Groundwater is derived principally from surface water (sources include rainfall, waterways, irrigation and water storages) that percolates through the soil until it reaches the water table. The water table is the level below which all the spaces between soil/rock materials are saturated with water. Groundwater is also found in layers of porous rock called aquifers.
Groundwater is an important part of the water cycle and is fundamentally linked to surface water. When groundwater is discharged into springs, wetlands, rivers and other waterways it is once again considered surface water. The physical properties of groundwater can vary greatly, particularly the dissolved mineral concentrations. Groundwater is usually extracted via bores either by pumping or under natural pressure for a variety of purposes, i.e. drinking and irrigating.
The direct impacts of groundwater extraction may include:
Last updated 7 September 2010