Water is so important to life, and all
living organisms depend on it.
And each place on earth has a unique
system of hydrology to follow after. Ground water is one of Honolulu’s most important
natural resources. It is used for drinking water, irrigation, and domestic, commercial,
and industrial needs. Ground water provides about 99 percent of Hawaii’s
domestic water and about 50 percent of all freshwater used in the State. The
most extensive and productive aquifers, permeable
formation from which water may be extracted, in the Hawaiian islands are formed by
volcanic rocks that erupted during the principal building stage of each
volcano.
Ground-water resources can be limited because
of water-quality, environmental, or economic concerns. Water beneath the ground
surface occurs in two principal zones: the unsaturated zone and the saturated
zone. In the unsaturated zone, the pore spaces in rocks contain both air and
water, whereas in the saturated zone, the pore spaces are filled with water.
The upper surface of the saturated zone is referred to as the water table,
which is the level that which water rises.
VIDEO: Better understanding of Groundwater .
In Hawaii, the major fresh groundwater
systems are below the lowest water table, and are either freshwater-lens or dike-impounded
systems. Where freshwater-lens and dike-impounded systems are adjacent, they
form a single, hydrologically connected ground-water flow system.
The main
factors limiting groundwater availability in the State of Hawaii are saltwater
intrusion, the reduction of discharge to streams and the ocean, and lowering of
water levels. When water is withdrawn from a freshwater lens, the freshwater
lens shrinks and saltwater or brackish water will intrude upward and landward
into parts of the aquifer that formerly contained freshwater. The degree of saltwater
intrusion depends on several factors, which include the hydraulic properties of
the rocks, recharge rate, pumping rate, and well location.
http://ga.water.usgs.gov/edu/earthgwaquifer.html
http://water.usgs.gov/ogw/unsaturated.html
http://hawaii.gov/dbedt/czm/initiative/wec/html/mountain/water/ground.htm
And my notes =]
