BASIC STUDY ON INFLUENCE OF U-SHAPED PLANT COLONY ON COARSE SEDIMENT MOVEMENT AFTER GRAVEL BAR RESTORATION

Abstract

 Focusing the influence of U-shaped vegetation zone formed after gravel bar restoration in two lane meandering segment of Kinugawa River, labotratory experiments and numerical analyses were performed on the flow field and coarse sediment movement during a flood. It is clarified that, in the deep side of the internal area of the U-shaped zone, coarse sand tends to be deposited due to velocity decrease and water depth increase, and, behind the U-shaped zone, sand is much more deposited due to extremely slow velocity. In addition, it is indicated that, in the outer edge of the U-shaped zone, the velocity is slightly fast, then sand can be flushed away and gravel can be deposited, which leads endemic species for gravel bed to fix easily. It is shown that the numerical analysis can reproduce the approximate trend of the experimental results.