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Perdok, U. (author), Crossman, M. (author), Verhagen, H.J. (author), Howard, S. (author), Simm, J. (author)The performance and durability of timber groynes (or 'groins') is highly dependent on the design and detailing of the structure. Using knowledge and experience developed over generations an effective functional design can be achieved, which may ultimately result in lower whole life costs and provide environmental advantages over alternative...conference paper 2003
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Verhagen, H.J. (author), Van Dijk, B. (author), Nederpel, A. (author)Medium height breakwaters are subjected to a considerable amount of overtopping. This implies the armour on the inner slope has to stable against overtopping waves. Existing equations do lack some basic understanding of the process of starting up movement of rock on the inner slopes. In case one relates the stability of the blocks on the inner...conference paper 2003
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Verhagen, H.J. (author), Van der Hoeven, M. (author), Thiel, B. (author)In a flume of BallastHam Dredging a falling apron model has been constructed and loaded by current. The tests have been done with different rock sizes, different layer thickness of the top storage of the apron and two different gradings. In summary it was found that for both the narrow graded rock layers as well as for wide graded riprap the...conference paper 2003
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Verhagen, H.J. (author), Van Dijk, B. (author), Nederpel, A. (author)Medium height breakwaters are subjected to a considerable amount of overtopping. This implies the armour on the inner slope has to stable against overtopping waves. Existing equations do lack some basic understanding of the process of starting up movement of rock on the inner slopes. In order to get more insight into this phenomenon a special...conference paper 2003
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Lam, N.T. (author), Verhagen, H.J. (author), Van der Wegen, M. (author)Application of an one-dimensional numerical model for hydrodynamic simulation of a complex lagooninlet system in Vietnam is presented. Model results help to get a better understanding on the behaviour of the system. Based on the numerical model results and analytic solutions, stability of tidal inlets is evaluated.conference paper 2003
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Schokking, L.A. (author), Janssen, P.C. (author), Verhagen, H.J. (author)The stability of stones in propeller-induced jet wash is still difficult to predict. Especially the trend of bowthrusters increasing in size and power in sea going ships (especially ferries) over the last years may be a reason for concern when dealing with the protection of slopes and beds. But also ships used in inland navigation are using...journal article 2003
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Lam, N.T. (author), Verhagen, H.J. (author), Van der Wegen, M. (author)This paper presents an application of an one-dimensional unsteady numerical model DUFLOW for hydrodynamic simulation of a complex lagoon-inlet system in Vietnam. The difficulties due to the lack of data for model boundary conditions is overcome by using sensitivity analysis approach for the uncertainties of boundary conditions. Model results are...journal article 2004
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Lam, N.T. (author), Verhagen, H.J. (author), Van der Wegen, M. (author)Stability analysis of tidal inlets is very important in providing knowledge on the behaviour of tidal inlet and lagoon systems. The analysis results can help to plan and manage the system effectively as well as to provide information for stability design of the inlets. This paper presents a method of building and applying the Escoffier diagram...journal article 2004
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De Jong, W. (author), Verhagen, H.J. (author), Olthof, J. (author)Physical model tests were done on an armour of Tetrapods, placed in a single layer. The objective of the investigations was to study the stability of the secondary layer, and to see if the material of this secondary layer could be washed out through the single layer of Tetrapods. It was concluded that secondary armour is not washed out through...conference paper 2004
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Verhagen, H.J. (author), Steenaard, J. (author), Tuan, T.Q. (author)A number of equations has been developed for calculation overtopping quantities over breakwaters, as well as equations to describe the stability of the inner slope. However, not all the water which overtops the outer boundary of the breakwater will reach the inner slope; part of the water is infiltrated in the crest. In this paper data are...conference paper 2004
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Verhagen, H.J. (author)Example for the the dataprocessing of wave data in such a way that design values for coastal structures can be determinedbook chapter 2004
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Lam, N.T. (author), Verhagen, H.J. (author), Van der Wegen, M. (author)Hydraulic characteristics of flow in a tidal inlet act an important role in morphological changes of the inlet. In normal conditions, inlet currents flush sediment out of the inlet to maintain its opening against longshore sediment transports that tend to close the inlet. The currents in the inlet are contributed by the tides and also from...journal article 2004
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Verhagen, H.J. (author)This paper gives an overview of some recent developments in structures for coastal protection. Single layer units like Accropode and Xbloc are rather popular at this moment; research indicates that also cubes can be placed in single layers. Also the use of heavy aggregates in concrete can be beneficial for the stability and economics. Structures...conference paper 2004
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Stive, M.J.F. (author), Terrile, E. (author), Reniers, A.J.H.M. (author), Verhagen, H.J. (author)Threshold of motion of coarse particles under regular shoaling waves is studied. Experiments were performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were created...conference paper 2005
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Stive, M.J.F. (author), Reniers, A.J.H.M. (author), Terrile, E. (author), Verhagen, H.J. (author)The threshold of motion of coarse particles under regular shoaling waves is studied. Experiments are performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth, combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were...conference paper 2005
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Verhagen, H.J. (author)In 1991 CUR in the Netherlands and CIRIA in the UK have published the "manual on the use of rock in coastal engineering", usually referred to as the "Rock Manual". This book of 600 pages gave an overview of the state of the art regarding the design of rock structures along coasts. In 1995 CUR published a adapted version of this book, also...conference paper 2005
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Verhagen, H.J. (author)Coastal engineering is a complex art. At this moment a limited number of phenomena can understood with the help of the laws of physics and fluid mechanics. For the remainder, formulas have been developed with limited accuracy. In addition, input data are also limited available, and form another source of uncertainty. Consequently, a sound...conference paper 2005
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Verhagen, S. (author)The principle of positioning with the Global Positioning System (GPS) is based on determining the distance of at least four GPS satellites to a receiver. For that purpose the so-called code measurements can be used, so that the position of the receiver can be determined up to several meters. In order to allow for navigation with centimeter...doctoral thesis 2005
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Verhagen, H.J. (author)In case of coasts with steep foreshores coastal structures suffer more from damage than normally could be expected from given boundary conditions at deep water. For that reason in many guidelines it is recommended to apply a heavier class of rock in those cases; manufacturers of single layer units (like Accropode, Core-loc or Xbloc) recommend a...conference paper 2005
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Terrile, E. (author), Reniers, A.J.H.M. (author), Stive, M.J.F. (author), Tromp, M. (author), Verhagen, H.J. (author)Incipient motion of coarse particles under regular shoaling waves is examined. Experiments are performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth, combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were created....journal article 2005