3645 resultaten

  • Providing support in relation to the implementation of the EU Soil Thematic Strategy : Potential of Earth Observation for improved soil monitoring

    Auteur: Wawer, R. (2019)

    The report provides an overview of remote sensing techniques and their maturity in assessing soils’ properties and degradation processes. The report also elaborates some practical examples where earth observation and soil information are linked and it gives a set of recommendations to further improve the use of Earth Observation for soil monitoring.

  • Providing support in relation to the implementation of the EU Soil Thematic Strategy : identification of priority areas for improving consistency and interoperability of EU-wide and national soil monitoring and information systems

    Auteurs: Vonhögen-Peeters, L.M.; Blauw, M. (2019)

    Action must be taken to improve the consistency and interoperability of SMIS. To achieve this goal, it is important to know what data and information MS have available, what the data and information gaps are and what is holding MS back from sharing information. These questions are addressed in this report.

  • Providing support in relation to the implementation of the EU Soil Thematic Strategy : Drivers and transboundary impacts of soil degradation

    Auteur: Hagemann, N. (2019)

    This report presents evidence of the societal challenges of transboundary impacts, the drivers, and consequences of soil degradation, as well as data and knowledge gaps. The message conveyed by the report is that there is clear evidence of transboundary impacts and drivers of soil degradation and that it has physical, ecological, economic and social causes. Soil degradation does not stop at borders.

  • A generating and absorbing boundary condition for dispersive waves in detailed simulations of free-surface flow interaction with marine structures

    Auteurs: Wellens, P.R.; Borsboom, M.J.A. (2019)
    Gepubliceerd in: Computers and fluids : an international journal (2019), pagina 1-20

    The boundaries of numerical domains for free-surface wave simulations with marine structures generate spurious wave reflection if no special measures are taken to prevent it. The common way to prevent reflection is to use dissipation zones at the cost of increased computational effort. On many occasions, the size of the dissipation area is considerably larger than the area of interest where wave interaction with the structure takes place. Our objective is to derive a local absorbing boundary condition that has equal performance to a dissipation zone with lower computational cost. The boundary condition is designed for irregular free-surface wave simulations in numerical methods that resolve the vertical dimension with multiple cells. It is for a range of phase velocities, meaning that the reflection coefficient per wave component is lower than a chosen value, say 2%, over a range of values for the dimensionless wave number kh. This is accomplished by extending the Sommerfeld boundary condition with an approximation of the linear dispersion relation in terms of kh, in combination with vertical derivatives of the solution variables. For this article, the boundary condition is extended with a non-zero right-hand side in order to to prevent wave reflection, while, at the same time, at the same boundary, generating waves that propagate into the domain. Results of irregular wave simulations are shown to correspond to the analytical reflection coefficient for a range of wave numbers, and to have similar performance to a dissipation zone at a lower cost.

  • Proceedings of the 14th International Peat Congress : peatlands in balance (Stockholm, Sweden, June 3-8, 2012)

    Originally published in 2012

  • Advancing global storm surge modelling using the new ERA5 climate reanalysis

    Auteurs: Dullaart, J.C.M.; Muis, S.; Bloemendaal, N.; Aerts, J.C.J.H. (2019)
    Gepubliceerd in: Climate Dynamics (2019), pagina 1-15

    This study examines the implications of recent advances in global climate modelling for simulating storm surges. Following the ERA-Interim global climate reanalysis, in 2018 the European Centre for Medium-range Weather Forecasts released its successor, the ERA5 reanalysis. Using the Global Tide and Surge Model, we analyse eight historical storm surge events driven by tropical- and extra-tropical cyclones. For these events we extract wind fields from the two reanalysis datasets and compare these against satellite-based wind field observations from the Advanced SCATterometer. The root mean squared errors in tropical cyclone wind speed reduce by 58% in ERA5, compared to ERA-Interim, indicating that the mean sea-level pressure and corresponding strong 10-m winds in tropical cyclones greatly improved from ERA-Interim to ERA5. For four of the eight historical events we validate the modelled storm surge heights with tide gauge observations. For Hurricane Irma, the modelled surge height increases from 0.88 m with ERA-Interim to 2.68 m with ERA5, compared to an observed surge height of 2.64 m. We also examine how future advances in climate modelling can potentially further improve global storm surge modelling by comparing the results for ERA-Interim and ERA5 against the operational Integrated Forecasting System. We find that a further increase in model resolution results in a better representation of the wind fields and associated storm surges, especially for small size tropical cyclones. Overall, our results show that recent advances in global climate modelling have the potential to increase the accuracy of early-warning systems and coastal flood hazard assessments at the global scale.

  • Assessing the fresh–saline groundwater distribution in the Nile Delta aquifer using a 3D variable-density groundwater flow model

    Auteurs: Mabrouk, M.; Jonoski, A.; Oude Essink, G.H.P.; Uhlenbrook, S. (2019)
    Gepubliceerd in: Water, volume 11 (2019) nummer 9

    The Nile Delta Aquifer (NDA) is threatened by salt water intrusion (SWI). This article demonstrates an approach for identifying critical salinity concentration zones using a three-dimensional (3D) variable-density groundwater flow model in the NDA. An innovative procedure is presented for the delineation of salinity concentration in 2010 by testing different simulation periods. The results confirm the presence of saline groundwater caused by SWI in the north of the NDA. In addition, certain regions in the east and southwest of the NDA show increased salinity concentration levels, possibly due to excessive groundwater extraction and dissolution of marine fractured limestone and shale that form the bedrock underlying the aquifer. The research shows that the NDA is still not in a state of dynamic equilibrium. The modeling instrument can be used for simulating future scenarios of SWI to provide a sustainable adaptation plan for groundwater resource.

  • Interdisciplinary science to support North Sea marine management : lessons learned and future demands

    Auteurs: Degraer, S.; Lancker, V. van; Dijk, T.A.G.P. van (2019)
    Gepubliceerd in: Hydrobiologia (2019), pagina 1-11

    The expected increase of maritime activities in the North Sea and the growing awareness of its natural environmental value require enhanced science-based environmental advice for more efficient and effective marine management. The North Sea Open Science Conference organised by the Royal Belgian Institute of Natural Sciences and the Belgian Biodiversity Platform in 2016 aimed to take stock of the present-day scientific knowledge on the North Sea ecosystem, its interactions with human activities and its management. The conference was structured along three themes: (1) ‘the scientific backbone of the North Sea ecosystem: adequacy of the knowledge base?’, (2) ‘A new era in environmental monitoring and assessment: what is at stake?’, and (3) ‘Sustainability: one for all, all for one?’. Focusing on ‘open science’, we welcomed about 200 participants from around the North Sea with different backgrounds and interests in environmental sciences. The participants were challenged to reflect on current and future challenges for the North Sea management and, in particular, to explore possible nature-friendly solutions for addressing these challenges during a series of introductory oral (69) and poster (59) presentations, and World Café and Fish Bowl participatory sessions. The participants agreed on six main actions to (1) provide a solid scientific base for marine management decisions; (2) develop society-driven research; (3) increase interdisciplinary science; (4) recognise the need for system knowledge; (5) improve communication, knowledge exchange, and collective implementation of scientific knowledge; and (6) build integrated knowledge bases. For each of these, concrete action points were identified, and this review gives the most important and relevant ones for creating the knowledge base and managerial framework for a sustainable North Sea.

  • Decline in terrestrial moisture sources of the Mississippi River Basin in a future climate

    Auteurs: Benedict, I.; Heerwaarden, C.C. van; Ent, R.J. van der; Weerts, A.H.; Hazeleger, W. (2019)
    Gepubliceerd in: Journal of hydrometeorology (2019), pagina 1-51

    Assessment of the impact of climate change on water resources over land requires knowledge on the origin of the precipitation and changes therein towards the future. We determine the origin of precipitation over the Mississippi River Basin (MRB) using high resolution (~25 km) climate model simulations for present and future climate (RCP4.5). Moisture resulting in precipitation over the MRB is tracked back in time using Eulerian offline moisture tracking, in order to find out where this water originally evaporated (i.e. the moisture sources). We find that the most important continental moisture sources are the MRB itself and the area southwest of the basin. The two most relevant oceanic sources are the Gulf of Mexico/Caribbean and the Pacific. The distribution of sources varies per season, with more recycling of moisture within the basin during summer and more transport of moisture from the ocean towards the basin in winter. In future winters, we find an increase in moisture source from the oceans (related to higher sea surface temperatures), resulting in more precipitation over the MRB. In future summers, we find an approximately five per cent decrease in moisture source from the basin itself, while the decrease in precipitation is smaller (i.e. lower recycling ratios). The results here are based on one climate model, and we do not study low-frequency climate variability. We conclude that Mississippi’s moisture sources will become less local in a future climate, with more water originating from the oceans.

  • Kustmöte 2019 : naturbaserade lösningar (Malmö, 17-18 September 2019)

    Originally published in 2019

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