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ERDC TR-04-1
3.8
GLOSSARY
Aggradation An increase in the channel bed elevation through deposition of
sediment
Alluvial fan Depositional landform with a conical shape that develops where
confined streams emerge from upland areas into zones of reduced stream
power
Anastomosing river Sinuous, low-gradient channels consisting of multiple
interconnected branches transporting a suspended or mixed load
Arroyo Entrenched ephemeral streams with vertical walls that form in desert
environments
Bankfull stage River level that completely fills the channel and begins to
spread out onto the floodplain; sometimes alternatively considered the 1.5-
year recurrence interval flow even if it is not associated with the incipient
inundation of the floodplain
Channel avulsion Rapid diversion of flow from one channel into another
Compound channel Channels with a single, low-flow meandering channel
inset into a wider braided flood zone active only during extreme events
Desert pavement Tightly interlocking gravel at the surface formed after years
of surface exposure in the absence of active streamflow over the surface
Discontinuous ephemeral stream A distinctive stream pattern characterized
by alternating erosional and depositional reaches
adjustments of the river channel's shape, planform, and gradient
Geomorphically effective flood The flood discharge most responsible for the
formation of physical features seen along the channel
Holocene Geologic epoch spanning the last 10,000 years
Hydrolysis Chemical weathering process whereby feldspars and iron-rich
minerals are converted to clay minerals through the replacement of cations
with water
Ordinary high water mark The line on the shore established by the fluctua-
tions of water and indicated by physical characteristics such as a clear,
natural line impressed on the bank, shelving, changes in the character of the
soil, destruction of terrestrial vegetation, or the presence of litter and debris
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