Environmental impact of various hydrodynamic effects produced by tug and barge traffic in the tidal channel of the River Parrett for delivering relatively large loads to a wharf in Combwich over the waterway. As the tug-barge tandem moves at very low depth Froude numbers and at even considerably lower length Froude numbers, the resulting vessel wave system almost perfectly matches the classical linear Kelvin wake and contains mostly short and short-crested waves. The typical wavelengths are well within the wavelengths of the wind waves for this sheltered waterway. The width of the channel is large enough for these waves to decay considerably at the channel margins. The impact of the resulting waves on the margins, most likely, is undetectable. No nonlinear wave-driven effects are expected. No specific impacts related with unusual wave approach direction are detectable. Owing to a possibly large blocking coefficient, a certain level of the production of a depression area (Bernoulli/pressure wake) and squat may occur. Sediment resuspension by the propulsion system of the tugboat is a local phenomenon and commonly accepted in river transport. The use of rising tide for the traffic very likely results in a weak net traffic-induced sediment transport upstream and/or onshore, filling the banks with sediment on the expense of volumes resuspended along the sailing line.
Research report: Soomere T. 2012. On the hydrodynamic impacts of barge traffic along the River Parrett. Expert opinion.