adapted to HTML from lecture notes of Prof. Stephen A. Nelson Tulane
Lakes and Streams
- Fresh Water
- Salty Water
Zone of Saturation
The area where all the pore space in the ground is filled with water.
Zone of Aeration
The area of where the pore space is mostly empty, or full of air.
The level below which the ground is saturated.
A large volume of the subsurface that is thoroughly saturated with
water, and through which water travels freely. It contains a large
volume of water which can be accessed for use.
A layer of impermeable material, for example clay, that prevents water
from passing through.
Perched water table
Subsurface area saturated with water above an aquiclude, forming a
local water table above the regional water table..
A measure of permeability. ( How fast does the water travel through
The difference in the elevation of the water table over a given length.
The rate of groundwater flow is dependent on the hydraulic
conductivity and hydraulic gradient.
The greater the conductivity or the greater the gradient the more
rapid groundwater flows.
The process by which water sorbed by plants is returned to the
atmosphere as a gas.
The combined processes of Evaporation and Transpiration.
The percentage of void space in a rock.
Well sorted sand may have a porosity of 30% to 40%.
Poorly sorted sand will have a lower porosity because the
finer grained sediment fills the spaces between the larger
Most igneous rocks have very low to no porosity.
Limestones may have a low or high porosity. If it has
undergone erosion or dissolution, it may even have large
The ease with which water can pass through a substance.
A substance through which water cannot pass is said to be
The permiability of various sediment types, ranging from most
permeable to least permeable, is:
Gravel Most permeable
Clay Least permeable
The term applied to water pressure due to the difference in the height
of water in a closed system. Water tends to reach its own level. This
phenomena may result in artesian wells and springs, and is used in
providing water to municipalities via a water tower.