How does groundwater work

Water in aquifers is brought to the surface naturally through a spring or can be discharged into lakes and streams. Groundwater can also be extracted through a well drilled into the aquifer. A well is a pipe in the ground that fills with groundwater.

This water can be brought to the surface by a pump. Shallow wells may go dry if the water table falls below the bottom of the well. Some wells, called artesian wells, do not need a pump because of natural pressures that force the water up and out of the well. In areas where material above the aquifer is permeable, pollutants can readily sink into groundwater supplies. Groundwater can be polluted by landfills, septic tanks, leaky underground gas tanks, and from overuse of fertilizers and pesticides.

The aquifer will therefore be saturated throughout its full thickness. Because the groundwater is under pressure, water will rise up a borehole drilled into the aquifer above the top of the aquifer. Aquifers are susceptible to contamination from a variety of anthropogenic activities. Restoring contaminated groundwater is at best expensive and often just not possible. It is therefore far better to prevent pollution occurring than to try and deal with the consequences.

The vulnerability of an aquifer to contamination is dependent on a number of factors, namely the type and thickness of overlying deposits both soil and drift geology , the thickness of the unsaturated zone i. Skip to main content. About the Project. World Water Distribution. The water table may lie deep or shallow depending on several factors such as the physical characteristics of the region, the meteorological conditions and the recharge and exploitation rates.

Heavy rains may increase recharge and cause the water table to rise. But in the other hand, an extended period of dry weather may cause the water table to fall. When groundwater reaches an aquifer it does not stand still. It normally will keep flowing but much slower than before reaching the aquifer. How fast groundwater flows depends on the characteristics of the aquifer.

The direction it moves is normally from high to lower levels ruled by gravity, unless there is any anthropogenic impact such as pumping wells. The groundwater will move until it discharges into another aquifer or another water body like a lake, a river, the ocean or until it is extracted by a well.

To be able to store and yield groundwater, an aquifer needs to have certain physical characteristics. It needs to have empty space pores or fractures where groundwater can be stored and the spaces need to be connected to allow it to flow through.