Variability of residual fluxes of suspended sediment in a multiple tidal-inlet system: the Dutch Wadden Sea
- 8.4k Downloads
In multiple tidal-inlet systems such as the Dutch Wadden Sea, the exchange of sediments between the coastal lagoon and the adjacent sea is controlled by the combined effect of the tides, wind-driven flows, and density-driven flows. We investigate the variability of residual (tidally averaged) fluxes of suspended sediment with the three-dimensional numerical model GETM in relation to forcing mechanisms and model parameters. Sediment transport is modeled with three sediment classes. A modified Partheniades-Krone formulation describes the erosion and deposition fluxes from a single-layer sediment pool. The model is initialized with a uniform sediment pool for each class and the spin up period amounts to six months. Simulations span 1 year. Comparisons with observations show that model results are fairly realistic. Residual fluxes of water and suspended sediment are episodic in nature and vary strongly throughout the year, mainly due to wind variability. The net balance between import and export of material is very sensitive to model parameters. Residual fluxes are sensitive to the geographical orientation and location of the inlets, and the effect of driving mechanisms on the residual fluxes and concentrations can be organized hierarchically, with wind forcing having the largest effect on concentration levels and variability.
KeywordsResidual flux Mud transport Numerical model Tidal inlet
This work was supported through the project PACE. (The future of the Wadden Sea sediment fluxes: still keeping pace with sea level rise?) by Netherlands organization for scientific research (NWO, ZKO-project 839.11.003). The authors would like to thank the Ministry of Public Works (Rijkswaterstaat) for making publicly available the data employed in this study, and Ulf Gräwe for fruitful discussions on the implementation of the sediment transport module. This manuscript has benefited from the comments and suggestions from two anonymous reviewers.
- Beets D, van der Spek A (2000) The Holocene evolution of the barrier and the back-barrier basins of Belgium and the Netherlands as a function of late Weichselian morphology, relative sea-level rise and sediment supply. Neth J Geosci 79:3–16Google Scholar
- Duran-Matute M, Gerkema T (subm.) Calculating residual flows through a multiple-inlet system: the conundrum of the tidal period. Ocean Dynam subm.:submGoogle Scholar
- Elias E, van der Spek A, Wang Z (2012) Morphodynamic development and sediment budget of the Dutch Wadden Sea over the last century. Neth J Geosci 91(3):293–310Google Scholar
- van Maren D, van Kessel T, Cronin K, Sittoni L (2015) The impact of channel deepening and dredging on estuarine sediment concentration. Cont Shelf Res 95:1–14. doi: 10.1016/j.csr.2014.12.010
- Ridderinkhof H (1998) On the sensitivity of the large scale transport and distribution of fine grained sediments in a tidal basin to the formulation of the erosion-sedimentation cycle. In: Dronkers J, Sheffers M (eds) Physics of estuaries and coastal seas, Balkema, pp 145–153Google Scholar
- Sassi M, Hoitink A, Vermeulen B (2012) Impact of sound attenuation by suspended sediment on ADCP backscatter calibrations. Water Resour Res 48(W09520). doi: 10.1029/2012WR012008
- Sassi M, Gerkema T, Duran-Matute M, Nauw J (subm.) Residual flows in the Marsdiep inlet inferred from observations and a numerical model. J Marine Res subm.:submGoogle Scholar
- Wang Z, Hoekstra P, Burchard H, Ridderinkhof H, De Swart HE, Stive M (2012) Morphodynamics of the Wadden Sea and its barrier island system. Ocean Coast Manage 68:39–57. doi: 10.1016/j.ocecoaman.2011.12.022
- Winterwerp J, Van Kesteren W (2004) Introduction to the physics of cohesive sediment in the marine environment. 1st edn. Elsevier, Amsterdam, p 466Google Scholar