Discussion on 'The effect of fresh water flow on siltation in the Humber estuary, Northeast UK' by Pontee NI, Whitehead PA and Hayes CM (ECSS vol. 60, 241-249)

This discussion identifies and presents recent data which show that suspended sediment concentrations in the macrotidal Humber-Trent-Ouse system are much higher, and extend further upstream, than originally presented. The importance of a link between tidal range, fresh water flow and recorded suspended sediment concentrations, is illustrated by reference to data collected under the UK Natural Environment Research Council (NERC) Land-Ocean Interaction Study (LOIS) initiative (1992-1998). Data recorded at Burringham, on the River Trent upstream of Trent Falls show a clear link between tidal range and suspended sediment concentrations which is strongly influenced by the downstream flushing effects of high fresh water flow events. While the arguments presented in this discussion do not contradict the main findings in the original paper it is proposed that a better understanding of siltation in the Humber system may be promoted by understanding the behaviour of the turbidity maximum in this system and its related mobile sediment population. It is suggested that the rapid reduction in suspended sediment concentration brought about by sudden increases in fresh water flow is probably indicative of the highly canalised nature of the tidal reaches of the Trent and Ouse.