4075 resultaten

  • Mid-Holocene vertebrate bone Concentration-Lagerstätte on oceanic island Mauritius provides a window into the ecosystem of the dodo (Raphus cucullatus)

    Auteurs: Rijsdijk, K.F.; Louw, P.G.B. de (2009)
    Gepubliceerd in: Quaternary science reviews, volume 28 (2009) nummer 1-2, pagina 14-24

    Although the recent history of human colonisation and impact on Mauritius is well documented, virtually no records of the pre-human native ecosystem exist, making it difficult to assess the magnitude of the changes brought about by human settlement. Here, we describe a 4000-year-old fossil bed at Mare aux Songes (MAS) in south-eastern Mauritius that contains both macrofossils (vertebrate fauna, gastropods, insects and flora) and microfossils (diatoms, pollen, spores and phytoliths).

  • Investigating the trends of import and export of sediment in the Western Scheldt estuary, The Netherlands by a process-based model

    Auteurs: Ofori, K.W.; Wegen, M. van der; Roelvink, J.A.; Ronde, J.G. de (2009)

  • Measurements and modelling of the effects of seagrass meadows on flow and sediment transport in the Bay of l'Ecluse, Dinard, France

    Auteur: Dijkstra, J.T. (2009)

  • Evaluation of flow fields for their impact on manoeuvring

    Auteurs: Kaarsemaker, M.H.A.; Weiler, O.M.; Verheij, H.J. (2010)

  • Predicting the population dynamics in Amoebophrya parasitoids and their dinoflagellate hosts using a mathematical model

    Auteurs: Salomon, P.S.; Stolte, W. (2010)
    Gepubliceerd in: Marine ecology progress series (MEPS), volume 419 (2010), pagina 1-10

    Free-living, photosynthetic marine dinoflagellates are frequently infected by microparasites of the genus Amoebophrya. Attacks by Amoebophrya can contribute to the termination of dinoflagellate blooms and have been suggested to influence the geographical distribution of certain host species. In the present work, we explored the population dynamics in Amoebophrya and their dinoflagellate hosts using the Rosenzweig–MacArthur modification of the traditional Lotka–Volterra predation model. The model was parameterized for 3 systems, Akashiwo sanguinea, Gymnodinium instriatum, and Karlodinium micrum, and their respective Amoebophrya parasitoids, using published experimental data. The potential for host control by Amoebophrya and the probability for host extinction were studied with respect to carrying capacity, a parameter that is influenced by e.g. eutrophication.

  • Comparison of varying complexity numerical models for the prediction of flood inundation in Greenwich, UK

    Auteurs: Fewtrell, T.J.; Bates, P.D.; Wit, A. de; Asselman, N.E.M.; Sayers, P. (2008)

    In recent years, urban flood modelling studies have taken the form of either validation against observations of a single event or benchmarking models of varying complexity for a synthetic flood event. In this paper, the latter framework is undertaken for hypothetic flooding scenarios at Greenwich on the River Thames, UK. A simple diffusion wave storage cell model, LISFLOOD-FP, is compared to a fully 2D hydrodynamic model, SOBEK, at multiple resolutions for a 1-in-100 year return period event. The models yield consistent results at the highest resolution (5 m) with minor differences accounted for by inertial effects and model schematisation. Secondly, both models predict significant degradation in model results at coarse resolutions compared to the high resolution benchmark. Specifically, results at 25 and 50 m suggest different flow structures emerge as the representation of urban structures becomes more coarse. As a result of this finding, the models are setup using a digital terrain model (DTM) with the buildings removed to investigate these emergent flow structures.

  • Processes around a TBM

    Auteurs: Talmon, A.M.; Bezuijen, A. (2009)

    Processes that occur around aTBM during tunnelling have been investigated while tunnelling insaturated sand.

  • Failure modes and mechanisms for flood defence structures

    Auteurs: Morris, M.W.; Allsop, W.; Buijs, F.A.; Kortenhaus, A.; Doorn, N.; Lesniewska, D. (2008)

    This paper reports on work undertaken through theFLOODsite Project (Task 4) in bringing together available information on failure modes for a number of representativeflood defence structure types, to support the development and implementation of system wide modelsfor flood risk assessment.

  • Quantification of uncertain bed roughness under design conditions and propagation to the design water levels : a case study for the river Rhine

    Auteurs: Warmink, J.J.; Klis, H. van der (2010)

  • Stability of stones under uniform flow

    Auteur: Hoffmans, G.J.C.M. (2010)
    Gepubliceerd in: Journal of hydraulic engineering, volume 136 (2010) nummer 2, pagina 129-136

    The present technical note aims to discuss a depth-averaged turbulence parameter in relation to the incipient motion of particles.

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