Ship-Generated Waves and Induced Turbidity in the Goeta AElv River in Sweden

摘要

Ship-generated waves were investigated in the Goeta AElv river, which is a major waterway on the Swedish west coast between the sea and Lake Vanern. Ships with a typical size of 85×15×5m (length × width × draft) travel at speeds between 5 and 10 knots, generating waves that cause sediment transport and erosion along the river bed and banks. Field measurements of the wave properties and turbidity were carried out during 17 ship passages, and comparisons were made with the most commonly used formulas for predicting ship waves. The formula proposed by the Permanent International Association of Navigation Congresses yielded the overall best agreement for the divergent (secondary) waves, whereas the drawdown (primary wave) could best be estimated from the vessel sinkage. The maximum recorded turbidity was mainly a function of the drawdown, and it could be well predicted from the parameterized bed shear stress. In conclusion, ship waves often induce bed and bank erosion in restricted waterways and, although simplistic formulas involve significant uncertainties, they are still useful tools for predictions. However, more studies are needed to determine the influence of a limited river cross section on the wave generation and the relationship between ship waves and sediment transport.