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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Bed morphodynamics at the intake of a side channel controlled by sill geometry
Ruijsscher, T.V. de; Hoitink, A.J.F. ; Naqshband, S. ; Paarlberg, A.J. - \ 2019
Advances in Water Resources 134 (2019). - ISSN 0309-1708
Bifurcation - Longitudinal training dam - Physical scale model - River morphology - Side channel

As part of a general trend towards river management solutions that provide more room for the river, longitudinal training dams (LTDs) have recently been constructed in the inner bend of the Dutch Waal River, replacing groynes. LTDs split the river in a main channel and a bank-connected side channel with a sill at the entrance. In the present study, a physical scale model with mobile bed was used to study morphological patterns and discharge division in the entrance region of such a side channel. Alternative geometric designs of the sill are tested to investigate the controls on the diversion of water and sediment into the side channel. After reaching a morphodynamic equilibrium, two bar features were observed in the side channel under low flow conditions. An inner-bend depositional bar emerged against the LTD, resembling depositional bars observed in sharp river bends. A second bar occurred in the most upstream part of the side channel, next to the sill, induced by divergence of the flow by widening of the channel and an increasing flow depth after the sill, hence defined as a divergence bar. The morphologically most active system in the side channel emerges for the configuration in which the sill height decreases in downstream direction. For such a geometry, the sediment that settles during low flow is largely eroded during high flow, reducing maintenance needs. A qualitative comparison based on a lab experiment mimicking field conditions demonstrates the realism of the experiments.

Exploring the fundamentals and biomimetic potential of tree frog attachment
Langowski, Julian - \ 2019
Meta-analysis reveals enhanced growth of marine harmful algae from temperate regions with warming and elevated CO2 levels
Brandenburg, Karen M. ; Velthuis, Mandy ; Waal, Dedmer B. Van de - \ 2019
Global Change Biology 25 (2019)8. - ISSN 1354-1013 - p. 2607 - 2618.
climate change - global warming - harmful algal blooms - ocean acidification - sea surface temperature

Elevated pCO2 and warming may promote algal growth and toxin production, and thereby possibly support the proliferation and toxicity of harmful algal blooms (HABs). Here, we tested whether empirical data support this hypothesis using a meta-analytic approach and investigated the responses of growth rate and toxin content or toxicity of numerous marine and estuarine HAB species to elevated pCO2 and warming. Most of the available data on HAB responses towards the two tested climate change variables concern dinoflagellates, as many members of this phytoplankton group are known to cause HAB outbreaks. Toxin content and toxicity did not reveal a consistent response towards both tested climate change variables, while growth rate increased consistently with elevated pCO2. Warming also led to higher growth rates, but only for species isolated at higher latitudes. The observed gradient in temperature growth responses shows the potential for enhanced development of HABs at higher latitudes. Increases in growth rates with more CO2 may present an additional competitive advantage for HAB species, particularly as CO2 was not shown to enhance growth rate of other non-HAB phytoplankton species. However, this may also be related to the difference in representation of dinoflagellate and diatom species in the respective HAB and non-HAB phytoplankton groups. Since the proliferation of HAB species may strongly depend on their growth rates, our results warn for a greater potential of dinoflagellate HAB development in future coastal waters, particularly in temperate regions.

Enhancement of co-production of nutritional protein and carotenoids in Dunaliella salina using a two-phase cultivation assisted by nitrogen level and light intensity
Sui, Yixing ; Muys, Maarten ; Waal, Dedmer B. Van de; Adamo, Sarah D'; Vermeir, Pieter ; Fernandes, Tânia V. ; Vlaeminck, Siegfried E. - \ 2019
Bioresource Technology 287 (2019). - ISSN 0960-8524
Food - Microalgae - Nitrogen limitation - Pigment - Single-cell protein

Microalga Dunaliella salina is known for its carotenogenesis. At the same time, it can also produce high-quality protein. The optimal conditions for D. salina to co-produce intracellular pools of both compounds, however, are yet unknown. This study investigated a two-phase cultivation strategy to optimize combined high-quality protein and carotenoid production of D. salina. In phase-one, a gradient of nitrogen concentrations was tested. In phase-two, effects of nitrogen pulse and high illumination were tested. Results reveal optimized protein quantity, quality (expressed as essential amino acid index EAAI)and carotenoids content in a two-phase cultivation, where short nitrogen starvation in phase-one was followed by high illumination during phase-two. Adopting this strategy, productivities of protein, EAA and carotenoids reached 22, 7 and 3 mg/L/d, respectively, with an EAAI of 1.1. The quality of this biomass surpasses FAO/WHO standard for human nutrition, and the observed level of β-carotene presents high antioxidant pro-vitamin A activity.

Approach for designing context-specific, locally owned interventions to reduce postharvest losses : Case study on tomato value chains in Nigeria
Plaisier, Christine ; Sibomana, Milindi ; Waal, Johannes van der; Clercx, Luud ; Wagenberg, Coen P.A. van; Dijkxhoorn, Youri - \ 2019
Sustainability 11 (2019)1. - ISSN 2071-1050 - 16 p.
Behavioural change - Context-specific interventions - Nigeria - Participatory approach - Plastic crate - Postharvest losses - Raffia basket - Supply chain - Tomato - Value chain development

Development projects on interventions to reduce postharvest losses (PHL) are often implemented largely independently of the specific context and without sufficient adaptation to the needs of people who are supposed to use them. An approach is needed for the design and implementation of specific, locally owned interventions in development projects. Our approach is based on Participatory Development and includes Living Lab and World Cafés. We applied the approach in a case study on reducing PHL in tomato value chains in Nigeria. The approach consists of nine steps. After scoping the sector, selected value chain stakeholders (case: farmers, transporters, traders, retailers) were gathered in Living Lab workshops. In the workshop, participants analyzed the product, information, and monetary flows in their own value chain, identified causes for PHL, and selected potential interventions to reduce these (case: plastic crates instead of raffia baskets to transport tomatoes). Selected interventions were implemented, tested, and monitored in pilot projects with the workshop participants. This was followed by an evaluation workshop. At the end of the case study, 89% of participants bought crates to keep using them in their value chain. Our approach resulted in context-specific, locally owned interventions to reduce PHL in the case study on tomato value chains in Nigeria. Its application in other countries, commodities, or interventions is needed to determine the effectiveness of the approach in a broader scope.

LPJmL4 Model Code
Schaphoff, Sibyll ; Bloh, Werner von; Thonicke, Kirsten ; Biemans, H. ; Forkel, Matthias ; Gerten, Dieter ; Heinke, Jens ; Jägermeyr, Jonas ; Müller, Christoph ; Rolinski, Susanne ; Waha, Katharina ; Stehfest, Elke ; Waal, Liesbeth de; Heyder, Ursula ; Gumpenberger, Marlies ; Beringer, Tim - \ 2018
Potsdam Institute for Climate Impact Research (PIK)
soil carbon - vegetation carbon - global carbon balance - permafrost distribution - discharge - fractional burned area - crop yields - global dynamic vegetation model - vegetation dynamics
LPJmL4 is a process-based model that simulates climate and land-use change impacts on the terrestrial biosphere, the water and carbon cycle and on agricultural production. The LPJmL4 model combines plant physiological relations, generalized empirically established functions and plant trait parameters. The model incorporates dynamic land use at the global scale and is also able to simulate the production of woody and herbaceous short-rotation bio-energy plantations. Grid cells may contain one or several types of natural or agricultural vegetation.
Karakterisering, uitbreiding en herstel kwaliteit van Veldbies-Beukenbossen
Hommel, Patrick ; Bijlsma, Rienk-Jan ; Jansman, Hugh ; Ouden, Jan den; Schaminée, Joop ; Waal, Rein de; Wallis de Vries, Michiel - \ 2018
Driebergen : VBNE, Vereniging van Bos- en Natuurterreineigenaren (OBN rapport 2018/OBN225-HE) - 180
Beoordeling van erosie en sedimentatie in en rond natuur in het Heuvelland: een samenvatting
Waal, Rein de - \ 2018
INNOVA Ezine 2 – Valencia Region, Droughts and Agricultural Interests in a Metropolitan Area in Spain
Timmermans, W. ; Jong, F. de; Martín, Adrià Rubio ; Bruijn, Daphne de; Harsema, H. - \ 2018
Wageningen : Blauwdruk
In the metropolitan area of Valencia the water use is intense and the region suffers from frequent droughts due to climate conditions. Valencia is surrounded by an agricultural landscape with deep cultural significance and with a multi-sectoral structure in which irrigated agriculture plays an important role in the consumption of water. The Albufera Natural Park, less than 10 km south of Valencia, is a freshwater lagoon and its surroundings rice plots. Given the predicted adverse effects of climate change, it is important for the City of Valencia to develop adaptation strategies for the future climate. The mandate for the INNOVA project is to develop a climate service that satisfies the water use needs to support the distribution of potable water to its users.

The second INNOVA e-zine shows the climate and adaptation challenges the Valencia region is facing. The first issue showed the Mirror Waal project in the Nijmegen area (NL).

From awareness of upcoming flooding risks, via complex planning and design efforts into the final result. Whereas Nijmegen is far in the Adaptation Cycle; the Valencia metropolitan area is between the steps of identifying adaptation options (Step 3) and assessing these options (Step 4).
INNOVA Ezine 1 – Nijmegen, the EU Green Capital 2018 and Room for the River Waal
Timmermans, W. ; Jong, F. de; Ginkel, M. van; Martinez, G. ; Bruijn, D. de; Harsema, H. - \ 2018
Wageningen : Blauwdruk
The Dutch city of Nijmegen is becoming well-known because of its planning approach that combines large scale climate adaptation measures with a strong emphasis on spatial quality. Nijmegen is situated along the Waal river, one of Europe’s largest transport and ecological corridors. More than 250M euro has been spent on a new bypass of the Waal, called the Mirror Waal, one of the major urban examples of the Dutch Room for the River project. This e-zine shows the Mirror Waal project. From awareness of upcoming flooding risks, via complex planning and design efforts into the final result, including innovative ecological engineering, new sport activities and spontaneous festivals. The e-zine is presented by the INNOVA project. It is the first e-zine out of ten. INNOVA is a research project aiming to facilitate the use of climate data and projections, scientifically known as climate services, in adaptation efforts by urban governments. The project focuses on three European cities, and a small island state. These are: Kiel Bay in Germany, Nijmegen in The Netherlands, Valencia in Spain, and finally, the French West-Indies Islands of Guadeloupe & Martinique.
Fungal parasites of a toxic inedible cyanobacterium provide food to zooplankton
Frenken, Thijs ; Wierenga, Joren ; Donk, Ellen van; Declerck, Steven A.J. ; Senerpont Domis, Lisette N. de; Rohrlack, Thomas ; Waal, Dedmer B. van de - \ 2018
Limnology and Oceanography 63 (2018)6. - ISSN 0024-3590 - p. 2384 - 2393.

During the end of spring and throughout summer, large-sized phytoplankton taxa often proliferate and form dense blooms in freshwater ecosystems. In many cases, they are inedible to zooplankton and prevent efficient transfer of energy and elements to higher trophic levels. Such a constraint may be alleviated by fungal parasite infections on large-sized phytoplankton taxa like diatoms and filamentous cyanobacteria, as infections may provide zooplankton with a complementary food source in the form of fungal zoospores. Zoospores have been shown to support somatic growth of large filter feeding zooplankton species. Here, we tested if selectively feeding zooplankton, more specifically rotifers, also can use fungal zoospores as a food source. Our results show that chytrid fungal parasites can indeed support population growth of rotifers (Keratella sp.). Specifically, in cultures of an inedible filamentous cyanobacterium (Planktothrix rubescens), Keratella populations rapidly declined, while in Planktothrix cultures infected with chytrids, Keratella population growth rate equaled the growth observed for populations fed with a more suitable green algal diet (Chlorella sorokiniana). Feeding of Keratella on zoospores was furthermore indicated by a reduced number of zoospores during the last sampling day. These findings not only imply that rotifers may survive on zoospores, but also that the zoospores can support high rotifer population growth rates. We thus show that fungal parasites of inedible cyanobacteria can facilitate grazers by providing them alternative food sources. Together, these results highlight the important role that parasites may play in the aquatic plankton food web.

Scale model of a training dam using lightweight granulates
Vermeulen, Bart ; Boersema, Matthijs ; Hoitink, Ton ; Sieben, Arjan ; Sloff, Kees ; Wal, Maarten van der - \ 2018
In: River Flow 2018 - Ninth International Conference on Fluvial Hydraulics. - EDP Sciences (E3S Web of Conferences ) - 7 p.

Longitudinal training dams (LTDs) are a promising alternative for river groynes. Here we summarize findings of a recent study focused on the along river transition from a series of river groynes to an LTD, where the flow divides between the fairway and the side channel between the LTD and the river bank. A scale model is setup using lightweight granulates made of polystyrene to create conditions that are dynamically similar to a prototype situation in the River Waal. The key advantage of using lightweight granulates is that both the Shields number and the Froude number are similar in the model and the prototype. A high flow and a low flow experiment were carried out. The bedforms in the physical model have dimensions that correspond to theoretical dune height predictions, and also the channel incision due to width reduction is in accordance with expectations. The scour holes that develop near the tip of the groynes, however, are too deep, which may relate to improper scaling of the local turbulent vortices, initiated at the groynes. The morphodynamic developments in the flow divergence zone are subtle, and are overwhelmed by the mobile bed response to the presence of groynes. Considering that the physical model over-predicts the erosion caused by groynes, this suggests that the LTD configuration subject to study results in a comparatively stable bed morphology.

Provinciaal meetnet verdroging Overijssel : Deel 4: Beschrijving en beoordeling van 21 meetpunten /
Hommel, P.W.F.M. ; Waal, R.W. de - \ 2018
Wageningen : Wageningen Environmental Research (Rapport / Wageningen Environmental Research 2896) - 85
Flow Bifurcation at a Longitudinal Training Dam : Effects on Local Morphology
Ruijsscher, Timo De; Naqshband, Suleyman ; Hoitink, Ton - \ 2018
In: River Flow 2018 - Ninth International Conference on Fluvial Hydraulics. - EDP Sciences (E3S Web of Conferences ) - 8 p.

Longitudinal training dams (LTDs) have been built over a length of 10 km in the Dutch River Waal as an alternative to groyne fields, splitting the river in a fairway and a bank-connected side channel in the inner bend. Here, we study the physical mechanisms governing the three-dimensional flow and its effect on local morphology at the flow divide using a mobile bed physical model of an LTD, centred around a side channel intake. In line with previous experiments, polystyrene granules are used as a lightweight sediment that allows to achieve dynamic similarity between the model and the prototype. An Acoustic Doppler Velocimetry (ADV) profiler is used to monitor the flow characteristics, whereas a line laser scanner set-up is used to measure the morphological imprint of the flow near the bifurcation point. To study the dependence of the results on the sill height at the side channel intake, different forms and heights of the sill are used. First results show striking similarities with measurements from the field pilot in the Waal River, as well as larger sedimentation in the side channel for a uniform low sill compared to a downstream increasing sill height.

Bodemerosie in en rond Natura 2000-gebieden in het Heuvelland : De herkenning en beoordeling van erosie- en sedimentatievormen
Waal, R.W. de; Bijlsma, R.J. ; Massop, H.T.L. - \ 2018
Natuurhistorisch Maandblad 107 (2018)9. - ISSN 0028-1107 - p. 158 - 165.
In de Natura 2000-gebieden in het Heuvelland worden habitattypen en andere natuurwaarden op hellingen in randzones grenzend aan landbouwpercelen negatief beïnvloed door de toestroom van voedselrijk water en sediment. Bij intensieve vormen van erosie kunnen natuurwaarden in de gebieden zelfs verdwijnen. In 2016 is vanuit het OBN (Ontwikkeling en Beheer Natuurkwaliteit) onderzoek uitgevoerd naar erosievormen nabij en in Natura 2000-gebieden en naar maatregelen waarmee negatieve effecten kunnen worden voorkomen of gestopt. Dankzij een periode met zware hoosbuien in de zomer van 2016 konden alle vormen van erosie in het veld goed bestudeerd en in samenhang beschreven worden. Dit artikel is een samenvatting van de gepubliceerde onderzoeksresultaten.
Impacts of warming on top-down and bottom-up controls of periphyton production
Kazanjian, Garabet ; Velthuis, Mandy ; Aben, Ralf ; Stephan, Susanne ; Peeters, Edwin T.H.M. ; Frenken, Thijs ; Touwen, Jelle ; Xue, Fei ; Kosten, Sarian ; De Waal, Dedmer B. Van; Senerpont Domis, Lisette N. De; Donk, Ellen van; Hilt, Sabine - \ 2018
Scientific Reports 8 (2018)1. - ISSN 2045-2322

Global warming profoundly impacts the functioning of aquatic ecosystems. Nonetheless, the effect of warming on primary producers is poorly understood, especially periphyton production, which is affected both directly and indirectly by temperature-sensitive top-down and bottom-up controls. Here, we study the impact of warming on gross primary production in experimental ecosystems with near-realistic foodwebs during spring and early summer. We used indoor mesocosms following a temperate temperature regime (control) and a warmed (+4 °C) treatment to measure biomass and production of phytoplankton and periphyton. The mesocosms' primary production was dominated by periphyton (>82%) during the studied period (April-June). Until May, periphyton production and biomass were significantly higher in the warm treatment (up to 98% greater biomass compared to the control) due to direct temperature effects on growth and indirect effects resulting from higher sediment phosphorus release. Subsequently, enhanced grazer abundances seem to have counteracted the positive temperature effect causing a decline in periphyton biomass and production in June. We thus show, within our studied period, seasonally distinct effects of warming on periphyton, which can significantly affect overall ecosystem primary production and functioning.

Samenwerken naar gemeenschappelijkheid in gezondheidspreventie. Een theorie die houvast geeft in de praktijk : Interprofessioneel werken en innoveren in teams. Samenwerking in nieuwe praktijken.
Aarts, M.N.C. ; Haar, M. ter - \ 2018
In: Interprofessioneel werken en innoveren in teams / de Waal, Vincent, Bussum : Uitgeverij Coutinho - ISBN 9789046906026 - p. 285 - 302.
Droge bossen van het Vecht- en Beneden-Reggegebied (Overijssel) : toestand en kansen voor herstel en beheer van de habitattypen Beuken-eikenbossen met hulst (H9120) en Oude eikenbossen (H9190)
Bijlsma, R.J. ; Waal, R.W. de; Hommel, P.W.F.M. - \ 2018
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2876) - 95
Continuous and cumulative acidification and N deposition induce P limitation of the micro-arthropod soil fauna of mineral-poor dry heathlands
Siepel, Henk ; Vogels, Joost ; Bobbink, Roland ; Bijlsma, Rienk Jan ; Jongejans, Eelke ; Waal, Rein de; Weijters, Maaike - \ 2018
Soil Biology and Biochemistry 119 (2018). - ISSN 0038-0717 - p. 128 - 134.
Allometry - Minerals - Mites - N:P ratio - Springtails - Stoichiometry
Phosphorus content of mineral-poor sandy soils is steadily decreasing due to leaching caused by continuous and cumulative acidification and N deposition. Sod-cutting as a traditional restoration measure for heathland vegetation appears to increase P limitation, as most of the P present is in the organic matter being removed by sod-cutting. Mineral weathering, the natural inorganic source of P, becomes limiting or has even ceased as a result of the depletion of minerals. Previous investigations indicate a P limitation of the macrofauna under these circumstances. If this also holds for the soil fauna, hampering of decomposition may occur. To test experimentally whether soil fauna is indeed limited by the amount of P in the system, we set up an experiment in sod-cut heathland in which we added P or Ca (as Dolokal), resulting in: P + Ca+, P + Ca-, P-Ca+ and P-Ca- (control) treatments and an extra reference block in the original grass encroached heathland vegetation. The Ca treatment was added because liming is used to recover from acidification effects, but as a side effect Ca may also bind P. Three growing seasons after the addition of P and Ca, we found a significant increase in herbivores and predators among the soil fauna, with herbivore numbers higher in the P+/Ca-plots than in the P+/Ca + plots, indicating a lower availability of P in the presence of added Ca. Predators increased in all P+ plots. Fungivorous browsers responded negatively to the treatment after three growing seasons, both to P and to Ca addition. Phoretic species responded rapidly either to fewer numbers (when these are fungivorous browsers) or to greater numbers (when these are herbivorous browsers) to P addition. P addition induced also an allometric effect, via the medium-sized species increasing in greater numbers than both the larger and smaller species.
Humusica 1, article 5: Terrestrial humus systems and forms — Keys of classification of humus systems and forms
Zanella, Augusto ; Ponge, Jean François ; Jabiol, Bernard ; Sartori, Giacomo ; Kolb, Ekart ; Bayon, Renée Claire Le; Gobat, Jean Michel ; Aubert, Michaël ; Waal, Rein de; Delft, Bas van; Vacca, Andrea ; Serra, Gianluca ; Chersich, Silvia ; Andreetta, Anna ; Kõlli, Raimo ; Brun, Jean Jacques ; Cools, Nathalie ; Englisch, Michael ; Hager, Herbert ; Katzensteiner, Klaus ; Brêthes, Alain ; Nicola, Cristina De; Testi, Anna ; Bernier, Nicolas ; Graefe, Ulfert ; Wolf, Ugo ; Juilleret, Jérôme ; Garlato, Andrea ; Obber, Silvia ; Galvan, Paola ; Zampedri, Roberto ; Frizzera, Lorenzo ; Tomasi, Mauro ; Banas, Damien ; Bureau, Fabrice ; Tatti, Dylan ; Salmon, Sandrine ; Menardi, Roberto ; Fontanella, Fausto ; Carraro, Vinicio ; Pizzeghello, Diego ; Concheri, Giuseppe ; Squartini, Andrea ; Cattaneo, Dina ; Scattolin, Linda ; Nardi, Serenella ; Nicolini, Gianni ; Viola, Franco - \ 2018
Applied Soil Ecology 122 (2018). - ISSN 0929-1393 - p. 75 - 86.
Humus - Humus classification - Humus forms - Humus systems - Humusica - Terrestrial humus forms
This article is an as simple as possible key of classification of terrestrial (aerobic, not submersed) topsoils (organic and organic-mineral series of soil horizons). Based on the introduction exposed in Humusica 1, article 1, and using vocabulary and definitions listed in article 4, a classification is proposed for better understanding the biological functioning of the soil, partially disclosing the process of litter digestion. Five types of terrestrial topsoils, called terrestrial humus systems, are described and illustrated with the help of photographs. Within each humus system, 3–4 humus forms are also revealed, corresponding to similar series of soil horizons generated in a relatively homogeneous environment whose range of ecological factors is not so large to overstep and cause the genesis of another different humus system. The article ends with a figure that shows the relationship between Tangel and Amphi humus systems, and a dichotomous key of classification that one can easily print and bring in the field for practicing humus classification.
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