A Very Short introduction to Ground
Water
http://www.ngwa.org/Fundamentals/teachers/Pages/Ground-Water-Introduction-and-Demonstration.aspx
http://en.wikipedia.org/wiki/Groundwater
www.karmayog.org (17.10.2013)
Groundwater is defined
as water that is found beneath the water table under Earths surface in soil pore spaces and in fractures of
rock formations. When rain falls to the ground, the water does
not stop moving. Some of it flows along the land surface to streams or lakes,
some is used by plants. Some evaporates and returns to the atmosphere. This is
ground water. And some seeps underground, into pores between sand, clay and
rock formations called aquifers. Water moves through aquifers much like a glass
of water poured onto a pile of sand.
A unit of rock or an
unconsolidated deposit is called an aquifer
when it can yield usable quantity of water. The depth at which soil pore spaces
or fractures and voids in rock becomes completely saturated with water is
called water table. Ground water is
recharged from and eventually flows to the surface naturally.
Ground water is
important because it forms 98 percent of all the usable fresh water on the planet and it is
about 60 times as plentiful as fresh water found in lakes and streams. Since groundwater
is not visible (in most cases), it is
often overlooked when considering all of the water on Earth, and yet, water
beneath the land surface is a valuable resource. Protecting it from
contamination and carefully managing its use will ensure its future as an
important part of ecosystems and human activity.
In India 97%
of rural population drinks ground water and about 30-40% of water used for agriculture comes from groundwater.
Therefore groundwater is valuable resource and must be protected from any
pollution. Water – from ground travels through pores in soils and rocks in
fractures and through weathered area of rock.
- The amount of pore space
present in rock and soil is known as porosity. - The ability of fluids to travel
through the rock or soil is known as permeability. - An aquifer is a body of water-saturated sediment or rock in
which water can move readily. - There are two main types
of aquifers: unconfined
and confined. - An unconfined aquifer is an aquifer that is exposed to the surface of
the land. - A confined aquifer is an aquifer that has a confining layer that
separates it from the land surface.