Publications

4073 results

  • Klimaatadaptatie en transitiemanagement

    Authors: Brugge, R. van der; Winter, R. de; Mens, M.J.P.; Haasnoot, M. (2020)
    Published in: Water governance (2020), page 13-19

    Het waterbeheer in Nederland staat voor een grote klimaatadaptatie opgave. Deze opgave vergt meer dan het verder optimaliseren van het watersysteem. Het vraagt namelijk ook om aanpassingen van de functies die van het water gebruik maken. We illustreren dat aan de hand van twee opgaven: droogte en zeespiegelstijging. Tot op heden slaagt men er echter niet goed in om die functieveranderingen te initiëren en gebiedstransities vorm te geven. Het Deltaprogramma, als nationaal klimaatadaptatieprogramma, zou zich daar meer op moeten gaan richten. Inzichten vanuit de theorie en praktijk van transitiemanagement kunnen helpen om de gebiedstransities vorm te geven.

  • The Ganga River Basin : a hydrometeorological approach

    Authors: Chauhan, M.V.; Ojha, C.S.P. (2020)

  • How are European countries planning for sea level rise?

    Authors: McEvoy, S.; Haasnoot, M.; Biesbroek, R. (2021)
    Published in: Ocean and coastal management, volume 203 (2021), page 1-11

    Sea level rise (SLR) is projected to have severe consequences for people and assets in European coastal areas. Planning for SLR is a critical step to ensure timely and adequate responses. Despite our rapidly increasing understanding of SLR impacts and the need to adapt, few studies have looked at how countries are planning for SLR. We surveyed experts from the 32 European countries with a coastline about how their country is planning for SLR. Our online survey focused on four areas: (1) whether SLR planning exists and at what level of government; (2) which climate information and scenarios are used in planning; (3) what planning horizons and corresponding levels of SLR are used; and (4) how uncertainty in handled and whether high-end sea level rise is being considered in planning. Additionally, we asked experts to assess the status of sea level rise planning in their country. Our results indicate that most coastal countries in Europe are planning for SLR, but 25% still do not. We find that the planning horizon 2100 is most common and many countries are considering around 1m (adjusted for local conditions) of SLR at that point in time. However, there are significant differences between countries, which may lead to unequal impacts, over time. We also find that RCP4.5 and RCP8.5 are the most widely used climate change scenarios, suggesting that countries are considering high-end climate change in planning, although this does not mean they consider high amounts of SLR. Important questions remain about how planning is realized into levels of protection or preparedness and whether the amounts of SLR and planning horizons currently in use will lead countries to act in time.

  • A data-driven surrogate approach for the temporal stability forecasting of vegetation covered dikes

    Authors: Jamalinia, E.; Tehrani, F.S.; Steele-Dunne, S.C.; Vardon, P.J. (2021)
    Published in: Water, volume 13 (2021) issue 1, page 1-25

    Climatic conditions and vegetation cover influence water flux in a dike, and potentially the dike stability. A comprehensive numerical simulation is computationally too expensive to be used for the near real-time analysis of a dike network. Therefore, this study investigates a random forest (RF) regressor to build a data-driven surrogate for a numerical model to forecast the temporal macrostability of dikes. To that end, daily inputs and outputs of a ten-year coupled numerical simulation of an idealised dike (2009–2019) are used to create a synthetic data set, comprising features that can be observed from a dike surface, with the calculated factor of safety (FoS) as the target variable. The data set before 2018 is split into training and testing sets to build and train the RF. The predicted FoS is strongly correlated with the numerical FoS for data that belong to the test set (before 2018). However, the trained model shows lower performance for data in the evaluation set (after 2018) if further surface cracking occurs. This proof-of-concept shows that a data-driven surrogate can be used to determine dike stability for conditions similar to the training data, which could be used to identify vulnerable locations in a dike network for further examination.

  • Optimale ondergrondse inpassing van open bodemenergiesystemen

    Authors: Bloemendal, M.; Kleinlugtenbelt, R.; Valstar, J.; Asten, M. van; Mars, J.F. (2020)
    Published in: H2O : tijdschrift voor drinkwatervoorziening en afvalwaterbehandeling (2020), page 1-8

    De ondergrondse potentie van bodemenergie wordt nog niet volledig benut en vooral in binnenstedelijke gebieden is nog ondergrondse ruimte beschikbaar. Te dicht op elkaar geplaatste (open) bodemenergiesysteembronnen kunnen elkaar echter negatief beïnvloeden. Er is onderzocht wat de invloed is van het dichter bij elkaar plaatsen van bodemenergiesysteembronnen op het energierendement van de bodemenergiesystemen. Hieruit blijkt dan er CO2 kan worden bespaard, zonder het energierendement van individuele systemen te verslechteren.

  • The long-term morphological response to sea level rise and different sediment strategies in the Western Scheldt estuary (The Netherlands)

    Authors: Röbke, B.R.; Elmilady, H.; Wegen, M. van der; Taal, M.D. (2020)

    The objective of this study is to gain insight into the relative impact of (extreme) sea level rise (SLR) and different sediment strategies, i.e. dredging and dumping and beach nourishments, on the hydro- and morphodynamic behaviour of the Western Scheldt estuary (The Netherlands) till the end of the 21st century. For this, a process-based numerical morphodynamic model (DElft3D version 4) is applied that accounts for continuously changing hydrodynamic boundary conditions associated with SLR as well as for different dredging and dumping strategies and beach nourishments.

  • Consolidation and strength development by horizontal drainage of soft mud deposits in lake Markermeer

    Authors: Barciela Rial, M.; Winterwerp, J.C.; Griffioen, J.; Kessel, T. van (2015)

    With the described experimental and mathematical methods, the characteristic consolidation parameters of the clayey soil can be obtained. Moreover, the effects of vegetation, evaporation/precipitation and organic geochemistry can be included in the equation (or boundary conditions or material parameters) in the future. Finally, the derived equations for consolidation with horizontal drainage can be implemented in a 2D transport model, such as Delft 3D. Thus, this method represents a powerful tool which can be used to develop engineering rules for wetland creation from soft sediment.

  • Drivers of nitrogen and phosphorus dynamics in a groundwater-fed urban catchment revealed by high-frequency monitoring

    Authors: Yu, L.; Rozemeijer, J.C.; Broers, H.P.; Breukelen, B.M. van; Middelburg, J.J.; Ouboter, M.; Velde, Y. van der (2021)
    Published in: Hydrology and earth system sciences, volume 25 (2021) issue 1, page 69-87

    Eutrophication of water bodies has been a problem causing severe degradation of water quality in cities. To gain mechanistic understanding of the temporal dynamics of nitrogen (N) and phosphorus (P) in a groundwater-fed low-lying urban polder, we applied high-frequency monitoring in Geuzenveld, a polder in the city of Amsterdam. The high-frequency monitoring equipment was installed at the pumping station where water leaves the polder. From March 2016 to June 2017, total phosphorus (TP), ammonium (NH4), turbidity, electrical conductivity (EC), and water temperature were measured at intervals of less than 20 min. This paper discusses the results at three timescales: annual scale, rain event scale, and single pumping event scale. Mixing of upwelling groundwater (main source of N and P) and runoff from precipitation on pavements and roofs was the dominant hydrological process governing the temporal pattern of the EC, while N and P fluxes from the polder were also regulated by primary production and iron transformations. In our groundwater-seepage controlled catchment, NH4 appeared to be the dominant form of N with surface water concentrations in the range of 2–6 mg N L−1, which stems from production in an organic-rich subsurface. The concentrations of NH4 in the surface water were governed by the mixing process in autumn and winter and were reduced down to 0.1 mg N L−1 during the algal growing season in spring. The depletion of dissolved NH4 in spring suggests uptake by primary producers, consistent with high concentrations of chlorophyll a, O2, and suspended solids during this period. Total P and turbidity were high during winter (range 0.5–2.5 mg P L−1 and 200–1800 FNU, respectively, where FNU represents Formazin Nephelometric Unit) due to the release of P and reduced iron from anoxic sediment to the water column, where Fe2+ was rapidly oxidized and precipitated as iron oxides which contributed to turbidity. In the other seasons, P is retained in the sediment by sorption to precipitated iron oxides. Nitrogen is exported from the polder to the receiving waters throughout the whole year, mostly in the form of NH4 but in the form of organic N in spring. P leaves the polder mainly during winter, primarily associated with Fe(OH)3 colloids and as dissolved P. Based on this new understanding of the dynamics of N and P in this low-lying urban catchment, we suggested management strategies that may effectively control and reduce eutrophication in urban polders and receiving downstream waters.

  • Numerical simulation of wave overtopping at dikes

    Authors: Chen, W.; Warmink, J.J.; Gent, M.R.A. van; Hulscher, S.J.M.H. (2020)
    Published in: ICCE 2020 : proceedings of the virtual International Conference Coastal Engineering 2020 (6-9 October 2020) (2020), page 1-10

    The average overtopping discharge is an important parameter for the design of flood defences. Several empirical formulas are available for predicting the overtopping discharge at dikes. However, these empirical formulas often have their specific applicable conditions. To complement with the empirical methods, a numerical model has been developed using the open source CFD package OpenFOAM to model the wave overtopping at dikes. Systematic calibration and validation of the numerical model are performed. The influences of the mesh, solver, turbulence model and roughness height on the modelled results of the average overtopping discharge have been investigated during the model calibration. The simulations show that the turbulence model increases the accuracy of the numerical model for predicting the average overtopping discharge under wave breaking conditions. The calibrated model is then validated by comparing the modelled average overtopping discharges with the measured ones from the physical model tests. Results show that the OpenFOAM model is capable of predicting the average overtopping discharge accurately at dikes that have a smooth straight waterside slope.

  • Stability of high density cubes in rubble mound breakwaters

    Authors: Yuksel, Y.; Gent, M.R.A. van; Cevik, E.; Kaya, H.A.; Gumuscu, I.; Yuksel, Z.T.; Yalciner, A.C. (2020)
    Published in: ICCE 2020 : proceedings of the virtual International Conference Coastal Engineering 2020 (6-9 October 2020) (2020), page 1

    An experimental research was carried out in the wave flume of the Coastal and Harbor Engineering laboratory at Yildiz Technical University. Normal and high density concrete cube armor unit breakwater models for a trunk section were tested to provide insight into their behavior. The experimental results show that the stability of high density blocks were found to be more stable and the damage initiation for high density blocks started at higher stability numbers compared to normal density cubes.

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