Groundwater and Hydrological Cycle

What is Groundwater?

When rain falls to the ground, the water does not stop moving. Some of it flows along the surface to streams or lakes, some of it is used by plants, some evaporates and returns to the atmosphere, and some sinks into the ground.

Groundwater is water that is found underground in the cracks and spaces in soil, sand and rock. Groundwater is stored in – and moves slowly through – layers of soil, sand and rocks called aquifers. Aquifers typically consist of gravel, sand, sandstone, of fractured rock, like limestone. These materials are permeable because they have large connected spaces that allow water to flow through. The speed at which groundwater flows depends on the size of the spaces in the soil or rock and how well the spaces are connected.

Source: Groundwater Foundation

What is the Hydrologic Cycle?

The Water Cycle or Hydrologic Cycle is a series of movements of water above, on, and below the surface of the earth. The water cycle consists of four distinct stages:

  • Storage
  • Evaporation
  • Precipitation
  • Runoff

Water may be stored temporarily in the ground; in oceans, lakes, and rivers; and in ice caps and glaciers. It evaporates from the earth’s surface, condenses in clouds, falls back to earth as precipitation (rain or snow), and eventually either runs into the seas or re-evaporates into the atmosphere. Almost all the water on the earth has passed through the water cycle countless times.

Source: “Water Cycle,” Microsoft Encarta Online Encyclopedia 2003. All Rights Reserved.