HR: 17:15h
AN: H42L-06    [PDF]
TI: Sediment Pulse Migration And Stopping Along The Sendai River, Japan
AU: * Kodama, Y
EM: kodama@fed.tottori-u.ac.jp
AF: Faculty of Education and Regional Sciences, Tottori University, 4-101, Koyama-minami, Tottori, 6808551 Japan
AU: Kobayashi, T
AF: Faculty of Education and Regional Sciences, Tottori University, 4-101, Koyama-minami, Tottori, 6808551 Japan
AU: Inoue, T
AF: Faculty of Education and Regional Sciences, Tottori University, 4-101, Koyama-minami, Tottori, 6808551 Japan
AU: Tashiro, K
AF: Faculty of Education and Regional Sciences, Tottori University, 4-101, Koyama-minami, Tottori, 6808551 Japan
AU: Shalkowski, A
AF: Faculty of Education and Regional Sciences, Tottori University, 4-101, Koyama-minami, Tottori, 6808551 Japan
AB: A pulse of sediment was tracked in the middle portion of the Sendai River, Tottori-prefecture: south-western Japan. During Typhoon Number 10 in 1998, a large landslide behind a quarry along the river contributed approximately 50,000 cubic meters (equivalent to c.a. 8,000 dump trucks) of metamorphic rock to the channel. We investigated the lithologic composition of the riverbed gravel in four classes (16-32mm, 32-64mm, 64-128mm and 128-256mm) at 15 different sites along a 6.5 km reach of the river. Investigations were conducted during four periods over the successive two years (1999 and 2000); in spring- after snowmelt floods and in autumn following floods in the rainy and typhoon seasons and also during a period in the summer of 2003. The lithologic composition data revealed sediment pulse movement in all 4-size classes. In the pulse for both the 16-32mm and the 32-64mm particles, a 6.2 km migration was observed from 1998 until 2000. While the sediment pulse migration in the 64-128mm and the 128-256mm particles was 5.6 km and 4 km respectively for the same period. As particle size segregation proceeds flood-by-flood, propagation rates of sediments pulses has decreased rapidly and have subsequently ceased to move in spite of some effective annual floods. During the period 2000 - 2003, only marginal migrations of sediment pulses were detected. Therefore, the authors consider that the loss of grain size mixture effects on sediment transport could explain the dearease in the migration rate of sediment pulses as well as the cessation of sediment pulse propagation. Keywords: sediment pulse, migration rate, lithologic composition, river-bed gravel, landslide
DE: 4558 Sediment transport
DE: 9320 Asia
SC: Hydrology [H]
MN: 2003 Fall Meeting