FLOOD06421

• County: Statewide
• Basin: Statewide
• Title: Highways in the River Environment
• Date: 2/1/1990
• Prepared By: Federal Highway Administration
• Floodplain - Doc Type: Educational/Technical/Reference Information

Revetment - Rigid or flexible armor placed on a bank or embankment as
protection against scour and lateral erosion.

Riffle - A natural shallow flow area extending across a streambed in which the
surface of flowing water is broken by waves or ripples. Typically, riffles alternate
with pools along the length of a strearTl channel.

Riparian - Pertaining to anything connected with or adjacent to the banks of a
stream.

Riprap - In the restricted sense, layer or facing or broken rock or concrete
dumped or placed to protect a structure or embankment from erosion; also the
broken rock or concrete suitable for such use. Riprap has also been applied to
almost all kinds of armor, including wire-enclosed riprap, grouted riprap, sacked
concrete, and concrete slabs.

fl.iver Traininq Structure - Any configuration constructed in a stream or placed
on, adjacent to, or in the vicinity of a stream bank that is intended to deflect
currents, induce sediment deposition, induce scour, or in some other way alter the
flow and sediment regimes of the stream.

Rock-and-Wire Mattress - A flat or cylindrical wire cage or basket filled with
stone, or other suitable material; and placed on a streambank wit.h a filter used as
protection against erosion.

fl.ouqhness Coefficient - Numeric,ll measure of the frictional resistance to flow
in a channel, as in the Manning or Strickler formulas.

Bubble - Rough, irregulClr fragments of random size placed on a streambank to
retard erosion. 1 he fragments may consist of broken concrete slabs, masonry, or
other suitable refuse.

Runoff - 1 hat part of precipitation which appears in surface streams of either
perennial or intermittent form.

Sack Revetment - Streambank protection consisting of sacks (e.g. burlap,
paper, or nylon) filled with mortar, COrlcrete, sand, stone or other available material
placed on a bank to serve as protection against erosion.

Saltation l.oad - Sediment bOUj1ced along the stream bed by energy and
turbulence of flow and by other moving particles.

Sand - Granular material that is srTlaller than 2.0mm and coarser than O.062mm.

;;cou~ - Erosion due to flowing water; usually considered as being localized as
opposed to 'Jeneral bed de'Jradation.

;>coured Depth - Total depth of the water from water surface to a scoured bed
level (compare 'depth of scour').

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