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We zijn op een nieuw punt aanbeland in het debat over klimaatbeleid. Ooit ging het over de vraag of de aarde daadwerkelijk opwarmt door menselijk toedoen. Vervolgens ging het over de vraag wat daaraan te doen valt. Nu gaat het steeds vaker over de vraag wie de kosten van klimaatmaatregelen en van klimaatschade moet betalen. De protesten van de ‘gele hesjes’ in Frankrijk hebben laten zien hoe belangrijk het is dat de verdeling van zulke klimaatkosten als rechtvaardig gezien wordt. Als dat niet het geval is, dan kan het draagvlak voor klimaatbeleid afkalven. Hoe kunnen rechtvaardige verdelingen eruit zien? Dat analyseert de Wetenschappelijke Raad voor het Regeringsbeleid (wrr) in dit rapport. De hoofdboodschap van dit rapport is dat er in klimaatbeleid stelselmatige aandacht moet zijn voor de rechtvaardigheid van verdelingen. Maatregelen dienen niet alleen beoordeeld te worden vanuit het perspectief van doelmatigheid en rechtmatigheid, maar ook vanuit het perspectief van rechtvaardigheid. Onze belangrijkste boodschap is daarom dat de mogelijke verdelingen van klimaatkosten al vooraf expliciet op tafel komen en worden doordacht. Dat helpt beleidsmakers om meer oog te krijgen voor mogelijke onbedoelde en ongewenste neveneffecten. Het leidt ook tot een meer afgewogen en transparanter politiek debat. En het zorgt ervoor dat het draagvlak voor klimaatbeleid op peil blijft. De wrr doet drie aanbevelingen hoe de overheid rechtvaardige verdelingen in het klimaatbeleid tot stand kan brengen: zorg voor (1) inhoudelijke verbreding, (2) procedurele verankering en (3) institutionele borging.

Research content This poster presents selected findings from the article Unsteady linearisation of bed shear stress for idealised storm surge modelling of 2021 for the participants in the NCK Days 2022, the yearly get-together of the Netherlands Centre for Coastal Research. The summary underlying the poster is available from the event's Book of Abstracts both as web page and as PDF document. The poster is open-access under a Creative Commons Attribution 4.0 International. Document design: structure and styling The conference organisers required the production of a paper-based poster in A0 format with portrait orientation. The document has been designed in A4 format, as available from the copy shared in this website. A resolution of 1200 dpi produced sharp enough images when printing in A0 size a document in PDF format. The whole document has been composed as a three-column table of a Google Doc document, with row-wise column merges which produce a well-marked layout consisting of stacked rows. In order to favour speed-reading, two font types and sizes produce a contrast between headings and narrative. Likewise, the text blocks are made of short and clearly spaced paragraphs, easy to point to and scan. The font size in the text body was readable when printed in A0 and, in retrospect for the specific venue the poster has been presented in, could still have been reduced to the same effect. Test prints confirmed that an additional margin would have been present around the page. The poster promotes a study published in a journal article, whereby the methods and results on display are already established. The audience is assumed to have been attracted by the poster title, thus to have been moved by an affinity for the topical area and to nurse a potential curiosity about reading the article in depth. As a result, the slant of this poster is intendedly descriptive, if not unimaginative; visuals are not especially meant or positioned to catch the eye. Document design: narrative and presentation The findings selected for the poster are those encapsulating the novelties of the article most compactly. This content selection provides maximum integration between narrative and scientific advances within the limited space of the document and of the interactions in a poster session. The table cells organise information progressively more detailed in the reading direction, broadly following a general-to-specific or abstraction-to-implementation order. During a poster session, the poster presenter could illustrate the content either in a bottom-up fashion starting from the results, supported by cartoons and graphs; or top-down, starting from the generalities presented as textual narrative. Outside the poster session, interested passerbys may find essential guidance into the topic scanning the poster in normal reading direction. Document design: on-line dissemination Hyperlinks to further resources, aimed at the digital poster version, are in blue. The DOI of this document has been reserved upon creating an unpublished Zenodo entry while drafting the poster. The DOI is shown in the poster so as to inform the viewers of the possibility to download the document after the conference. The poster has been uploaded ahead of the event and embargoed until the planned day of the off-line presentation. The publication date is the date of the poster session. Description authored by Giordano Lipari, {"references":["Roos PC, Lipari G, Pitzalis C, Reef KRG, Campmans GHP, Hulscher SJMH. Unsteady Linearisation of Bed Shear Stress for Idealised Storm Surge Modelling. Journal of Marine Science and Engineering. 2021; 9(11):1160. https://doi.org/10.3390/jmse9111160"]}

Scheepvaart zorgt lokaal voor een verhoging van de stroomsnelheid en turbulentie bovenop de al aanwezige rivierafvoer. De geometrie van de rivierduinen ondervindt indirect effect van de scheepsstromingen middels de dynamiek van de kribvlammen. Daarmee zet dit onderzoek een eerste stap in het kwantificeren van het scheepvaarteffect op de ontwikkeling van rivierduin

Global climate change affects all aspects of river processes. It is expected that discharge extremes will occur more often in the future and that the probability of high and low flows in a shorter period will increase. Given these changes in hydrometeorological conditions, the question arises whether it is possible to set up a hydraulic model that simulates both high, intermediate and low flows in rivers accurately. However, hydraulic models are currently calibrated for a specific discharge range. Consequently, it is not possible to evaluate the effects of river interventions for a wide range of conditions with such a calibrated model. Therefore, this study gives an overview of the current state of hydraulic calibration approaches applied in literature and aims to give insights in how these calibration approaches can be improved such that a hydraulic model can be calibrated and applied for varying discharge conditions. Exploring the literature showed that the most commonly used parameter for calibration is roughness that is calibrated one time for one specific discharge or calibrated separately for different calibrated ranges.

Sandy beaches are very attractive to people worldwide. The attractiveness of sandy beaches increases the demands for the construction of buildings at the beach-dune interface. These buildings alter the local airflow patterns in the surrounding area which, in turn, induces changes in the aeolian sediment transport and morphological patterns around buildings at the beach. In the present study, the impact of spacing between adjacent buildings in a rowon the erosion and deposition patterns in the surrounding area and downstream is studied.A computational fluid dynamics model using OpenFOAM is developed to simulate the three-dimensional airflow patterns around a row of ten full-scale buildings at the beach. The spacing between two adjacent buildings is systematically changed between 0.1wand4w, where w is the buildings’ width.Based on the horizontal wake flow patterns close to the bed, a spacing of 0.9w appears to be the critical spacing belowwhich the neighboring buildings significantly affect each other, and the secondary flow structures in the lee of buildings are quite complex.Results show different near-bed erosion and deposition patterns around buildings as the spacing between two adjacent buildings increases.The initial morphological changes around buildings are fully independent and buildings act as isolated buildings when the spacing between buildings increases to 4w.

We present a depth-resolving model that is capable of resolving the vertical flow and suspended sediment structures in the surf and in the swash zones. The model uses the RANS equations to simulate hydrodynamics, and includes sediment transport using an advection diffusion approach. The model is first validated hydrodynamically using measured surface elevations. The results from the model show a strong vertical dependence in the suspended sediment flux, and that at certain cross-shore locations the wave-averaged sediment transport moves onshore where the average flow velocity is offshore-directed. These physical processes are important to consider when designing more practical, long-term depth-averaged models for simulating coastal morphodynamics.

Sandbanks are large-scale dynamic bedforms of sandy sediment that are found in shallow seas. They may occur in areas where the sediment supply is limited such as on the Belgian Continental Shelf. These sandbanks serve important ecological and economic functions (e.g. sand extraction). However, our understanding of the long-term morphodynamics of tidal sandbanks under sediment-scarce conditions is limited due to a lack of process-based modelling support. Here, we study equilibrium cross-sections and the morphodynamic evolution towards an equilibrium by extending a process-based model to account for sediment scarcity. Our model includes a non-erodible layer, which limits sediment entrainment. The model results show that the presence of a non-erodible layer limits the amplitude of a sandbank and sharpens the crest in its equilibrium state. The bank width remains unaffected. Furthermore, our results show that sandbanks reach equilibria faster when a non-erodible layer is present. However, the rate of amplitude growth of a bank crest is unaffected for a long period after the non-erodible layer is exposed under the conditions in this study. Our results are valuable for identifying potential impacts of sand extractions in sandbank fields with limited sand available in the seabed.

Flooding is one of the most damaging and frequent natural hazards in the world and it is expected that flood events will affect even more people in the future due to climate change, land use change and population growth. The use of proper evacuation schemes has the potential to reduce the consequences of a flood event, i.e. reducing the damage and the number of life-losses and cattle-losses, in areas at risk significantly. Typically, sophisticated two-dimensional (2D) hydraulic models are used to simulate flood propagation of severe flood events to inform flood management decisions. Although these models have proven to be accurate in predicting flood wave propagation and inundation extents in areas with complex dynamic interactions, these models cannot be used for short-term flood forecasting due to the high computational demands and long simulation times. For this reason, emulators (e.g. artificial neural networks (ANNs)) have gained much attention in recent years. In this study, we set up neural networks that are able to predict the dike failure locations during flood events and corresponding outflow hydrographs, based on discharge measurements at an upstream gauge station. These outflow hydrographs can be used to predict the potential inundated areas, enabling evacuation of the people in the areas at risk on time.

The ebb-tidal delta of the Ameland Inlet system is of great ecological importance since it hosts a variety of benthic habitats. In a pilot project, a (mega)nourishment of 5 million cubic meters of sand was carried out on the outer ebb-tidal delta. Since the strong correlation between habitat preference and sediment characteristics on the ebb-tidal delta, it is crucial to gain insight in the mechanisms governing sediment sorting in this area. To study the initial response of grain size distribution patterns, and subsequently potential changes to benthic habitats, process-based models are useful tools. Here, we present a hydro- morphodynamic model of the Ameland Inlet which is able to simulate grain size sorting patterns. Building upon previous modelling efforts, we specifically focus on the inclusion of graded sediment transport and bed stratigraphy. The simulations, here with the nourishment excluded, reveal that the model results on grain size distribution can be related well to the forcing in combination with the local depth. Particularly, it turns out that tidal motion is responsible for the sorting pattern in the deeper parts of the ebb-tidal delta, whereas the grain size distribution in the shallower, offshore parts is particularly shaped by wind and wave processes. Model sensitivity to several numerical parameters (thickness transport layer, MORFAC) is also investigated and seems relatively small, although further investigation is needed here. A preliminary comparison reveals that the model results compare qualitatively well to field data, although the shallower offshore areas seem to be predicted too coarse in the model

Erosion by overtopping waves can lead to failure of grass-covered earthen flood defences. Previous studies have indicated that cover failure starts at changes in material or geometry defined as transitions. In this study, the overtopping flow at geometrical transitions is modelled and their effect on the hydraulic load is quantified. A numerical model is developed in the OpenFOAM software and simulates the overtopping flow over the crest and the landward slope of a grass-covered flood defense. Two types of geometrical transitions were studied: slope changes and height differences. These transitions are representative for the landward crest line, the landward toe, erosion holes on the slope and a road on the crest. New relations are developed for the maximum shear stress and the maximum normal stress as result of the geometrical transitions using design parameters such as the geometry and the overtopping volume. These relations can be used in existing calculation methods to include the effects of geometrical transitions on the hydraulic load for the design and the safety assessment of flood defences.

The overtopping flow velocity and layer thickness are closely related to the stability of coastal structures. Some empirical formulas are available for estimating the overtopping flow velocities and layer thicknesses. However, these empirical equations were derived based on experiments where only limited amount of wave conditions and dike configurations (mostly smooth straight waterside slopes) were tested. Therefore, the extrapolation of existing empirical equations to cases that are outside of the applicable ranges remains uncertain. Numerical modelling has become an important complementary tool to physical experiments. In this study, we developed a 2DV numerical model based on the OpenFOAM framework to simulate the overtopping flow velocity and layer thickness at the waterside edge of the dike crest. This model is validated by comparing the modelled overtopping flow parameters with the measured ones from physical experiments. The model validation shows that the 2DV OpenFOAM model is capable of predicting the overtopping flow parameters with a low probability (2%) of exceedance reasonably well although the overtopping layer thickness is slightly overestimated.