Cpesc - Flash Cards

Front 1

Accretion

Back 1

Outward growth of bank or shore by sedimentation. Increase or extension of boundaries of land by action
of natural forces.

Front 2

Active Construction Area.

Back 2

The area where the contractor intends to be actively involved in soil disturbing work This may include areas where soils have been disturbed,
as well as areas where soil disturbance has not yet occurred.

Front 3

Aggradation.

Back 3

General and progressive rising of a stream bed by deposition of sediment. Modification of the earth's
surface in the direction of uniformity of grade or slope by deposition as in a river bed.

Front 4

Aggressive.

Back 4

Refers to the corrosive properties of soil and water.

Front 5

Alluvial.

Back 5

Referring to deposits of silts, sands, gravels, and similar detrital material which have been transported by
running water

Front 6

Alluvium.

Back 6

Stream-borne materials deposited in and along a channel.

Front 7

Apron

Back 7

A lining of the bed of the channel upstream or downstream from a lined or restricted waterway. A floor or
lining of concrete, rock, etc., to protect a surface from erosion, such as the pavement below chutes, spillways, at the
toes of dams, or along the toe of bank protection.

Front 8

Aqueduct

Back 8

(1) A major conduit. (2) The entire transmission main for a municipal water supply that may consist of a
succession of canals, pipes, tunnels, etc. (3) Any conduit for water; especially one for a large quantity of flowing
water. (4) A structure for conveying a canal over a river or hollow.

Front 9

Aquifer

Back 9

Water-bearing geologic formations that permit the movement of ground water.

Front 10

Arid Area

Back 10

Area receiving less than 10 inches of rainfall per year.

Front 11

Armor

Back 11

Artificial surfacing of bed, banks, shore or embankment to resist erosion or scour.

Front 12

Arroyo

Back 12

Waterway of an ephemeral stream deeply carved in rock or ancient alluvium.or sco

Front 13

Artesian Waters

Back 13

Percolating waters confined below impermeable formations with sufficient pressure to spring or
well up to the surface.

Front 14

Articulated

Back 14

Made flexible by hinging, particularly of small rigid slabs adapted to revetment.

Front 15

Backfill

Back 15

Earth used to fill a trench or excavation.

Front 16

Backing Layerrs

Back 16

A layer of graded rock between rock riprap and underlying engineering fabric or filter layer to
prevent extrusion of the soil or filter layer material through the riprap.

Front 17

Backwater

Back 17

An unnaturally high stage in stream caused by obstruction or confinement of flow, as by a dam, a bridge,
or a levee. Its measure is the excess of unnatural over natural stage, not the difference in stage upstream and downstream from its cause.r

Front 18

Baffle

Back 18

A pier, vane, sill, fence, wall, or mound built on the bed of a stream to parry, deflect, check, or disturb the
flow, or to float on the surface to deflect or dampen cross currents or waves.

Front 19

Bank

Back 19

The lateral boundary of a stream-confining water flow. The bank on the left side of a channel looking
downstream is called the left bank, etc.«

Front 20

Bank Protection

Back 20

Revetment or other armor protecting a stream bank from erosion, includes devices used to deflect
the forces of erosion away from the bank.

Front 21

Bar

Back 21

An elongated deposit of alluvium within a channel or across its mouth.

Front 22

Barrier

Back 22

A low dam or rack built to control flow of debris.age/pj

Front 23

Base Floode

Back 23

The flood or tide having a 1 percent chance of being exceeded in any given year (100-year flood). The
'base flood' is commonly used as the 'standard flood' in Federal flood insurance studies (see Regulatory Flood).l

Front 24

Base Floodplain

Back 24

The area subject to flooding by the base flood

Front 25

Base Flow

Back 25

The groundwater flow contribution to a creek. During dry periods, base flow constitutes the majority of
stream flow.

Front 26

Basin

Back 26

(1) The surface of the area tributary to a stream or lake. (2) Space above or below ground capable of retaining
or detaining water or debris.

Front 27

Bay

Back 27

An indentation of bank or shore, including erosional cuts and slipouts, not necessarily large.N

Front 28

Beach

Back 28

The zone of sedimentary material that extends landward from the low water line to the place where there is
marked change in material or form, or to the line of permanent vegetation (usually the effective limit of storm waves).
The seaward limit of a beach, unless otherwise specified, is the mean low water line. A beach includes foreshore and
backshore.

Front 29

Bed

Back 29

The earth below any body of water, limited laterally by bank or shore.

Front 30

Bed Load

Back 30

Sediment that moves by rolling, sliding, or skipping along the bed, and is essentially in contact with the
stream bed.

Front 31

Bedding

Back 31

The foundation under a drainage structure

Front 32

Beneficial Uses

Back 32

As referred to in the State Water Quality Standards, beneficial uses are activities that range from
recreational to agricultural uses, depending on the source of the water.

Front 33

Berm

Back 33

(1) A bench or terrace between two slopes. (2) A nearly horizontal part of the beach or backshore formed at
the high water line by waves depositing material. Some beaches have no berms, other have one or several—ÏÇ

Front 34

Best Management Practice (BMP)

Back 34

(1)A measure that is implemented to protect water quality
and reduce the potential for pollution associated with storm water runoff. (2) Any program, technology, process,
silting criteria, operating method, measure, or device that controls, prevents, removes, or reduces pollution.

Front 35

Block

Back 35

Precast prismatic unit for riprap structure.eg

Front 36

Bluff

Back 36

A high, steep bank composed of erodible materialsmage/pj

Front 37

Boom

Back 37

Floating log or similar element designed to dampen surface waves or control the movement of drift.

Front 38

Boulder

Back 38

Largest rock transported by a stream or rolled in the surf; arbitrarily heavier than 12 kg and larger than 200
mm.w.

Front 39

Braided Stream

Back 39

A stream in which flow is divided at normal stage by small islands. This type of stream has the
aspect of a single, large channel with which there are subordinate channels.

Front 40

Breakwater

Back 40

A fixed or floating structure that protects a shore area, harbor, anchorage, or basin by intercepting
waves.

Front 41

Bulkhead

Back 41

A steep or vertical structure placed on a bank, bluff, or embankment to retain or prevent sliding of the
land and protect the inland area against damage.ockwav

Front 42

Bulking

Back 42

The increase in volume of flow due to air entrainment, debris, bedload, or sediment in suspension

Front 43

Buoyancy

Back 43

Uplift force on a submerged body equal to the mass of water displaced, times the acceleration of gravity


Front 44

Canal

Back 44

An artificial, open channel

Front 45

Canyon

Back 45

A large, deep valley; also the sub-marine counterpart

Front 46

Capacity

Back 46

The effective carrying ability of a drainage structure. Generally measured in cubic meters per second

Front 47

Capillarity

Back 47

The attraction between water and soil particles, which cause water to move in any direction through the
soil mass regardless of gravitational forces.

Front 48

Capillary Water

Back 48

Water which clings to soil particles by capillary action. It is normally associated with fine sand, silt,
or clay, but not normally with coarse sand and gravel.

Front 49

Catch Basin

Back 49

A drainage structure which collects water. May be either a structure where water enters from the side
or through a grating.

Front 50

Causeway

Back 50

A raised embankment or trestle over swamp or overflow areas

Front 51

Cavitation

Back 51

Erosion by suction, especially in the partial vacuum of a diverging jet.

Front 52

Channel

Back 52

The space above the bed, and between banks, occupied by a stream

Front 53

Channelization

Back 53

The process of making a channel or channels. A channel is the bed of a stream or river, or the
hollow or course in which a stream flows.k.

Front 54

Check

Back 54

A sill or weir in a channel to control stage or velocity

Front 55

Check Dam

Back 55

A small dam generally placed in steep ditches for the purpose of reducing the velocity in the ditch

Front 56

Clean Water Act (CWA)

Back 56

The Federal Water Pollution Control Act enacted in 1972 by Public Law 92-500 and
amended by the Water Quality Act of 1987. The Clean Water Act prohibits the discharge of pollutants to Waters of
the United States unless said discharge is in accordance with an NPDES permit. The 1987 amendments include
guidelines for regulating municipal, industrial, and construction storm water discharges under the NPDES program.

Front 57

Cleanout

Back 57

An access opening to a roadway drainage system. Usually consists of a manhole shaft, a special chamber
or opening into a shallow culvert or drain.

Front 58

Cliff

Back 58

A high, steep face of rock; a precipice

Front 59

Cloudburst

Back 59

Rain storm of great intensity usually over a small area for a short duratione

Front 60

Coast

Back 60

(1) The strip of land, of indefinite width (up to several kilometers), that extends from the shoreline inland to
the first major change in terrain features. (2) As a combining form, upcoast is northerly and downcoast is southerly.

Front 61

Cobble

Back 61

Rock, smaller than a boulder and larger than gravel; arbitrarily 0.5 to 12 kg, or 75 to 200 mm in diame

Front 62

Coefficient of Runoff

Back 62

Percentage of gross rainfall, which appears as runoff

Front 63

Composite Hydrograph

Back 63

A plot of mean daily discharges for a number of years of record on a single year time base
for the purpose of showing the occurrence of high and low flowsckwav

Front 64

Concentrated Flow

Back 64

Flowing water that has been accumulated into a single, fairly narrow stream

Front 65

Concentration

Back 65

In addition to its general sense, means the unnatural collection or convergence of waters so as to
discharge in a narrower width, and at greater depth or velocity

Front 66

Conduit

Back 66

Any pipe, arch, box or drain tile through which water is conveyedng jet.

Front 67

Cone

Back 67

Physiographic form of sediment deposit washed from a gorge channel onto an open plain; a debris cone, also
called an alluvial fan.

Front 68

Confluence

Back 68

A junction of streams

Front 69

Constriction

Back 69

An obstruction narrowing a waterway

Front 70

Construction Activity

Back 70

Includes clearing, grading, or excavation and contractor activities that result in soil
disturbance.

Front 71

Construction Site

Back 71

The area involved in a construction project as a whole

Front 72

Contraction

Back 72

The reduction in cross sectional area of flowg

Front 73

Control

Back 73

(1) A section or reach of an open conduit or stream channel which maintains a stable relationship between
stage and discharge. (2) For flood, erosion, debris, etc., remedial means or procedure restricting damage to a tolerable
level.

Front 74

Conveyance

Back 74

(1) A measure of the water carrying capacity of a stream or channel. (2) Any natural or man-made
channel or pipe in which concentrated water flows..

Front 75

Core

Back 75

Central zone of dike, levee, rock groin, jetty, etc.e/pj

Front 76

Cradle

Back 76

A concrete base generally constructed to fit the shape of a structure that is to be forced through earthen
material by a jacking operation. The cradle is constructed to line and grade. Then, the pipe rides on the cradle as it is
worked through the given material by jacking and tunneling methods. Also serves as bedding for pipes in trenches in
special conditions.

Front 77

Creek


Back 77

A small stream, usually active

Front 78

Crest


Back 78

(1) Peak of a wave or a flood. (2) Top of a levee, dam, weir, spillway or other water barrier or control


Front 79

Crib


Back 79

An open-frame structure loaded with earth or stone ballast to act as a baffle in bank protection

Front 80

Critical Depth

Back 80

(Depth at which specific energy is a minimum) - The depth of water in a conduit at which under certain other conditions the maximum flow will occur. These other conditions are: 1) the conduit is on the critical
slope with the water flowing at its critical velocity, and 2) there is an adequate supply of water. The depth of water
flowing in an open channel or a conduit partially filled, for which the velocity head equals one-half the hydraulic
mean depth.s.

Front 81

Critical Flow

Back 81

That flow in open channels at which the energy content of the fluid is at a minimum. Also, that flow
which has a Froude number of onerd

Front 82

Critical Slope

Back 82

That slope at which the maximum flow will occur at the minimum velocity. The slope or grade that is
exactly equal to the loss of head per meter resulting from flow at a depth that will give uniform flow at critical depth;
the slope of a conduit which will produce critical flow.

Front 83

Critical Velocity

Back 83

Mean velocity of flow when flow is at critical depth.epj

Front 84

Culvert

Back 84

A closed conduit, other than a bridge, which allows water to pass under a highway. A culvert has a span of
less than 6.1 m, or if multispan, the individual spans are 3.0 m or less.

Front 85

Current

Back 85

Flow of water, both as a phenomenon and as a vector. Usually qualified by adjectives like downward,
littoral, tidal, etc. to show relation to a pattern of movement.sh,

Front 86

Cutoff Wall

Back 86

A wall at the end of a drainage structure, the top of which is an integral part of the drainage structure.
This wall is usually buried, and its function is to prevent undermining of the drainage structure if the natural material
at the outlet of the structure is scoured by the water discharging from the end of the structure. Cutoff walls are
sometimes used at the upstream end of a structure when there is a possibility of erosion at this point.

Front 87

Debris

Back 87

Any material including floating woody materials and other trash, suspended sediment, or bed load moved by
a flowing stream.

Front 88

Debris Barrier

Back 88

A deflector placed at the entrance of a culvert upstream, which tends to deflect heavy floating debris
or boulders away from the culvert entrance during high-velocity flow.

Front 89

Debris Basin

Back 89

Any area upstream from a drainage structure utilized for the purpose of retaining debris, in order to
prevent clogging of drainage structures downstreamhockwav

Front 90

Debris Rack

Back 90

straight barrier that, when placed across the stream channel, tends to separate light and medium
floating debris from stream flow and prevent the debris from reaching the culvert entrance

Front 91

Degradation

Back 91

General and progressive lowering of the longitudinal profile of a channel by erosion

Front 92

Denuded

Back 92

Land stripped of vegetation

Front 93

Deposit

Back 93

An earth mass of particles settled or stranded from moving water or wind

Front 94

Depth

Back 94

Vertical distance: (1) from surface to bed of a body of water, (2) from crest or crown to invert of a conduiterp

Front 95

Design Discharge

Back 95

The quantity of flow that is expected at a certain point as a result of a design storm. Usually
expressed as a rate of flow in cubic meters per second

Front 96

Design Flood

Back 96

The peak discharge (when appropriate, the volume, stage, or wave crest elevation) of the flood
associated with the probability of exceedance selected for the design of an encroachment in a FEMA flood plain.

Front 97

Design Frequency

Back 97

The recurrence interval for hydrologic events used for design purposes. As an example, a design
frequency of 50 years means a storm of a magnitude that would be expected to recur on the average of every 50 years
(See Probability of Exceedance).

Front 98

Design High Water

Back 98

The flood stage or tide crest elevation adopted for design of drainage and bank protection
structures (See Design Flood and High Water).

Front 99

Design Storm

Back 99

That particular storm which contributes runoff which the drainage facilities were designed to handle.
This storm is selected for design on the basis of its probability of exceedance or average recurrence interval (See
Probability of Exceedance)

Front 100

Detention

Back 100

The process of temporarily collecting and holding back storm water for later release to receiving waterss-powerp

Front 101

Detention Storage

Back 101

Surface water moving over the land is in detention storage. Surface water allowed to temporarily
accumulate in ponds, basins, reservoirs or other types of holding facility and which is ultimately returned to a
watercourse or other drainage system as runoff, is in detention storage (See Retention Storage)

Front 102

Detritus

Back 102

Loose material such as rock, sand, silt, and organic particles.

Front 103

Dike

Back 103

(1) Usually an earthen bank alongside and parallel with a river or open channel to restrict overflow (See
Levee). (2) An asphalt, concrete berm along the edge of a shoulder

Front 104

Dike, Finger

Back 104

Relatively short embankments constructed normal to a larger embankment, such as an approach fill to a
bridge. Their purpose is to impede flow and direct it away from the major embankment bed.

Front 105

Dike, Spurer

Back 105

Relatively short embankments constructed at the upstream side of a bridge end for the purpose of
aligning flow with the waterway opening and to move scour away from the bridge abutmentwaves.

Front 106

Dike, Toe

Back 106

Embankment constructed to prevent lateral flow from scouring the corner of the downstream side of an
abutment embankment. Sometimes referred to as training dikesflash,

Front 107

Dike, Training

Back 107

Embankments constructed to provide a transition from the natural stream channel or floodplain, both
to and from a constricting bridge crossing

Front 108

Discharge

Back 108

A volume of water flowing out of a drainage structure or facility. Measured in cubic meters per second.ms-powerp

Front 109

Dissipate

Back 109

Expend or scatter harmlessly, as of energy of moving water

Front 110

Disturbed Areas

Back 110

Areas that have been purposefully cleared, grubbed, excavated, or graded by the contractor;
ground surface that has been disrupted by construction activities, including construction access/roads, staging, and
storage sites producing significant areas of exposed soil and soil piles

Front 111

Ditch

Back 111

Small artificial channel, usually unlined

Front 112

Diversion

Back 112

(1) The change in character, location, direction, or quantity of flow of a natural drainage course (a
deflection of flood water is not a diversion). (2) Draft of water from one channel to another. (3) Interception of runoff
by works which discharge it through unnatural channels

Front 113

Downdrain

Back 113

A prefabricated drainage facility assembled and installed in the field for the purpose of transporting
water down steep slopes

Front 114

Downdrift

Back 114

The direction of predominant movement of littoral materials

Front 115

Drain

Back 115

Conduit intercepting and discharging surplus ground or surface waterwind

Front 116

Drainage

Back 116

(1) The process of removing surplus ground or surface water by artificial means. (2) The system by which the waters of an area are removed. (3) The area from which waters are drained; a drainage basin

Front 117

Drainage Area (Drainage Basin) (Basin)

Back 117

That portion of the earth's surface upon which falling precipitation flows
to a given location

Front 118

Drainage Course

Back 118

Any path along which water flows when acted upon by gravitational forces

Front 119

Drainage Divide

Back 119

The rim of a drainage basin. A series of high points from which water flows in two directions, to
the basin and away from the basinword

Front 120

Drainage System

Back 120

Usually a system of underground conduits and collector structures which flow to a single point of
dischargew

Front 121

Drawdown

Back 121

The difference in elevation between the water surface elevation at a constriction in a stream or conduit
and the elevation that would exist if the constriction were absent. Drawdown also occurs at changes from mild to
steep channel slopes and weirs or vertical spillways.

Front 122

Drift

Back 122

(1) Floating or non-mineral burden of a stream. (2) Deviation from a normal course in a cross current, as in
littoral drift

Front 123

Drop

Back 123

Controlled fall in a stream to dissipate energy

Front 124

Dry Weather Flows

Back 124

A small amount of water which flows almost continually due to lawn watering, irrigation or
springs

Front 125

Dune

Back 125

A sand wave of approximately triangular cross section (in a vertical plane in the direction of flow) formed by
moving water or wind, with gentle upstream slope and steep downstream slope and deposition on the downstream
slope

Front 126

Easement

Back 126

Right to use the land of others

Front 127

Ebb

Back 127

Falling stage or outward flow, especially of tidesage/pj

Front 128

Eddy Loss

Back 128

The energy lost (converted into heat) by swirls, eddies, and impact, as distinguished from friction losss-powerp

Front 129

Eddy

Back 129

Rotational flow around a vertical axis

Front 130

Embankment

Back 130

Earth structure above natural groundis

Front 131

Embayment

Back 131

Indentation of bank or shore, particularly by progressive erosion forces

Front 132

Encroachment

Back 132

Extending beyond the original or customary limits, such as by occupancy of the river and/or flood
plain by earth fill embankment

Front 133

Endwall

Back 133

A wall placed at the end of a culvert. It may serve three purposes: 1) to hold the embankment away from
the pipe and prevent sloughing into the pipe outlet channel, 2) to provide a wall which will prevent erosion of the
roadway fill, and 3) to prevent flotation of the pipennels

Front 134

Energy

Back 134

Potential or kinetic, the latter being expressed in the same unit (meters) as the former

Front 135

Energy Dissipater

Back 135

A structure for the purpose of slowing the flow of water and reducing the erosive forces present in
any rapidly flowing body of waterrd

Front 136

Energy Grade Line

Back 136

The line which represents the total energy gradient along the channel. It is established by
adding together the potential energy expressed as the water surface elevation referenced to a datum and the kinetic
energy (usually expressed as velocity head) at points along the stream bed or channel floor

Front 137

Energy Head

Back 137

The elevation of the hydraulic grade line at any section plus the velocity head of the mean velocity of
the water in that section

Front 138

Entrance

Back 138

The upstream approach transition to a constricted waterway

Front 139

Entrance Head

Back 139

head required to cause flow into a conduit or other structure; it includes both entrance loss and
velocity head.

Front 140

Entrance Loss

Back 140

The head lost in eddies and friction at the inlet to a conduit or structurecswpp

Front 141

Environmental Protection Agency (EPA)

Back 141

Government agency that issued the regulations to control
pollutants in storm water runoff discharges (Clean Water Act and NPDES permit requirements)

Front 142

Ephemeral

Back 142

Of brief duration, as the flow of a stream in an arid region6533

Front 143

Equalizer

Back 143

A drainage structure similar to a culvert but different in that it is not intened to pass a design flow in a given direction. Instead it is often placed level to permitpassage of water in either direction.

Front 144

Erosion

Back 144

The wearing away of natural (earth) and unnatural (embankment, slope protection, structure, etc.) surfaces
by the action of external forces. In the case of drainage terminology, this term generally refers to the wearing away of
the earth's surface by flowing water. It can also refer to the wear on a structural surface by flowing water and the
material carried thereinF?

Front 145

Erosion Control

Back 145

Vegetation, such as grasses and wildflowers, and other materials, such as straw, fiber, stabilizing
emulsion, protective blankets, etc., placed to stabilize areas disturbed by grading operations, reduce loss of soil due to
the action of water or wind, and prevent water pollution

Front 146

Erosion Control

Back 146

Vegetation, such as grasses and wildflowers, and other materials, such as straw, fiber, stabilizing
emulsion, protective blankets, etc., placed to stabilize areas disturbed by grading operations, reduce loss of soil due to
the action of water or wind, and prevent water pollution.V

Front 147

Estuary

Back 147

That portion of a river channel occupied at times or in part by both sea and river flow in appreciable
quantities. The water usually has brackish characteristics.lash,

Front 148

Evaporation

Back 148

A process whereby water as a liquid is changed into water vapor, typically through heat supplied from
the sunrp

Front 149

Excavationn

Back 149

The process of removing earth, stone, or other materials

Front 150

Existing Vegetation

Back 150

Any vegetated area that has not already been cleared and grubbed

Front 151

Face

Back 151

The outer layer of slope revetmentd

Front 152

Fan

Back 152

A portion of a cone, but sometimes used to emphasize definition of radial channels. Also reference to spreading
out of water or soils associated with waters leaving a confined channel

Front 153

Feasible

Back 153

Economically achievable or cost-effective measures which reflect a reasonable degree of pollutant
reduction, achievable through the application of available nonpoint pollution control practices, technologies,
processes, site criteria, operating methods, or other alternatives

Front 154

Fetch

Back 154

The unobstructed distance over water in which waves are generated by wind of relatively constant direction
and speed

Front 155

Filter

Back 155

A porous article or mass (as of fabric or even-graded mineral aggregate) through which water will freely pass,
but which will block the passage of soil particlesflash,

Front 156

Filter Fabric(RSP fabric)

Back 156

An engineering fabric (geotextile) placed between the backfill and supporting or
underlying soil through which water will pass and soil particles are retainedv

Front 157

Filter Layerc

Back 157

A layer of even-graded rock between rock riprap and underlying soil to prevent extrusion of the soil
through the riprap

Front 158

Filter Sock

Back 158

A fabric tube filled with wood chips, compost or some other filter medium, used to filter sediment from
storm water or to reduce velocity of flow in channels and slopeslow.

Front 159

Filter Strip

Back 159

A strip of vegetation left between exposed soil and a ditch or other receiving water for the express
purpose of trapping sediment

Front 160

Flocculants

Back 160

Substances (chemical additives) that cause solids suspended in storm water to aggregate into a mass and
settle out of suspension

Front 161

Flood Frequency

Back 161

Also referred to as exceedance interval, recurrence interval or return period. The average time
interval between actual occurrences of a hydrological event of a given or greater magnitude; the percent chance of
occurrence is the reciprocal of flood frequency, e.g., a 2 percent chance of occurrence is the reciprocal statement of a
50-year flood (See Probability of Exceedance)

Front 162

Flood Plane

Back 162

The position occupied by the water surface of a stream during a particular flood. Also, loosely, the
elevation of the water surface at various points along the stream during a particular flood

Front 163

Flood Stage

Back 163

The elevation at which overflow of the natural banks of a stream begins to cause damage in the reach in
which the elevation is measured

Front 164

Flood Waters

Back 164

Former stream waters which have escaped from a watercourse (and its overflow channel) and flow or
stand over adjoining lands. They remain as such until they disappear from the surface by infiltration, evaporation, or
return to a natural watercourse. They do not become surface waters by mingling with such waters or stream waters by
eroding a temporary channelty of

Front 165

Floodplain Encroachment

Back 165

An action within the limits of the base flood plain

Front 166

Floodplain

Back 166

Normally dry land areas subject to periodic temporary inundation by stream flow or tidal overflow. Land
formed by deposition of sediment by water; alluvial land-flash,

Front 167

Flow

Back 167

A term used to define the movement of water, silt, sand, etc.; discharge; total quantity carried by a streamwerp

Front 168

Flow Line

Back 168

A term used to describe the line connecting the low points in a watercoursecswpp

Front 169

Flow, Steady

Back 169

Flow at constant discharge

Front 170

Flow, Unsteady

Back 170

Flow on rising or falling stages

Front 171

Flow, Varied

Back 171

Flow in a channel with variable section

Front 172

Free Outletd

Back 172

A condition under which water discharges with no interference such as a pipe discharging into open air.ms-powerp

Front 173

Free Watertd

Back 173

Water which can move through the soil by force of gravity4a56533

Front 174

Freeboard

Back 174

(1) The vertical distance between the level of the water surface usually corresponding to the
design flow and a point of interest such as a bridge beam, levee top or specific location on the roadway grade. (2) The
distance between the normal operating level and the top of the sides of an open conduit; the crest of a dam, etc. designed to allow for wave action, floating debris, or any other condition or emergency, without overtopping the
structure

Front 175

French Drain

Back 175

A trench loosely backfilled with stones, the largest stones being placed in the
bottom, with the size of stones decreasing towards the top. The interstices between the stones serve as a passageway
for water

Front 176

Friction

Back 176

Energy-dissipating conflict among turbulent water particles disturbed by irregularities of channel surfacepowerp

Front 177

Froude Number

Back 177

A dimensionless expression of the ratio of inertia forces to gravity forces, used as an index to
characterize the type of flow in a hydraulic structure in which gravity is the force producing motion, and inertia is the
resisting force. It is equal to a characteristic flow velocity (mean, surface, or maximum) of the system divided by the
square root of the product of a characteristic dimension (as diameter of depth) and the gravity constant (acceleration
due to gravity) all expressed in consistent units Fr = V/(gy)1/2

Front 178

Gabion

Back 178

A wire basket or cage filled with stone and placed as, or as part of, a bank-protection structurel surfacepowerp

Front 179

Gauging Station

Back 179

A location on a stream where measurements of stage or discharge are customarily made. The
location includes a reach of channel through which the flow is uniform, a control downstream from this reach and
usually a small building to house the recording instruments

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General Permitn

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A general permit for storm water discharges associated with industrial or
construction activity issued by EPA or a delegated state under the NPDES storm water regulationsr.

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Gorge


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A narrow, deep valley with steep or vertical banks

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Grade


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Elevation of bed or invert of a channel

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Grade to Drain

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A construction note often inserted on a plan for the purpose of directing the Contractor to slope a
certain area in a specific direction, so that the surface waters will flow to a designated location

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Gradient (Slope)

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The rate of ascent or descent expressed as a percent or as a decimal as determined by the ratio of the
change in elevation to the length

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Gradually Varied Flow

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In this type of flow, changes in depth and velocity take place slowly over large distances,
resistance to flow dominates and acceleration forces are neglectedv

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Gravel

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Rock larger than sand and smaller than cobble, arbitrarily ranging in diameter from 5 to 50 mm

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Groin

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A fingerlike barrier structure usually built perpendicular to the shoreline or oblique to primary motion of
water, to trap littoral drift, retard erosion of the shore, or to control movement of bed material

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Ground Water

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That water which is present under the earth's surface. Ground water is situated below the surface of
the land, irrespective of its source and transient status. Subterranean streams are flows of ground waters parallel to and
adjoining stream waters, and usually determined to be integral parts of the visible streams

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Grouted

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Bonded together with an inlay or overlay of cement mortar

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Gulch

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A relatively young, well-defined and sharply cut, erosional channel

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Gully

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Dimunitive of Gulch

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Head

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Represents and available force equivelant to a certian depth of water. The height of water above any point or plane of reference.

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Headcutting

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Progressive scouring and degrading of a streambed at a realtivly rapid rate in the upstream direction. (Think Waterfalls moving backwards)

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High Water

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Maximum flood stage of a stream or lake; periodic crest stage of tide.

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Hydraulic

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Pertianing to water in motion and the mechanics of the motion.

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Hydraulic Gradient

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A line the represents the realtive force available due to the potentail energy available.

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Hydraulic Jump

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Transition of flow from the rapid state to the tranquil state.

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Hydraulic Mean Depth

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The area of the flow cross section divided by the water surface width.

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Hydraulic Radius

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The cross sectional area of a stream of water divided by the length of that part of its periphery in contact with its containing conduit; the ratio of area to the wetted permieter.

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Hydric

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Somthing having to do with an abundance of water.

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Hydrograph

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A graph showing stage, flow, velocity, or other property of water with respect to time.

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Hydrographic

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Pertaining to the measurement or studies of bodies of water and associated terrain.

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Hydrography

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Water Surveys of surface waters, navigable waters and water courses.

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Hydrologic

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Pertaining to the cyclic phenominon of waters of earth.

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Hydrology

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The science of dealing with the occurance and movement of water upon and beneith the land areas of earth

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Hydrophyte

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A perrenial vascular aquatic plant having its overwintering buds underwater. Water loving plants

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Hydrostatic

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Pertaining to pressure by and within water due to gravitation acting through depth.

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Hyetograph

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Graphical representation of rainfall intensity against time

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Impinge

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To strike and attack directly, as in curvinlinier flow where current does not follow the curve but continues on tangent into the bank on the outside of bend in the channel.

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Inlet Time

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Time required for storm runoff to flow from the most remote point, in flow time, of a drainage area to a drain inlet or culvert.

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Invert

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The bottom of a drainage facility along which the lowest flows would pass.

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Invert Paving

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Generall applies to metal pipes where it is desireable to improve flow characteristics or prevent corrosion at low flows. The bottom portion of the pipe is paved with asphaltic material, concrete, or air-blown mortor.

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Inverted siphon

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A pipe for conducting water beneith a depressed place.

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Isohyetal Line

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A line on a map or chart that joins points recieving the sam amount of precipitation.

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Isovel

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A line on a diagram of a channel connecting points of equal volum.

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Jack

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Bank protection element consisting of wire or cable strung on three mutually perpendicular struct connected at thier centers.

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Jacking Operations

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Means of construction a pipeline under a highway without Open excavation.

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Jam

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Wedged collection of drift in a constriction channel.

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Jet

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An effluent stream from a restricted channel, includeing a fast current through a slower stream.

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Jetty

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An elongated aftificial obstruction that extends out into a stream or the sea from shore for the purposes of controling shoaling and scour by deflecting flow currents and waves.

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Jump

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Sudden transition from a supercritical flow to that of the complimentary subcritical flow. Conserving momentum and dissipating energy

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Kolk

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Rotational flow around a horizontil axis, induced by a reef and breaking the surface.

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Lag

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Vasiourly defined as the tim efrom teh beginning of rainfall to peak of runoff

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Laminar Flow

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The type of lfow ehre each particals in the flow travels parallel to evey other particle in one direction and the headloss is approximately proportional to the velocity

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Levee

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An embankment to prevent inundation. (New Orleans)

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Littoral

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Pertaining to or along hte shore, particularly teo describe currents, deposits, and drift.

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Littoral Drift

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The sedimentary material moved along the shore line because of wave current.

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Littoral Transport

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The movement of Littoral Drift along the shoreline because of wave action and currents.

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Local Depression

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A low area in the pavement or gutter established to collect surface waters on a street and directing these waters to a drainage inlet.

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Longshore

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Parallel to and near the shoreline.

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Marginal

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Within a borederland area, more general and extensive than riparian.

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Marsh

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An area of soft wet or periodically submerged land, generally treeless and usually charaterized by grasses and other low vegitation.

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Mature

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Classification for streams that have established flat gradients not subject to further scour.

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Maximum Historical Flood

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The maximum historical flood ever encountered at any highway location.

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Mean Annual Flood

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The flood discharge with a reoccurance interval of 2.33 years.

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Mean Depth

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For a stream at any stage, the wetted normal section divided by the surface width. Hydraulic Mean Depth.

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Meander

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"Stream" and erodable channel ususally in and erodable, alluvial valley.

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Meander Plug

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Deposits of cohesive materials in old channel bend-ways.

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Meander Scroll

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Evidence of historaical meander patterns in teh from of visible lines on the inside of meander bends.

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Mud Flow

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A well-mixed mass of water and alluvium that, because of its high viscosity, and low fluidity as compated to water, moves at a much slower rate.

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Natural and Benificial Floowplain Values

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Includes but limited to fish, wildlife, plants, open space, natural beauty, scientific study, outdoor recreation.

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Navigable Waters

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Waterways determined to be used in interstate and international commerce.

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Negative Projecting Conduits

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A structure installed in a trench with the top below the top of trench, then backfilled and covered with embankment.

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Non-point Sources

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Diffuse sources from which contaminants originate to accumulate into surface and ground water sources.

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Nonuniform Flow

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A flow in which the velocities differ from point to point along the stream or conduit.

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Normal Depth

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The depth at wich flow is steady and hydraulic characteristics are uniform.

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Normal Water Surface

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The free surface assocaited with flow in natural streams.

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Nourshiment

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The process of replenshing a beach, through either accreation, longshore transport or deposition of dredged material

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Open Channel

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Any conveyance where water flows with a free surface.

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Ordinary High Water Mark

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The line on the shore physically expressed, showing the fluctuation of water levels

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Overflow

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Discharge of a strem over it's banks.

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Overtopping Floods

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A flood that has the probability to exceed and overtop a hydraulic structure, highway, watershed divide, or structures to provide emergency relief.

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Peak Flow

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Maximum montary stage or discharge of a stream in flood. Design Discharge.

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Pebble

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Stone 10-75 mm in diameter, including coarse gravel and small cobble.

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Perched water

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Ground water above the level of the water table and separated from it by a sone of impermeable material.

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Percholating waters

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Waters the infiltrate into the ground into an aquifer.

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Physiographic Region

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A geographic area whose pattern of landforms differ significantly from that of adjacent regions.

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Piping

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Water passing through an embankment and carring with it smaller particles to the surface at the downstream face.

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Poised Stream

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A stream that is neither degrading or aggrading its channel and is nearly in equilibrium as to sediment transport and supply.

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Positive Projecting Conduit

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A structure installed in a tranch taht the top projects above the level of the trench and is then covered with embankment.