Environmental Engineering Reference
In-Depth Information
leaching agricultural or industrial pollutants or substances from leaking
underground storage tanks (USTs) are contaminating groundwater.
Groundwater hydrology:
The branch of hydrology that deals with groundwater, its
occurrence and movements, its replenishment and depletion, the properties
of rocks that control groundwater movement and storage, and the methods
of investigation and use of groundwater.
Groundwater recharge:
The inflow to a groundwater reservoir.
Groundwater runoff:
A portion of runoff that has passed into the ground, has
become groundwater, and has been discharged into a stream channel as
spring or seepage water.
H
Habitat:
The place or type of site where species and species assemblages are typi-
cally found or successfully reproduce.
Habitat conservation:
Protecting an animal or plant habitat to ensure that the use of
that habitat by the animal or plant is not altered or reduced.
Habitat fragmentation:
The breaking up of a specific habitat into smaller, uncon-
nected areas.
Half-life:
The time it takes for an isotope to lose half of its radioactivity.
Halogen lamp:
A type of incandescent lamp that lasts much longer and is more
efficient than the common incandescent lamp. The lamp uses a halogen
gas, usually iodine or bromine, that causes the evaporating tungsten to be
redeposited on the filament, thus prolonging its life.
Halogenated substances:
A volatile compound containing halogens, such as chlo-
rine, fluorine, or bromine.
Hardwoods:
Usually broad-leaved and deciduous trees.
HDR (hot dry rock):
Subsurface geologic formations of abnormally high heat con-
tent that contain little or no water.
Head:
The product of the water's weight and a usable difference in elevation gives a
measurement of the potential energy possessed by water.
Head-of-tide:
The farthest point upstream where a river is affected by tidal
fluctuations.
Heat content:
The amount of heat energy available to be released by the transforma-
tion or use of a specified physical unit of an energy form (e.g., a ton of coal,
a barrel of oil, a kilowatt-hour of electricity, a cubic foot of natural gas, a
pound of steam). The amount of heat energy is commonly expressed in
British thermal units (Btu).
Note:
Heat content of combustible energy forms
can be expressed in terms of either gross heat content (higher or upper heat-
ing value) or net heat content (lower heating value), depending on whether
or not the available heat energy includes or excludes the energy used to
vaporize water (contained in the original energy form or created during the
combustion process). The Energy Information Administration (EIA) typi-
cally uses gross heat content values.
Heat exchanger:
A device for transferring thermal energy from one fluid to another.
