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Using surrogates, including scaling issues, in laboratory flumes and basins
Surrogates are partial replicas of biota, mimicking specific organism traits of relevance to the aims and objectives of the study. Physical surrogates range from generalised forms, such as hemispheres or plastic rods, to resin casts that precisely replicate morphology and texture. There are a number of practical and research benefits to using surrogates in place of living organisms but also significant limitations. Therefore, it is important that their use is carefully considered.
Using 18th-century storm-surge data from the Dutch coast to improve the confidence in flood risk estimates
For the design of cost-effective coastal defence a precise estimate is needed of the 1/10 000 per year storm surge. A more precise estimate requires more observations. Therefore, the three greatest storm surges that hit the northern part of the Holland Coast in the 18th century are reconstructed.
Safety Standards of Flood Defenses
Current design codes like the Eurocode use safety or reliability classes to assign target reliabilities to different types of structures or structural members according to the potential consequences of failure. That, in essence, is a risk-based criterion. A wide range of structures is designed with such codes, and distinction is made between reliability classes. These reliability classes are not necessarily well suited for flood defense systems, neither are the design rules and partial safety factors, which are calibrated for a wide range of standard applications. For a flood defense system protecting a large area from flooding, on the other hand, it is worthwhile to base the design and safety assessment standards on a risk assessment - a tailor-made solution. The investments can be considerable and the stakes are high, especially for low-lying delta areas, where the consequences of flooding can be devastating. In order to answer the question "How safe is safe enough?" a framework for acceptable risk is required. Subsequently, from acceptable risk we can deduce target reliabilities for the protection system as a whole as well as for its elements. For practical application, these target reliabilities can then be translated into design and assessment rules for example, using LRFD (load and resistance factor design) to derive partial safety factors.
A fresh look on effective river restoration : key conclusions from the REFORM project
There is increasing emphasis in Europe on river restoration driven by demands of the Water Framework Directive (WFD). REFORM (REstoring rivers FOR effective catchment Management) brought together 26 renowned research institutes and applied partners from 15 European countries to generate tools for cost-effective restoration of river ecosystems, and for improved monitoring of the biological effects of physical change by investigating natural, degradation and restoration processes in a wide range of river types across Europe. The interdisciplinary team of REFORM has made significant advances in clearly presenting fundamental concepts to look at hydrology, geomorphology, vegetation and aquatic biological communities in an integrated framework. The strength of REFORM also lies in the development of guidelines for measurement and conceptual frameworks to understand why restoration might succeed or fail and how restoration can be improved.
Troebel water verhelderd
Veel ondiepe meren en plassen in Nederland zijn nog altijd te troebel. Hoewel algenbloei vaak als boosdoener wordt beschouwd, speelt de opwerveling van sediment ten gevolge van wind, stroming, (macro)fauna en menselijk gebruik ook een belangrijke rol. Grontmij, Deltares en NIOO-KNAW onderzochten de relatieve bijdrage van belangrijke spelers in dit omwoelingsproces.
The extended Rijn Maas Monding model
The model of the Rijn Maas Monding (Rhine Meuse Estuary, RMM) is extended. A comparison with the hydrodynamic SOBEK reference model showed good agreement. A preliminary test with the morphological model has been performed but the morphological model needs improvement.
Shale gas and groundwater quality
In this report a literature review is presented on the environmental impacts of chemicals used in the fracturing process of shale gas extraction. The fracturing process and the chemicals that are used are briefly described. Two of these chemicals, polyacrylamide (a friction reducer) and glutaraldehyde (a biocide), are described more extensively with respect to their environmental properties such as aerobic and anaerobic bacterial, chemical or physical degradation.
Robustness of economically efficient flood protection standards
Poster presented at ICFM-5 (Tokyo) which describes how Monte Carlo-analysis was used in combination with cost-benefit analysis in order to determine the uncertainties around economically efficient flood protection standards. This study was done in the context of the CBA for Flood Protection in the 21st Century.
Quantifying the seaward effect of closing a major surge barrier during storms
We examined how peak water levels along the northern Dutch coast are affected by the closing of a surge barrier near the mouth of the River Ems. The Ems Barrier, located in northwest Germany near Emden, was put into operation in 2002. Previous modeling studies indicated that closing the Ems Barrier results in higher highwater levels seaward of the barrier, as compared to an open barrier situation, but disagree on the magnitude of this effect.
Delen van ervaringen met ecosysteemdiensten
Beschrijft op hoofdlijnen wat het concept Ecosysteemdiensten (ESD) inhoudt, waar we nu staan met de toepassing ervan, wat de belangrijkste ontwikkelingen zijn en wat voor ervaringen er dus mogelijk ook al gedeeld zouden kunnen worden.