Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Data underlying “Multi-Scale monitoring and modelling of the Kapuas River Delta”
    Kästner, K. ; Vermeulen, B. ; Hoitink, A.J.F. ; Geertsema, T.J. - \ 2019
    hydrodynamics - morphodynamics - sand-bedded rivers - sediment transport - tropics
    unprocessed raw data: - water level (pressure gauge) - velocity (boat mounted VADCP and HADCP) - turbulence (bottom mounted coupled VADCP) - bathymetry (single beam) - side scan sonar - bed material grain size - water samples (suspended sediment concentration) - particle size (lisst casts) - salinity (gauged)
    The Importance of Combined Tidal and Meteorological Forces for the Flow and Sediment Transport on Intertidal Shoals
    de Vet, P.L.M. ; van Prooijen, B.C. ; Schrijvershof, R.A. ; van der Werf, J.J. ; Ysebaert, T. ; Schrijver, M.C. ; Wang, Z.B. - \ 2018
    Journal of Geophysical Research: Earth Surface 123 (2018)10. - ISSN 2169-9003 - p. 2464 - 2480.
    hydrodynamics - intertidal area - morphology - numerical model - sediment transport - wind

    Estuarine intertidal areas are shaped by combined astronomical and meteorological forces. This paper reveals the relative importance of tide, surge, wind, and waves for the flow and sediment transport on large intertidal shoals. Results of an intensive field campaign have been used to validate a numerical model of the Roggenplaat intertidal shoal in the Eastern Scheldt Estuary, the Netherlands, in order to identify and quantify the importance of each of the processes over time and space. We show that its main tidal creeks are not the cause for the dominant direction of the net flow on the shoal. The tidal flow over the shoal is steered by the water level differences between the surrounding channels. Also during wind events, the tidal flow (enhanced by surge) is dominant in the creeks. In contrast, wind speeds of order 40 times the typical tidal flow velocity are sufficient to completely alter the flow direction and magnitude on an intertidal shoal. This has significant consequences for the sediment transport patterns. Apart from this wind-driven flow dominance during these events, the wind also increases the bed shear stress by waves. For the largest intertidal part of the Roggenplaat, only ∼1–10% of the yearly transport results from the 50% least windy tides, even if the shoal is artificially lowered half the tidal range. This dominance of energetic meteorological conditions in the transports matches with field observations, in which the migration of the creeks and high parts of the shoal are in line with the predominant wind direction.

    Fate of nano- and microplastic in freshwater systems: A modeling study
    Besseling, Ellen ; Quik, Joris T.K. ; Sun, Muzhi ; Koelmans, Bart - \ 2017
    Environmental Pollution 220 (2017)Part A. - ISSN 0269-7491 - p. 540 - 548.
    microplastics - particles - water pollution - water quality - sedimentation - fresh water - hydrodynamics - microplastics - deeltjes - waterverontreiniging - waterkwaliteit - sedimentatie - zoet water - hydrodynamica
    Riverine transport to the marine environment is an important pathway for microplastic. However, information on fate and transport of nano- and microplastic in freshwater systems is lacking. Here we present scenario studies on the fate and transport of nano-to millimetre sized spherical particles like microbeads (100 nm–10 mm) with a state of the art spatiotemporally resolved hydrological model. The model accounts for advective transport, homo- and heteroaggregation, sedimentation-resuspension, polymer degradation, presence of biofilm and burial. Literature data were used to parameterize the model and additionally the attachment efficiency for heteroaggregation was determined experimentally. The attachment efficiency ranged from 0.004 to 0.2 for 70 nm and 1050 nm polystyrene particles aggregating with kaolin or bentonite clays in natural freshwater. Modeled effects of polymer density (1–1.5 kg/L) and biofilm formation were not large, due to the fact that variations in polymer density are largely overwhelmed by excess mass of suspended solids that form heteroaggregates with microplastic. Particle size had a dramatic effect on the modeled fate and retention of microplastic and on the positioning of the accumulation hot spots in the sediment along the river. Remarkably, retention was lowest (18–25%) for intermediate sized particles of about 5 μm, which implies that the smaller submicron particles as well as larger micro- and millimetre sized plastic are preferentially retained. Our results suggest that river hydrodynamics affect microplastic size distributions with profound implications for emissions to marine systems.
    De relatie tussen bodemdieren en hydro- en morfodynamiek in het sublitoraal en litoraal van de Westerschelde
    Ysebaert, T. ; Craeymeersch, J.A.M. ; Wal, Daphne van der - \ 2016
    IMARES (Rapport / IMARES C066/16) - 84
    bodemfauna - bodembiologie - hydrodynamica - westerschelde - soil fauna - soil biology - hydrodynamics - western scheldt
    Deze studie, in opdracht van Rijkswaterstaat, heeft als doel de relatie tussen bodemdiergemeenschappen en abiotische omgevingsvariabelen nader te onderzoeken en daarmee een betere onderbouwing te verkrijgen van de grens tussen hoog- en laagdynamische gebieden in de sublitorale en litorale gebieden van de Westerschelde.
    Natural foreshores as an alternative to traditional dike re-enforcements: a field pilot in the large shallow lake Markermeer, The Netherlands
    Penning, W.E. ; Steetzel, H.J. ; Santen, R. van; Fiselier, J. ; Lange, H.J. de; Vuik, V. ; Ouwerkerk, S. ; Thiel de Vries, J.S.M. van - \ 2015
    In: E-proceedings of the 36th IAHR World Congress. - 2015 : - 4
    nature development - flood control - dykes - riparian vegetation - coasts - hydrodynamics - natuurontwikkeling - hoogwaterbeheersing - dijken - oevervegetatie - kusten - hydrodynamica
    Natural foreshores are shallow zones and beaches with a gradual slope and a (near-)natural vegetation that can be used
    as an additional protection against flooding by reducing the wave attack on existing dikes, or can even completely
    replace an existing dike system. In order to test the applicability of this concept a 500 m long pilot section of a sandy
    foreshore was constructed along an already existing dike in the large shallow lake Markermeer, the Netherlands. The
    pilot was equipped with permanent monitoring equipment for hydrodynamics and meteorological conditions and monthly
    surveys of the morphology of the pilot section. These measurements will be carried out for the coming four years. This
    paper presents the first results after the construction and the first winter season with the pilot in place.
    Verkenning kansen schelpdierkweek Westerschelde
    Smaal, A.C. - \ 2014
    Yerseke : IMARES (Rapport / IMARES Wageningen UR C155/14) - 17
    schaal- en schelpdierenteelt - visserij - hydrodynamica - waterkwaliteit - inventarisaties - westerschelde - shellfish culture - fisheries - hydrodynamics - water quality - inventories - western scheldt
    In dit rapport wordt ingegaan op de vraag: Wat zijn de mogelijkheden voor de schelpdiervisserij en/of - kweek in de Westerschelde, en waar zijn deze activiteiten vanuit het huidige ruimtegebruik te ontwikkelen. Daartoe is op basis van bestaande informatie een overzicht gegeven van de randvoorwaarden voor schelpdierkweek en de ruimte die er binnen de randvoorwaarden te vinden is. De randvoorwaarden en kansen zijn getoetst aan de inzichten van de kwekers. De conclusie luidt dat de Westerschelde mogelijkheden biedt voor schelpdierkweek, maar dat er wel beperkingen zijn vanuit de randvoorwaarden. Een nadere verkenning is nodig op een aantal testlocaties; door de kwekers zijn elf potentiele locaties aangegeven.
    Preparing for climate change: a research framework on the sediment - sharing systems of the Dutch, German and Danish Wadden Sea for the development of an adaptive strategy for flood safety
    Oost, A.P. ; Wang, Z.B. ; Groot, A.V. de; Duren, L.A. ; Valk, L. van der - \ 2014
    Deltares (Rapport / Deltares 1209152-000) - 47
    klimaatverandering - geologische sedimentatie - hoogwaterbeheersing - hydrodynamica - natuurwaarde - wetlands - waddenzee - climatic change - geological sedimentation - flood control - hydrodynamics - natural value - wetlands - wadden sea
    The report proposes a research framework which follows a learning-by-doing approach along the three research lines: monitoring & data analysis, system research & modelling and field experiments (pilots). All studies together will take several decades, partially due to the many questions, partially because studying changes in the system via the above-mentioned research lines takes time. Research programs developed on basis of this framework may focus on a part of the research issues
    Swimming of the pea crab (Pinnotheres pisum)
    Versteegh, C.P.C. ; Muller, M. - \ 2014
    Animal Biology 64 (2014)3. - ISSN 1570-7555 - p. 239 - 260.
    artemia larvae - locomotion - hydrodynamics - transition - kinematics - model - wake
    Aquatic organisms have to deal with different hydrodynamic regimes, depending on their size and speed during locomotion. The pea crab swims by beating the third and fourth pereiopod on opposite sides as pairs. Using particle tracking velocimetry and high-speed video recording, we quantify the kinematics and vortices in the wake of the pea crab. Where the proximal parts of the pereiopods beat in antiphase, their distal parts show an overlapping beat period. By using four instead of two limbs for propulsion, an uninterrupted forward movement is established, reducing the influence of the acceleration reaction. Before body speed is maximal, force generation of the pereiopods seems most active when passing an orthogonal position with the body.
    Conditional responses of benthic communities to interference from an intertidal bivalve
    Colen, C. van; Thrush, S. ; Vincx, M. ; Ysebaert, T. - \ 2013
    PLoS ONE 8 (2013)6. - ISSN 1932-6203
    cerastoderma-edule - terrigenous sediment - ecosystem services - macoma-balthica - coastal - habitats - hydrodynamics - disturbance - resilience - sandflats
    Habitat-modifying organisms that impact other organisms and local functioning are important in determining ecosystem resilience. However, it is often unclear how the outcome of interactions performed by key species varies depending on the spatial and temporal disturbance context which makes the prediction of disturbance-driven regime shifts difficult. We investigated the strength and generality of effects of the filter feeding cockle Cerastoderma edule on its ambient intertidal benthic physical and biological environment. By comparing the magnitude of the effect of experimental cockle removal between a non-cohesive and a sheltered cohesive sediment in two different periods of the year, we show that the outcome of cockle interference effects relates to differences in physical disturbance, and to temporal changes in suspended sediment load and ontogenetic changes in organism traits. Interference effects were only present in the cohesive sediments, though the effects varied seasonally. Cockle presence decreased only the density of surface-dwelling species suggesting that interference effects were particularly mediated by bioturbation of the surface sediments. Furthermore, density reductions in the presence of cockles were most pronounced during the season when larvae and juveniles were present, suggesting that these life history stages are most vulnerable to interference competition. We further illustrate that cockles may enhance benthic microalgal biomass, most likely through the reduction of surface-dwelling grazing species, especially in periods with high sediment load and supposedly also high bioturbation rates. Our results emphasize that the physical disturbance of the sediment may obliterate biotic interactions, and that temporal changes in environmental stressors, such as suspended sediments, may affect the outcome of key species interference effects at the local scale. Consequently, natural processes and anthropogenic activities that change bed shear stress and sediment dynamics in coastal soft-sediment systems will affect cockle-mediated influences on ecosystem properties and therefore the resilience of these systems to environmental change.
    Structure and function of the median finfold in larval teleosts
    Boogaart, J.G.M. van den; Muller, M. ; Osse, J.W.M. - \ 2012
    Journal of Experimental Biology 215 (2012). - ISSN 0022-0949 - p. 2359 - 2368.
    fish larvae - allometric growth - engraulis-mordax - dermal skeleton - danio-rerio - body-size - zebrafish - fin - behavior - hydrodynamics
    This paper offers a structural and mechanical analysis of the median finfold in larval teleosts. The median finfold is strengthened by bundles of collagen fibres, known as actinotrichia. We demonstrate that these structures contribute to increase the mass of backward accelerated water during swimming. The amount, dimensions, orientation and growth of actinotrichia were measured at various locations along the finfold in several developmental stages of common carp (Cyprinus carpio) and zebrafish (Danio rerio). Actinotrichia morphology, using light microscopy (e.g. diameter, orientation) and electron microscopy (which revealed their anchoring at proximal and distal ends), correlated with expected lateral forces exerted on the water during swimming. An analytical model is proposed that predicts the extent of camber from the oblique arrangement of the actinotrichia and curvature of the body. Camber of the finfold during swimming was measured from high-speed video recordings and used to evaluate the model predictions. Based on structural requirements for swimming and strain limits for collagen, the model also predicts optimal orientations of actinotrichia. Experimental data confirm the predictions of the model.
    Natuur en veiligheid, gaan ze nog samen?
    Makaske, B. ; Maas, G.J. - \ 2012
    Vakblad Natuur Bos Landschap 9 (2012)2. - ISSN 1572-7610 - p. 28 - 31.
    vegetatiebeheer - uiterwaarden - rivieren - natuurontwikkeling - hydrodynamica - overijssel - vegetation management - river forelands - rivers - nature development - hydrodynamics - overijssel
    "Natuur en veiligheid gaan duurzaam samen in het winterbed van de rivieren", zo stelde Han Sluiter in het Vakblad NBL van september 2011. Het was een reactie op een recent onderzoek van Alterra en Duurzame Rivierkunde, waarin wordt geconcludeerd dat de huidige rivierkundige maatregelen onvoldoende ruimte bieden voor grootschalige natuurontwikkeling langs de IJssel. De auteurs van deze publicatie geven een samenvatting van dit onderzoek en bespreken vervolgens de reactie van Han Sluiter.
    Quick Scan Monitoring Delta Programme Wadden Sea Area
    Stapel, J. ; Dankers, N.M.J.A. - \ 2012
    IMARES : IMARES (Report / IMARES Wageningen UR C074/12) - 25
    hydrodynamica - geologische sedimentatie - geomorfologie - erosie - zandsuppletie - projecten - informatiediensten - monitoring - wadden - hydrodynamics - geological sedimentation - geomorphology - erosion - sand suppletion - projects - information services - monitoring - tidal flats
    Welke informatie is bekend over: veiligheid, natuur en sociaaleconomische ontwikkeling in het Delta Programma Waddengebied. Naar aanleiding van deze Quickscan worden de volgende vijf monitoringstaken voorgesteld die grotendeels parallel kunnen worden uitgevoerd. Een aantal taken kunnen gefaseerd worden uitgevoerd: • Organisatie: Overzicht en analyse van monitoringbehoefte, Opzetten klimaat monitoring netwerk en harmonisatie en Data Management (gefaseerd) • Trend Analyse van historische ecologische en sociaaleconomische datasets• Hydrodynamische en geomorfologische monitoring in kombergingsgebieden en model ontwikkeling (gefaseerd) • Quick Reaction Force (gefaseerd): Organisatie en protocolontwikkeling, apparatuuraanschaf en -kalibratie en registratie van erosie onmiddellijk na stormperiodes en hersteltijd (semi-natuurlijke flexibiliteit onder invloed van zandsuppletie) • Monitoring van sociaaleconomische en governance ontwikkelingen en projectvoortgang
    Mosselwad, onderzoeksprogramma voor herstel van mosselbanken in de Waddenzee
    Jansen, J.M. ; Dankers, N.M.J.A. ; Ens, B.J. - \ 2012
    De Levende Natuur 113 (2012)3. - ISSN 0024-1520 - p. 110 - 112.
    mytilus edulis - mossels - overleving - hydrodynamica - ecologisch herstel - asteroidea - aythya - wetenschappelijk onderzoek - waddenzee - mytilus edulis - mussels - survival - hydrodynamics - ecological restoration - asteroidea - aythya - scientific research - wadden sea
    Hoe staat het met de schelpdieren in de Waddenzee? Aan de hand van langjarige tijdreeksen geven we een overzicht van de ontwikkeling van Mossel (Mytilus edulis), Kokkel (Cerastoderma edule), Nonnetje (Macoma balthica) en nieuwkomer de Japanse oester (Crassostrea gigas). Hierbij speelt de vraag welke factoren bepalend zijn voor de aantalsontwikkeling van de verschillende soorten
    Onzekere debietschattingen
    Mulder, H.M. ; Schipper, P.N.M. ; Jongman, E. ; Heijkers, J. - \ 2011
    Stromingen : vakblad voor hydrologen 16 (2011)3. - ISSN 1382-6069 - p. 33 - 43.
    hydrodynamica - afvoer - waterstroming - schatting - hydrodynamics - discharge - water flow - estimation
    De meest fundamentele en daarmee belangrijkste activiteit van hydrologen is het opstellen van waterbalansen. Immers, waterbalansen vormen het hart van elke watersysteemanalyse, inclusief het ontwikkelen, kalibreren en valideren van modellen. Naast de neerslag en verdamping vormen de aan- en afvoer van oppervlaktewater de belangrijkste componenten van de Nederlandse waterbalans. Die worden indirect afgeleid uit metingen bij klepstuwen, afsluiters, pompgemalen e.d. In dit artikel gaan wij in op de vraag hoe accuraat met zulke meetmethodes de debieten aan- en afvoeren in de praktijk kunnen worden geschat en hoe dit verbeterd kan worden. Wij concluderen dat de onzekerheden groot zijn en dat er veel te verbeteren is over het gehele traject: het uitvoeren van de metingen, het ijken van de formules van de meetopstellingen met alternatieve meetmethodes, de opslag en verwerking van de ruwe meetdata naar debieten en het kwantificeren van onzekerheden daarin.
    Role of sediment transport in operation and maintenance of supply and demand based irrigation channels : application to Machai Maira Branch canals
    Munir, S. - \ 2011
    Wageningen University. Promotor(en): E. Schulz, co-promotor(en): C.T. Hoanh. - [S.l. : S.n. - ISBN 9789085858508 - 267
    geologische sedimentatie - irrigatiekanalen - hydrodynamica - modelleren - pakistan - geological sedimentation - irrigation channels - hydrodynamics - modeling - pakistan
    Like in many emerging and least developed countries, agriculture is vital for Pakistan’s
    national economy. It contributes 21% to the annual gross domestic product (GDP),
    engages 44% of total labour force and contributes 60% to the national export. Pakistan
    has a total area of 80 Mha (million hectares) with 22 Mha arable land, out of which 17
    Mha is under irrigation, mostly under canal irrigation. Due to the arid to semi-arid
    climate, the irrigation is predominantly necessary for successful crop husbandry in
    Pakistan.
    The development of modern irrigation in Indo-Pakistan started in 1859 with the
    construction of the Upper Bari Doab Canal on Ravi River and with the passage of time
    the irrigation system of Pakistan grew up to the world’s largest contiguous gravity flow
    irrigation system, known as the Indus Basin Irrigation System (IBIS). In the IBIS almost
    all irrigation canals are directly fed from rivers, while river flows carry heavy sediment
    loads. Irrigation canals receiving such flows get massive amounts of sediments, which
    are then deposited in the irrigation canals depending upon the hydrodynamic conditions
    of the canals. Sediment deposition in irrigation canals causes serious operation and
    maintenance problems. Studies reveal that silt reduces up to 40% of the available
    discharge in irrigation canals.
    Researchers have been striving since long to manage this problem in a sustainable
    way and a number of approaches have been introduced in this connection. As a first step
    sediments are controlled at river intakes by silt excluders and ejectors. Then a canal
    design approach is adopted for keeping sediments in suspension and to distribute them
    as much as possible on the irrigated fields. Even then sediments tend to deposit in
    irrigation canals and become a serious problem in canal operation and maintenance,
    which then requires frequent desilting campaigns to keep water in the canals running. It
    causes a continuous burden on the national economy. In emerging and least developed
    countries, adequate and timely availability of funds for operation and maintenance is
    generally a problem. It causes delays in canal maintenance, which affects their hydraulic
    performance. Water is then delivered inadequately and inequitably to the water users.
    The story becomes further complicated when it comes to downstream controlled
    demand based irrigation canals under flexible operation. In fixed supply based operation,
    canals always run at full supply discharge and such operation, generally, does not allow
    sediment deposition in the canal prism due to sufficient velocities. Whereas in demand
    based flexible operation the canals cannot run always at full supply discharge but instead
    the discharge is changing depending upon the crop water requirement in the canal
    command area. Such type of canal operation is not always favourable to sediment
    transport as under low discharges, flow velocities fall quite low and hence sediment
    deposition may occur in the canal prism. The questions arise here what sort of
    hydrodynamic relationships prevent sediment deposition in downstream controlled
    irrigation canals and how these relationships can be adopted, while catering crop water
    requirements of the command area? How the maintenance needs can be minimized by
    managing sediment transport through better canal operation?
    This study has been designed to investigate such type of relationships and practices
    in order to manage sediment transport in downstream controlled demand based irrigation
    canals and to attain maximum hydraulic efficiency with minimum maintenance needs.
    The hypothesis of the study states that in demand based irrigation canals the volume of
    silt deposition can be minimized and even the sediments which deposit during low crop
    water requirement periods can be re-entrained during peak water requirement periods. In
    this way a balance can be maintained in sediment deposition and re-entrainment by
    adequate canal operation.
    Two computer models have been used in this study, namely, Simulation of
    Irrigation Canals (SIC) and SEdiment TRansport in Irrigation Canals (SETRIC). Both
    models are one-dimensional and are capable of simulating steady and unsteady state
    flows (SETRIC only steady state flows) and non equilibrium sediment transport in
    irrigation canals. The SIC model has the capability to simulate sediment transport under
    unsteady flow conditions and can assess the effect of sediment deposition on hydraulic
    performance of irrigation canals. Whereas the SETRIC model has the advantage of
    taking into account the development of bed forms and their effect on resistance to flow,
    which is the critical factor in irrigation canal design and management. In the SETRIC
    model, a new module regarding sediment transport simulations in downstream
    controlled irrigation canals has been incorporated.
    The study has been conducted on the Upper Swat Canal – Pehure High Level Canal
    (USC-PHLC) Irrigation System, which consists of three canals, Machai Branch Canal,
    PHLC and Maira Branch Canal. The Machai Branch Canal has upstream controlled
    supply based operation and the two other canals have downstream controlled demand
    based operation respectively. These canals are interconnected. The PHLC and Machai
    Branch canals feed Maira Branch Canal as well having their own irrigation systems.
    PHLC receives water from Tarbela Reservoir and Machai Branch Canal from the Swat
    River through USC. Water from Tarbela Reservoir, at present, is sediment free, whereas
    the water from Swat River is sediment laden. However, various studies have indicated
    that soon Tarbela Reservoir will be filled with sediments and will behave as run of the
    river system. Then PHLC will also receive sediment laden flows. The design discharges
    of Machai, PHLC and Maira Branch canals are 65, 28 and 27 m3/s respectively. The
    command area of the USC-PHLC Irrigation System is 115,800 ha.
    The USC-PHLC Irrigation System has been remodelled recently and water
    allowance has been increased from 0.34 l/s/h to 0.67 l/s/h. The upper USC system, from
    Machai Branch head to RD 242 (a control structure from where the downstream control
    system starts), was remodelled in 1995, whereas the system downstream of RD 242 was
    remodelled in 2003. The upper part of Machai Branch Canal up to an abscissa of about
    74,000 m is under fixed supply based operation, whereas the lower part of Machai
    Branch Canal, Maira Branch Canal and the PHLC are under semi-demand based flexible
    operation. The semi-demand based system is operated according to crop water
    requirements and follows a Crop Based Irrigation Operations (CBIO) schedule. When
    the crop water demand falls below 80% of the full supply discharge, a rotation system is
    introduced among the secondary offtakes. During very low crop water requirement
    periods the supplies are not reduced beyond a minimum limit of 50% of the full supply
    discharge because of the canal operation rule.
    The study consisted of fieldwork of two years in which daily canal operation data,
    monthly sediment inflow data in low sediment periods and weekly sediment data in peak
    concentration periods were collected. Three mass balance studies were conducted in
    which all the water and sediment inflows and outflows were measured with suspended
    sediment sampling at selected locations along the canal and boil sampling at the
    offtaking canals, immediately downstream of the head regulators. Further in the four
    months during the peak sediment season June, July, August and September, mass
    balance studies were conducted by boil sediment sampling in order to estimate water and
    sediment inflow to and outflow from the system. To determine the effect of sediment
    transport on the canals’ morphology, five cross-sectional surveys were conducted and
    changes in bed levels were measured. On the basis of these field data the two computer
    models, used in this study, were calibrated and validated for flow and sediment transport
    simulations.
    The downstream control component of the system is controlled automatically and
    the PHLC has been equipped with the Supervisory Control and Data Acquisition
    (SCADA) system at the headworks. Any discharge withdrawal or refusal by Water
    Users Associations (WUA) through offtaking secondary canals, or any discharge
    variation in the inflow from Machai Branch Canal is automatically adjusted by the
    SCADA system at Gandaf Outlet, the PHLC headworks. The SCADA system has
    Proportional Integral (PI) discharge controllers. The study found that the existing PI
    coefficients led to delay in discharge releases and resulted in a long time to achieve flow
    stability. The discharge releases showed an oscillatory behaviour which affected the
    functioning of hydro-mechanically operated downstream control “Aval Orifice” (AVIO)
    and “Aval Surface” (AVIS) gates. After calibration and validation of the model the PI
    controllers were fine-tuned and proposed for improved canal operation, which would
    help in system sustainability and in improved operational efficiency of the canals.
    Field data show that during the study period sedimentation in the studied irrigation
    canals remained within control limits. The incoming sediment loads were, generally,
    lower than the sediment transport capacities of the studied irrigation canals. Hence this
    incoming sediment load was transported by the main canals and distributed to the
    offtaking canals. The sediment transport capacities of the studied irrigation canals were
    computed at steady and unsteady state conditions. The canal operation data showed that
    the system was operated on Supply Based Operation (SBO) approach rather than CBIO.
    The morphological data revealed that there was no significant deposition in the studied
    canals. Therefore there was no particular effect on the canal operation and the hydraulic
    efficiencies, attributed to sediment transport.
    As mentioned earlier, the Tarbela Reservoir will soon be filled with sediments and
    consequently PHLC will get sediment laden flows from the reservoir. Various studies
    have been taken into account to project the time when sediment laden flows will flow
    into the PHLC and what will be the characteristics and concentrations of the incoming
    sediments to the PHLC from the reservoir. The studies project that the sediment inflow
    from the Tarbela Reservoir will be much higher than the sediment transport capacities of
    the PHLC and Maira Branch Canal under full supply discharge conditions. This scenario
    will create sediment transport problems in downstream controlled canals, particularly
    when they will be operated under CBIO.
    Various management options have been simulated and are presented in order to
    better manage sediments in the studied canals under the scenario of sediment inflow
    from Tarbela Reservoir. The hydraulic performance of downstream controlled canals
    will be affected under this scenario and frequent maintenance and repair will be required
    to maintain the canals. Various options have been analysed to deal with the problem.
    The study presents a sediment management plan for downstream controlled irrigation
    canals by improvements in canal design and operation in combination with the need of
    settling ponds at the canal headworks.
    Currently sedimentation in the irrigation canals under study is not a big issue for
    canal operation and maintenance (O&M). However, it would emerge as a major problem
    when sediment discharge from the Tarbela Reservoir starts. The canals’ maintenance
    costs will soar and the hydrodynamic performance of these canals will also be affected.
    In this study, a number of ways have been evaluated and proposed to deal with the
    approaching problem of sediment transport in these irrigation canals in order to keep
    their hydraulic performance at desired levels and to minimize the maintenance costs.
    The first and the foremost effect of sediment deposition will be reduction in canals’ flow
    conveyance capacities, which will result in raise of water levels. The raise of water
    levels will cause a reduction in water supply to the canals due to automatic flow releases.
    It can be dealt with by a temporary and limited raise in target water levels depending
    upon the maximum headloss at the downstream AVIS/AVIO cross regulator. Further, to
    minimize the effect of water level raise on discharge through the AVIS/AVIO gates, the
    decrement in such canals can be kept relatively small, in order to make the gates less
    sensitive to water level changes. Further, for efficient withdrawal of sediment to the
    secondary canals, it is needed to locate the secondary offtakes close to AVIS/AVIO
    cross regulators on the downstream side. More sediment will be discharged because the
    turbulent mixing of sediment at the downstream side of the control structures keeps
    more sediment in suspension. In addition, during the peak sediment concentration
    periods, the canals need to be operated at supply based operations, in order to minimize
    the deposition.
    Sediment transport in general and in irrigation canals in particular, is one of the
    most studied and discussed topic in the field of fluid mechanics all over the world. It
    also has been studied extensively in Indus Basin in order to design and manage irrigation
    canals receiving sediment laden flows. The outcome of Lacey’s regime theory and the
    subsequent work are the result of these studies. In addition to regime method various
    other methods like permissible velocity method, tractive force method and the rational
    methods, etc., have been developed for stable canal design. Anyhow, as a matter of fact,
    the management of sediment transport in irrigation canals is still a challenging task even
    after all these investigations and studies. Because most of the knowledge on sediment
    transport is empirical in nature, most sediment transport formulae have inbuilt
    randomness, which makes predictions difficult, when conditions are changed. It needs a
    lot of care while applying a sediment transport formula, developed under one set of
    conditions, to other situations. Therefore, it becomes extremely important to understand
    the origin of the development of the formulae and the limitations associated with them
    before applying some sediment transport formulae to different conditions and
    circumstances. The introduction of numerical modelling made it comparatively easy to
    test and shape the sediment transport relationships to some local conditions by running a
    variety of simulations and calibrating the formula in light of the field measurements. The
    sediment transport predictions can be made reliable in this way and can be used for
    further analysis.
    Onzekerheden in debietmetingen : analyse van debietgegevens voor Monitoring Stroomgebieden
    Mulder, H.M. ; Tol-Leenders, T.P. van; Siderius, C. ; Walvoort, D.J.J. ; Bolt, F.J.E. van der - \ 2009
    Wageningen : Alterra (Alterra-rapport 1956) - 78
    hydrodynamica - hydrologie - stroomgebieden - monitoring - wateraanvoer - gegevensanalyse - hydrologie van stroomgebieden - nederland - hydrodynamics - hydrology - watersheds - monitoring - water advance - data analysis - catchment hydrology - netherlands
    Deze rapportage “Onzekerheden in debietmetingen” vormt een onderdeel van het project ‘Monitoring Stroomgebieden’. Voor het kwantificeren van de landbouw in de belasting van het oppervlaktewater en de ontwikkeling van een monitoringsmethodiek is het noodzakelijk om een goed beeld te hebben van de waterkwaliteit, maar ook van de waterkwantiteit in een stroomgebied. Over onzekerheden in waterkwantiteitsmetingen is relatief veel bekend, echter de informatie over onzekerheden in debietmetingen is gering. Omdat inzicht in deze onzekerheden van belang is voor de hierboven beschreven doelen van het project Monitoring Stroomgebieden is onderzoek verricht naar de onzekerheden van debietmetingen en de consequenties van deze bevindingen voor het project ‘Monitoring stroomgebieden.
    Bouwsteen riviermorfologie en -dynamiek Rijntakken t.b.v. het koepelbeheerplan natura2000 rivierengebied
    Maas, G.J. ; Makaske, B. - \ 2008
    Wageningen : Alterra - 7
    rivieren - natuurbescherming - hydrodynamica - geomorfologie - vegetatie - fysische geografie - rivierengebied - habitatrichtlijn - natura 2000 - uiterwaarden - gelderse poort - overijssel - rivers - nature conservation - hydrodynamics - geomorphology - vegetation - physical geography - rivierengebied - habitats directive - natura 2000 - river forelands - gelderse poort - overijssel
    Voor de Natura2000 gebieden Rijntakken wordt een koepelbeheerplan opgesteld. Dit koepelbeheerplan betreft de habitat- en vogelrichtlijngebieden in het rivierengebied. Specifieke kenmerken van het rivierengebied, zoals de relatie tussen rivierdynamiek, morfologie en de Natura2000 doelen worden uitgewerkt in het koepelplan. Dit document is één van de bouwstenen daarvoor. De volgende onderdelen komen in deze bouwsteen achtereenvolgens aan de orde: * Een indeling van de Rijntakken in riviertrajecten met een korte beschrijving van de belangrijkste morfologische en hydraulische kenmerken; * de kansrijke gebieden voor morfodynamische processen (sedimentatie-erosie); * betekenis van deze specifieke kenmerken (rivierdynamiek) voor de realisatie van de natura2000doelen (abiotische randvoorwaarden); * vanuit de specifieke kenmerken van de riviertakken het aangeven van de potenties voor de belangrijkste N2000-doelstellingen: hardhoutooibos, zachthoutooibos, stroomdalgraslanden, moeras en moerasruigten, pioniervegetaties op slikoevers
    Water in beweging : Het meten van afvoeren
    Boiten, W. - \ 2008
    Wageningen : Wageningen Universiteit, Centrum voor Water en Klimaat, Leerstoelgroep Hydrologie en Kwantitatief Waterbeheer - 42
    hydrodynamica - afvoer - meting - monitoring - hydrologie - hydraulische systemen - hydrodynamics - discharge - measurement - monitoring - hydrology - hydraulic structures
    Deze uitgave is bedoeld als afscheid van het werken in de hydrometrie. Boiten begon zijn werk bij het Waterloopkundig Laboratorium met de afvoer bij IJsselkop, als gevolg van de geplande Rijnkanalisatie. Hij beeindigt zijn werkzaamheden als gastdocent bij Wageningen Universiteit. In het jaar, waarin het hydraulica laboratorium aan het Nieuwe Kanaal definitief de deuren sluit. Kortom: een echte afronding van het werkveld binnen de hydrometrie. De publicatie bevat o.a. foto's van de Rossum overlaat, Hobrad overlaat, Parshall Flume, Khafagi venturi, Crump overlaat
    Flow patterns of larval fish: undulatory swimming in the intermediate flow regime
    Müller, U.K. ; Boogaart, J.G.M. van den; Leeuwen, J.L. van - \ 2008
    Journal of Experimental Biology 211 (2008)2. - ISSN 0022-0949 - p. 196 - 205.
    locomotor function - rainbow-trout - vortex wake - dorsal fin - hydrodynamics - kinematics - zebrafish - forces - generation - morphology
    Fish larvae, like many adult fish, swim by undulating their body. However, their body size and swimming speeds put them in the intermediate flow regime, where viscous and inertial forces both play an important role in the interaction between fish and water. To study the influence of the relatively high viscous forces compared with adult fish, we mapped the flow around swimming zebrafish (Danio rerio) larvae using two-dimensional digital particle image velocimetry (2D-DPIV) in the horizontal and transverse plane of the fish. Fish larvae initiate a swimming bout by bending their body into a C shape. During this initial tail-beat cycle, larvae shed two vortex pairs in the horizontal plane of their wake, one during the preparatory and one during the subsequent propulsive stroke. When they swim `cyclically' (mean swimming speed does not change significantly between tail beats), fish larvae generate a wide drag wake along their head and anterior body. The flow along the posterior body is dominated by the undulating body movements that cause jet flows into the concave bends of the body wave. Patches of elevated vorticity form around the jets, and travel posteriorly along with the body wave, until they are ultimately shed at the tail near the moment of stroke reversal. Behind the larva, two vortex pairs are formed per tail-beat cycle (the tail beating once left-to-right and then right-to-left) in the horizontal plane of the larval wake. By combining transverse and horizontal cross sections of the wake, we inferred that the wake behind a cyclically swimming zebrafish larva contains two diverging rows of vortex rings to the left and right of the mean path of motion, resembling the wake of steadily swimming adult eels. When the fish larva slows down at the end of a swimming bout, it gradually reduces its tail-beat frequency and amplitude, while the separated boundary layer and drag wake of the anterior body extend posteriorly to envelope the entire larva. This drag wake is considerably wider than the larval body. The effects of the intermediate flow regime manifest as a thick boundary layer and in the quick dying-off of the larval wake within less than half a second
    Redistribution of velocity and bed-shear stress in straight and curved open channels by means of a bubble screen: laboratory experiments
    Blanckaert, K. ; Buschman, F.A. ; Schielen, R. ; Wijbenga, J.H.A. - \ 2008
    Journal of Hydraulic Engineering 134 (2008)2. - ISSN 0733-9429 - p. 184 - 195.
    waterbouwkunde - kanalen, klein - hydrodynamica - waterstroming - buigen - herverdeling - snelheid - turbulentie - laboratoriumproeven - hydraulic engineering - channels - hydrodynamics - water flow - bending - redistribution - velocity - turbulence - laboratory tests - submerged vanes - secondary flows - alternate bars - topography - bends - rivers
    Open-channel beds show variations in the transverse direction due to the interaction between downstream flow, cross-stream flow, and bed topography, which may reduce the navigable width or endanger the foundations of structures. The reported preliminary laboratory study shows that a bubble screen can generate cross-stream circulation that redistributes velocities and hence, would modify the topography. In straight flow, the bubble-generated cross-stream circulation cell covers a spanwise extent of about four times the water depth and has maximum transverse velocities of about 0.2 ms¿1. In sharply curved flow, it is slightly weaker and narrower with a spanwise extent of about three times the flow depth. It shifts the counter-rotating curvature-induced cross-stream circulation cell in the inwards direction. Maximum bubble-generated cross-stream circulation velocities are of a similar order of magnitude to typical curvature-induced cross-stream circulation velocities in natural open-channel bends. The bubble screen technique is adjustable, reversible, and ecologically favorable. Detailed data on the 3D flow field in open-channel bends is provided, which can be useful for validation of numerical models
    Galilean invariant lattice Boltzmann scheme for natural convection on square and rectangular lattices
    Sman, R.G.M. van der - \ 2006
    Physical Review. E, Statistical nonlinear, and soft matter physics 74 (2006)2. - ISSN 1539-3755 - 17 p.
    hydrodynamics - simulations - diffusion - relaxation - dispersion - models - cavity - number - flow
    In this paper we present lattice Boltzmann (LB) schemes for convection diffusion coupled to fluid flow on two-dimensional rectangular lattices. Via inverse Chapman-Enskog analysis of LB schemes including source terms, we show that for consistency with physics it is required that the moments of the equilibrium distributions equal those of the Maxwell-Boltzmann distribution. These constraints can be satisfied for the rectangular D2Q9 lattice for only fluid flow in the weakly compressible regime. The analysis of source terms shows that fluxes are really defined on the boundaries of the Wigner-Seitz cells, and not on the lattice sites where the densities are defined¿which is quite similar to the staggered grid finite-volume schemes. Our theoretical findings are confirmed by numerical solutions of benchmark problems for convection diffusion and natural convection. The lattice Boltzmann scheme shows remarkably good performance for convection diffusion, showing little to non-numerical diffusion or numerical dispersion, even at high grid Peclet numbers
    A method for measuring effects of bioturbation and consolidation on erosion resistance of aquatic sediments
    Zambrano, L. ; Beijer, J.A.J. ; Roozen, F.C.J.M. ; Scheffer, M. - \ 2005
    Archiv für Hydrobiologie 162 (2005)3. - ISSN 0003-9136 - p. 327 - 337.
    sediment - hydrodynamica - geologische sedimentatie - erosie - zoet water - waterstroming - aquatische ecosystemen - waterbodems - sediment - hydrodynamics - geological sedimentation - erosion - fresh water - water flow - aquatic ecosystems - water bottoms - wind-induced resuspension - shallow lake
    Sediment erosion by water movement affects turbidity and thus benthic communities in numerous aquatic systems. This aspect has been widely studied in coastal habitats and estuaries, but less studied in freshwater systems such as shallow lakes. Here we present a simple device to study the effects of biota on the resistance of aquatic sediments to erosion by water movement. Circular 75 l tanks are used to incubate selected sediments with microbial communities. The tank size allows addition of organisms such as small fish, invertebrates and aquatic plants. Effects are studied by gradually increasing water movement by means of a rotor and continuously monitoring the increase of suspended solids. The water speed needed for resuspension is a measure of sediment erosion resistance. With this device we found a linear increment of erosion resistance over time if sediments are left undisturbed, and a significant reduction of erosion resistance with small holes punched randomly in the top layer of sediment (to mimic the effect of benthivorous fish foraging behaviour). Fish biotic perturbation was indicated by a reduction of sediment resistance associated with benthivorous fish presence. However, three spined stickleback did not create the same effect. Measurements with this simple device are reasonably precise and suggest that the set-up can be used to study effects of numerous factors that may affect sediment erosion resistance. For example, sediment consolidation associated with light, temperature, and microbial and plant colonization, along with sediment perturbation related to big invertebrates and fish behaviour.
    Uitspoelingsgevoelige gronden op de kaart; werkwijze en resultaten
    Kekem, A.J. van; Hoogland, T. ; Horst, J.B.F. van der - \ 2005
    Wageningen : Alterra (Alterra-rapport 1080) - 89
    bodemwater - grondwaterstand - uitspoelen - nitraten - cartografie - bodemeigenschappen - hydrodynamica - bodemwaterbeweging - veengronden - dierlijke meststoffen - overheidsbeleid - nederland - bodemkarteringen - kaarten - geostatistiek - soil water - groundwater level - leaching - nitrates - mapping - soil properties - hydrodynamics - soil water movement - peat soils - animal manures - government policy - netherlands - soil surveys - maps - geostatistics
    Voor de uitvoering van het mestbeleid in Nederland is het van belang om de uitspoelingsgevoeligheid voor nitraat van de bodems in Nederland zo goed mogelijk te kennen. Deze uitspoelingsgevoeligheid hangt o.a. af van de grondsoort en de grondwaterstand om hiervan een inschatting te maken dienen basisbestanden van de bodem en de grondwaterstanden voldoende nauwkeurig en actueel dienen te zijn. Uit een quick scan bleek dat 47% van de oppervlakte veengronden in Oost-Nederland is gedeformeerd naar een ander bodemtype, met name zandgronden. Voor de zand- en lössgronden van Nederland is met een geostatistische methode de grondwaterdynamiek geactualiseerd en er is een methodiek ontwikkeld om op basis hiervan de landbouwpercelen op zand- en lössgronden te classificeren naar uitspoelingsgevoeligheid. Deze berekeningen zijn uitgevoerd voor verschillende scenario's waarin is gevarieerd met de GHG grens, de areaal fractie per perceel en een kanscriterium. In het gewijzigd beleid is ervoor gekozen om niet op perceelsniveau uitspoelingsgevoelige gronden aan te wijzen. Daarom is het areaal uitspoelingsgevoelige grond ook voor pixels van 25x25 meter berekend. Voor de zandgronden bedraagt het areaal uitspoelingsgevoelige gronden met een GHG ≥ 70 cm en een GLG ≥ 120, ongeveer 335000 ha, 36% van het landbouw areaal op zandgronden
    Multistress van verontreiniging en hydrodynamiek op populaties van Oligochaeta in de uiterwaarden; een onderzoek in de Afferdensche en Deestsche Waarden
    Ma, W.C. ; Vliet, P.W. van; Bodt, J.M. - \ 2004
    Wageningen : Alterra (Alterra-rapport 877) - 107
    oligochaeta - annelida - verontreiniging - stress - hydrodynamica - populatie-ecologie - biodiversiteit - bodem - nederland - gelderland - land van maas en waal - uiterwaarden - oligochaeta - annelida - pollution - stress - hydrodynamics - population ecology - biodiversity - soil - netherlands - gelderland - land van maas en waal - river forelands
    Dit rapport beschrijft een onderzoek naar de populatie-ecologie van regenwormen (Oligochaeta, Lumbricidae) in de Afferdensche en Deestsche Waarden (ADW), een uiterwaarde van de rivier de Waal. Ondanks het feit dat de bodem in dit gebied is verontreinigd en elk jaar overstromingen plaatsvinden komen regenwormen er in een grote soortsdiversiteit en in grote aantalsdichtheden voor. Afhankelijk van de bodemgesteldheid omvat de totale gemiddelde populatie een biomassa van 1500 kg per hectare. De uiterwaarden vormen hiermee een belangrijk voedselzoekgebied voor vermivore (wormenetende) faunasoorten en dragen als zodanig bij aan de totale biodiversiteit van de natuur in Nederland. Om de ecologische betekenis van multipele stress in beeld te brengen is onderzoek verricht naar de invloed van potentieel sturende omgevingsfactoren, waaronder hoogteligging, textuur en verontreiniging van de bodem, nutriëntengehalten en bodemvocht. Uit (multivariate) statistische analyse bleek dat de hydrodynamiek van het gebied en het bodemvochtgehalte belangrijke sturende variabelen vormden voor de soortsdiversiteit en populatiedichtheden, terwijl de aanwezige metaalverontreiniging in dit opzicht van mindere betekenis was. Vanuit het oogpunt van praktische toepasbaarheid leveren de resultaten belangrijke aanknopingspunten op voor het bodem- en natuurbeheer van de uiterwaarden in Nederland.
    Actualisatie grondwaterdynamiek waterschap De Dommel
    Hoogland, T. ; Hoogerwerf, M.R. ; Kekem, A.J. van - \ 2004
    Wageningen : Alterra (Alterra-rapport 1008) - 44
    bodemwater - grondwaterstand - cartografie - monitoring - hydrodynamica - bodemwaterbeweging - uitspoelen - nederland - noord-brabant - soil water - groundwater level - mapping - monitoring - hydrodynamics - soil water movement - leaching - netherlands - noord-brabant
    Omdat de provinciale kartering van de grondwaterdynamiek (Gd) volgens het waterschap de Dommel vooral in de beekdalen te droog gekarteerde waarden liet zien, zijn in opdracht van het waterschap geactualiseerde ruimtelijke bestanden gemaakt van de gemiddelde hoogste, voorjaars- en laagste grondwaterstand (GHG, GVG en GLG) en van de grondwatertrap (Gt). Als basisinformatie zijn hierbij aanvullende incidentele metingen en tijdreeksen van grondwaterstanden gebruikt. Door toepassing van technieken uit de tijdreeksmodellering en regressietechnieken is een uniforme set puntschattingen van GHG, GVG en GLG verkregen. Deze gegevens zijn, gewogen naar kwaliteit, gebruikt om relaties met recent verzamelde hoogte-gegevens (het AHN) te leggen. Door gebiedsdekkende toepassing van deze relaties en een statistische foutencorrectie zijn gedetaileerde ruimtelijkebestanden verkregen met de resolutie van het AHN waarin GHG, GVG en GLG en hun voorspelfout worden weergegeven. De geactualiseerde Gd-kaart geeft vooral in de beekdalen een natter beeld dan de provinciale kartering en levert een groter nauwkeurigheid in de gekarteerde grondwaterdynamiek.
    Meetschotten Bargerveen. Ontwerp, constructie en ijking
    Boiten, W. ; Dommerholt, A. ; Romelingh, J.C.F. - \ 2004
    Wageningen : Sectie Waterhuishouding (Rapport / Sectie Waterhuishouding 120) - 29
    veengronden - natuurreservaten - hydrologie - meting - monitoring - hydrodynamica - afvoer - drenthe - peat soils - nature reserves - hydrology - measurement - monitoring - hydrodynamics - discharge - drenthe
    Delen van het Bargerveen zijn gespaard gebleven voor grootschalige vervening. In 1968 kocht het rijk de eerste hectares natuurreservaat in het Bargerveen. In 1995 werd de inrichting van het inmiddels 2000 ha grote natuurreservaat voltooid. Deze inrichting heeft vooral als doel, uiteindelijk weer een levend hoogveen te krijgen dat uit zichzelf aangroeit. Dat kan alleen onder natte omstandigheden. Daartoe heeft Staatsbosbeheer in de periode 1970-1998 veertig kilometer dammen van het ondoorlatend zwartveen aangelegd om zoveel mogelijk regenwater vast te houden.
    Veranderende draagkracht van de Oosterschelde voor kokkels
    Geurts van Kessel, A.J.M. ; Kater, B.J. ; Prins, T.C. - \ 2003
    IJmuiden [etc,] : RIVO (RIVO rapport C062/03) - 128
    schaal- en schelpdierenvisserij - kokkels - hydrodynamica - habitats - crassostrea gigas - visbestand - milieueffect - voedingsgedrag - concurrentie tussen dieren - biomassa productie - draagkracht - nederland - oosterschelde - aquatische ecosystemen - stormvloedkeringen - visserijbiologie - shellfish fisheries - clams - hydrodynamics - habitats - crassostrea gigas - fishery resources - environmental impact - feeding behaviour - animal competition - biomass production - carrying capacity - netherlands - eastern scheldt - aquatic ecosystems - storm surge barriers - fishery biology
    Effecten van veranderingen in hydrodynamiek en morfologie door de Deltawerken op de habitatgeschiktheid voor kokkels. Rapportage uit het lange termijn onderzoeksprogramma voedselreservering Oosterschelde, in het kader van de tweede evaluatie Nederlands schelpdiervisserijbeleid (EVA II)
    Gas and liquid distribution in the monolith film flow reactor
    Heibel, A.K. ; Vergeldt, F.J. ; As, H. van - \ 2003
    AIChE Journal 49 (2003)12. - ISSN 0001-1541 - p. 3007 - 3017.
    mass-transfer - porous-media - packed-columns - maldistribution - hydrodynamics - performance - dispersion - scale
    The gas-liquid distribution in a monolith film flow reactor is investigated in the scope of this work. Magnetic resonance imaging (MRI) and a customized liquid collection method hate been successfully applied to determine the liquid distribution over the monolith cross-section. Using a well-positioned spray nozzle liquid distributor, very uniform distributions are found which address the needs for applications that require high single-pass conversions. Due to the lack of radial convective flow in monoliths, the initial distribution propagates through the reactor. With a correct positioned spray nozzle distributor, a far more uniform distribution than the natural one for trickle beds is obtained. MRI, applied to study the local gas-liquid distribution in a monolith channel, clearly shows the accumulation of the liquid in the corners of the individual channel with an arc-shaped gas-liquid interface. Differences in local liquid holdup over the channel corners were found, which is described as channel scale nonuniformities. The experimental results are in good agreement with a fundamental hydrodynamic model based on the Navier-Stokes equations. The average liquid saturation is conveniently described with an engineering correlation ßL = 6.6 . (Fr2Ls/ReLs)0.46, as a function of the liquid phase Reynolds and Froude number
    Hydrodynamics of a liquid-liquid-solid fluidized-bed bioreactor
    Zessen, E. van - \ 2003
    Wageningen University. Promotor(en): Hans Tramper, co-promotor(en): Arjen Rinzema; Rik Beeftink. - [S.l.] : S.n. - ISBN 9789058088758 - 199
    bioreactoren - hydrodynamica - wervelbedden - fermentatie - biotechnologie - bioreactors - hydrodynamics - fluidized beds - fermentation - biotechnology
    If a batchwise bioconversion and subsequent ( i.e. serial) downstream processing are adopted as a standard production strategy, a low overall productivity may result for certain types of biotransformations (substrate- or product-inhibited fermentations). An alternative to sequential processing would be the integration of bioconversion and downstream processing by controlled supply of substrate to the reaction in situ , or by controlled removal of product from the reaction in situ . Such integration involves a multi-phase reactor in which a helper phase may serve as substrate reservoir or as product sink. A new type of multi-phase bioreactor was developed, containing a continuous liquid phase, a dispersed liquid phase, and a dispersed solid phase; it may be conceived of as a 3-phase liquid-liquid-solid fluidized bed. This thesis focuses on the hydrodynamic aspects of such a 3-phase fluidized bed; a general design strategy was developed. Within this 3-phase system, a liquid-solid fluidized bed consisting of biocatalytic gel beads in a continuous medium phase, and a liquid-liquid extraction column or spray column, consisting of organic droplets in a continuous medium phase can be discerned. The hydrodynamic characteristics of these constituent 2-phase systems were studied as well. At the end this thesis reviews the current status of the newly developed 3-phase liquid-liquid-solid fluidized-bed bioreactor; it outlines additional research to be performed for a full understanding of its hydrodynamicbehavior. Additional steps that have to be taken for practical implementation of the 3-phase fluidized bed as a new type of bioreactor are emphasized.

    Actualisatie van de grondwaterdynamiek; volledige herkartering of beperkte actualisatie?
    Bierkens, M.F.P. ; Hoogland, T. - \ 2002
    Wageningen : Alterra (Alterra-rapport 602) - 39
    bodemwater - grondwaterspiegel - cartografie - nederland - monitoring - hydrodynamica - geo-informatie - geostatistiek - grondwaterstand - hydrologie kartering - soil water - water table - mapping - monitoring - netherlands - hydrodynamics
    Het maken van grondwaterdynamiekkaarten (Gd-kaarten) is betrekkelijk duur, met name vanwege het vele veldwerk. Het is dus van belang om na te gaan of bij een hernieuwde kartering het gebruik van de oude kaart en informatie over ingrepen sinds de vorige kartering kan leiden tot kostenbesparing. In dit onderzoek zijn vier alternatieven getoetst op nauwkeurigheid en kosten: grondwaterdynamiekkartering zonder gebruik te maken van een bestaande Gd-kaart; volledige herkartering gebruikmakend van een bestaande Gd-kaart en informatie over ingrepen; herkartering met geringe dichtheid van veldwaarnemingen gebruikmakend van een bestaande Gd-kaart en informatie over ingrepen; herkartering met reguliere dichtheid zich beperkend tot de zone waar wordt vermoed datingrepen effect hebben gehad en gebruikmakend van een bestaande Gd-kaart. Bij de toesting is gebruik gemaakt van een numeriek laboratorium om de "werkelijke" Gd-kaart te construeren. De belangrijkste aanbeveling uit dit onderzoek is om een Gd-herkartering te beperken tot gebieden waar ingrepen hebben plaatsgevonden en in deze gebieden een grotere waarnemingsdichtheid dan normaal (> 1 per kmr) te hanteren.
    Water measurement with flumes and weirs
    Clemmens, A.J. ; Wahl, T.L. ; Bos, M.G. ; Replogle, J.A. - \ 2001
    International Institute for Land Reclamation and Improvement/ILRI (ILRI publication 58) - 382
    stuwen - overlaten - hydrodynamica - afvoer - ontwerp - monitoring - hydrologie - meetinstrumenten - simulatiemodel - waterbeheer - weirs - spillways - hydrodynamics - discharge - design - monitoring
    Inrichting debietmeetnet Vallei en Eem : vooronderzoek, richtingsadvies en ontwerp van een lange overlaat achter de Grebbesluis
    Boiten, W. - \ 2001
    Wageningen : Wageningen Universiteit (Rapport / Wageningen Universiteit, Omgevingswetenschappen, Sectie Waterhuishouding 102) - 17
    hydrodynamica - afvoer - waterstroming - doorstroommeters - sluizen - overlaten - utrecht - gelderse vallei - hydrodynamics - discharge - water flow - flow meters - sluices - spillways - utrecht - gelderse vallei
    Debietmetingen Gelderse Vallei
    Statistical Analysis of Daily Discharge Data of the River Meuse and its Tributaries (1968-1998): Assessment of Drought Sensitivity
    Uijlenhoet, R. ; Wit, M.J.M. de; Warmerdam, P.M.M. ; Torfs, P.J.J.F. - \ 2001
    Wageningen : Sub-department Water Resources (Rapport 100) - 40
    hydrologie van stroomgebieden - neerslag - watersystemen - klimaatverandering - hydrodynamica - maas - frankrijk - belgië - limburg - catchment hydrology - precipitation - water systems - climatic change - hydrodynamics - river meuse - france - belgium - limburg
    The rivers Rhine and Meuse fulfill important functions in the water supply of The Netherlands. Global climate change may affect the hydrological behaviour of these rivers and consequently the availability of water for a variety of purposes. The possible effects of global climate change on the discharge regime of the river Rhine system has been studied extensively during recent years. The Meuse, however, has received significantly less attention.
    Debietmeetstations in het gebied Halkenbroek
    Boiten, W. - \ 2000
    Wageningen : Landbouwuniversiteit Wageningen (Rapport / Sectie Waterhuishouding, [Departement] Omgevingswetenschappen, Wageningen Universiteit 93)
    hydrodynamica - afvoer - monitoring - hydrodynamics - discharge - monitoring
    Levering drie Rossum-stuwen Schouwen West
    Boiten, W. - \ 1998
    Wageningen : Landbouwuniversiteit Wageningen (Rapport / Landbouwuniversiteit Wageningen, Afdeling Waterhuishouding 76) - 5
    hydrodynamica - vloeistoffen (liquids) - vloeistoffen (fluids) - stroming - kanalen - kanalen, klein - meting - snelheid - nederland - zeeland - zeeuwse eilanden - hydrodynamics - liquids - fluids - flow - canals - channels - measurement - velocity - netherlands - zeeland - zeeuwse eilanden
    Sediment transport in irrigation canals
    Mendez V., N.J. - \ 1998
    Agricultural University. Promotor(en): E. Schultz; L.C. van Rijn. - Rotterdam etc. : Balkema - ISBN 9789054104131 - 285
    irrigatiewater - transport - waterverdeling - hydrodynamica - hydraulica - suspensies - sediment - irrigation water - transport - water distribution - hydrodynamics - hydraulics - suspensions - sediment

    The world population is rapidly increasing and is expected to double to about 10 billion by the year 2050. To support an increasing population in terms of food sufficiency, more and more water will be required. Irrigation is the most critical component of the modern package of inputs to effect high crop production. Irrigation has been the largest recipient of public agricultural investment in the developing world. Hence, continued investment in irrigation along with reforms in institutional arrangements for management of water are very much necessary to ensure adequate supply of food. Simultaneously, water requirements for other purposes, domestic, industrial and hydropower will steadily increase as well. Under this competing situation irrigation will have to become increasingly more efficient in the future.

    Improved management and operation activities must be implemented to prevent recurring degradation of irrigation projects. Clogging of turnouts and reduction of the conveyance capacity of canals by siltation are problems frequently met in irrigation systems. Annually, high investments are required for rehabilitation of irrigation systems in order to keep them suitable for their purposes. New development of irrigation projects or upgrading of existing schemes will require a better understanding of the sediment transport process under the prevailing flow conditions in irrigation canals. Applicability of the existing sediment transport relationships on irrigation canals has to be better understood. In this way predictions on sediment deposition in irrigation canals will be more reliable.

    The present study is focused on sediment transport in irrigation canals which may have a serious impact on the operation and maintenance activities. The design of the canal system either should be based on the transport of all the in the water present sediment to the fields or to places in the canal system, where the deposition can be removed with least costs. Sedimentation should be prevented in canals and near structures, as it will hamper and endanger a proper irrigation management. In the design and operation of irrigation canals with sediment-laden water several aspects related to irrigation criteria and sediment transport must be taken into consideration. The need for conveying different discharges at a required water level to meet the irrigation requirement and at the same time to convey the sediment load with a minimum deposition and/or erosion in the canal system should be the main criteria for the canal design. Irrigation canals are generally designed upon the assumption of uniform and steady flow.

    It is also assumed that there exists an equilibrium situation where the sediments entering into the irrigation canals will be transported without settling or erosion. However, uniform and steady flow are seldom found in reality. In the operation of an irrigation system the flow is predominantly non-uniform. While the sediment transport is highly dependent on the flow conditions it is obvious that the sediment transport capacity of the canals varies as well.

    Development on sediment transport in open channels have been mainly focused on river engineering. Even though certain similarities between rivers and irrigation canals are present, these concepts are not fully applicable to irrigation canals. A description and analysis of the sediment transport concepts under the specific conditions of irrigation canals will contribute to improve the understanding of these concepts and will help to decide on the applicability of them on simulation of the sediment transport processes for particular conditions of water flow and sediment inputs. A mathematical model which includes sediment transport concepts for the specific conditions of irrigation canals will become an important and timely tool for designers and managers of those systems.

    The aim of this research is to present a detailed analysis of the sediment transport processes, a physical and mathematical description of the behaviour of sediment transport under flow conditions encountered in irrigation canals and to develop a model to predict sediment transport and the deposition or entrainment rate for various flow conditions and sediment inputs.

    Sediment transport processes

    Sediment transport and water flow are interrelated and cannot be separated. From a mathematical point of view the interrelation can be described for a one-dimensional phenomenon without changes in the shape of the cross section by the following equations:

    • governing water flow equations : continuity and dynamic equations;
    • governing sediment equations : resistance to flow, sediment transport equations, continuity equation for sediment mass.

    Water flow equations : although one-dimensional flow hardly can be found in nature, water flow in an irrigation canal will be considered to be one-dimensional. Under this assumption, the general equations for one dimensional flow can be described by the Saint Venant equations. The amount of water flowing into irrigation canals during the irrigation season and moreover during the life time of irrigation canals is not constant. For the time depending changes in the bottom of the canal the water flow can be easily schematized as quasi-steady which means that the time depending factors in the Saint Venant equations can be neglected.

    Resistance to flow : the resistance to flow in open channels is affected by several factors, among which the development of bed forms play an important role. Determination of the friction factor of a movable bed is a complex problem that requires knowledge of an implicit process of flow conditions and bed form development. In order to predict the type of bed forms in irrigation canals the theories developed by Liu, Simons and Richardsons, Bogardi and van Rijn were compared to a selected set of laboratory and field data. Also a comparison of the most widely used methods to predict the resistance to flow with field and flume data has contributed to select an appropriate method for similar situations. The selected methods for predicting the resistance to flow were: White, Bettes and Paris (1979), Brownlie (1983) and van Rijn (1984c).The objective was to find the appropriate theories to describe the bed form and to estimate the resistance to flow (friction factor) in irrigation canals.

    From the performance of each predictor of bed form type and friction factor method when compared with selected field and laboratory data some conclusions can be drawn:

    • the theories of van Rijn and Simons and Richardson behave as the best to predict the bed form in irrigation canals;
    • all the bed forms described for the lower regime (ripples, mega-ripples and dunes) can be expected in irrigation canals;
    • the prediction of the friction factor by using the previously described methods takes only into account the bottom friction;
    • the van Rijn method for predicting the friction factor shows the best results when compared with the selected data.

    Another important feature related to the resistance of water flow in irrigation canals is the estimation of the friction factor of a irrigation canal with composite hydraulic roughness. The development of bed forms on the bottom, different material on the bottom and side of the canal or vegetated side banks are typical situations for the composite roughness conditions in irrigation canals. The most common cross sections in irrigation canals are the trapezoidal and rectangular cross section with a relatively small value for the bottom width-water depth ratio. In these cross-sections the velocity distribution is strongly affected by the varying water depth on the side slope and the boundary condition imposed to the velocity at the side wall. A method to estimate the effective roughness in a trapezoidal canal with composite roughness along the wetted perimeter which uses the theoretical velocity distribution in the cross section, is proposed.

    In order to predict the effective roughness in irrigation canals with composite roughness, the existing methods for predicting the effective roughness and the proposed method in this study have been compared with a selected set of laboratory data, which has been collected in the hydraulic laboratory of the Wageningen Agricultural University. The aim of the experiments has been to investigate the friction factor in a trapezoidal canal having varying roughness on side and bottom and to find an appropriate method to estimate the friction factor in a non-wide canal with different roughness along the wetted perimeter. From the comparison the main conclusion can be drawn that the proposed method gives better results than the other methods.

    For rectangular cross sections with composite roughness the existing methods for estimating the effective roughness can not explicitly be used. Therefor it is proposed to estimate the composite roughness in rectangular cross sections by the same principle as used for the side wall correction. The procedure to estimate the effective roughness in rectangular cross sections has been tested with a selected set of laboratory data used by Krüger. The proposed method predicts more than 95% of the measured values of the composite roughness within a range of error of 15%.

    Sediment transport equations : sediment transport equations are related to the way in which the sediment is transported: namely in equilibrium and non-equilibrium condition.

    Sediment transport predictors for equilibrium conditions have been established for different conditions. The use of those equations should be restricted to the conditions for which they were developed. However a comparison of the different equations under similar flow and sediment characteristics, both in irrigation canals and from field and laboratory data will be a useful tool to evaluate the suitability of each equation under these particular flow conditions. In this study, five of the most widely used equations to compute sediment transport have been compared, namely the Ackers and White, Brownlie, Engelund and Hansen, van Rijn and Yang equations. These equations have been compared with field and laboratory data. The objective was to find more reliable predictors of the sediment transport capacity under the flow conditions prevailing in irrigation canals. From that evaluation some remarks can be drawn:

    • prediction of the sediment transport in irrigation canals within an error factor less than 2 is hardly possible;
    • based on an overall evaluation of all performance criteria for each equation, the Ackers and White and Brownlie equations seem to be the best to predict the sediment transport rate in irrigation canals.

    Sediment transport theories have been developed for wide, open channels. Most of the man-made irrigation canals are not considered as wide canals. Recommended values for the ratio of bottom width and water depth (B/h) in those canals are smaller than 8. Existing methods for calculating the total sediment transport capacity for the entire cross section of a non-wide canal do not take into account the velocity distribution over the cross section. A new method to compute the total sediment transport by using a cross section integrated method is proposed, which is based on the assumption of a quasi two-dimensional model. The objective is to consider the effect of the side banks on the distribution of velocities and to adapt the sediment transport predictors for computing the sediment transport for the entire cross section of a non-wide canal. The existing methods and the proposed method to compute the total sediment transport in non-wide canals were compared with a selected set of laboratory data. Based on the overall comparison the proposed method gives better results than the existing methods for computing the sediment transport capacity for the whole cross section.

    An interesting phenomenon of the non-equilibrium sediment transport in irrigation canals is the adjustment of the actual sediment transport to the sediment transport capacity of the irrigation canal. To simulate the sediment transport under non-equilibrium conditions, the Gallapatti's depth integrated model for adaptation of the suspended load has been used. It has been assumed that the adaptation length for bed load is the same adaptation length for suspended load. Therefore the Gallapatti's depth integrated model can be used to describe the approach of the total sediment concentration to the transport capacity of the irrigation canal.

    Application of mathematical modelling of sediment transport in irrigation canals

    In order to simulate the sediment transport in irrigation canals, a computer program (SETRIC) has been developed. The computer program can simulate water flow, sediment transport and changes of bottom level in a network composed by a main canal and several laterals with/without tertiary outlets. Also some hydraulics structures are included in the program: overflow and undershot type, submerged culverts and inverted siphons, flumes and drops.

    The computer program is based on a sub-critical, quasi-steady, uniform or non-uniform flow (gradually varied flow). The water flow can be simulated in open channels, with a rectangular or trapezoidal cross section with single or composite roughness. Only friction losses are considered. No local losses due to changes in the bottom level, cross section or discharges are taken into account. However, changes in the bottom level are included.

    Sediment characteristics are defined by the sediment concentration at the head of the canal and sediment size is characterized by the mean diameter d 50 . The range of values is 0.05 mm≤d 50 ≤0.5 mm. A uniform sediment size distribution has been assumed.

    The simulation periods take into account the variation of the irrigation water requirement during the growing season. The growing season is divided into four stages depending on the crop development and climate conditions. The program assumes a maximum of four different periods in which the discharges along the system can be varied.

    Maintenance activities can also be included into the program. Those maintenance activities are referred to the obstruction degree due to weed growth on the banks and by its effect on the roughness condition of the canal. From that point of view three types of maintenance are included in the program: ideal maintenance, well maintained and poor maintained.

    Some applications of the model to simulate sediment transport in irrigation canals are shown. The results can not be generalized so that they can only be applied for the local flow conditions and sediment characteristics of each application. The applications are meant to show the applicability of the model and to improve the understanding of the sediment transport process for situations usually encountered in irrigation systems. The sediment deposition in an irrigation canal during a certain period will be simulated for each of the different applications. The sediment transport capacity of the irrigation canal is computed according to the Ackers and White's predictor method. The adjustment towards the sediment transport capacity is according to the Gallapatti's depth integrated model. A sediment mass balance in each reach of the canal will give either the net deposition or net entrainment between the two boundaries of a specific canal reach. From the application cases some conclusions are drawn:

    Changes of discharges : during the simulations for reductions of discharge to 80% of the design value (equilibrium condition), more than 40% of the incoming sediment load was deposited.

    Changes in the incoming sediment load : the effect of changes in the incoming sediment load on the sediment transport include the effect of variations in the incoming sediment concentration and in the median sediment size during the irrigation season and/or the lifetime of an irrigation canal. For 100% of variation in the incoming sediment concentration about 30% of the incoming sediment load is expected to settle into the canal. A similar behaviour is observed for the case of changes in the design value of the median size of the incoming sediment. For instance a total of about 45% of the incoming sediment during the simulation period is deposited when the sediment size deviates 100% from the equilibrium size.

    Controlled sediment deposition : two scenarios to concentrate the sediment deposition at the head reach of a canal were simulated. They can be described as: widening (scenario 1) and deepening (scenario 2). No additional considerations for optimizing economical cost and sediment deposition were done. For the specific flow and sediment transport conditions scenario 2 trapped 4 times more sediment than an irrigation canal without control and 1.3 times more than scenario 1.

    Sediment transport predictor : large differences in the computed sediment deposition were observed among the sediment transport predictors. The hydraulic conditions during the simulation period gave a low sediment transport capacity for the Engelund and Hansen predictor and larger for Brownlie and Ackers and White predictors. By using the Engelund and Hansen's predictor the sediment deposition was 2 and 3 times more that the Brownlie and Ackers and White's predictors respectively.

    Flow control structures : two types of flow control structures were compared: overflow type and undershot type. The observed total deposition in both cases is rather similar. A larger difference was observed in the distribution of the sediment deposition along the canal. That difference was mainly concentrated in the upstream part of the structure.

    Maintenance activities : maintenance was related to weed infestation and it was simulated by assuming optimal maintenance and no maintenance at all during the irrigation season. No direct effect of the growth of the weed on the sediment transport is considered. More sediment deposition was observed in the ideally maintained canal than the non-maintained canal. Due to the constant water level at the downstream side of the irrigation canal the flow condition within the canal behaved as: in the ideally maintained canal a gradually varied flow (backwater curve) remained constant during the simulation period. A continuous deposition was observed during all the time along the irrigation canal. In the non-maintained canal the initial flow condition changed in time from a backwater curve to a drawdown curve due to the constant water level at the downstream end and due to the variation of the water level within the canal imposed by the variation of the roughness condition. A sediment deposition period followed by an entrainment period was observed during the irrigation season.

    Operation activities : for simulating the effect of the operation procedures on the sediment deposition in the main canal four scenarios were investigated. The four scenarios are: scenario 1 (continuous flow); scenario 2 (rotational flow by hour); scenario 3 (rotational flow by day); scenario 4 (rotational flow by week). From the comparison the following conclusions can be drawn:

    • the largest total sediment deposition was observed in scenario 1. Total sediment deposition in scenarios 2, 3 and 4 was rather similar;
    • large differences were observed in the distribution of the sediment deposition within the reaches of the main canal.

    By considering the results of the applications of the mathematical modelling, it can be concluded that model is a useful tool for assessing the sediment deposition within irrigation canals under different flow conditions and sediment characteristics. Nevertheless, the mathematical model's performance can most probably be improved when it is applied in more situations. Monitoring of the sediment deposition in irrigation networks is required to evaluate the model under specific conditions and to investigate the response in time and space of the bottom level to determined water flows and sediment characteristics. Influences of the type and operation of flow control structures, geometrical characteristics of the canals, water flow and incoming sediment characteristics on the deposition, which the mathematical model predicts, will contribute to a better understanding of the sediment transport processes in irrigation canals.

    Passage of sediment through flumes and over weirs
    Bos, M.G. ; Wijbenga, J.H.A. - \ 1997
    Irrigation and Drainage Systems 11 (1997)1. - ISSN 0168-6291 - p. 29 - 39.
    stuwen - overlaten - rivieren - waterlopen - kanalen - water - geologische sedimentatie - hydrodynamica - hellingen, glijbanen - kanalen, klein - weirs - spillways - rivers - streams - canals - water - geological sedimentation - hydrodynamics - chutes - channels
    This paper reports on laboratory research on the sediment passage capability through long-throated flumes and broad-crested weirs with which the Froude number in the approach channel does not exceed 0.6 over a distance of about 20 times the water depth upstream of the structure. Design rules are given for any combination of flume or weir in combination with any channel.
    Flow resistance and hydraulic capacity of water courses with aquatic weed growth; Part 2
    Querner, E.P. - \ 1997
    Irrigation and Drainage Systems 11 (1997)2. - ISSN 0168-6291 - p. 171 - 184.
    onkruidbestrijding - kanalen - kanalen, klein - waterwegen - schadelijke waterplanten - hydrodynamica - vloeistoffen (liquids) - vloeistoffen (fluids) - stroming - rivieren - waterlopen - water - afvoer - drainage - sloten - hydrologie - modellen - analogen - weed control - canals - channels - waterways - aquatic weeds - hydrodynamics - liquids - fluids - flow - rivers - streams - water - discharge - drainage - ditches - hydrology - models - analogues
    Assessment of the effect of kinetics on colloid facilitated radionuclide transport in porous media.
    Weerd, H. van de; Leijnse, A. - \ 1997
    Journal of Contaminant Hydrology 26 (1997). - ISSN 0169-7722 - p. 245 - 256.
    grondwaterstroming - hydrodynamica - vloeistoffen (liquids) - vloeistoffen (fluids) - stroming - poreus medium - toepassingen - isotopen - straling - radioactiviteit - modellen - onderzoek - groundwater flow - hydrodynamics - liquids - fluids - flow - porous media - applications - isotopes - radiation - radioactivity - models - research
    Binding of radionuclides to natural colloids can significantly alter their transport behaviour in porous media. Dependent on the interaction between radionuclides, colloids and the solid matrix, radionuclide transport may be enhanced or retarded as a result of the presence of colloids. Often, equilibrium models are used to describe interactions between radionuclides, colloids and the solid matrix. However, experimental results indicate that kinetic processes may be important. In this paper, a model for coupled colloid and radionuclide transport in porous media is presented. Kinetic relationships are incorporated for the interaction between radionuclides, colloids and solid matrix. With this transport model, column experiments have been simulated, and modelling results are compared with experimental data reported in literature. It appears that kinetic interaction relationships are required to adequately model the experimental data.
    Hydrodynamics, sediment transport and light extinction off Cape Bolinao, Philippines
    Rivera, P.C. - \ 1997
    Agricultural University. Promotor(en): L. Lijklema; W. van Vierssen. - Rotterdam : Balkema - ISBN 9789054104087 - 244
    delta's - estuaria - hydraulica - hydrodynamica - rivieren - waterlopen - kanalen - water - geologische sedimentatie - kusten - modellen - theorie - onderzoek - oceanografie - deltas - estuaries - hydraulics - hydrodynamics - rivers - streams - canals - water - geological sedimentation - coasts - models - theory - research - oceanography

    Observational and numerical modelling studies of the hydrodynamics, sediment transport, and light extinction were undertaken in the marine environment around Cape Bolinao in the Lingayen Gulf (Northwest Philippines). Abundant with ecologically important seagrasses and benthic organisms, Cape Bolinao is presently threatened with siltation and eutrophication problems. For this reason intensive field measurements of relevant enviromnental variables which include currents, tides, temperature, salinity, total suspended solids (TSS), ash-free dry weight (AFDW), sedimentation flux, grain size distribution and organic content of bottom sediments, gilvin absorption, phytoplankton concentration, and light extinction were executed from August 1993 to June 1995. Laboratory experiments were simultaneously undertaken to determine the sedimentation and light extinction characteristics of various sediment fractions. Using time series and regression analyses, the results were analyzed and presented. A set of numerical models were developed and applied in the area around Cape Bolinao and the Lingayen Gulf. A prognostic model for the hydrodynamics, driven by realistic wind and tide forces, was developed independently for the cape (fine-resolution model) and the gulf (coarse resolution model). An operational open boundary condition based on the method of wave propagation is discussed. The hydrodynamical predictions were used, in conjunction with a diagnostic surface wave model, to force the suspended sediment transport model. The transport model, which is based on the time-dependent advection-diffusion equation, is third order accurate in space and time. For a realistic description of the suspended sediment transport process in Cape Bolinao, resuspension and sedimentation fluxes were included in the numerical model using existing parameterizations. The predicted suspended sediment concentrations were used in a diagnostic model for light extinction. This later model is based on the assumption that the contributions of the optically active components to the attenuation of the photosynthetically available radiation (PAR) are linearly additive. Calibration of the numerical models using field observations produced a set of parameter values which is deemed representative for the area of investigation. Using these parameter values, the overall model predictions were in good agreement with field observations. Finally, using the integrated model, the impact of river sediment loads (treated as a conservative tracer) in the Bolinao reef system was quantified.

    Displacement imaging in porous media using the line scan NMR technique
    Dusschoten, D. van; Noort, J. van; As, H. van - \ 1997
    Geoderma 80 (1997). - ISSN 0016-7061 - p. 405 - 416.
    hydrodynamica - vloeistoffen (liquids) - vloeistoffen (fluids) - stroming - poreus medium - kernmagnetische resonantie - kernmagnetische resonantiespectroscopie - hydrodynamics - liquids - fluids - flow - porous media - nuclear magnetic resonance - nuclear magnetic resonance spectroscopy
    Displacement imaging is a recent, powerful NMR method with which distributions of displacements can be acquired of e.g. fluids within a porous medium. Both motion parallel and perpendicular to the flow direction may be observed within a time window of a few milliseconds to several seconds. By combining displacement imaging with the line scan technique, one-dimensionally resolved measurements with a high temporal resolution (<1 min) of the spatial dependency of motion can be obtained. Here we present displacement images of flow through two simple model systems for soil: an unconsolidated glass bead water system and a sintered glass bead filter. It is demonstrated that the combination of displacement imaging and spatial resolution along a line is important to access both bulk displacement and local displacements in relation to the local porosity.
    NMR methods for imaging of transport processes in micro-porous systems.
    As, H. van; Dusschoten, D. van - \ 1997
    Geoderma 80 (1997). - ISSN 0016-7061 - p. 389 - 403.
    hydrodynamica - vloeistoffen (liquids) - vloeistoffen (fluids) - stroming - poreus medium - kernmagnetische resonantie - kernmagnetische resonantiespectroscopie - hydrodynamics - liquids - fluids - flow - porous media - nuclear magnetic resonance - nuclear magnetic resonance spectroscopy
    Flow measurement in open channels for hydrological networks.
    Boiten, W. - \ 1996
    In: Utilizacion y manejo sostenible de los recursos hidricos : [proceedings of the seminar, San Jose, Costa Rica, 28 November and 1 December 1994] / Reynolds Vargas, J., - p. 187 - 198.
    kanalen - kanalen, klein - stroming - vloeistoffen (fluids) - hydrodynamica - vloeistoffen (liquids) - meting - snelheid - canals - channels - flow - fluids - hydrodynamics - liquids - measurement - velocity
    Het opstellen van de afvoerkrommen van klepstuwen
    Boiten, W. - \ 1995
    Wageningen : LH (Rapport / Landbouwuniversiteit, Vakgroep Waterhuishouding 52) - 48
    berekening - kanalen - hydrodynamica - oppervlakkige afvoer - overlaten - stuwen - calculation - canals - hydrodynamics - runoff - spillways - weirs
    De stromingsweerstand en de berekening van de afvoer in begroeide waterlopen
    Querner, E.P. - \ 1995
    Het Waterschap 80 (1995)9. - ISSN 1380-4251 - p. 350 - 356.
    schadelijke waterplanten - kanalen - kanalen, klein - sloten - stroming - vloeistoffen (fluids) - hydrodynamica - vloeistoffen (liquids) - onderhoud - waterwegen - onkruidbestrijding - aquatic weeds - canals - channels - ditches - flow - fluids - hydrodynamics - liquids - maintenance - waterways - weed control
    Maaionderhoud in waterlopen is een belangrijke taak van waterschappen. Het vermogen om water af te voeren is afhankelijk van de aanwezigheid van waterplanten en oevervegetatie en bepaalt het tijdstip van onderhoud. Met behulp van de stromingsweerstanden de mate van begroeiing met water- en oevervegetatie wordt het debiet in een waterloop berekend. Het dwarsprofiel van een waterloop wordt opgedeeld in een onbegroeid en een begroeid gedeelte. Voor het onbegroeide deel is met behulp van metingen in het veld en in een modelgoot een stromingsweerstand afgeleid. De stroming door het begroeide deel is te verwaarlozen. Het oppervlak dat door waterplanten wordt ingenomen, is gedurende het groeiseizoen gemeten.
    Afvoerrelatie meetoverlaat Stemerdinkbrug.
    Dommerholt, A. - \ 1995
    Wageningen : Landbouwuniversiteit Wageningen (Rapport / Landbouwuniversiteit, Vakgroep Waterhuishouding 60) - 28
    afvoer - stroming - hydrodynamica - hydrologie - meting - modellen - onderzoek - oppervlakkige afvoer - overlaten - snelheid - stuwen - nederland - gelderland - discharge - flow - hydrodynamics - hydrology - measurement - models - research - runoff - spillways - velocity - weirs - netherlands - gelderland
    Morra park : voorlopige resultaten grond- en oppervlaktewater meetnet.
    Arts, M.P.T. ; Dijksma, R. - \ 1995
    Wageningen : Landbouwuniversiteit Wageningen (Rapport / Landbouwuniversiteit, Vakgroep Waterhuishouding 65) - 9
    kanalen - hydraulica - hydrodynamica - hydrologie - instrumenten (meters) - meting - monitoring - rivieren - waterlopen - stedelijke gebieden - water - nederland - friesland - gemeenten - netwerken - canals - hydraulics - hydrodynamics - hydrology - instruments - measurement - monitoring - rivers - streams - urban areas - water - netherlands - friesland - municipalities - networks
    Meetnet voor afvoermetingen in de Renkumse Beken.
    Arts, M.P.T. ; Boiten, W. - \ 1995
    Wageningen : Landbouwuniversiteit Wageningen (Rapport / Landbouwuniversiteit, Vakgroep Waterhuishouding 64) - 30
    kanalen - afvoer - stroming - hydrodynamica - hydrologie - instrumenten (meters) - meting - monitoring - verslagen - registratie - rivieren - oppervlakkige afvoer - overlaten - rivierafvoer - waterlopen - snelheid - water - stuwen - nederland - gelderland - netwerken - veluwe - canals - discharge - flow - hydrodynamics - hydrology - instruments - measurement - monitoring - records - registration - rivers - runoff - spillways - stream flow - streams - velocity - water - weirs - netherlands - gelderland - networks - veluwe
    Afvoer van het Renkums beekdal
    Afvoerrelaties klepstuwen op de samenvloeiing van de Veengoot en de Van Heeckerenbeek.
    Boiten, W. - \ 1995
    Wageningen : Landbouwuniversiteit Wageningen (Rapport / Landbouwuniversiteit, Vakgroep Waterhuishouding 53) - 11
    berekening - kanalen - hydrodynamica - oppervlakkige afvoer - overlaten - water - stuwen - gelderland - calculation - canals - hydrodynamics - runoff - spillways - water - weirs - gelderland
    Handboek debietmeten in open waterlopen.
    Boiten, W. ; Dommerholt, A. ; Soet, M. - \ 1995
    Wageningen : Landbouwuniversiteit Wageningen (Rapport / Landbouwuniversiteit, Vakgroep Waterhuishouding 51) - 158
    kanalen - kanalen, klein - stroming - vloeistoffen (fluids) - hydrodynamica - hydrologie - instrumenten (meters) - vloeistoffen (liquids) - meting - monitoring - snelheid - handboeken - netwerken - canals - channels - flow - fluids - hydrodynamics - hydrology - instruments - liquids - measurement - monitoring - velocity - handbooks - networks
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