating the water balance


  P = Q + E + ΔS
• Positive water balance


  Typically wet
• Negative water balance


  Typically dry
• Water balance


  • Changes seasonally - more surplus in winter, more use in summer
• The water balance affects how much water is stored in the drainage basin
• Features on a flood hydrograph

  • Lag time
  • Peak discharge
  • Bankfull discharge
  • Rising limb
  • Receding limb
  • Rainfall
  • Baseflow
• Humans impact the water cycle through

  • Soil drainage
  • Abstraction
  • Deforestation
• Soil damage from farming practices, deforestation increasing erosion and throughflow, and over-abstraction causing droughts are examples of human impacts on the water cycle
• Land use change and urbanisation can increase surface runoff and reduce transpiration, leading to drier air
• River Eden basin


  • Higher than national average rainfall due to relief
  • Steep slopes impacting lag time and discharge
  • Impermeable igneous rock in the west, permeable limestone in other areas