The Effects of Training Works on the Loose-Boundary Regime of the Wash

This is the second of two papers describing the loose-boundary regime of the Wash. Both show that the prerequisite for accretion is the continual circulation of large quantities of sediment in the creeks and channels of the Wash, which, in the absence of man-made interference or natural catastrophe, is essentially in dynamic balance or regime. The first paper showed that on the foreshore this sediment circulation takes place mainly in the creeks. It described the resulting accretional pattern in front of newly constructed reclamation embankments and explained that the significance of this accretional mechanism along the margin lies in the light it throws on a similar accretional process along the sides of channels. The present paper illustrates the presence of this accretional mechanism along the sides of channels by describing the effects of training walls along the outfall channels of the Welland, Nene and Great Ouse and explains the causative link of foreshore accretion along the sides of channels with shoaling in the channels themselves. The paper concludes that an appreciation of this subtle mechanism could help engineers design better training works with reduced risks of accretion in the channels.