What is groundwater?
Groundwater is water beneath the ground surface.
When rain falls on the surface, some of the water may run off directly over the surface into rivers, streams and drains, some may evaporate and some may be taken up by plants. However, a significant proportion of the rain is absorbed by the soil, and subsequently seeps into deeper layers of soil and rock below the surface.
At a certain depth below the ground, the soils and rock will become saturated with the water that has seeped through from above. The boundary between this deeper, permanently saturated ground and the shallower, drier ground above is known as the water table.
Generally the water table, or the levels of saturated ground, are higher in winter and reach a peak in the spring.
Groundwater flows in slow and predictable ways, but is not widely monitored or widely understood as it cannot be seen and requires expensive boreholes to measure.