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<br />Asphalt Block - Precast or broken pieces of asphalt that can be hand-placed or <br />dumped on a streambank or filter for protection against erosion. <br /> <br />Asphalt (bulk) - Mass of uncompacted asphalt usually dumped from a truck <br />(upper bank protection) or a barge (lower bank protection) that is placed to protect <br />the bank against erosion. <br /> <br />AveraQe Velocity - Velocity at a given cross section determined by dividing <br />discharge by cross-sectional area. <br /> <br />Avulsion - A sudden change in channel course that occurs when a stream <br />suddenly breaks through its banks; usually associated with flood or a catastrophic <br />events. <br /> <br />Backfill - The material used to refill a ditch or other excavation, or the process <br />of doing so. <br /> <br />Backwater - The increase in water surface elevation relative to the ele'/ation <br />occurring under natural channel and floodplain conditions, induced upstream from a <br />bridge or other structure that obstructs or constricts a channel. <br /> <br />Backwater Area - The low-lying lands adjacent to a stream that may become <br />flooded due to backwater effects. <br /> <br />Bank - The side slopes of a channel between which the streamflow is normally <br />confined. <br /> <br />Bank. Left. RiQht - The side of a channel as viewed in a downstream direction. <br /> <br />Bankfull DischarQe - Dischar<]e th8t, on the average, fills a channel to the point <br />of overflowing. <br /> <br />Bar - An elongated deposit of alluvium, not permanently vegetated, within or <br />along the side of a channel. <br /> <br />Bed - The bottom of a channel. <br /> <br />Bed Form - A recognizable relief feature on the bed of a channel, such as a <br />ripple, dune or bar. <br /> <br />Bed Layer - A flow layer, several grain diameters thick (usually two) <br />immediately above the bed. <br /> <br />Bed Load - Sediment that is transported in a stream by rolling, sliding, or <br />skipping along the bed or very close to it; considered to be within the bed layer. <br /> <br />!3ed Load DischarQe (or bed load) - 1 he quantity of bed load passing a cross <br />section of a stream in a unit of time. <br /> <br />Bed Material - Material found on the bed of a stream (may be transported as <br />bed load or in suspension). <br /> <br />Bed Sediment Dischar'le - The part of the total sediment dischar<]e that is <br />composed of grain sizes found in the bed and is equal to the transport capability of <br />the flow. <br /> <br />xl <br /> <br />I <br />J <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />-- <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />-I <br />I <br />