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Sediment- and morphodynamics of shoreface nourishments along the North-Holland coast
The coastal policy in the Netherlands is primarily aimed at protecting the low-lying areas against flooding. Historically, the coastal area was (and is) protected by series of dune ridges. Vulnerable locations in the beach-dune system were reinforced by building groynes, dikes and seawalls. Since about 1950, sand nourishments were occasionally applied to reinforce weak parts of the sea defence. In 1990, the Dutch government decided to fight structural coastal erosion. A reference coastline was appointed that was based on the coastline position of that year. Since then, the actual coastline position is checked against this reference every year (see, e.g., Hillen & Roelse, 1995; Van Koningsveld & Mulder, 2004). Locations that have lost significant volumes of sediment due to coastal erosion are nourished with sand.
Observations and modeling of steep-beach grain-size variability
Novel observations of surface grain-size distributions are used in combination withintra-wave modeling to examine the processes responsible for the sorting of sedimentgrains on a relatively steep beach (slope = 1:7.5).
Multimetal accumulation in crustaceans in surface water related to body size and water chemistry
Field-exposed organisms accumulated increasing amounts of Mn, Cd, Co and Ni with increasing dissolved metal concentrations. Accumulation gradually stabilized at higher concentration levels. Significant relations were found between accumulated Mn and Co for fractional occupancy of the biotic ligand and dissolved metal concentrations.
Scour protection performance of an innovative composite rubber mat at offshore wind turbine foundations
This paper describes selected aspects of the hydraulic stability of a composite matserving as scour protection at offshore wind turbine foundations.
A new coastal flood forecasting system for the Netherlands
Accurate forecasts of waves, currents and sea level are crucial for operationalmanagement and for issuing warnings during extreme events. This paper gives an overview of the many developments that are needed for an accurate and reliable forecasting system. In addition to accurate and robust numerical models, one needs scheduling with backup options, quality control of observations, good interactive displays of many datasets, manual override for operators, and much more.
Post-processing hydrological ensemble predictions intercomparison experiment
Reports on the intercomparison experiment for post-processing techniques that has been initiated in 2011 by the International Community on Hydrologic Ensemble Predictions. The design of this intercomparison experiment and the data sets available are presented. The post-processing methods that have been applied to date are listed and example results are shown. It is expected that through the exchange and joint verification and analysis of the post-processing results, the intercomparison experiment will contribute to a fast improvement and applicability of post-processing techniques.
Nuisance foam events and Phaeocystis globosa blooms in Dutch coastal waters analyzed with fuzzy logic
Phaeocystis globosa is a nuisance algal species because it can cause foam on beaches which are associated with coastal blooms. Models of Phaeocystis have considered its bloom dynamics, but not the foam formation. The process of foam formation is poorly understood which limits the suitability of traditional deterministic model approaches. We therefore applied fuzzy logic to simulate observed Phaeocystis bloom dynamics in coastal waters of the North Sea and foam formation on adjacent beaches.
Advancing data assimilation in operational hydrologic forecasting : progresses, challenges, and emerging opportunities
Data assimilation (DA) holds considerable potential for improving hydrologic predictions as demonstrated in numerous research studies. The need for effective DA of useful hydrologic data into the forecast process has become increasingly recognized in recent years. This motivated a hydrologic DA workshop in Delft, the Netherlands in November 2010, which focused on advancing DA in operational hydrologic forecasting and water resources management. As an outcome of the workshop, this paper reviews, in relevant detail, the current status of DA applications in both hydrologic research and operational practices, and discusses the existing or potential hurdles and challenges in transitioning hydrologic DA research into cost-effective operational forecasting tools, as well as the potential pathways and newly emerging opportunities for overcoming these challenges. Several related aspects are discussed, including (1) theoretical or mathematical aspects in DA algorithms, (2) the estimation of different types of uncertainty, (3) new observations and their objective use in hydrologic DA, (4) the use of DA for real-time control of water resources systems, and (5) the development of community-based, generic DA tools for hydrologic applications. It is recommended that cost-effective transition of hydrologic DA from research to operations should be helped by developing community-based, generic modeling and DA tools or frameworks, and through fostering collaborative efforts among hydrologic modellers, DA developers, and operational forecasters.
MtBE, wat moeten we er mee?! : aantonen en stimuleren biologische afbraak van MtBE
Deltares heeft samen met industriële partners een strategie ontwikkeld voor het aantonen van de biologische afbraak en het beheersen van MtBE-gerelateerde grondwater- en bodemvervuiling.
Is er al een versnelde zeespiegelstijging?
In dit artikel wordt ingegaan op de vraag in hoeverre Nederland rekening moet houden met een versnelde zeespiegelstijging. Voor het ontwerpen van dijken, dammen, sluizen, stormvloedkeringen e.d. moet rekening gehouden worden met versnelde zeespiegelstijging vanwege de lange levensduur, grote investering en weinig flexibiliteit. Voor zandsuppleties wordt thans uitgegaan van een relatieve zeespiegelstijging (ten opzichte van de bovenkant van het pleistoceen) van 20 cm per eeuw. De afgelopen eeuw heeft een stijgsnelheid van 19 cm per eeuw laten zien. De koppeling van deze lineaire trendlijn aan het lage KNMI’06-scenario levert een stijging van ongeveer 23 cm per eeuw voor het heden op. Omdat een significante versnelling niet is aangetoond, is het advies om het huidige uitgangspunt van 20 cm per eeuw vooralsnog te handhaven. Over circa zes jaar (cyclus van de toetsing van de primaire waterkeringen) kan opnieuw worden bekeken of het suppletieprogramma aangepast moet worden aan nieuwe inzichten. Dat is een verantwoorde strategie vanwege de grote flexibiliteit van het suppletieprogramma.