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Within the frame work of the realisation of the ‘Sigmaplan’ for the river Schelde in Flanders (Belgium), a large-scale dike breaching experiment following overflow was held at Lillo (Antwerp) in 2012. The outcomes of the breach test serve to unveil the impact of a chosen breach growth model, to set application limits, to come up with guidelines for proper selection and usage of the model to be applied.Breach growth models are used to predict the breach dimensions and to estimate the flow through the breach. All assessed models pretty well succeed in this. However, starting from various premises and taking into account a (limited) set of different breaching mechanisms, the use of today’s state-of-the-art breach growth models is not entirely trouble free

Flood defense failures are rare events but when they do occur lead to significant amounts of damage. The defenses are usually designed for rather low-frequency hydraulic loading and as such typically at least high enough to prevent overflow. When they fail, flood defenses like levees built with modern design codes usually either fail due to wave overtopping or geotechnical failure mechanisms such as instability or internal erosion. Subsequently geotechnical failures could trigger an overflow leading for the breach to grow in size Not only the conditions relevant for these failure mechanisms are highly uncertain, also the model uncertainty in geomechanical, internal erosion models, or breach models are high compared to other structural models. Hence, there is a need for better validation and calibration of models or, in other words, better insight in model uncertainty. As scale effects typically play an important role and full-scale testing is challenging and costly, historic flood defense failures can be used to provide insights into the real failure processes and conditions. The recently initiated SAFElevee project at Delft University of Technology aims to exploit this source of information by performing back analysis of levee failures at different level of detail. Besides detailed process based analyses, the project aims to investigate spatial and temporal patterns in deformation as a function of the hydrodynamic loading using satellite radar interferometry (i.e. PS-InSAR) in order to examine its relation with levee failure mechanisms. The project aims to combine probabilistic approaches with the mechanics of the various relevant failure mechanisms to reduce model uncertainty and propose improvements to assessment and design models. This paper describes the approach of the study to levee breach analysis and the use of satellites for breach initiation analysis, both adopted within the SAFElevee project.

Het klimaat verandert en de zeespiegel stijgt. Daarover bestaat geen twijfel, hoewel er nog wel onzekerheid bestaat over de snelheid van de veranderingen, en soms over de precieze richting daarvan. Ondanks deze onzekerheden is het verstandig te anticiperen op wat komen gaat. Daar zijn we in Nederland dan ook al volop mee bezig. In de afgelopen jaren is in diverse projecten en programma’s zoals Kennis voor Klimaat, het Deltaprogramma en STOWA/Deltaproof, veel kennis opgedaan over mogelijke strategieën om ons aan te passen aan de veranderende klimatologische omstandigheden. Maar hoe zien dergelijke adaptatiestrategieën er precies uit en hoe kom je tot een concrete invulling? Dit rapport geeft een overzicht van concrete maatregelen die kunnen worden ingezet bij adaptatie in verband met de toenemende overstromingsrisico’s. Het rapport richt zich vooral op wat gemeenten, provincies en waterschappen kunnen doen.

Flood risk management in Europe and worldwide is not static but constantly in a state of flux. There has been a trend towards more integrated flood risk management in many countries. However, the initial situation and the pace and direction of change is very different in the various countries. In this paper, we will present a conceptual framework that seeks to explain why countries opt for different flood risk management portfolios. The developed framework utilises insights from a range of policy science concepts in an integrated way and considers, among others, factors such as geographical characteristics, the experience with flood disasters, as well as human behavioural aspects.

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Accurate estimates of design water levels are essential, because they determine the required dimensions of the flood defences. Hydrodynamic models are used for the prediction of flood water levels to support flood safety and are often applied in a deterministic way. However, the modelling of river processes involves numerous uncertainties. Literature has shown that the hydraulic roughness is one of the main sources of uncertainty in hydrodynamic computations. Knowledge of the type and magnitude of uncertainties is crucial for a meaningful interpretation of the model outcomes and their usefulness in decision making. We show that the uncertainty of a complex model factor, such as the hydraulic roughness, can be quantified explicitly. The hydraulic roughness has been unravelled in separate components, which have been quantified separately and then combined and propagated through the model. Expert opinions revealed that the uncertainty due to bed form roughness in the main channel and vegetation roughness in the floodplains were shown to be the major contributors. Quantifica-tion of these sources and propagation through the WAQUA model using Monte Carlo analyses showed that this resulted in a 95% confidence interval around the Design Water Levels (DWL) of 68 cm for the river Waal. This uncertainty range consisted of the uncertainty due to bed forms with an uncertainty of 49 cm on the DWL, and an uncertainty of 34 cm due to vegetation roughness uncertainty. The main source of uncertainty was shown to be the variability of the roughness values depending on the various possible roughness models.

The UrbanFlood project is creating an Early Warning System framework that can be used to link sensors via the Internet to predictive models and emergency warning systems. The project includes four pilot sites to apply and validate at full scale the technology being developed in the project: Amsterdam (Netherlands), Boston (UK) and Rhine River (Germany). This paper focuses on a description of the sensor instrumentation installed at the pilot sites and the emerging conclusions from the analysis of the results obtained to date. The sensors installed at the various sites include various MEMS modules to measure displacement and pore pressure and fibre optic cables able to detect strains. The gathered data are used for dike stability evaluation with different models and also, combined with an Artificial Intelligence (AI) component, for detection of anomalies in dike behaviour. Detected anomalies trigger assessment of the likelihood of levee breach and the consequences in terms of flood propagation and damage in the defended urban area.

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Dit rapport geeft de samenvatting van de rapportage over het project Gebiedsstandaardisatie, een onderzoek met als hoofddoel een gestandaardiseerde indeling van Nederland op ecologische grondslag (milieubeheergebieden) te ontwerpen. Het ontwerp is gebaseerd op een hierarchische reeks van milieubeheereenheden op verschillende schaalniveaus, te weten ecozone, ecoprovincie, ecoregio, ecodistrict, ecosectie, ecoserie, ecotoop en eco-element. Uitgangspunt was een bestaand ecosysteemmodel waarin de componenten atmosfeer/klimaat, gesteente, relief/landvorm, grondwater, oppervlaktewater, bodem, vegetatie en fauna zijn opgenomen. Op bais van de ecodistrictenkaart zijn gevoeligheidskaarten gemaakt voor de thema's verzuring, vermesting, verontreiniging en verdroging. De gevoeligheid is aangegeven in vier klassen die een indicatie geven van de omvang van te verwachten effecten bij een gegeven belasting of ingreep, zonder rekening te houden met waarden of functies van het gebied of met belasting of ingrepen in verleden en heden.

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Dit rapport is een afsluiting van het project Ecosysteemrendement. Doel van dit project is de ontwikkeling van een onderzoeksinstrument om prioriteiten te kunnen stellen in het gebiedsgerichte stoffenbeleid door het berekenen van effecten op ecosystemen als gevolg van stoffenbelasting. Het onderzoeksinstrument bestaat uit twee hoofdonderdelen: ecosysteemclassificaties en een risico-georienteerde voorspellingsmethodiek. Bij de classificatie van ecosysteemeenheden bleek de onderbouwing vanuit empirische onderzoeksgegevens tijdrovend, zodat de indeling vooral het kwantificeren van allerlei proceskenmerken en bijbehorende voedselwebstructuren behoeft. Het grootste knelpunt bij het berekenen van natuurwinst en -verlies blijkt het ontbreken van dosis-effectrelaties van "voldoende" stoffen op "voldoende" biotische compartimenten. Voor de meeste stoffen zal een gebiedsgerichte risico-analyse de kans berekenen op overschrijding van bestaande normen en/of grenswaarden in zowel het abiotisch milieu als in het voedselweb.

In many parts of the world, flooding is a big risk. There are numerous strategies to reduce flood risk. The amount of flood risk reduction strategies grows exponentially with the amount of possible measures that can be implemented and possible timings when measures can be implemented. In this paper, the use of a financial method called “equivalent annual cost” (EAC) is assessed to reduce that number of strategies and evaluate cost-optimal strategies. The use of EAC allows the comparison between short-term and long-term measures by expressing them into an annual interest weighted expected expenditure. As soon as a measure has to be implemented (i.e. the annual risk becomes too large or the safety standards are exceeded), the EAC for all combinations of measures is determined and the combination is implemented with the lowest EAC. This almost leads to cost-optimal flood risk reduction strategies that, by manual optimization, can be improved further. A case study has also been performed in the Hollandsche IJssel which proved the use of EAC. Here it has led to cost-optimal flood risk reduction strategies. The method is tested in one case and it is recommended to apply and test it in other cases as well.

Both in the USA and in the Netherlands, extensive studies on approaches for identifying flood risks (the combination of levee failure probabilities and consequences) are ongoing. A related topic concerns evacuation and emergency management (EEM). The magnitude of life loss is directly influenced by the effectiveness of EEM. Different models can be used to define the effectiveness of evacuation. The main objective of this study is to compare Dutch and American methods for evacuation as part of flood risk management strategies for a number of case studies in the US. A second, additional objective is to explore how approaches for EEM that have been recently developed in the Netherlands, can be applied in the United States. This research shows the benefits and limitations for the application of different types of models. This research contributes to the improvement of methods for emergency management, in the Netherlands, the US and other countries.

Decisions about flood risk management are usually based on the reduction in flood risk compared to the implementation costs of the strategy. It is common practice to express flood risk (the combination of flood probabilities and potential flood damages) into a single number. The downside of this approach is that explicit information about how the system responds to the whole range of possible discharges is lacking. This type of information is relevant when a robust system is desired. We consider robust (fluvial) flood risk systems to have the ability to remain functioning under a range of river discharges. To understand system robustness, it is thus useful to analyze how the flood impact varies over a range of possible events. We applied a method to quantify the robustness of flood risk systems on a fluvial flood risk system in the Netherlands: the IJssel River, a branch of the Rhine River, and its flood-prone area. We compared four alternative system configurations of the IJssel River Valley, and analyzed their robustness, applying the following criteria: resistance threshold, response severity, proportionality and recovery threshold. The robustness analysis provides us with clues about how to enhance a flood risk system’s robustness. We found that a system with unbreachable embankments scores best on overall robustness, because it has the least uncertain resistance threshold, the most proportional damage increase with increasing discharge, and the least uncertainty about where and when floods will occur. This shows that a robustness perspective helps to develop strategies that reduce the flood risks without increasing the consequences of beyond-design floods

Operation of flood barrier gates is sometimes hampered by flow-induced vibrations. Although the physics is understood for specific gate types, it remains challenging to judge dynamic gate behaviour for unanticipated conditions. This paper presents a hybrid modelling system for predicting vibrations by combining machine learning with physics-based modelling so that critical situations can be avoided. In the outlined data-driven approach gate response data is acquired by sensors and stored in a database. For an underflow gate under submerged flow conditions, gate opening and "reduced velocity" are the attributes for classification into safe and unsafe situations. Results from physical scale model tests are used to illustrate the proposed technique. A finite-element model for computational fluid-structure interaction simulations, presently under development, is applied to provide complementary input to the system’s database. The system described in this paper contributes to safer gate control and can become a useful aid in flood barrier management.

We present a data-driven modelling approach for detection of anomalies in flood defences (levees, dykes, dams, embankments) equipped with sensors. An auto-regressive linear model and feed-forward neural network were applied for modelling a transfer function between the sensors. This approach has been validated on a dike in Boston, UK—one of the pilot sites of the UrbanFlood project— that showed both normal and abnormal sensor behaviour. Comparison of the linear and non-linear mod- els is presented. The suggested model-based anomaly detection approach will extend functionality of the developed Artificial Intelligence component of the UrbanFlood Early Warning System.

Deze knelpuntenanalyse is een eerste stap in een verkenning van de zoetwaterproblematiek. Doel van de landelijke knelpuntenanalyse is om vast te stellen waar de toekomstige watervraag groter is dan de waterbeschikbaarheid, hetzij qua hoeveelheid, hetzij qua kwaliteit. Daartoe is de watervraag van diverse gebruikers in beeld gebracht, evenals de waterbeschikbaarheid, nu en in de toekomst. Voor het verkennen van de toekomst is gebruik gemaakt van deltascenario's.

We extend Jackson and Watts's (2002) result on the coincidence of S-stochastically stable and core stable networks from marriage problems to roommate problems. In particular, we show that the existence of a side-optimal core stable network, on which the proof of Jackson and Watts (2002) hinges, is not crucial for their result.

This report gives an overview of the history of flood risk management along the Scheldt estuary. Thepurpose of this overview is twofold. It documents the results obtained in the first activity of the Task25 Pilot, being focused on flood risk analysis, both in historical perspective and with regard to currentpolicies. Secondly, it provides an introduction to the Scheldt estuary for other partners in theFLOODsite project which will use the Scheldt Pilot for their own tasks and activities.The Scheldt estuary is a clear example where integrated water management is required. Integratedmeans in this case: meeting the objectives for 3 major basic functions and values of the estuary: safety,accessibility (navigation) and ecology. Recently finalised and ongoing projects, such as Proses and theSIGMA plan show a highly multidisciplinary approach in order to fulfil these objectives.From the perspective of flood risk management we see a significant difference in approach betweenBelgium and the Netherlands. The Belgian New Sigma Plan has used an approach that is strikinglysimilar to the FLOODsite methodology, i.e. going through the three phases Risk Analysis, RiskAssessment and Flood Management Strategy formulation. In contrast, the Dutch flood riskmanagement was developed over a long historical period, with the Delta Plan as the final apotheosis.In the time the Delta Plan was formulated, there was hardly any attention and technology available todetermine flood probability and flood damage.

In dit rapport is voor het eerst getracht op een systematische wijze de vraag te beantwoorden hoe bestendig Nederland is tegen klimaatverandering – en tegen de daarmee gepaard gaande zeespiegelstijging. Daarbij zijn de recent gepubliceerde klimaatscenario’s van het KNMI voor 2050 gebruikt, alsmede vier sociaal-economische scenario’s met een zichttijd tot 2040. Wat het klimaat betreft ziet het ernaar uit dat dit in Nederland gaat lijken op het klimaat zoals dat momenteel heerst in Zuidwest-Frankrijk. In dit deelproject ‘Nulmeting klimaatbestendigheid’ is het primair de bedoeling om een methode te ontwikkelen waarmee de mate van klimaatbestendigheid van Nederland kan worden bepaald, en daarmee de behoefte aan maatregelen om gesteld te staan voor toekomstige situaties als gevolg van klimaatverandering in beeld te brengen. Ten tweede wordt beoogd om met behulp van deze methode een – voorlopige en grofstoffelijke – nulmeting uit te voeren om aldus inzicht te verschaffen over hoe het momenteel met de klimaatbestendigheid van Nederland is gesteld en wat het resultaat van adaptatiemaatregelen voor verschillende toekomstscenario’s is

Regulating rivers has reduced the natural dynamic processes, altered the landscape and its biodiversity. Along large rivers that serve manifold functions, rehabilitation attempts have recovered stretches or certain features, but complete restoration probably will be a utopia. Key questions of the conference were e.g. how sustainable or effective are we so far; how well did we assess our achievements; what are the costs and benefits, opportunities and constraints, the end-points? More than 50 oral contributions and over 40 posters were presented at the conference, 45 of which, from 14 different countries, are published as peer-reviewed papers in this issue

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Couples looking for jobs in the same labor market may cause instabilities. We determine a natural preference domain, the domain of weakly responsive preferences, that guarantees stability. Under a restricted unemployment aversion condition we show that this domain is maximal for the existence of stable matchings. We illustrate how small deviations from (weak) responsiveness, that model the wish of couples to be closer together, cause instability, even when we use a weaker stability notion that excludes myopic blocking. Our remaining results deal with various properties of the set of stable matchings for “responsive couples markets”, viz., optimality, filled positions, and manipulation.

De in dit artikel gepresenteerde lange-termijnvisie geeft een denkbare ontwikkelingsrichting aan, in de lijn van Plan Ooievaar, maar aangepast aan en andere geofysische context (klimaatverandering) en een andere maatschappelijke context (postmoderne)

We consider the allocation of a finite number of indivisible objects to the same number of agents according to an exogenously given queue.We assume that the agents collaborate in order to achieve an efficient outcome for society.We allow for side-payments and provide a method for obtaining stable outcomes.