armor layer — A layer of sediment that is coarse relative to ttie material 

 underlying it and is erosion resistant to frequently occurring floods; 

 it may form naturally by the erosion of finer sediment, leaving coarser 

 sediment in place or it may be placed by man to prevent erosion. 



aufeis — An ice feature that is formed by water overflowing onto a surface. 



such as river ice or gravel deposits, and freezing, with subsequent 

 layers formed by water overflowing onto the ice surface itself and 

 f reez i ng. 



backwater analysis — A hydraulic analysis, the purpose of which is to 



compute the water surface profile in a reach of channel with varying 

 bed slope or cross-sectional shape, or both. 



bank — A comparatively steep side of a channel or floodplain formed by an 

 erosional process; its top is often vegetated. 



bank-full discharge — Discharge corresponding to the stage at which the 

 overflow plain begins to be flooded. 



bar — An alluvial deposit or bank of sand, gravel, or other material, at 

 the mouth of a stream or at any point in the stream flow. 



beaded stream — A small stream containing a series of deep pools intercon- 

 nected by very small channels, located in areas underlain by permafrost. 



bed — The bottom of a watercourse. 



bed load — Sand, silt, gravel or soil and rock detritus carried by a stream 

 on, or immediately above its bed. 



bed load material — That part of the sediment load of a stream which is 



composed of particle sizes found in appreciable quantities in the shift- 

 ing portions of the stream bed. 



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