Suspended sediment fluxes in the tidal Ouse, UK

✍ Scribed by R. J. Uncles; J. A. Stephens

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 472 KB
• Volume: 13
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/(sici)1099-1085(199905)13:7<1167::aid-hyp796>3.0.co;2-d

✦ Synopsis

A strong turbidity maximum (TM) of suspended particulate matter (SPM) was observed in the upper Humber and lower Ouse during both spring and neap tides of May 1994. Near-bed concentrations within the TM sometimes exceeded ¯uid mud levels following slack water periods. SPM within the TM comprised very ®negrained material. Its low organic content demonstrated that the SPM was essentially mineral, clastic sediment. Generally, tidal advection of SPM was the dominant ¯ux mechanism and the pronounced ¯ood±ebb asymmetry in the tidal currents was re¯ected in these ¯uxes. However, the presence of ¯uid mud near the downestuary margins of the TM on the early ebb resulted in a strong, up-estuary shear ¯ux that opposed the ebb-directed advection. This mechanism therefore acted to maintain ®ne sediment in the TM region. SPM concentrations in the in¯owing fresh water at Naburn Weir were much less than those observed within the TM region (5300 mg l À1 compared with 470 000 mg l À1 ). The estimated mean SPM transport into the tidal Ouse across Naburn Weir was about 4 kg s À1 (42 and 511 kg s À1 ) during 1994. In the TM area, the SPM transported during the course of a single spring tide ¯ood was roughly equivalent to 30 months of Naburn SPM in¯ows at average 1994 levels. The tidally averaged SPM transport in the TM region was directed into the estuary and, per tide, was roughly equivalent to three months of Naburn inputs.