Drainage basin

• Outputs

  • Transpiration
  • Evaporation
  • River run-off
• Inputs

  • precipitation
• Storage

  • Interception
  • Surface storage
  • Vegitation storage
  • soil water storage
  • groundwater storage
  • channel storage
• Transfers

  • Throughfall stemflow
  • Surface run-off
  • Infiltration
  • Throughflow
  • Percolation
  • Groundwater flow
  • Channel flow
• A drainage basin is an open system with four elements - inputs, storage, transfers and outputs
• The main input is all forms of precipitation including rain, snow sleet and hail.
• Some precipitation will be stored by vegetaion. Large leaves on trees temporarily hold the precipitation which allows it to either evaporate or to drip to the ground and slowley infiltrate into the soil. The tree roots will draw up some of this water and it will be released from the system as transpiration takes place.
• Some is stored on the surface in lakes, while the rest infiltates to be stored as soil moisture or percolates down into permeable rocks to be stored as groundwater.
• From storage, water is transferred via overland flow and flows horizontally in the soil as throughflow. Bellow the watertable, groundwater or baseflow movements are taking place.
• Along with evaporation and transpiration, rivers flowing into the sea are key outputs in a drainage basin.