Environmental Engineering Reference
In-Depth Information
Hydrothermal:
Pertaining to hot water.
Hydrothermal reservoir:
An aquifer, or subsurface water, that has sufficient heat,
permeability, and water to be exploited without stimulation or enhancement.
I
Idle capacity:
The component of operable capacity that is not in operation and not
under active repair but is capable of being placed in operation within 30
days; also, capacity not in operation but under active repair that can be
completed within 90 days.
Idle cropland:
Land in cover and soil improvement crops and cropland on which
no crops were planted. Some cropland is idle each year for various physi-
cal and economic reasons. Acreage diverted from corps to soil-conserving
uses (if not eligible for and used as cropland pasture) under federal farm
programs is included in this component. Cropland enrolled in the federal
Conservation Reserve Program (CRP) is included in the idle cropland.
Impedance:
The opposition to power flow in an AC circuit—that is, any device that
introduces such opposition in the form of resistance, reactance, or both. The
impedance of a circuit or device is measured as the ratio of voltage to cur-
rent, where a sinusoidal voltage and current of the same frequency are used
for the measurement; it is measured in ohms.
Impoundment:
A body of water, such as a pond, confined by a dam, dike, floodgate,
or other barrier, which is used to collect and store water for future use.
Incandescent lamp:
A glass enclosure in which light is produced when a tungsten
filament is electrically heated so that it glows. Much of the energy is con-
verted into heat; therefore, this class of lamp is a relatively inefficient source
of light. Included in this category are the familiar screw-in light bulbs, as
well as somewhat more efficient lamps, such as tungsten halogen lamps,
reflector or R-type lamps, parabolic aluminized reflector (PAR) lamps, and
ellipsoidal reflector (ER) lamps.
Incident light:
Light that shines onto the face of a solar cell or module.
Indicator species:
A species used as a gauge for the condition of a particular habitat,
community, or ecosystem. A characteristic or surrogate species for a com-
munity or ecosystem.
Indigenous:
Native to an area.
Indigenous species:
A species that, other than as a result of an introduction, histori-
cally occurred or currently occurs in a particular ecosystem.
Induced seismicity:
Refers to typically minor earthquakes and tremors that are
caused by human activity that alters the stresses and strains on the Earth's
crust. Most induced seismicity is of an extremely low magnitude, and in
many cases human activity is merely the trigger for an earthquake that
would have occurred naturally in any case.
Industrial wood:
All commercial roundwood products except fuelwood.
Injection:
The process returning spent geothermal fluids to the subsurface.
Sometimes referred to as
reinjection
.
