Water in the Ground
1. Explain how the porosity and permeability affect the storage and movement of groundwater.
2. Describe the water table and features associated with it.
3. Explain how artesian formations affect groundwater.
4. Distinguish among hot springs, geysers, and fumaroles.
Water stored in the Earth's crust is known as groundwater. Groundwater is an important resource as it is pumped out of the ground to supplement the world's fresh water supplies. The amount and quality of our groundwater supply is affected by the following:
The porosity of the soil is the percent of the soil that is air space. Porosity ultimately affects the amount of water a particular rock type can hold and depends on a couple of different factors.
The ability of the ground water to pass through the pore spaces in the rock is described as the rock's permeability. Permeable layers of rock that store and transport water are called aquifers. While porosity and permeability usually go hand-in-hand, though some porous rocks are not permeable and some impermeable rocks are porous. Permeability is affected mostly by the size and arrangement of the grains in the soil.
The Water Table
As rain and runoff enter the soil the water begins to fill the pore spaces in the ground. The water will continue to work its way down until it accumulates above an impermeable layer (bedrock). Just like the soil horizons the areas of saturated an partially saturated soils can be defined as layers (bottom up) .
The water table is an area at the top of the zone of saturation and is a common term used to describe the availability of available groundwater for use. The water table's distance from Earth's surface depends on many factors including:
Last modified: November 18, 2003