Abstract

The purpose of this study is to investigate flow behavior and bed fluctuation in rivers with tall riparian trees. The experiments were made in tilting flume with model trees installed locally along the right-hand side of the flume. Sands were used as bed materials and stainless cylinders as model trees. Sediment transport mode by water was bed load. The right-hand side of the flume with the tree zone causes sediment deposition in its upstream part and bed erosion in its downstream part. The left-hand side without the tree zone produces sediment deposition in the relatively upstream part and deep erosion in the relatively downstream part. Numerical simulation of flow behavior and bed variation around the tree zone shows that resistance of the tree zone causes flow movement from the right-hand side to the left-hand side and deeper erosion at the opposite side of the tree zone by flow concentration.

Keywords: riverbed variation, riparian trees, sediment transport rate, bed shear stress and drag force