Drainage Glossary E-R
ErosionThe wearing away of the land surface by water, wind, ice, gravity, or other geological agents.
Excess RainfallThe amount of rainfall that runs directly off an area.
Farm or Field TileA small diameter clay pipe installed in an agricultural area to allow drainage or farmland.
Filter StripUsually a long, relatively narrow area (usually 20-75 feet wide) of undisturbed or planted vegetation used to retard or collect sediment for the protection of watercourses, reservoirs, or adjacent properties.
Flap-GateA device that allows liquids to flow in only one direction in a pipe. Backflow preventers are used on outlet pipes to prevent a reverse flow during flooding situations.
FloodplainLand immediately adjoining a stream which is inundated when the discharge exceeds the conveyance of the normal channel. The channel proper and the areas adjoining the channel which have been or hereafter may be covered by the regulatory or 100-year flood. Any normally dry land area that is susceptible to being inundated by water from any natural source. The floodplain includes both the floodway and the floodway fringe districts.
FloodwayThe channel of a river or stream and those portions of the flood plains adjoining the channel which are reasonably required to efficiently carry and discharge the peak flow of the regulatory flood of any river or stream.
FlumeA constructed channel lined with erosion-resistant materials used to convey water on the steep grades without erosion.
Foundation DrainA pipe or series of pipes that collects groundwater from the foundation or footing of structures to improve stability.
GabionA wire mesh cage, usually rectangular, filled with rock and used to protect channel banks and other sloping areas form erosion.
GradationThe distribution of the various sized particles that constitute a sediment, soil, or other material, such as rip-rap.
- The slope of a road, a channel, or natural ground.
- The finished surface of a canal bed, roadbed, top of embankment, or bottom of excavation; any surface prepared to a design elevation for the support of construction, such as paving or the laying of a conduit.
- To finish the surface of a canal bed, roadbed, top of embankment, or bottom of excavation, or other land area to a smooth, even condition.