Sediment mobility in response to tidal and wind-driven flows along the Belgian shelf, southern North Sea
Baeye, M.; Fettweis, M.; Voulgaris, G.; Van Lancker, V. (2012). Sediment mobility in response to tidal and wind-driven flows along the Belgian shelf, southern North Sea, in: Baeye, M. Hydro-meteorological influences on the behaviour and nature of sediment suspensions in the Belgian-Dutch coastal zone = Hydro-meteorologische effecten op het gedrag en samenstelling van sedimentsuspensies in de Belgisch-Nederlandse kustzone. pp. 33-50
In: Baeye, M. (2012). Hydro-meteorological influences on the behaviour and nature of sediment suspensions in the Belgian-Dutch coastal zone = Hydro-meteorologische effecten op het gedrag en samenstelling van sedimentsuspensies in de Belgisch-Nederlandse kustzone. PhD Thesis. Ghent University: Ghent. 170 pp., more
The effect of hydro-meteorological forcings (tidally- and wind-induced flows) on the transport of suspended particulate matter (SPM), on the formation of highconcentrated mud suspensions and on the occurrence of sand-mud suspensions has been studied using long-term multi-parametric observations. Data have been collected in a coastal turbidity maximum area (southern North Sea) where a mixture of sandy and muddy sediments prevails. Data have been classified according to variations in sub-tidal alongshore currents, with the direction of sub-tidal flow depending on wind direction. This influences the position of the turbidity maximum; as such also the origin of SPM. Winds blowing from the NE will increase SPM concentration, whilst SW winds will induce a decrease. The latter is related to advection of less turbid English Channel water, inducing a shift of the turbidity maximum towards the NE and the Westerscheldt estuary. Under these conditions, marine mud will be imported and buffered in the estuary. Under persistent NE winds, high-concentrated mud suspensions are formed and remain present during several tidal cycles. Data show that SPM consists of a mixture of flocs and locally eroded sand grains during high currents. This has implications towards used instrumentation: SPM concentration estimates from optical backscatter sensors will only be reliable when SPM consists of cohesive sediments only; with mixtures of cohesive and non-cohesive sediments, a combination of both optical and acoustic sensors are needed to get an accurate estimate of the total SPM concentration.
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