Bed shear stress in the southern North Sea as an important driver for suspended sediment dynamics |
| |
Authors: | Emil Vassilev Stanev Mikhail Dobrynin Andrey Pleskachevsky Sebastian Grayek Heinz Günther |
| |
Institution: | (1) Institute for Coastal Research, GKSS Research Centre, Geesthacht, Germany;(2) Institute for Chemistry and Biology of the Sea (ICBM), University of Oldenburg, Oldenburg, Germany |
| |
Abstract: | This paper addresses the spatial and temporal patterns of drivers for sediment dynamics in coastal areas. The basic assumption
is that local processes are dominating. The focus is put on the bed shear stress in the southern part of North Sea giving
the basic control for deposition–sedimentation and resuspension–erosion. The wave-induced bed shear stress is formulated using
a model based on the concept that the turbulent kinetic energy associated with surface waves is a function of orbital velocity,
the latter depending on the wave height and period, as well as on the water depth. Parameters of surface waves are taken from
simulations with the wave spectrum model WAM (wave model). Bed shear stress associated with currents is simulated with a 3D
primitive equation model, Hamburg Shelf Ocean Model. Significant wave height, bed shear stress due to waves and currents,
is subjected to empirical orthogonal functions (EOF) analysis. It has been found that the EOF-1 of significant wave height
represents the decrease of significant wave height over the shallows and, due to fetch limitation, along the coastlines. Higher
order modes are seesaw-like and, in combination, display a basin-scale rotational pattern centred approximately in the middle
of the basin. Similar types of variability is also observed in the second and third EOF of bed shear stress. Surface concentrations
of suspended matter derived from MERIS satellite data are analysed and compared against statistical characteristics of bed
shear stress. The results show convincingly that the horizontal distribution of sediment can, to a larger extent, be explained
by the local shear stress. However, availability of resuspendable sediments on the bottom is quite important in some areas
like the Dogger Bank. |
| |
Keywords: | Sediment transport Wind waves Temporal and spatial patterns Suspended matter |
本文献已被 SpringerLink 等数据库收录! |
|