Suspended sediment fluxes in the Humber catchment, UK

An extensive sediment monitoring network was established within the LOIS pr ogramme, involving 10 of the main tributaries of the River Humber (UK). Its primary purpose was to measure the flux of suspended sediment to the estua ry. A turbidity monitoring system was developed to provide a continuous rec ord of suspended sediment concentration in the rivers, from which the fluxe s were calculated. Linear relationships were established between suspended sediment concentration and turbidity (with slopes varying from 0.89 to 1.69 ) to enable the conversion of nephelometric turbidity [NTU] to suspended se diment concentration [mg l(-1)]. Potential uncertainties were identified an d quantified. The suspended sediment flux to the Humber (November 1994-Octo ber 1997) was calculated to be 699 861 t, equivalent to a yield of 15 t km( -2) yr(-1). Large temporal and spatial variations in the flux were measured during the monitoring period, in response to factors such as climate, land use, catchment scale, deposition and reservoir trapment. The particle size composition of the suspended sediment was measured and found to vary littl e, except at very high discharges, when it coarsened. The organic content o f the sediment was found to be directly related to the discharge of sewage effluent to the rivers. Copyright (C) 1999 John Wiley & Sons, Ltd.