Geothermal resourcesTypically underground reservoirs of hot water or steam created by heat from the Earth, but also include subsurface areas of dry hot rock.
Glacial tillAn unsorted, unstratified mixture of fine and coarse rock debris deposited by a glacier.
GlareThe excessive brightness from a direct light source that makes it difficult to see what one wishes to see.
GlintA momentary flash of light resulting from a spatially localized reflection of sunlight. See also Glare
Global WarmingA popular term used to describe the increase in average global temperatures due to the greenhouse effect.
glucanThe polymer of glucose with a repeating unit of C6H10O5. Cellulose is a form of glucan. Can be hydrolyzed to glucose. (Source: Voet, D.; Voet, J. G.
glucoseA type of sugar; the chief source of energy for living organisms.
glycerin(C3H8O3) A liquid by-product of biodiesel production. Glycerin is used in the manufacture of dynamite, cosmetics, liquid soaps, inks, and lubricants.
gr/SCFGrains of pollutant per standard cubic foot of gas. A measure of dust particles in a gas stream.
Graben (fault-bounded basins)An elongated crustal block that is relatively depressed (down dropped) between two parallel normal faults or horsts. See also Half-graben
Graminoid herbaceousA grass or plant of similar growth form, such as sedges, rushes, and others.
Grandfathered rightsIn Arizona, grandfathered water rights are based on historic use of groundwater for five years prior to the designation of an Active Management Area.
GraniteA coarse-grained felsic intrusive (or plutonic) igneous rock with at least 65% silica.
GranodioritesA plutonic igneous rock, formed by an intrusion of silica-rich magma, which cools in batholiths or stocks below the Earth's surface.
GrasslandsGrasslands are characterized as lands dominated by grasses rather than large shrubs or trees.
GraverA small tool with a sharp tip that was used to engrave bone, stone, wood, or other materials.
GrazingConsumption of native forage from rangelands or pastures by livestock or wildlife.
Grazing allotmentAn area where one or more livestock operators graze their livestock. An allotment generally consists of federal land but may include parcels of private or…
Grazing leaseAn authorization that permits the grazing of livestock on public lands outside the grazing districts during a specified period of time (Section 15 of the…
Great BasinAn area covering most of Nevada and much of western Utah, as well as portions of southern Oregon and southeastern California, consisting primarily of…
Green loggingThe logging of timber that is still alive.
Green ton2,000 pounds of undried biomass material. Moisture content must be specified if green tons are used as a measure of fuel energy.
Greenhouse EffectA popular term used to describe the heating effect due to the trapping of long wave (length) radiation by greenhouse gases produced from natural and human…
Greenhouse GasSome greenhouse gases, which contribute to the greenhouse effect, occur naturally in the atmosphere while others result from human activities such as the…
Greenhouse gase (GHG)(GHG)Heat-trapping gases that cause global warming. Natural and human-made greenhouse gases include water vapor, carbon dioxide, methane, nitrogen oxides…
Greenhouse GasesThose gases, such as water vapor, carbon dioxide, tropospheric ozone, methane, and low level ozone that are transparent to solar radiation, but opaque to…
GridA common term referring to an electricity transmission and distribution system.
Grid connectionJoining a plant that generates electric power to a utility system so that electricity can flow in either direction between the utility system and the…
Gross heating value (GHV)(GHV)The maximum potential energy in the fuel as received, considering moisture content (MC). It reflects the heat used to evaporate moisture.
GroundA device used to protect the user of any electrical system or appliance from shock.
Ground failurePermanent ground displacement capable of damaging structures that may occur as a result of differential settlement, liquefaction, lateral spreading, or…
Ground fault matsMats made of insulating materials that do not conduct electricity.
Ground motion (shaking)The movement of the Earth's surface from earthquakes. Ground motion is produced by seismic waves that are generated by a sudden slip on a fault and travel…
GroundwaterAll water below the surface of the land. It is water found in the pore spaces of bedrock or soil, and it reaches the land surface through springs or it…
Groundwater basin: (1) A general term used to define a groundwater flow system that has defined boundaries and may include permeable materials that are capable of storing…
Groundwater overdraftThe condition in which water extractions from an aquifer exceed recharge processes in such excess as to cause substantial and sustained decreases in…
Groundwater rechargeInflow of water to a ground-water reservoir from the surface. Infiltration of precipitation and its movement to the water table is one form of natural…
guaiacylA chemical component of lignin. It has a six-carbon aromatic ring with one methoxyl group attached.
GypsumA soft mineral composed of hydrated calcium sulfate (CaSO4?2H20); occurs as an evaporite residue from ancient lakes in arid basins (e.g.
Gypsum badlandsBadlands dominated by soils derived from the mineral gypsum (hydrated calcium sulfate).
HabitatThe natural environment where people, animals and plants live. In an aquatic environment, it includes the water, topography, structure and cover present…
Habitat alterationA change in the particular environment or place where an organism or species lives.
Habitat degradationDecline in habitat quality that accompanies non-natural forms of disturbance.
Habitat typeAn aggregation of all land areas potentially capable of producing similar plant communities at climax.
Half-grabenA geological term that describes a sedimentary basin where one side is bounded by a normal (extensional) fault.
HammermillA device consisting of a rotating head with free-swinging hammers which reduce chips or hogged fuel to a predetermined particle size through a perforated…
Hand pileA pile of slash constructed by a crew, not by machine. Hand piles are typically less than 10´ high and less than 12´ in diameter.
HarassmentThe intentional or unintentional disturbance of individual animals causing them to flee a site or avoid use of an area.
HardpanA dense, often impermeable soil horizon cemented with silica, iron oxides, calcium carbonate, or organic matter.
hardwoodOne of the botanical groups of dicotyledonous trees that have broad leaves in contrast to the conifers or softwoods.
HardwoodsUsually broad-leaved and deciduous trees.
Hazardous materialAny material that poses a threat to human health and/or the environment. Hazardous materials are typically toxic, corrosive, ignitable, explosive, or…
Hazardous wasteBy-products of society that can pose a substantial or potential hazard to human health or the environment when improperly managed.
HeadThe upper horizontal part of a window frame or window opening.
HeaderA masonry wall unit of brick which is laid so that its short end is exposed.
Headwater(1) The source and upper reaches of a stream; also the upper reaches of a reservoir; (2) the water upstream from a structure or point on a stream; (3) the…
Heat ExchangerA device used to transfer heat from a fluid (liquid or gas) to another fluid where the two fluids are physically separated.
Heat rateThe ratio of fuel energy input as heat per unit of net work output; a measure of a power plant thermal efficiency, generally expressed as Btu per net…
Heat transfer efficiencyThe useful heat output released to a room divided by the actual heat produced in the firebox.
Heat transfer fluid (HTF)(HTF)Fluids that transfer heat generated at the solar collectors to a heat exchanger where steam is produced to run a steam generator.
Heating ValueThe amount of heat produced from the complete combustion of a unit of fuel. The higher (or gross) heating value is that when all products of combustion…
Heavy metalsMetallic elements with high atomic weights (e.g., mercury, chromium, cadmium, arsenic, and lead); can damage living things at low concentrations and tend…
HectareAn area equal to 2.47 acres. There are 100 hectares in 1 square kilometer.
Hedonic – (modeling approach)The hedonic method is a regression technique used to estimate the prices of qualities or models that are not available on the market in particular…
Hedonic statistical frameworkA method of assessing the impact of various structural (number of bedrooms, bathrooms, square footage, age, etc.
HeliostatA device that tracks the movement of the sun; used to orient solar concentrating systems.
hemicelluloseAny cellulose-like carbohydrate, but excluding cellulose itself. Together with pectin and lignin, hemicelluloses form the cell wall matrix.
HerbaceousThe plant strata that contain soft, not woody, stemmed plants that die to the ground in winter.
herbaceous energy cropsPerennial non-woody crops that are harvested annually, though they may take two to three years to reach full productivity.
herbaceous plantsNon-woody species of vegetation, usually of low lignin content such as grasses.
Herd Area (HA)(HA)Following passage of the Wild Free-Roaming Horses and Burros Act (WFRHBA) in 1971, the Bureau of Land Management was directed to identify areas where wild…
Herd Management Area (HMA)(HMA)An area that has been designated for management of wild horses and/or burros.
HerpetofaunaAmphibian and reptile species including frogs, toads, salamanders, turtles, lizards, and snakes.
Hertz (Hz)(Hz)The unit of measurement of frequency, equivalent to one cycle per second.
hexoseAny of various simple sugars that have six carbon atoms per molecule (e.g. glucose, mannose, and galactose.)
HibernaculaCaves or other structures used by bats for hibernation.
High liquefaction potentialRefers to the susceptibility of soils to liquefy when subjected to sudden loading, such as intense ground shaking from an earthquake.
Higher Heating Value (HHV)(HHV)The maximum heating value of a fuel sample, which includes the calorific value of the fuel (bone dry) and the latent heat of vaporization of the water in…
Highly discordant land useRefers to development that is at variance with the existing condition of the land. It might also be described as incongruous.
HistoricThe time period after the appearance of written records. In the New World, this generally refers to the time period after the beginning of European…
Historic propertiesAny prehistoric or historic districts, sites, buildings, structures, or objects included in, or eligible for inclusion in, the National Register of…
Historic resourcesMaterial remains and the landscape alterations that have occurred since the arrival of Euro-Americans.
Hog fuel or hogged fuelWood residues processed through a chipper or mill to produce coarse chips normally used for fuel.
HogbacksAn eroded steep ridge of resistant rocks produced by erosion of the broken edges of highly tilted strata.
holocelluloseThe total carbohydrate fraction of wood; cellulose plus hemicellulose.
HoloceneThe past 10,000 years of geologic time. The most recent epoch of the Quaternary period.
Horizon lineThe apparent line in the landscape formed by the meeting of the visible land surface and the sky.
Horizontal angle of viewThe angle of landscape viewed in sharp focus, measured along the horizon, without turning the head. See also Vertical angle of view; Angle of view
Horsepower (hp)(hp)A unit of rate of operation. Electrical hp: a measure of time rate of mechanical energy output; usually applied to electric motors as the maximum output…