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Giardino, A (author), Schrijvershof, R. (author), Nederhoff, C.M. (author), de Vroeg, H (author), Brière, CDE (author), Tonnon, Pieter Koen (author), Caires, S. (author), Walstra, D.J.R. (author), Sosa, J. (author), van Verseveld, WJ (author), Schellekens, J. (author), Sloff, C.J. (author)
The West African coastal barrier is maintained by significant wave-driven longshore sand transport. This sand originates from rivers and large coastal sand deposits. Today, however, much of the fluvial sand is trapped behind river dams and/or interrupted at several locations by port jetties. As a result, the sandy coastal barrier is eroding...
journal article 2018
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Monecke, Katrin (author), Meilianda, Ella (author), Walstra, D.J.R. (author), Hill, Emma M. (author), McAdoo, Brian G. (author), Qiu, Qiang (author), Storms, J.E.A. (author), Masputri, Aisha Sri (author), Mayasari, Cut Deasy (author), Nasir, Muhammad (author), Riandi, Indra (author), Setiawan, Agus (author), Templeton, Caroline K. (author)
We model postseismic changes to the shoreline of West Aceh, Indonesia, a region largely affected by the December 2004 Sumatra-Andaman earthquake and ensuing Indian Ocean tsunami, using a cross-shore morphodynamic model. Subsidence of 0.5–1.0 m and tsunami scouring during the 2004 event caused the complete destruction of the beach and the...
journal article 2017
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Walstra, D.J.R. (author), Ruessink, BG (author)
Based on model hindcasts of the bar cycle at two locations along the Dutch coast, the dominant processes and mechanisms that govern the bar amplitude growth and decay during net inter-annual offshore migration, the occurrence of bar switches and the inter-site differences in the bar cycle return period (Tr) are identified. Bar growth and decay...
conference paper 2017
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de Boer, W.P. (author), Huisman, B.J.A. (author), Yoo, Jeseon (author), McCall, Robert (author), Scheel, F. (author), Swinkels, Cilia M. (author), Friedman, Josh (author), Luijendijk, A.P. (author), Walstra, D.J.R. (author)
conference paper 2017
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van der Vegt, H. (author), Storms, J.E.A. (author), Walstra, D.J.R. (author), Howes, N.C. (author)
Abstract Understanding the processes and conditions at the time of deposition is key to the development of robust geological models which adequately approximate the heterogeneous delta morphology and stratigraphy they represent. We show how the mechanism of sediment transport (the proportion of the sediment supply transported as bed load vs....
journal article 2016
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Walstra, D.J.R. (author)
Nearshore sandbars have a lifetime of many years, during which they exhibit cyclic, offshore directed behaviour with strong alongshore coherence. A bar is generated near the shoreline and grows in height and width while migrating offshore, before finally decaying at the seaward limit of the surf zone. It may take 10 to 15 years for a bar to...
doctoral thesis 2016
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Walstra, D.J.R. (author), Wesselman, Daan (author), van der Deyl, Eveline (author), Ruessink, BG (author)
Inter-annual bar dynamics may vary considerably across sites with very similar environmental settings. In particular, the variability of the bar cycle return period (Tr) may differ by a factor of 3 to 4. To date, data studies are only partially successful in explaining differences in Tr, establishing at best weak correlations to local...
journal article 2016
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Monecke, K. (author), Templeton, C.K. (author), Finger, W. (author), McAdoo, B. (author), Meilianda, E. (author), Storms, J.E.A. (author), Walstra, D.J.R. (author)
conference paper 2014
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van der Vegt, H. (author), Storms, J.E.A. (author), Walstra, D.J.R. (author)
The assessment and production of hydrocarbon resources incorporates geological models created from core and wireline well data, as well as seismic data. This data is spatially discrete but is used create a spatially continuous model. However, the heterogeneity within depositional environments is on a smaller spatial scale than the available data...
conference paper 2014
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Reyns, J. (author), Dastgheib, A. (author), Ranasinghe, R.W.M.R.J.B. (author), Luijendijk, A.P. (author), Walstra, D.J.R. (author), Roelvink, J.A. (author)
A hampering factor in the application of morphodynamic models is the potential excessive time needed to complete a simulation. One way to upscale a model run is the use of a morphological factor, or MORFAC. In this paper, we investigate the upper limit to the value of the MORFAC as a function of model geometry and timestep for a schematized case...
conference paper 2014
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Duong, M.T. (author), Ranasinghe, D. (author), Luijendijk, A.P. (author), Walstra, D.J.R. (author), Roelvink, D. (author)
Tidal inlets are of great societal importance and are also the most morphologically dynamic regions in the coastal zone. Therefore, they are of great scientific interest. Their behaviour is governed by the delicate balance of oceanic processes such as tides, waves and mean sea level (MSL), and fluvial/estuarine processes such as riverflow. All...
conference paper 2014
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Huisman, B.J.A. (author), Van Thiel De Vries, J.S.M. (author), Walstra, D.J.R. (author), Roelvink, J.A. (author), Ranasinghe, R.W.M.R.J.B. (author), Stive, M.J.F. (author)
Understanding of the behaviour of coastline perturbations at soft-coastlines is essential for modelling coastal evolution at decadal time scales. Many coastline models do, for example, implicitly assume dominant diffusive behaviour of coastline features. The validity of this assumption is investigated for the Dutch coast on the basis of data on...
conference paper 2013
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Walstra, D.J.R. (author), Ruessink, G. (author), Hoekstra, R. (author), Tonnon, P.K. (author)
Input reduction is imperative to long-term (> years) morphodynamic simulations to avoid excessive computation times. Here, we discuss the input-reduction framework for wave-dominated coastal settings introduced by Walstra et al. (2013). The framework comprised 4 steps, viz. (1) the selection of the duration of the original (full) time series of...
conference paper 2013
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Blossier, B. (author), Briere, C. (author), Roelvink, J.A. (author), Walstra, D.J.R. (author)
Sand beach profiles can exhibit nearshore sandbars with complex 3D patterns. Under energetic conditions, these patterns disappear and the bars get to a certain extent alongshore uniform. This phenomenon is called a reset. The existing literature mainly concerns the development of the bar patterns (3D) or the cross-shore migration of sandbars (2D...
conference paper 2012
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Hoekstra, R. (author), Walstra, D.J.R. (author), Swinkels, C.S. (author)
In October and November 2009 a pilot project has been executed at the Delfland Coast in the Netherlands, constructing three small sandy headlands called Sand Groynes. Sand Groynes are nourished from the shore in seaward direction and anticipated to redistribute in the alongshore due to the impact of waves and currents to create the sediment...
conference paper 2012
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Walstra, D.J.R. (author), De Vroeg, J.H. (author), Van Thiel de Vries, J.S.M. (author), Swinkels, C. (author), Luijendijk, A.P. (author), De Boer, W.P. (author), Hoekstra, R. (author), Hoonhout, B. (author), Henrotte, J. (author), Smolders, T. (author), Dekker, F. (author), Godsey, E. (author)
In order to conceive any realistic plan for post-Katrina island restoration, it is necessary to understand the physical processes that move sand along the littoral drift zone off the coast of Mississippi. This littoral zone influences the character of the Mississippi barrier islands as they exist in an ever changing cycle. To help in this...
conference paper 2012
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Walstra, D.J.R. (author), Hoyng, C.W. (author), Tonnon, P.K. (author), Van Rijn, L.C. (author)
This experimental study focuses on the morphological development of a near-equilibrium profile on which to types of shoreface nourishments are placed. As previous studies have indicated that the efficiency of nourishments is mainly influenced by water depth in which they are constructed, two cross-shore locations are considered for an accretive...
conference paper 2011
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Ranasinghe, R.W.M.R.J.B. (author), Swinkels, C. (author), Luijendijk, A.P. (author), Bosboom, J. (author), Roelvink, D. (author), Stive, M.J.F. (author), Walstra, D.J.R. (author)
The Morphological Acceleration Factor (MORFAC) approach for morphodynamic upscaling enables the simulation of long term coastal evolution. However the general validity of the MORFAC concept for coastal applications has not yet been comprehensively investigated. Furthermore, a robust and objective method for the a priori determination of the...
conference paper 2010
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Luijendijk, A. (author), Henrotte, J. (author), Walstra, D.J.R. (author), van Ormondt, M. (author)
A quasi-three-dimensional model (quasi-3D) has been developed through the implementation of an analytical 1DV flow model in existing depth-averaged shallow water equations. The model includes the effects of waves and wind on the vertical distribution of the horizontal velocities. Comparisons with data from both physical and field cases show that...
conference paper 2010
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Geleynse, N. (author), Storms, J.E.A. (author), Stive, M.J.F. (author), Jagers, H.R.A. (author), Walstra, D.J.R. (author)
Present?day observations and classical classification schemes of alluvial deltas address feeder channel dynamics and multiple sediment fractions. However, high?resolution physics?based mathematical models have not been applied to address formation of both fluvio?deltaic links (channels) and nodes (diffluences and confluences), and their...
journal article 2010
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