Boundary Shear in Curved Channel with Side Overflow

The characteristic changes in the boundary shear stress field of a channel bend at the intersection with a side overflow are investigated in this paper. On the basis of a field survey on bottom topography changes of the meandering river Allan Water at the cut-off section, a detailed study of boundary shear stresses in an idealized rigid bed model was undertaken. Both mathematical and experimental approaches were employed in the idealized model study. The analysis of results showed that continual reductions in shear stresses occurred in the bend at the side overflow region. The maximum reduction of shear stresses was 37% in cases of low side overflows and 82% in cases of high side overflows. These reductions were attributed to the development of stagnation and separation zones at the intersection associated with strong lateral outward currents. Based on the idealized model study, the features observed in the bed topography of Allan Water at the cutoff section are most likely to develop in cases of combined bend and high side overflows.