Journal of the Japan Society of Erosion Control Engineering, Vol.59,No.5,2007
Translation and dispersion of sediment pulses induced by an extreme rainfall
in mountain rivers
Tomoyoshi MIYAZAKI Motohiro KUREBAYASI Takashi YAMADA Tomomi MARUTANI
Abstract
Understanding linkage between channel process along a river course and hill]slope
process with lateral sediment sources can be significant for management of sedimentary
systems. The linkage that is characterized by distribution of storm]induced sediment
in a river channel is often expressed as sediment pulse (wave). This paper examines
the propagation of sediment pulse formed by storm]induced sediment flow in two
river channels of Southern Hokkaido, and classifies the patterns of sediment pulse
based on difference in the distribution of accumulated sediment volume. Longitudinal
changes in sediment volume along a river channel were modified to a sediment mass
curve. Auto]correlation and cross]correlation analyses were employed for examining
sediment mass curves. The sediment pulses demonstrated with sediment mass curve
was classified to four patterns, such as decreasing, increasing, intermediate
and periodic types. Decreasing type along a transport]limited channel and increasing
type along a supply]limited channel were dominated. Periodic type was not influenced
by sedimentary link between channel and hill]slope but independently occurred
by available sediment along a channel. Furthermore these types of sediment pulse
were resulted to be influenced by channel width, channel slope and (quasi]) stream
power. Although the highest peak of sediment pulse has been demonstrated at the
channel reach with wide section and/or gentle slope, it has shown dispersed and
lower peak at the channel reach with larger stream power.
Key words:sediment pulse, periodic or intermittent sediment supply, sediment mass
curve, auto]correlation and cross]correlation analyses
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