2.1.2 - The Drainage Basin as a System

Open system
1. Water can enter and leave the system
2. The drainage basin is a subset of the global hydrological cycle It is defined as a catchment area forming part of the Earth's surface area which is drained by a particular stream or river It is an open system which allows energy and matter to be transferred across its boundary (the watershed or drainage divide) from external areas
Input
1. Water entering the system
  1. Precipitation - any product of the condensation of atmospheric water vapor that falls under gravity.
Flow
1. The movement of water between components
  1. Throughfall: Rainwater dripping from leaves and branches towards the ground (rain drops fall through the plants)
  2. Stemflow: Water flows along tree trunks and plant stems towards the ground
  3. Infiltration: Downward movement of water from ground surface into the soil
    1. Throughflow: Sideways movement of water through the soil pores
    2. Percolation: Downward movement of water from soil to rock layer
      1. Groundwater flow: Movement of water through the rock layer
  4. Overland flow: Sheet of water moving along the surface
    1. Two forms of overland flow
      1. Infiltration-excess: Intense rainfall means not all water can infiltrate soil, therefore runs along the surface
      2. Saturation-excess: Excessive rainfall saturates soil so no more water can infiltrate
  5. Channel flow: movement of water through the river channel
Store
1. Where water is held in the system
  1. Interception: Water held on leaves and plant surfaces
  2. Vegetation store: Water within the biomass (plants and animals)
  3. Surface store: Water on the ground e.g. puddles
  4. Soil moisture store: Water held in soil
  5. Channel store: Water held in river channels
  6. Groundwater store: Water stored within rock layer
Outputs
1. Water leaving the system
  1. Channel discharge: Water leaving via river channels
  2. Evapotranspiration
    1. Evaporation
      1. Change of state from water to gas (caused by temperature and wind speed)
    2. Transpiration
      1. Water vapour released from plants

Nächster

2.1.2 - The Drainage Basin as a System

Beschreibung

Zusammenfassung der Ressource

Medienanhänge

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