Point bar deposits in narrow sharp bends

Meandering channels typically deposit sediments near their inner bank to form point bars. Laboratory experiments with narrow sharp bends show that under identical flow conditions the configuration of point bars depends on particle size. Explanation to this grain-size effect is found in a three-dimensional particle stability. Despite favorable secondary currents, coarse grains tend to move toward the thalweg and coarse-grained point bar deposits are eroded as the side-slope angle approaches the angle of repose of the bed material. Calculated results coincide with experimental observations. Point bars are considerably smaller for coarse-sand deposits than fine sands.