Vegetation Seeds Settling Pattern On Alternate Sandbars In A Straight Channel And The Effect On River Bed Morphology

The objective of this study is to observe the characteristics of hydrochory seeds transported by running water on bare sandbars, and to confirm the differences of bed morphology change without vegetation and with vegetation patches on sandbars by means of laboratory experiments. In the experiments, after sandbars were formed, enough amounts of alfalfa seeds were supplied from the inlet section of the flume. The result showed that seeds did not settle at all on sandbars under a constant discharge. On the other hand, alfalfa seeds settled significantly at the front edge of sandbars during the recession stage of the discharge. In addition, alfalfa seeds were settled at the same location on sandbars after alfalfa seeds grew up on sandbars. These results imply that invading vegetation has specific settling characteristics with making vegetation patches on sandbars.