Observations of a narrow zone of high suspended particulate matter (SPM) concentrations along the Dutch coast

Hout, C.M. van der; Gerkema, Theo; Nauw, Janine J.; Ridderinkhof, H.

doi:10.1016/j.csr.2015.01.002

Cited by 20 publications

(43 citation statements)

References 53 publications

(87 reference statements)

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“…Field surveys have confirmed the presence of fines in the region; mud deposits and areas with high turbidity are frequently observed off the Dutch coast and along the southern bight of the North Sea (Fettweis & Van den Eynde, 2003;Van Alphen, 1990;van der Hout et al, 2015van der Hout et al, , 2017Visser et al, 1991). Detailed surveys of the size distribution of sands (Huisman et al, 2016) give a reasonable estimate of the fraction of fine sediment (<63μm) on the seabed and the spatial and temporal variability of transient mud deposits close to our measurement sites (Figure 1a).…”

Section: 1029/2018gl077936supporting

confidence: 78%

“…While the emplacement of the Sand Engine undoubtedly provides a large source of coastal sediment, monitoring has shown that the particle size distribution around it has coarsened since its construction (Huisman et al, 2016). Moreover, observed suspended sediment concentrations are in the same range as those observed prior to its construction (Flores et al, 2017;Horner-Devine et al, 2017;van der Hout et al, 2015). This suggests that the Sand Engine does not provide a large source of fine sediments.…”

Section: Study Site and Methodsmentioning

confidence: 98%

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Wave Generation of Gravity‐Driven Sediment Flows on a Predominantly Sandy Seabed

Flores

Rijnsburger

Meirelles

et al. 2018

Geophysical Research Letters

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Wave‐supported gravity flows (WSGFs) generate rates of sediment flux far exceeding other cross‐shelf transport processes, contributing disproportionately to shelf morphology and net cross‐shelf fluxes of sediment in many regions worldwide. However, the conditions deemed necessary for the formation of WSGF limit them to a narrow set of shelf conditions; they have been observed exclusively in regions where the seabed consists of very fine‐grained sediment and typically co‐occur with nearby river flood events. Here we document the occurrence of a WSGF event on a predominantly sandy seabed and in the absence of a preceding river flood. Our measurements confirm that the dynamics are governed by the friction‐buoyancy balance observed in other WSGF and that WSGF can form in mixed grain‐size environments and transport high concentrations of sand. The occurrence of WSGF on a predominantly sandy seabed suggests that they may occur under a much wider range of conditions and, given the global prevalence of sandy shelves, they may be a more frequent and more ubiquitous feature of shelf dynamics than previously thought.

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Section: 1029/2018gl077936supporting

confidence: 78%

Section: Study Site and Methodsmentioning

confidence: 98%

Wave Generation of Gravity‐Driven Sediment Flows on a Predominantly Sandy Seabed

Flores

Rijnsburger

Meirelles

et al. 2018

Geophysical Research Letters

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“…Stratification leads to the suppression of turbulence at the pycnocline [Geyer, 1993;de Nijs et al, 2010], trapping suspended matter below it. The continuous change between stratified and well-mixed conditions in shallow river plumes, such as the Rhine, complicates the task of inferring subsurface SPM fluxes from remote sensing data or surface measurements [Pietrzak et al, 2011;van der Hout et al, 2015]. Geyer et al [2004] concluded that sediment transport in river-influenced regions is often dominated by near-bottom fluxes, which suggests that near-bed measurements are required to avoid erroneous conclusions about the magnitude and direction of transport.…”

Section: Introductionmentioning

confidence: 99%

“…Processes leading to SPM transport in the Rhine ROFI are strongly tied to density stratification patterns [van der Hout et al, 2015;Joordens et al, 2001]. Variations in stability of the Rhine ROFI occur at different timescales [Simpson et al, 1993;Simpson, 1997].…”

Section: Introductionmentioning

confidence: 99%

The impact of storms and stratification on sediment transport in the Rhine region of freshwater influence

et al. 2017

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We present measurements of along and across‐shore sediment transport in a region of the Dutch coast 10 km north of the Rhine River mouth. This section of the coast is characterized by strong vertical density stratification because it is within the midfield region of the Rhine region of freshwater influence, where processes typical of the far‐field, such as tidal straining, are modified by the passage of distinct freshwater lenses at the surface. The experiment captured two storms, and a wide range of wind, wave, tidal and stratification conditions. We focus primarily on the mechanisms leading to cross‐shore sediment flux at a mooring location in 12 m of water, which are responsible for the exchange of sediment between the nearshore and the inner shelf. Net transport during storms was directed offshore and influenced by cross‐shelf winds, while net transport during spring tides was determined by the mean state of stratification. Tidal straining dominated during neap tides; however, cross‐shore transport was negligible due to small sediment concentrations. The passage of freshwater lenses manifested as strong pulses of offshore transport primarily during spring tides. We observe that both barotropic and baroclinic processes are relevant for cross‐shore transport at depth and, since transport rates due to these competing processes were similar, the net transport direction will be determined by the frequency and sequencing of these modes of transport. Based on our observations, we find that wind and wave‐driven transport during storms tends move fine sediment offshore, while calmer, more stratified conditions move it back onshore.

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“…The north Norfolk coast of the UK and the southern coast of the Netherlands, where two of the farms under investigation 20 were located, are characterized by shallow water depths (<25 m), high winter nutrient concentrations (Hydes et al, 1999;Proctor et al, 2003;Foden et al, 2011;Laane, 2005;Troost et al, 2014), and high turbidity (Dyer and Moffatt, 1998;Bristow et al, 2013;Pietrzak et al, 2011;Van der Hout et al, 2015). In contrast to the north Norfolk coast, the Dutch coastal area has lower salinity, potential for episodic salinity stratification (De Ruyter et al, 1997), and a higher N/P ratio due to larger reductions in anthropogenic riverine phosphate loading since the late 1980's (Lenhart et al, 2010).…”

Section: Southern North Seamentioning

confidence: 99%

Modelling potential production and environmental effects of macroalgae farms in UK and Dutch coastal waters

Molen

Ruardij

Mooney

et al. 2017

Preprint

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Abstract. There is increasing interest in macroalgae farming in European waters for a range of applications, including food, chemical extraction and as biofuels. This study uses a 3D numerical model of hydrodynamics and biogeochemistry to investigate potential production and environmental effects of macroalgae farming in UK and Dutch coastal waters. The 15 model included four experimental farms in different coastal settings in Strangford Lough (Northern Ireland), in Sound of Kerrera and Lynn of Lorne (northwest Scotland), and in the Rhine Plume (The Netherlands), as well as a hypothetical largescale farm off the UK north Norfolk coast. The model could not detect significant changes in biogeochemistry and plankton dynamics at any of the farm sites averaged over the farming season. The results showed a range of macroalgae growth behaviours in response to simulated environmental conditions. These were then compared with in-situ observations where 20 available, showing good correspondence for some farms and less good correspondence for others. At the most basic level, macroalgae production depended on prevailing nutrient concentrations and light conditions, with higher levels of both resulting in higher macroalgae production. It is shown that under non-elevated and interannually varying winter nutrient conditions, farming success was modulated by the timings of the onset of increasing nutrient concentrations in autumn and nutrient drawdown in spring. Macroalgae carbohydrate content also depended on nutrient concentrations, with higher 25 nutrient concentrations leading to lower carbohydrate content at harvest. This will reduce the energy density of the crop and so affect its suitability for conversion into biofuel. For the hypothetical large-scale macroalgae farm off the UK north Norfolk coast the model suggested high, stable farm yields of macroalgae from year to year with substantial carbohydrate content and limited environmental effects.

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Observations of a narrow zone of high suspended particulate matter (SPM) concentrations along the Dutch coast

Cited by 20 publications

References 53 publications

Wave Generation of Gravity‐Driven Sediment Flows on a Predominantly Sandy Seabed

Wave Generation of Gravity‐Driven Sediment Flows on a Predominantly Sandy Seabed

The impact of storms and stratification on sediment transport in the Rhine region of freshwater influence

Modelling potential production and environmental effects of macroalgae farms in UK and Dutch coastal waters

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