Journal of the Japan Society of Erosion Control Engineering, Vol.64,No.3, 2011

Influence of the multiple sediment supplies from the tributaries on the evolution of the initial sediment pulse in a torrential river

Tomoyoshi MIYAZAKI, Takashi YAMADA, Tomomi MARUTANI


Abstract

Sediment supply from lateral sources influences on the distribution of sediment along a main stream. And the estimation of the longitudinal distribution is very important for sediment surveys at the catchment scale. A sediment pulse, composed of coarse sediment derived from lateral inputs, was observed during a storm in the Ribira Creek, Atsubetsu River catchment, Southern Hokkaido, Japan in 2003. The sediment volume supplied from tributary channels was measured using aerial photography and aerial laser scanner data. The deposited sediment volume was measured directly from digital elevation models. The initial sediment pulse along the Ribira creek was estimated by fitting a curve to the distribution of sediment storage volume with longitudinal distance. Auto]correlation and cross]correlation analysis was employed to examine the distribution of sediment mass observed along the 12km channel course. The fitted curve had a spatial periodicity and the peak intervals were 1,500m and 3,600m, while the phase lags by distance against the supplied sediment distribution ranged between 100|300m, 1,600|2,600m, 3,600|4,200m respectively. As a result, the distribution of sediment mass induced by the multiple lateral supplies, changes cyclically with distance and includes longer travel distance components than would result from a single lateral input.

Key wordsFinitial sediment pulse, multiple sediment supplies from the tributaries, auto]correlation and cross]correlation analyses, travel distance, sediment sorting


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