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Observations of the morphodynamic behaviour of an intertidal mudflat at different timescales (1998)
| Content Provider | CiteSeerX |
|---|---|
| Author | Itchener, Helen J. M. Whitehouse, Richard J. S. |
| Description | Eds.), Sedimentary Processes in the Intertidal Zone. The Geological Society, London, Special Publications 139 |
| Abstract | Abstract: This paper concerns the morphological (bed level) behaviour of the intertidal mudflat at Portishead on the Severn Estuary and discusses how the prevailing hydraulic and cohesive sediment processes contribute to bserved changes in the bed level. The characteristics of the mudflat behaviour d ing a fortnightly cycle is presented, based upon a continuous high resolution time series of the bed level measured at one location during 31 tidal immersions. During spring tides the sediment supply to the mudflat is increased and the tidal-mean bed elevation is at least 10mm higher following the peak of spring tides than on the previous or following neaps. On a tide by tide basis the bed level varies by 10-20mm and the preservation of fresh mud deposits on the intertidal area is controlled by the hydraulic onditions prevailing during the shallow water phase of the tide (less than 0.5 m depth) and the processes operating during the dry part of the tide. Hence, the bed level is controlled by the phasing of the tidal range (ambient sediment supply) with local water depth and wave activity. In comparison, on the annual timescale the bed level variation on the middle and upper mudflat is of the order of 100 mm and seasonal changes in storminess, ubaerial environment and biostabilization appear to play a significant role. Quantitative methods of predicting the surface elevation of sub-tidal and intertidal areas in muddy estuaries and coasts are required to en-able effective management s rategies and engin-eering design. The management of subtidal deposits usually concerns the navigability of an estuary and the need for dredging whilst the intertidal deposits and saltmarshes provide valu-able natural protection against coastal flooding |
| File Format | |
| Publisher Date | 1998-01-01 |
| Access Restriction | Open |
| Content Type | Text |
