-
Facultative
bacteria: Bacteria
that can live under aerobic or anaerobic conditions.
-
Faucet aerator: Device that can
be installed in a sink to reduce water use.
-
Fecal coliform: The portion of
the coliform bacteria group which is present in the intestinal tracts and feces
of warm-blooded animals. A common pollutant in water.
-
Fen: A type of wetland
that accumulates peat deposits. Fens are less acidic than bogs, deriving most
of their water from groundwater rich in calcium and magnesium.
-
Fermentation: The conversion
of organic matter to methane, carbon dioxide and other molecules by anaerobic
bacteria.
-
Fermentation,
anaerobic: Process
in which carbohydrates are converted in the absence of oxygen to hydrocarbons
(such as methane).
-
Field capacity: The amount of
water held in soil against the pull of gravity.
-
Filter: A device used
to remove solids from a mixture or to separate materials. Materials are frequently
separated from water using filters.
-
Filter medium: The permeable
material that separates solids from liquids passing through it.
-
Filtrate: A liquid that
has passed through the filter medium.
-
Filtration: The mechanical
process which removes particulate matter by separating water from solid material,
usually by passing it through sand.
-
First draw: The water that
comes out when a tap is first opened. It is likely that is has the highest level
of lead contamination from weathering of pipelines.
-
First in
time, first in right:
Sentence indicating that
older water rights have priority over more recent rights if there is not enough
water to satisfy all rights.
-
Fission: Reproduction
of microorganisms by means of cell division.
-
Fixed ground
water: Water
held in saturated material that it is not available as a source of water for
pumping.
-
Floc: A flocculent
mass that is formed in the accumulation of suspended particles. It can occur
naturally, but is usually induced in order to be able to remove certain particles
from wastewater.
-
Flocculation: Large scale treatment
process involving gentle stirring whereby small particles in flocs are collected
into larger particles so their weight causes them to settle to the bottom of
the treatment tank.
-
Flood: The temporary
inundation of normally dry land areas resulting from the overflowing of the
natural or artificial confines of a river or other body of water.
-
Flood damage: The economic
loss caused by floods, including damage by inundation, erosion, and/or sediment
deposition. Damages also include emergency costs and business or financial losses.
Evaluation may be based on the cost of replacing, repairing, or rehabilitating;
the comparative change in market or sales value; or the change in the income
or production caused by flooding.
-
Flood forecasting: Prediction of
stage, discharge, time of occurrence, and duration of a flood, especially of
peak discharge at a specified point on a stream, resulting from precipitation
and/or snowmelt.
-
Flood fringe: The portion of
the floodplain where water depths are shallow and velocities are low.
-
Flood irrigation: Irrigation
systems that control the water table with lateral supply ditches. These include
open field ditch systems (furrows), semi-closed conveyance systems, subsurface
conduit systems, crown flood systems, and continuous flood systems. Also includes
seepage or subsurface irrigation systems. The efficiencies of these flood irrigation
systems range from 20 to 80 percent, however, an average of 60 percent is commonly
used for estimating water requirements. May also be referred to as subsurface
irrigation.
-
Flood peak: The highest magnitude
of the stage of discharge attained by a flood. Also called peak stage or peak
discharge.
-
Floodplain: Any normally
dry land area that is susceptible to being inundated by water from any natural
source. This area is usually low land adjacent to a stream or lake.
-
Floodproofing: Any combination
of structural and nonstructural additions, changes, or adjustments to structures
that reduce or eliminate flood damage.
-
Floodway: The channel of
a river or stream and those parts of the adjacent floodplain adjoining the channel
that are required to carry and discharge the base flood.
-
Flora: Plant population
of a region.
-
Flotation: A solids-liquid
or liquid-liquid separation procedure, which is applied to particles of which
the density is lower than that of the liquid they are in. there are three types:
natural, aided and induces flotation.
-
Flow:
The rate of water discharged
from a source; expressed in volume with respect to time, e.g., cubic meter/s,
liter per minute (Lpm).
-
Flow augmentation: The addition
of water to a stream, especially to meet instream flow needs.
-
Flux: The rate at which
a Reverse Osmosis Membrane allows water to pass through it.
-
Food chain: A sequence of
organisms, each of which uses the next, lower member of the sequence as a food
source.
-
Food web: The complex intermeshing
of individual food chains in an ecosystem.
-
Forbay: The water behind
a dam.
-
Forfeited
water right:
A water right canceled because of several consecutive years of nonuse.
-
Fouling: The deposition
of organic matter on the membrane surface, which causes inefficiencies.
-
Fragmentation: The subdivision
of a solid in fragments. The fragments will then adhere to the nearest surface.
-
Free groundwater: Water in interconnected
pore spaces in the zone of saturation down to the first impervious barrier,
moving under the control of the water table slope.
-
Freezing: The change of
a liquid into a solid as temperature decreases. For water, the freezing point
is 32 f or 0oC.
-
Fresh: salt
water interface or the region where fresh water
and salt water meet. In the edwards region, it is commonly referred to as the
"bad water line", although it is a zone and not a line.
-
Freshwater: Water that contains
less than 1,000 milligrams per liter (mg/L) of dissolved solids; generally,
more than 500 mg/L of dissolved solids is undesirable for drinking and many
industrial uses.
-
Frost: A covering of
minute ice crystals on a cold surface.
-
Furrow diking: Water-saving
agricultural irrigation practice in which a long, narrow groove or trench is
made in the earth by a plow. The dike is usually placed at one end of the field
to collect runoff.
