3864 results

  • Building for Nature : preserving threatened bird habitat in port design

    Authors: Muller, J.R.M.; Chan, Y.; Piersma, T.; Chen, Y.; Aarninkhof, S.G.J.; Hassell, C.J.; Tao, J.; Gong, Z.; Wang, Z.B.; Maren, D.S. van (2020)
    Published in: Water, volume 12 (2020) issue 8, page 1-22

    The fast economic development of the People’s Republic of China has created an increasing demand for usable land, resulting in large-scale land reclamations along the coastal zone. One of these regions is Tongzhou Bay (Jiangsu coast), a region characterized by large intertidal mudflats and deep tidal channels with potential for the development of agri-aquaculture and the construction of a deep-sea port. However, these intertidal mudflats also provide vital ecosystem services and support many wildlife species, including several endangered migratory shorebirds within the East Asian–Australasian Flyway. With increasing realization of the importance of maintaining such ecological values, a more integrated coastal development strategy is needed. This study aims to develop a sustainable integrated design for the Tongzhou Bay port, following a “Building with Nature” approach. We use a morphodynamic model to compute habitat suitability for two shorebird species. Several port configurations were developed on the basis of three design criteria: (1) create area for future port development, whilst (2) preserving existing high-value ecotopes for shorebirds and (3) enhance the natural accretion rate of such ecotopes. Simulation results showed a clear dierence in siltation patterns, preservation and enhancement of preferred ecotopes. This work therefore demonstrates the potential and importance of morphological and habitat suitability modelling when designing large-scale reclamations and port constructions, especially in dynamic areas such as Tongzhou Bay.

  • Bank erosion processes in regulated navigable rivers

    Authors: Duro, G.; Crosato, A.; Kleinhans, M.G.; Roelvink, J.A.; Uijttewaal, W.S.J. (2020)
    Published in: Journal of geophysical research : earth surface, volume 25 (2020) issue 7, page 1-26

    Vessel‐induced waves affect the morphology and ecology of banks and shorelines around the world. In rivers used as waterways, ship passages contribute to the erosion of unprotected banks, but their short‐ and long‐term impacts remain unclear. This work investigates the effects of navigation on bank erosion along a reach of the regulated Meuse River with recently renaturalized banks. We apply UAV‐SfM photogrammetry, RTK‐GPS, acoustic Doppler velocimetry, aerial and terrestrial photography, soil tests, and multibeam echosounding to analyze the progression of bank retreat after riprap removal. After having analyzed the effects of ship‐generated waves and currents, floods, and vegetation dynamics, a process‐based model is proposed to estimate the long‐term bank retreat. The results show that a terrace evolves in length and depth across the bank according to local lithology, which we clustered in three types. Floods contribute to upper‐bank erosion‐inducing mass failures, while near‐bank flow appears increasingly ineffective to remove the failed material due to terrace elongation. Vegetation growth at the upper‐bank toe reduces bank failure and delays erosion, but its permanence is limited by terrace stability and efficiency to dissipate waves. The results also indicate that long‐term bank retreat is controlled by deep primary waves acting like bores over the terrace. Understanding the underlying drivers of bank evolution can support process‐based management to optimize the benefits of structural and functional diversity in navigable rivers.

  • A risk-based groundwater modeling framework in coastal aquifers : a case study on Long Island, New York, USA

    Authors: Karamouz, M.; Mahmoodzadeh, D.; Oude Essink, G.H.P. (2020)
    Published in: Hydrogeology journal : official journal of the International Association of Hydrogeologists (IAH) (2020), page 1-23

    A methodology is proposed to define indices for quantifying risks under the threat of reducing in groundwater levels, the existence of saltwater intrusion (SWI), and an increasing nitrate contamination load in submarine groundwater discharge (SGD). The proposed methodology considers coastal regions under geological heterogeneity and it is tested on a groundwater system in Nassau County of Long Island, New York (USA). The numerical model is constructed with the SEAWAT code. The parameter uncertainty of this model is evaluated by coupling the Latin hypercube sampling method (as a sampling algorithm) and Monte Carlo simulation to consider the uncertainty in both hydraulic conductivity and recharge rate. The indices are presented in spatial maps that classify areas of risk to potential threats. The results show that two of the water districts have a high risk under conditions of decreasing groundwater level. Salinity occurs in the southern and southwestern parts of the Nassau County aquifer and a considerable area of high risk of SWI is identified. Furthermore, the average SGD rate with the associated fluxes of nitrate is estimated as 81.4 million m3/year (average 0.8 tons of nitrate through SGD per year), which can adversely affect the quality of life in the local coastal ecosystems. The framework developed in this study could help the water district managers to identify high-risk areas for short-term and long-term planning and is applicable to other coastal settings.

  • Assessment of numerical methods for estimating the wall shear stress in turbulent Herschel–Bulkley slurries in circular pipes

    Authors: Mehta, D.; Thota Radhakrishnan, A.K.; Lier, J.B. van; Clemens, F.H.L.R. (2020)
    Published in: Journal of hydraulic research (2020), page 1-19

    This article concerns the turbulent flow of Herschel–Bulkley slurries through circular horizontal pipes, in particular, that of concentrated domestic slurry obtained upon separation of domestic waste water and reduction in the use of water for domestic purposes. Experiments with a rheologically equivalent clay (kaolin) slurry indicated a non-Newtonian behaviour of the Herschel–Bulkley type. A modified wall function was developed to enable the Reynolds-averaged Navier–Stokes simulation of Herschel–Bulkley slurries to estimate the wall shear stress. Despite the accuracy achieved, the use of Reynolds-averaged Navier–Stokes models for an entire waste water system is impractical. Therefore, this article assesses the accuracy of semi-empirical models in estimating frictional losses. It also discusses possible modifications of existing models to encompass Herschel–Bulkley behaviour. An evaluation suggests that most existing models deliver estimates of comparable accuracy; however, the probability of these estimates being reliable, while accounting for experimental errors in quantifying the actual frictional losses, is rather low.

  • High-level abundances of methanobacteriales and syntrophobacterales may help to prevent corrosion of metal sheet piles

    Authors: Zandt, M.H. in 't; Kip, N.; Frank, J.; Jansen, S.; Veen, J.A. van; Jetten, M.S.M.; Welte, C.U. (2019)
    Published in: Applied and enviromental microbiology, volume 85 (2019) issue 20, page 1-15

    Iron sheet piles are widely used in flood protection, dike construction, and river bank reinforcement. Their corrosion leads to gradual deterioration and often makes replacement necessary. Natural deposit layers on these sheet piles can prevent degradation and significantly increase their life span. However, little is known about the mechanisms of natural protective layer formation. Here, we studied the microbially diverse populations of corrosion-protective deposit layers on iron sheet piles at the Gouderak pumping station in Zuid-Holland, the Netherlands. Deposit layers, surrounding sediment and top sediment samples were analyzed for soil physicochemical parameters, microbially diverse populations, and metabolic potential. Methanogens appeared to be enriched 18-fold in the deposit layers. After sequencing, metagenome assembly and binning, we obtained four nearly complete draft genomes of microorganisms (Methanobacteriales, two Coriobacteriales, and Syntrophobacterales) that were highly enriched in the deposit layers, strongly indicating a potential role in corrosion protection. Coriobacteriales and Syntrophobacterales could be part of a microbial food web degrading organic matter to supply methanogenic substrates. Methane-producing Methanobacteriales could metabolize iron, which may initially lead to mild corrosion but potentially stimulates the formation of a carbonate-rich protective deposit layer in the long term. In addition, Methanobacteriales and Coriobacteriales have the potential to interact with metal surfaces via direct interspecies or extracellular electron transfer. In conclusion, our study provides valuable insights into microbial populations involved in iron corrosion protection and potentially enables the development of novel strategies for in situ screening of iron sheet piles in order to reduce risks and develop more sustainable replacement practices.

  • Analyse van de bijdrage van verschillende emissieroutes van gewasbeschermingsmiddelen aan de waterkwaliteit

    Authors: Kruijne, R.; Wenneker, M.; Montforts, M.; Weert, J.P.A. de; Loon, A.F. van (2020)

    Vanuit de Delta Aanpak Waterkwaliteit is besloten tot een extra inspanning om er voor te zorgen dat de waterkwaliteitsdoelen van de Kaderrichtlijn Water (KRW) in 2027 gehaald worden. Sinds 2018 krijgt dit vorm in de Kennis Impuls Waterkwaliteit (KIWK) en één van de onderwerpen in dit programma betreft de emissieroutes van gewasbeschermingsmiddelen die problemen veroorzaken met de waterkwaliteit en met de drinkwaterfunctie van oppervlaktewater en grondwater. De doelstelling van het onderhavige project is om de belangrijkste aangrijpingspunten voor emissiereductie te identificeren. In voorliggend rapport wordt het resultaat van fase 1 van dit project beschreven. De deeldoelstelling van deze fase is het inventariseren van de beschikbare kennis en het identificeren van de kennishiaten. Dit biedt aanknopingspunten voor waterbeheerders om de KRW-doelen en de doelen van de 2e nota Duurzame Gewasbescherming te realiseren.

  • Het Landelijk Waterkwaliteitsmodel : uitbreiding van het Nationaal Water Model met waterkwaliteit ten behoeve van berekeningen voor nutriënten

    Authors: Bolt, F.J.E. van der; Kroon, T.; Groenendijk, P.; Renaud, L.V.; Roovaart, J.C. van den; Janssen, G.M.C.M.; Loos, S.; Cleij, P.; Linden, A.M.A. van der; Marsman, A. (2020)

    De stuurgroep Nationaal Water Model heeft de opdracht gegeven een landelijk waterkwaliteitsmodel nutriënten te ontwikkelen. Dit Landelijk WaterKwaliteitsModel (LWKM) is gebaseerd op de recentste data, gebruikt de resultaten van het Landelijk hydrologisch Model en bouwt waar mogelijk voort op of maakt gebruik van onderdelen van eerdere modelinstrumenten als STONE en het Landelijk KRW-Verkenner Model (LKM). Dit rapport beschrijft de opzet, de realisatie, de gebruikte invoergegevens, de initialisatie, de kalibratie, de toetsing en resultaten van de eerste versie van het LWKM.

  • Verschil in uitloging van PFAS uit grond en bagger

    Authors: Wintersen, A.; Osté, L.A.; Meiracker, R. van den; Breemen, P. van; Roskam, G.D.; Spijker, J. (2020)

    De uitloging van PFAS uit landbodem, uiterwaardebodem en waterbodem (bagger) is vergelijkbaar voor deze drie categorieën bodems. Poly- en perfluoralkylstoffen (PFAS) is een verzamel naam voor duizenden stoffen. PFOS en PFOA zijn twee veelvoorkomende PFASverbindingen die in heel Nederland verspreid kunnen worden aangetroffen in concentraties van enkele microgrammen per kilogram grond of bagger. Om te voorkomen dat deze stoffen zich verder door het milieu verspreiden, zijn er eisen gesteld aan het gebruik van grond en bagger waar PFAS in zit. Grond en bagger kunnen onder andere worden gebruikt bij het ondieper maken van plassen waaruit ooit zand en klei is gewonnen. Bij dit soort toepassingen onder oppervlaktewater zullen PFOS en PFOA in ongeveer dezelfde mate vrijkomen uit de drie soorten bodems die zijn onderzocht.

  • Uncertainties in projections of sandy beach erosion due to sea level rise : an analysis at the European scale

    Authors: Athanasiou, P.; Dongeren, A.R. van; Giardino, A.; Vousdoukas, M.I.; Ranasinghe, R.; Kwadijk, J.C.J. (2020)
    Published in: Scientific reports : an open-access multidisciplinary journal, volume 10 (2020), page 1-25

    Sea level rise (SLR) will cause shoreline retreat of sandy coasts in the absence of sand supply mechanisms. These coasts have high touristic and ecological value and provide protection of valuable infrastructures and buildings to storm impacts. So far, large-scale assessments of shoreline retreat use specific datasets or assumptions for the geophysical representation of the coastal system, without any quantification of the effect that these choices might have on the assessment. Here we quantify SLR driven potential shoreline retreat and consequent coastal land loss in Europe during the twenty-first century using different combinations of geophysical datasets for (a) the location and spatial extent of sandy beaches and (b) their nearshore slopes. Using data-based spatially-varying nearshore slope data, a European averaged SLR driven median shoreline retreat of 97 m (54 m) is projected under RCP 8.5 (4.5) by year 2100, relative to the baseline year 2010. This retreat would translate to 2,500 km2 (1,400 km2) of coastal land loss (in the absence of ambient shoreline changes). A variance-based global sensitivity analysis indicates that the uncertainty associated with the choice of geophysical datasets can contribute up to 45% (26%) of the variance in coastal land loss projections for Europe by 2050 (2100). This contribution can be as high as that associated with future mitigation scenarios and SLR projections.

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