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
    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
    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
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