Water movement (the water cycle)

The water cycle refers to the cyclic movement of water between the atmosphere, the land and the sea. Water is present in the atmosphere as water vapour. It evaporates from inland water bodies, oceans and the land surface. It can also evaporate from the leaves of plants (evapotranspiration). Water vapour condenses to form clouds and is returned to the land and its water bodies as rain, snow and hail. This water flows into our water bodies as surface run-off, or, seeps into the ground where it can be used by plants. The cycle begins again when this water returns to the atmosphere through evaporation.

Changes to the environment, such as removal of vegetation, can affect the rate and path of water movement, altering the natural balance of the water cycle. This often means that more water than usual filters into the ground and recharges the groundwater system. A salinity problem can occur when salt is mobilised by a change in the water cycle balance.