|
Acre-foot (AF) |
The volume of
water require to over one acre to a depth of one foot. 1 acre-foot= 43,560 cubic feet or 326,000 gallons. |
|
Capacity |
The load for
which a generator, turbine, transformer, transmission circuit,
apparatus, station or system is rated. Capacity is also used
synonymously with capacity. |
|
Circuit Breaker |
Any switching device
that is capable of closing or interrupting an electrical circuit. |
|
Confluence |
The combining of two
streams. |
|
Conservation Pool |
Usable storage in
reservoir for hydropower, recreation, water quality, fish and
wildlife management, navigation, and water supply purposes,
designed to be filled during normal and high flow periods for use
during low flow periods. |
Cubic Feet per
Second (cfs) |
1cfs=450
gallons per minute (gpm) |
|
Demand |
The rate of
water flow through, over, or around water control facilities. The
rate of flow is measured by stream gage or calculated from
predetermined rating tables. The term may be applied to the rate
of flow from each individual source (such as a particular turbine)
or to be algebraic summation from all individual sources (which
would be the total rate of flow). Total discharge is synonymous
with outflow. |
|
Discharge |
The rate of water
flow through, over, or around water control facilities. The rate
of flow is measured by stream gage or calculated from
predetermined rating tables. The term may be applied to the rate
of flow from each individual source (such as a particular turbine)
or to be algebraic summation from all individual sources (which
would be the total rate of flow). Total discharge is synonymous
with outflow. |
|
Drawdown |
The distance that
the water surface elevation of a storage reservoir is lowered from
a given or starting elevation as a result of the withdrawal of
water to meet some project purpose(s) such as power generation or
creating flood control space. |
Drought Contingency
Plan |
Detailed drought management plan that addresses current water
conditions in the Savannah River Basin, and serves as a baseline
for future |
|
Drought Indicators |
Mechanisms which reflect drought conditions
and severity. Drought indicators consist of hydrologic indicators
such as streamflow, rainfall, reservoir storage levels and
groundwater levels, meteorological indicators such as rainfall,
and human activity indicators, which include navigation cutbacks
and reduction in hydropower generation. |
|
Drought Response |
A response network consists of trigger levels
and appropriate management action. Triggers are predetermined
standards reflecting drought intensity which induce responses. |
|
Effluent |
Waste material
discharges into the environment. |
|
Flood Control Pool |
Storage above the conservation pool elevation
designed to store floodwater and reduce flooding downstream. |
|
Flow |
The amount of
water passing a given point within a given period of time. |
|
Forebay |
The impoundment immediately above a dam or
hydroelectric plant intake structure. The term is applicable to
all types of hydroelectric developments (e.g. storage,
run-of-river, and pumped-storage). |
|
Generating Unit |
A single power producing unit,
comprised of a turbine, generator, and related equipment. |
|
Generation |
The act or process of producing
electricity from other forms of energy. Also, the amount of
electric energy so produced. |
|
Generator |
The electrical equipment in
power systems that converts mechanical energy to electrical
energy. |
|
Governor |
The device which measures and
regulates turbine speed by controlling wicket gate angle to adjust
water flow to the turbine. |
|
Guide Curve |
(also Rule Curve or Target Pool Levels).
Guides established to regulate and manage optimum pool elevations
for yearly operations at impoundments. Rule curves can be
designed to regulate storage for flood control, hydropower
production, and other operating objectives, as well as a
combination of objectives. |
|
Hydroelectric Plant |
An electric power plant that
uses water to generate power. |
|
Hydropower Power |
The energy that is produced
from water. |
|
Impoundment |
A confined
body of water such as a reservoir or lake. Typically created by a
dam to store water that is released to meet to maintain authorized
purposes |
|
Inflow |
The rate of water flow into a reservoir or
forebay during a specified period. |
|
Kilowatt (kW) |
The electric unit of power, which equals
1,000 watts or 1.341 horsepower. |
|
Kilowatt hour (kWh) |
Unit for measuring electric energy
consumption or generation over time; it equals one kilowatt of
power applied for one hour of time. A typical home uses about 800
kilowatt hours per month. |
|
Load |
The amount of electric power consumed/delivered at a given point. |
|
Megawatt(mW) |
Unit of electric power, used for measuring
rate of producing or consuming electric energy. One megawatt =
1,000 kilowatts or 1 million watts. A megawatt is equal to 1,341
horsepower. |
Meteorological
Conditions |
Atmospheric phenomena and weather of a region. |
|
Minimum Discharge |
The minimum flow that must be released from a
project to meet environmental or other non-power requirements. |
|
Minimum Pool Level |
The lowest elevation to which the pool is to be drawn. |
|
Multi-Purpose Reservoir |
A reservoir planned to be used for more than one purpose. |
|
Normal Pool Level |
The elevation to which the reservoir surface
will rise during ordinary conditions. |
|
Outage |
The period during which a generating unit,
transmission line, or other facility is out of service. |
|
Peak Demand Month |
The month or months of highest power demand. |
|
Peaking Plant |
A powerplant which is normally operated to
provide power during maximum load periods. |
|
Penstock |
A conduit carries water from the reservoir to
the turbine in a hydroelectric plant. |
|
pH |
The condition represented by a number, used
to express both acidity and alkalinity on a scale whose values run
from 0 to 14 with 7 representing neutrality, numbers less than 7
increasing acidity. |
|
Powerplant |
A generating station where prime movers (such as turbines),
electric generators, and auxiliary equipment for producing
electricity are located. |
|
Pumped storage |
A hydropower facility that has reservoir
pumps which also serve as generators, installed in the dam.
During the night, when cheap surplus power is available, the pumps
are run to pump water from a lower reservoir to an upper reservoir
(upstream). During mid-day, when valuable peaking power is
needed, the units are reversed and water is released back to the
lower reservoir to generate electricity. |
|
Releases |
A determined amount of water that is allowed
to pass through or discharged from a dam. |
|
Reregulation Structure |
Peaking power plants generally release water
only a few hours per day. A reregulation structure is a smaller
dam located downstream that is capable of storing the intermittent
slugs of water and releasing a continuous flow. |
|
Rule Curve |
Same as “Guide Curve.” |
|
Streamflow |
The rate at which water passes a given point
in a stream, usually expressed in cubic feet per second. |
|
Switchyard |
An assemblage of electrical equipment for the
purpose of tying together two or more electric circuits through
switches, selectively arranged in order to permit a circuit to be
disconnected or to change the electric connection between the
circuits. In a hydroelectric project, the switchyard is the point
at which the energy generated at the project is connected to the
distribution system. |
|
Tailrace |
The area below a dam; the channel that
carries water away from a dam. |
|
Thermally Stratify |
During the warm months of the year, the sun
heats the upper layers of the lake. Since the warm water rises,
the surface of the lake continues to warm while the bottom layer
stays cold. During the winter months, the upper layers of the
lake are cooled. The warmer water on the bottom rises, causing
destratification, or “turnover”, of the lake. |
|
Transformer |
An electromagnetic device used to change the
electricity from the generator to usable voltage levels. |
|
Transmission Line |
The high voltage lines that
carry electricity from the hydropower plant to the electric
distribution system. |
|
Triggering Mechanism |
An indicator that is put in place to indicate
the need to initiate or terminate specific action before a crisis
occurs. At the action levels, the trigger elevation will initiate
a series of actions that will culminate in the reduction of
releases from the projects. |
|
Turbine |
Large blades that are turned by the force of
water pushing against it; is connected to the generator. |
|
Voltage |
The force which
causes the current to flow through an electrical conductor. |
|
Watt |
Basic unit of
electrical power that is produced at one time or rate of doing
work. The rate of energy transfer equivalent to one ampere
flowing under a pressure of one volt at unity power factor. One
horsepower is equivalent to approximately 746 watts. |
|
Wheeling |
The transfer of power and energy from one utility over the
transmission system of a second utility for delivery to a third
utility, or to a load of the first utility. |
|
Wicket Gates |
Adjustable vanes that control the amount of
water that can enter the turbine. |
|
Top of Page
ABBREVIATIONS |
|
AF |
acre-feet |
|
cfs |
cubic feet per second |
|
cu |
cubic |
|
ft |
foot, feet |
|
gal |
gallons |
|
gph |
gallons per hour |
|
gpm |
gallons per minute |
|
km |
kilometer |
|
kv |
kilovolt |
|
kva |
kilovolt-amperes |
|
kWh |
kilowatts per hour |
|
m |
meter |
|
mgd |
million gallons per
day |
|
mi |
mile |
|
MWH |
Megawatts per hour |
|
MSA |
Metropolitan
Statistical Area |
|
NGVD |
National Geodetic
Vertical Datum |
|
rpm |
revolutions per
minute |
|
SAD |
South Atlantic
Division |
|
SEPA |
Southeast Power
Administration |
|
sq |
square |
|
WES |
Waterways Experiment
Station |
|
/ |
per |
Top of Page
CONVERSION FACTORS |
|
Length
1 mi = 5,280 ft = 1.609 km
1 km = 0.6214 mi = 3,281 ft
Area
1 sq mi = 640 acres = 2.590 sq km
1 acre = 43,560 sq ft = 4,047 sq m
Volume
1 AF = 325,872 gal = 1,233 cu m
1 AF = 43,560 cu ft = 1,613 cu yd
1 cfs-day = 1.983 AF
1 cubic foot = 7.48 gallons = 0.0283 cubic
meters
1 cfs-day = 1.983 AF
1 cubic meter = 35.51 cubic feet
Discharge Rate
1 cu m/sec = 15,850 gpm = 70.04 acre-ft/day
1 cfs = 2,228 gpm = 0.646317 mgd = 1.983
AF/day
1 AF/day = 226.3 gpm = 0.5042 cfs
1 gpm = 8.0208 cu ft/hr
1 cubic foot per second (cfs) =
448.83
gallons per minute (gpm)
0.646 million gallons per day
(mgd)
0.0283 cubic meters per second (cms)
Energy
1 kilowatt
–hour (kWh) = 3,413 BTU [i]
1 kilowatt
(kW) = 1,000 watts
= 1.341 horsepower
= 56.88 BTU/minute
= 737.56
ft-lbs/second
1 megawatt (MW) = 1,000 kilowatts
= 1 million watts
1 gigawatt (gW) = 1,000 megawatts
Energy Equivalents
1 barrel of
oil (42 gallons) = 470 kWh at 27% efficiency [i]
= 520 kWh
at 30 % efficiency
= 660 kWh
at 38% efficiency [iii]
1 ton of coal = 2,500 kWh at 37% efficiency [iv]
1,000 cubic feet of natural gas =
59 kWh at 27% efficiency
[ii]
83 kWh at 38% efficiency [iii]
[i] 1 BTU (British Thermal Unit) is the
amount of energy required to raise the temperature of one
pound of water one degree Fahrenheit.
[ii] Typical efficiency for a combustion
turbine.
[iii]
Typical efficiency for new oil- or gas-fired base load steam
plant or combined cycle plant.
[iv] Typical efficiency for a new base load
coal-fired steam plant.
|
