2024-03-28T14:53:21Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/679972022-11-17T02:08:08Zhdl_2115_20046hdl_2115_138Sediment pulse発生後における土砂の波状移動と分級現象Influence of the mobility of the coarse particles on the sediment pulse evolution in torrential rivers宮崎, 知与山田, 孝丸谷, 知己initial sediment pulse and its evolutionparticle size sortingthe mobility of the coarse particlesquasi-stream-powermagnitude of the sediment deliveryUnderstanding how sediment supply from lateral source influences on sediment distribution along a channel reach is a key issue for preliminary surveying of sediment disaster. Sediment pulse formed by storm-induced sediment supply from lateral source was investigated for four years after 2003 storm at Kita-iwanai-ninosawa Creek located in a headwater catchment of Tokachi River, Eastern Hokkaido, Japan. Cross-section measuring and sediment sampling were conducted on site, and the relationship between longitudinal changes in sediment volume transformed to a sediment mass curve and grain size distribution was examined. In this paper, the ratio of sediment delivery magnitude (M) against quasi-stream power (Ps) was employed as an efficiency index (M/Ps) of sediment transfer. The result is an follows: 1) Although storm-induced sediment pulse formed by quite lots of sediment input is not identified by deference in grain size, sediment pulses gradually reproduced by low-water flow after storm event have characteristics of grain size distribution. 2) Magnitude of sediment delivery with large materials (>75 mm) decreases downstream because of their short travel distance even by flooding. However, selective transport of smaller materials by low-water flow increases the magnitude of sediment delivery. 3) Comparing sediment mass curves, the wave peak by large-magnitude flooding is higher than that by small-magnitude flooding, and the wave length by large-magnitude flooding is shorter than that by small-magnitude flooding. 5) The efficiency index (M/Ps) of sediment transfer yielded by storm-induced sediment supply is quite high, but it gradually decreases with time after initial sediment supply.砂防学会Journal Articleapplication/pdfhttp://hdl.handle.net/2115/67997https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/67997/1/61%282%29_5.pdf0286-83852187-4654AN1056478X砂防学会誌6125152008-07jpninfo:doi/10.11475/sabo.61.2_5publisher