This page was last updated by the Content Provider on 01-Aug-2007
Glossary
The following are definitions of terms used throughout this website.
Acre-foot
A volume of water equivalent to one acre of land covered to a depth of one foot.
Advance engineering and design work
Work done by Corps of Engineer offices in preparation of a project for construction.
Alluvial
Of, pertaining to, or composed of sediment deposited by flowing water, as in a riverbed, flood plain, or delta.
Appropriation
The setting aside of money by Congress, through legislation, for a specific use.
Authorization
House and Senate Public Works Committee resolutions or specific legislation which provides the legal basis for conducting studies or constructing projects. The money necessary for accomplishing the work is not a part of the authorization, but must come from an appropriation by Congress.
Bank and channel stabilization
The process of preventing bank erosion and channel degradation.
Basin
(l) Drainage area of a lake or stream, such as a river basin.
(2) A naturally or artificially enclosed harbor for small craft, such as a yacht basin.
Breakwater
A wall built into the water to protect a shore area, harbor, anchorage, or basin from the action of waves.
Concrete-gravity structure
A type of concrete structure in which resistance to overturning is provided by its own weight.
Confluence
The place where streams meet.
Dam
A barrier constructed across a valley for impounding water or creating a reservoir.
Degree of protection
The amount of protection that a flood control measure is designed for, as determined by engineering feasibility, economic criteria, and social, environmental, and other considerations.
Dike
An embankment to confine or control water.
Diversion channel
(l) An artificial channel constructed around a town or other point of high potential flood damages to divert floodwater from the main channel to minimize flood damages.
(2) A channel carrying water from a diversion dam.
Earthfill dam
A dam, the main section of which is composed principally of earth, gravel, sand, silt, and clay.
Flood capacity
The flow carried by a stream or floodway at bankfull water level. Also, the storage capacity of the flood pool at a reservoir.
Flood plain
Valley land along the course of a stream which is subject to inundation during periods of high water that exceed normal bankfull elevation.
Flood proofing
Techniques for preventing flood damage to the structure and contents of buildings in a flood hazard area.
Groin
A wall-like structure built perpendicular to the shore to trap sand and prevent beach erosion.
Habitat
The total of the environmental conditions which affect the life of plants and animals.
Harbor of refuge
A harbor provided at an inhospitable coastline to allow vessels to shelter during storms.
Headwaters
(l) The upper reaches of a stream near its source.
(2) The region where ground waters emerge to form a surface stream.
(3) The water upstream of a structure.
Impervious blanket
A covering of relatively waterproof soils, such as clays, through which water percolates at about one-millionth of the speed with which it passes through gravel.
Jetty
A structure similar to a groin built on a seashore to prevent erosion due to currents and tide.
Left or right bank of river
The left-hand or right-hand bank of a stream when the observer faces downstream.
Levee
A dike or embankment, generally constructed close to the banks of the stream, lake, or other body of water, intended to protect the landside from inundation or to confine the stream flow to its regular channel.
Low flow augmentation
The increase of water flows to more desirable volumes above the natural stream flows.
Mouth of river
The exit or point of discharge of a stream into another stream, a lake, or the sea.
Navigable waters of the United States
Those waters of the United States subject to the ebb and flow of the tide shoreward to the new high water mark.
Penstock
A sluice or gate used to control a flow of water.
Pierhead line
The line in navigable waters formerly used to delineate waterward limits of blanket permit authority for open pile structures. This authority was rescinded May 27, l970, and permits are now required for all construction in navigable waters of the United States.
Reach
A length, distance, or leg of a channel or other watercourse.
Reservoir
A pond, lake, tank, basin, or other space, either natural or created in whole or in part by the building of a structure such as a dam, which is used for storage, regulation, and control of water.
Revetment
(l) A facing of stone, concrete, or sandbags to protect a bank of earth from erosion.
(2) A retaining wall.
Revetted levee
A stone or concrete faced embankment raised to prevent a river from overflowing.
Riprap
A layer, facing, or protective mound of randomly placed stones to prevent erosion, scour, or sloughing of a structure or embankment. Also, the stone so used.
Rock dike
An embankment built principally of rock.
Rubblemound
A type of breakwater built of large quarried rock dumped on top of each other and built to an elevation that storm waves would not overtop.
Seawall
A concrete, stone, or metal wall or embankment constructed along a shore to reduce wave erosion and encroachment by the sea.
Setback levee
A levee that is constructed away from the water's edge.
Shoal
A place in any body of water where the water is especially shallow.
Sill
(l) A horizontal beam forming the bottom of the entrance to a lock.
(2) Also, a low, submerged dam like structure built to control riverbed scour and current speeds.
Spall
A fragment or flake from stone or ore.
Spillway
A waterway or a dam or other hydraulic structure used to discharge excess water to avoid overtopping of a dam.
Stage
The elevation of the water surface above or below an arbitrary datum.
Standard project flood
A flood that may be expected from the most severe combination of meteorological and hydrological conditions characteristic of the geological region involved.
Tide box
A gravity drainage structure with a one-way valve.
Toe drain
A filter on the free side of a dam or levee at the lower end to protect it against piping, or seepage of water carrying materials.
Tributary
A stream or other body of water that contributes its water to another stream or body of water.
Wetlands
Areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support a prevalence of vegetation typically adapted for life in saturated soil conditions.
