Publications

4075 results

  • Tweede mening KRW-doelactualisaties waterschappen Noord-Brabant

    Authors: Roovaart, J.C. van den; Wortelboer, F.G.; Liefveld, W.; Spier, J. (2020)

    Provincie Noord-Brabant heeft aan Deltares en Bureau Waardenburg gevraagd om een tweede meningsvorming uit te voeren over de geactualiseerde doelen voor de biologie en nutriënten voor oppervlaktewaterlichamen conform de Kaderrichtlijn Water voor de 3e stroomgebiedbeheerplannen, zoals door de Brabantse waterschappen in concept zijn vastgesteld. Op basis van een groot aantal door de waterbeheerders aangeleverde documenten, data en aanvullende interviews is aan de hand van een set criteria een analyse uitgevoerd over het proces van technische doelactualisatie, het ambitieniveau van de maatregelpakketten en de onzekerheden die hierbij een rol spelen. De conclusie is dat de doelactualisatie door de Brabantse waterschappen op een zorgvuldige wijze is uitgevoerd op basis van een combinatie van eigen expertise, inhuur van externen en het gebruik van nationale tools, waarbij de nationale richtsnoeren zijn gevolgd. De documentatie is uitgebreid en vrij volledig te noemen.

  • Hydrologische en economische effecten van twee maatregelpakketten voor Deltaprogramma Zoetwater fase II

    Authors: Mens, M.J.P.; Schasfoort, F.E.; Hunink, J.C.; Pouwels, J.R.; Delsman, J.R.; Jong J. de (2020)

    Dit rapport beschrijft de hydrologische en economische effecten van een deel van het bestuurlijke Voorkeurspakket en een deel van het Economisch kansrijk pakket van het Deltaprogramma Zoetwater fase II. Deze effecten zijn berekend met het Nationaal Water Model en de effectmodules landbouw en scheepvaart, en worden gebruikt als input voor de maatschappelijke kosten-batenanalyse van het bestuurlijke Voorkeurspakket. In dit rapport wordt met Voorkeurspakket verwezen naar het deel van het bestuurlijke Voorkeurspakket dat met het Nationaal Water Model kon worden doorgerekend. Het bestuurlijke Voorkeurspakket betreft een in een bestuurlijk proces tot stand gekomen selectie uit de totale lijst met maatregelen die door de Zoetwaterregio’s en Rijkswaterstaat zijn voorgesteld voor fase II van het Deltaprogramma (periode 2022-2027). Op dezelfde manier wordt met het Economisch pakket in dit rapport verwezen naar dat deel van het Economisch kansrijk pakket dat met het Nationaal Water Model kon worden doorgerekend. Het Economisch kansrijk pakket is een andere selectie uit dezelfde lijst met maatregelen, en betreft maatregelen die in een eerdere analyse als rendabel uit de bus zijn gekomen.

  • Cofactoren voor bodemdieren in de Waddenzee : beschrijving van data en modeluitvoer

    Authors: Herman, P.M.J.; Weerdenburg, R. van (2020)

    De mogelijke ecologische effecten van het verlies van lading door de MSC Zoe bij de Nederlandse Waddenzee worden op meerdere manieren onderzocht. Eén van de benaderingen is het opstellen van statistische modellen voor populaties die potentieel hinder van het ladingverlies hebben ondervonden. Om de statistische modellen voor bodemdieren optimaal te kunnen gebruiken, is het belangrijk te beschikken over een adequate beschrijving van het habitat. De habitatbeschrijving kan dan in het statistisch model worden meegenomen. Voor de Waddenzee en de Nederlandse kustzone ten noorden van de Waddenzee is een recent opgesteld en gekalibreerd hydrodynamisch model gebruikt als bron van de cofactoren voor de beschrijving van het habitat van bodemdieren. Afgeleide cofactoren betreffen hoogteligging, droogvalduur en schuifspanning op het sediment door golven en stroming. In dit rapport wordt de methode toegelicht en worden de cofactoren gedefinieerd. Bijkomende cofactoren betreffen de mediane korrelgrootte van het sediment. Voor de Waddenzee wordt dit afgeleid uit het SIBES bemonsteringsprogramma. Voor de kustzone worden gegevens uit het DINO loket van TNO gebruikt.

  • Efficient two-layer non-hydrostatic wave model with accurate dispersive behaviour

    Authors: Ridder, M.P. de; Smit, P.B.; Dongeren, A.R. van; McCall, R.T.; Nederhoff, K.; Reniers, A.J.H.M. (2021)
    Published in: Coastal engineering : an international journal for coastal, harbour and offshore engineers, volume 164 (2021), page 1-16

    A 2-layer non-hydrostatic model with improved dispersive behaviour is presented. Due to the assumption of a constant non-hydrostatic pressure distribution in the lower layer, the dispersive behaviour is improved without much additional computational time. A comparison with linear wave theory showed that this 2-layer model gives a better result for the dispersion relation and shoaling of waves in intermediate water. This means that the 2-layer model is applicable in shallow and intermediate water depths (up to relative depths kh equals 4), whereas the 1-layer model is only applicable in shallow water depths (kh smaller than 1). Three laboratory experiments, including a fringing reef and a barred beach, were used to validate the presented mode for different hydrodynamic conditions. Based on these results, it can be concluded that the 2-layer model can be applied to accurately simulate the bulk wave height and spectral properties. The low frequency wave height, the setup and in particular the second order statistics contain more scatter, but the model accurately captured the general trend. Furthermore, the model showed good results for complex bathymetries in shallow to intermediate water.

  • The influence of a berm and roughness on the wave overtopping at dikes

    Authors: Chen, W.; Gent, M.R.A. van; Warmink, J.J.; Hulscher, S.J.M.H. (2020)
    Published in: Coastal engineering : an international journal for coastal, harbour and offshore engineers, volume 156 (2020), page 1-15

    A reliable estimation of average wave overtopping discharge is important for dike design and safety assessment. Berms and roughness elements are widely applied to reduce the overtopping discharge over dikes. In this study, the effects of a berm and roughness on the wave overtopping discharge are investigated by means of physical model tests. New empirical formulae are derived from the analysis of the experimental data in order to provide more accurate estimations of reductive influence of berms and roughness on the wave overtopping discharge. Additionally, a new formula is developed to estimate the reductive influence of varying roughness along the waterside slopes with a berm. The new equations show a significantly better performance within the tested range when compared with existing formulae for the average overtopping discharge.

  • Bioconcentration of organotin cations during molting inhibits Heterocypris incongruens growth

    Authors: Nolte, T.M.; Cooman, W. de; Vink, J.P.M.; Elst, R.; Ryken, E.; Ragas, A.M.J. (2020)

    The densely populated North Sea region encompasses catchments of rivers such as Scheldt and Meuse. Herein, agricultural, industrial, and household chemicals are emitted, transported by water, and deposited in sediments, posing ecological risks. Though sediment monitoring is often costly and time-intensive, modeling its toxicity to biota has received little attention. Due to high complexity of interacting variables that induce overall toxicity, monitoring data only sporadically validates current models. Via a range of concepts, we related bio-physicochemical constituents of sediment in Flanders to results from toxicity bioassays performed on the ostracod Heterocypris incongruens. Depending on the water body, we explain up to 90% of the variance in H. incongruens growth. Though variable across Flanders’ main water bodies, organotin cations and ammonia dominate the observed toxicity according to toxic unit (TU) assessments. Approximately 10% relates to testing conditions/setups, species variabilities, incoherently documented pollutant concentrations, and/or bio-physicochemical sediment properties. We elucidated the influence of organotin cations and ammonia relative to other metal(oxides) and biocides. Surprisingly, the tributylin cation appeared ∼1000 times more toxic to H. incongruens as compared to “single-substance” bioassays for similar species. We inferred indirect mixture effects between organotin, ammonia, and phosphate. Via chemical speciation calculations, we observed strong physicochemical and biological interactions between phosphate and organotin cations. These interactions enhance bioconcentration and explain the elevated toxicity of organotin cations. Our study aids water managers and policy makers to interpret monitoring data on a mechanistic basis. As sampled sediments differ, future modeling requires more emphasis on characterizing and parametrizing the interactions between bioassay constituents. We envision that this will aid in bridging the gap between testing in the laboratory and field observations.

  • Changes in chlorophyll concentration and phenology in the North Sea in relation to de-eutrophication and sea surface warming

    Authors: Desmit, X.; Nohe, A.; Vieira Borges, A.; Prins, T.C.; Cauwer, K. de; Lagring, R.; Zande, D. van der; Sabbe, K. (2020)

    At least two major drivers of phytoplankton production have changed in recent decades in the North Sea: sea surface temperature (SST) has increased by app. 1.6 C between 1988 and 2014, and the nitrogen and phosphorus loads from surrounding rivers have decreased from the mid-1980s onward, following reduction policies. Long time series spanning four decades (1975–2015) of nutrients, chlorophyll (Chl), and pH measurements in the Southern and Central North Sea were analyzed to assess the impact of both the warming and the de-eutrophication trends on Chl. The de-eutrophication process, detectable in the reduction of nutrient river loads to the sea, caused a decrease of nutrient concentrations in coastal waters under riverine influence. A decline in annual mean Chl was observed at 11 out of 18 sampling sites (coastal and offshore) in the period 1988–2016. Also, a shift in Chl phenology was observed around 2000, with spring bloom formation occurring earlier in the year. A long time series of pH in the Southern North Sea showed an increase until the mid-1980s followed by a rapid decrease, suggesting changes in phytoplankton production that would support the observed changes in Chl. Linear correlations, however, did not reveal significant relationships between Chl variability and winter nutrients or SST at the sampling sites. We propose that the observed changes in Chl (annual or seasonal) around 2000 are a response of phytoplankton dynamics to multiple stressors, directly or indirectly influenced by de-eutrophication and climate warming.

  • Meteorologically generated long-period waves and their impact on the Dutch primary national flooding protection system

    Authors: Jong, M.P.C. de; Reijmerink, S.P.; Beckers, J.V.L. (2020)
    Published in: Natural hazards (2020), page 1-23

    During storms, long-period water level oscillations can occur on the North Sea. The meteorological phenomena that cause these oscillations are known to a large extent and include atmospheric single pulse perturbations or oscillations of longer duration and larger spatial scale (De Jong in Origin and prediction of seiches in Rotterdam harbour basins, Delft University of Technology, 2004). During such events, standing waves, or ‘seiches’, can occur in the ports along the Dutch North Sea coast. These seiches need to be considered in the height criteria for the dikes and other flood protection works around the port basins. Over the last decades, several projects on the climatology of seiching have been performed by Deltares under assignment by the Dutch Ministry of Public Works. Results of these projects served to update the height criteria for the storm surge barriers in the Port of Rotterdam, and as input to the design of two large new sea locks for other coastal ports, in IJmuiden and Terneuzen. This paper describes the three project locations: the statistical and hydrodynamical analyses of seiche events at these locations and the translation of the results into a buffer, or ‘seiche allowance’, to the height criteria.

  • Large scale water wave topography measurements using Free Surface Synthetic Schlieren

    Authors: Oldenziel, G.; Moreno-Rodenas, A.M.; Bruinsma, N. (2020)
    Published in: Proceedings of the 6th IAHR Europe Congress : hydro-environment research and engineering - no frames, no borders (Warsaw, February 15-18, 2021) (2020), page 1-2

    Free-surface synthetic Schlieren (FS-SS) has been introduced to reconstruct the free surface of fluids (Moisy et al., 2009). In the current work the first application of the method to a domain on the order of O(1 m2) is shown. A regular wave is reconstructed and a quantification of the signal amplitude residual with respect to a wave height meter is presented.

  • Modeling compound flooding in coastal systems using a computationally efficient reduced-physics solver: including fluvial, pluvial, tidal, wind- and wave-driven processes

    Authors: Leijnse, T.W.B.; Ormondt, M. van; Nederhoff, C.M.; Dongeren, A.R. van (2021)
    Published in: Coastal engineering : an international journal for coastal, harbour and offshore engineers, volume 163 (2021), page 1-18

    SFINCS, a new reduced-physics solver to compute compound flooding in coastal systems due to fluvial, pluvial, tidal, wind- and wave-driven processes in a computationally efficient way, is presented and validated for a number of verification and application cases. The model solves simplified equations of mass and momentum, which are driven by storm surge and wave boundary conditions, precipitation rates and upstream river discharges. It includes spatially-varying infiltration and bed roughness terms as well as an absorbing-generating seaward boundary to enable wave-driven flooding. Furthermore, advection and wind stress terms can be included. We demonstrate for the application case of hurricane impact on Jacksonville (Florida, USA) that the observed flooding was a combination of fluvial, pluvial, tidal and wind-driven flooding and that this can be modeled well using the reduced-physics solver. We show that the addition of an advection term to the momentum equations is necessary to model shock flows such as dam breaks but also incident broken waves. Thus, wave-driven flooding can be modeled with high computational efficiency and adequate accuracy as demonstrated for the case of Hernani (the Philippines). The model results show the potential of achieving good accuracy at limited computational expense.

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