Intratidal and spatial variability over a slope in the Ems estuary: Robust along-channel SPM transport versus episodic events

https://doi.org/10.1016/j.ecss.2020.106902Get rights and content
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Highlights

  • Lateral transport of water and SPM mostly shows a vertically layered structure, but is subject to abrupt transitions.

  • Strong spatial variability is observed in the lateral circulation patterns.

  • Small-scale and episodic events have little effect on the overall transport of SPM, which is ebb-dominated.

Abstract

Results from measurements are presented that were collected during a full tidal cycle in the Ems estuary, involving two landers and an anchored research vessel. The conditions were characterized by very weak winds, no wave effects, and low river run-off, so that the state was close to tide-only. We find that the lateral (i.e., cross-slope) transport of water and suspended particulate matter (SPM) much of the time shows a vertically layered structure, which is however subject to sudden transitions. Moreover, even on the small spatial scale of these measurements (i.e., within a distance of 200 m), a strong lateral variability is observed in the circulation patterns. We analyze its dynamics by means of dimensionless parameters. In addition, near-bottom peaks in SPM concentration are observed, notably during early flood. However, these episodic events have little effect on the overall transport of SPM, which involves the whole water column: the measurements show a high vertically integrated SPM signal during late ebb, resulting in an ebb-dominance in the transport at this position in the tidal channel.

Keywords

Lateral circulation
SPM transport
Ems estuary
EDoM18

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