The rock manual - Dredging Engineering Research Laboratory

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32 Terra et Aqua | Number 110 | March 2008Figure 9. Current Deflecting Walldownstream a tidal harbourentrance combined with a sill.the basin as indicated by the negativesedimentation in Table III.CASE STUDY “BREMERHAVENNORDSCHLEUSE”For harbour type A from 50% (smallentrance) to 90% (B E=B H) of the waterexchange result from density and floweffect. Water exchange in harbour type Bis permanently larger than 90% with smallvariations owing to the angle a. Limitationon the reduction of one of both maineffects will not result in optimised harbourgeometry.For the Test Case “Bremerhaven Nordschleuse”the calibrated model will be usedto redesign the entrance of the harbour infront of the North Lock (Figure 2). Fourdifferent entrance variations were tested:1 The entrance width was reduces by 40%.2 A Current Deflection Wall (CDW) wastested to reduce the flow effect(Leeuwen, Hofland, 1999; Figure 9).3 Density currents were influenced by usinga sill / bottom level difference in front ofthe complete entrance width.4 The combination of the level differenceand a CDW was tested.The results are shown in Table IV. The waterexchange between river and harbour wasreduced significantly by reducing theentrance width. The sedimentation heightwas only notably reduced by a combinationof two measures. A relation between waterexchange and the mean sedimentationheight could not be found.CONCLUSIONSSediment intrusion from tide- and densitydrivenestuaries into a diverting harbourbasin will remain a major factor in operationand maintenance of harbours. For optimisationof orientation of the harbour axis andentrance width an effective method ofsignificantly decreasing harbour sedimentation3-dimensional simulations havereached a reliable standard for identificationof the governing local processes, from flow,tide, density effects on sediment intrusionand deposition. Maintenance dredging,fluidisation measures or structures againstsedimentation can be rationally supported.REFERENCESDHI (2003a). MIKE 3: Estuarine and CoastalHydraulics and Oceanography, ScientificDocumentation, Danish Hydraulic Institute,Horsholm, Denmark.DHI (2003b). MIKE 3: Estuarine and CoastalHydraulics and Oceanography, Mud TransportModule, Danish Hydraulic Institute, Horsholm,Denmark.Ekebjaerg, L., Justensen, P. (1991). An explicitscheme for advection-diffusion modelling in twodimensions, Computer Methods in AppliedMechanics and Engineering, (88) 3.Franzius-Institut (2003). Sedimentation inbrackwasserbeeinflussten Häfen, Teilprojekt:Maßnahmen zur Minimierung der Sedimentationim Bereich brackwasserbeeinflusster Vorhäfen,Final report of the combined BMBF researchproject, Franzius-Institut, University of Hannover,Germany.Langendoen, E. (1992). Flow Patterns andTransport of Dissolved Matter in Tidal Harbours,Communications on Hydraulic and GeotechnicalEngineering, University of Delft.Leeuwen, S. and Hofland, B. (1999). The CurrentDeflecting Wall in a Tidal Harbour with DensityInfluences. Final Report in the Framework of theEuropean Community’s Large Scale Installationsand Facilities Programme III, Delft,The Netherlands.Mehta, A.J. (1986). Characterization of CohesiveSediment Properties and Transport Processes inEstuaries, Lecture Notes on Coastal EstuarineStudies, Issue 14, Springer Verlag, Berlin,New York.Rohr, F., 1933, Wasser- und Sinkstoff-Bewegungen in Fluss- und Seehäfen,Dissertation, R. Oldenbourg, Munich.Stoschek, O. (2004). Sedimentation undGegenmaßnahmen in tide- und brackwasserbeeinflusstenHäfen: eine Analyse mit Hilfe3-dimensionaler Simulationen, Dissertation,Mitteilungen des Franzius-Instituts, Issue No. 90.Stoschek, O., Geils, J., Matheja, A. andZimmermann, C. (2003). Dredging Alternatives –The Current Deflection Wall Minimizing DredgingActivities in Harbours. CEDA Dredging Days,Amsterdam, Netherlands.Vested, H.J., Justensen, P. and Ekebjaerg, L. (1992).Advection dispersion modelling in three dimensions,Appl. Mathematical Modelling, Vol. 16.
Books/Periodicals Review 33BOOKS/PERIODICALS REVIEWThe Rock Manual: The Use of Rock in HydraulicEngineeringBY CIRIA, CUR, CETMEFPublished by CIRIA. 2007.ISBN: 0-86017-683-5. 1267 pp. + CD.When you think of rock, you think of hard rock orsolid rock, but in this case also of heavy rock. Thismanual, counting 1267 pages, feels like a rock andmust weigh a few kilos. So if you are travelling youmay not want to carry it in your luggage. Luckily, inthe front of the hard copy of the book is also a CDwith the whole manual in PDF format. However, sincethe resolution of the pictures in the PDF files is notvery high, the CD is suitable as a search tool, but notas a replacement of the book. The electronic versioncan also be found on the websites of CIRIA (www.ciria.org, click on Bookshop, or www.ciriabook.com)and CETMEF (www.cetmef.equipement.gouv.fr).Rock is a commonly used construction material in thehydraulic environment. It is used in the marine andfluvial environments to provide protection againstscour and erosion and to limit wave overtopping andflooding. Estimates suggest that at least 10 milliontonnes of armourstone per year are used inconstruction across Europe.In 1991 CIRIA/CUR published the original Manual onthe Use of Rock in Coastal and Shoreline Engineering,commonly referred to as “The Rock Manual”. Thiswas followed in 1995 by the Manual on the Use ofRock in Hydraulic Engineering by CUR. This newedition of “The Rock Manual” has been completelyrevised and updated by a joint UK, French and Dutchteam represented by CIRIA, CETMEF and CUR,respectively, and presents current good practice forthe design and construction of rock structures forerosion and flood control at coasts and rivers.Where appropriate it presents new or emergingtechnologies that have not, at the time of thewriting, become standard practice, to allow thereader to be fully aware of, and make the best useof, the latest research findings.The target audience for the manual is wide andincludes planners, developers, engineeringconsultants and designers, architects, buildingmanagers, facility managers, contractors, producersand suppliers, owners, staff from regulators, fundersand educational institutions. The guidance is suitablefor worldwide applications with the stated aim ofachieving a long-term improvement in the use ofrock and will promote conservation of naturalsystems in balance with the proper protection ofhuman life and property. Although the editorssuggest that the reader should have a degree in CivilEngineering and at least two years of experience,Mechanical Engineers with an affinity to CivilEngineering should be able to understand themanual as well.The manual is a very good enchiridion and isrecommended to all who are involved in the use ofrock in hydraulic engineering.This book is available from www.ciriabooks.com.S.A. MIEDEMAFACTS ABOUTEnvironmental Impact AssessmentsINTERNATIONAL ASSOCIATION OF DREDGINGCOMPANIESJanuary 2008. 4 pp. Available free of charge.Dredging is a complicated matter and nowadaystrying to be an expert in everything is impossible.Yet all kinds of stakeholders come into contact withsome of the technical aspects of dredging and areconfronted with terminology that is not obviouslycomprehensible. FACTS ABOUT EnvironmentalImpact Assessments is the third in an ongoing seriesof leaflets published by the International Associationof Dredging Companies (IADC). The aim of this newseries of concise, easy-to-read leaflets is to give aneffective overview of essential facts about specificand important dredging and maritime constructionsubjects. Questions such as “What is the differencebetween an EIA, an EIS, an EES and an ES?” and“What is the World Bank definition of an EIA?” areanswered in a succinct and clear manner. For thoseneeding more in-depth or detailed information, areference list of other literature is provided.These publications are part of IADC’s on-going effortto support clients and others in understanding thefundamental principles of dredging and maritimeconstruction – because providing effectiveinformation to all involved parties is an essentialelement in achieving a successful dredging project.All “FACTS ABOUT…” are available in PDF form onthe IADC website: www.iadc-dredging.com. Printedcopies can be ordered by contacting the IADCSecretariat: info@iadc-dredging.com.MC
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Page 7 and 8: Immediate Displacement of the Seabe
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Page 11 and 12: New Possibilities for Ripper Dredgi
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