The effect of freshwater flow on siltation in the Humber Estuary, north east UK

This paper investigates the impact of variations in freshwater discharge from the Rivers Trent and Ouse on a number of factors related to siltation in the Humber Estuary. These factors include suspended sediment concentrations, bed sediment composition, bed levels and channel mobility. Seasonal increases in freshwater discharge can reduce siltation rates and lower bed levels in both the Inner and Outer parts of the estuary. Such seasonal variations in freshwater flow also lead to the downstream displacement of sandy bed sediments as well as the turbidity maximum. More extreme flood events can lead to discrete shifts in the channel configuration within the Inner Estuary. It is suggested that in the Humber there are critical values of freshwater discharge, with the exceedance of upper threshold conditions leading to reductions in bed levels and the switching of channel positions, and the reduction of flows below lower threshold conditions leading to pronounced increases in sedimentation.