The Water Cycle as a System

The Water Cycle as a System

1. Inputs - Components allowing things to enter the system

   • Precipitation - Water falling from the atmosphere to the ground. Takes the form of Rain. Snow, Sleet or Hail

2. Outputs - Components allowing things to leave the system

   • Transpiration - The process by which plants absorb water through the roots and then give off water vapor through pores in their leaves.
   • Evaporation - The process by which water changes state from a liquid to a gas (water vapour). This occurs when the water if heated, causing the droplets to become vapour.
   • Channel Flow - The downhill movement of water within rivers.

3. Stores - Components holding something within the system

   • Aquifer - A body of permeable rock which containing groundwater.
   • Vegetation
   • Clouds - Created when water droplets are allowed to form around a cloud condensation nuclei
   • Surface Storage; Lakes, Rivers
   • Soil Moisture - Water that is held in the spaces between soil particles.

4. Flows - Components allowing things to move through the system

   • Throughflow - Water flowing through the soil
   • Groundwater flow - Water flowing through rocks
   • Surface Run-off - Water, from rain, snowmelt, or other sources, that flows along the surface
   • Infiltration - The process by which water on the surface enters the soil.

5. Dynamic Equilibrium - A state of balance between continuing processes

6. Feedback Mechanisms

   • Positive Feedback Loop - Sequence of events amplifying a change. Promotes instability
     • Climate Change causes permafrost to melt, triggering the release of the greenhouse gas Methane.
   • Negative Feedback Loop - Sequence of events dampening a change. Promotes stability
     • Increased temperatures promote plant growth, increasing rates of photosynthesis which removes CO2 from the atmosphere.