Author(s): M. Spannring

Linked Author(s):

Keywords: Groynes; Sediment Transport; Numerical Simulation

Abstract: In this paper a concept is introduced to predict the erosion of the river bed after the building of non submerged groynes. An extensive parameter study was carried out on a numerical model. The analysis of the results shows, that the cross section of the river bed-after the river bed has reached a state of eqilibrium-can be approximated by a parabola of 4th order. Assuming that the river is straight and groynes are arranged on both sides of the river, the parabola can be determined by the knowledge of two characteristic values: ·maximum erosion in the middle of the river; ·position of the point in the cross section where erosion is setting in. The maximum erosion in the middle of the river can be estimated by the use of analytical relations for the calculation of bed degradation due to a long contraction, while the groyne effect is taken into account by introducing a groyne coefficient. Approximating the shape of the bottom shear stress in the cross section, the spot where erosion is setting in is determined by that point where the critical shear stress is reached. This paper concentrates on investigations concerning maximum degradation in the river axis in case of non submerged groynes.

DOI:

Year: 1999