Abstract
The objective of this study is to observe the characteristics of lotic seeds distribution 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 and numerical analysis. In the experiments, after sandbars were formed, enough amounts of alfalfa seeds were supplied from the inlet section of the flume. The result of experimental flume tests showed that alfalfa seeds, transported by flow, were settled at the front edge of sandbars during the recession stage of the discharge. This is because, the flow at most downstream areas of sandbars and the front edge of sandbars decreased earlier than that of middle area of sandbars during decreasing of discharge, as shown with the numerical results. This flow causes the specific seeds deposition areas. Those results imply that invading vegetation has specific settling characteristics and make vegetation patches on sandbars.
