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Measurements on the interaction between dunes and dikes during extreme storm events
This paper presents video-based measurements of morphological experiments in the Vinjé wave basin. The experiments were carried out to study effects of fixed structures on dune erosion. We developed a new measurement method based on video images, that successfully uses the differences between two succeeding images to derive detailed and accurate measurements of the bathymetry. We also developed a method to monitor the position of the dune crest during the experiments by using the variations of the color intensities along a cross-shore transect to determine the dune crest position. Measurements nicely represent the episodic collapsing dune front. The measurements also show an increased erosion near a connection between a dune and a dike compared to an undisturbed dune section. The additional amounts of dune erosion are larger at breaches in a dike and in a dune foot revetment.
Volume-of-fluid model ComFLOW simulations of wave impacts on a dike
ComFLOW is a 3D Volume-of-Fluid (VOF) model to solve the incompressible Navier-Stokes equations including free surface, or to solve the Navier-Stokes equations for two-phase flow problems. The problem statement of the present study reads: Is ComFLOW capable of accurate prediction of wave impacts on (impermeable) coastal structures such as dikes? And, if so, what are the preferred model settings and associated computing times? In this paper, ComFLOW is validated for this purpose by comparison against pressure data as measured in the Delta flume by pressure sensors at dikes.
Models and analysis for flood control systems
Overall goal of the project is to define a framework for Smart Levees, including the development of new models for levee safety monitoring and underlying IT infrastructure. This report contains the findings of the research on: model development, based on IJkdijk experiments and LiveDijk Eemshaven ; real time levee monitoring with improvement of robustness ; remote sensing levee monitoring techniques.
Scaling perspective for a dike monitoring system
This document elaborates on the research that is done to investigate the scaling perspective for a dike monitoring system from a financial perspective. Deals with the different stakeholders and their involvement with a Flood Control System, the parameters influencing the severity of a flood and the consequences a flood has on the economy in first order and second order effects. This is done by making an inventory of the risk of flooding by means of the RAMCAP framework.
Architecture and prototype dike monitoring system
This document defines the solution architecture of a Flood Control System.
Visualisation of levee quality based on sensor data
Describes a vision on a Flood Control System, the requirements for such a system and several visualisation forms. First outlines an envisioned system approach for an integral Flood Control System on top of a variety of dike monitoring systems which will be implemented by water boards in the near future. Then describes an analysis of the Dutch water management situation and defines two scenarios as a basis for requirements gathering for an FCS. Concludes with different views on sensor data for the different stakeholders involved in water management. For different roles in water management a few specific visualisations are designed and implemented.
Added value of sensor streams in dike monitoring systems
Sensor values from various sensors in real levees are coupled to models on dike stability. This is illustrated with two cases: IJkdijk and LiveDijk. The IJkdijk case is representative of a crisis situation. During the controlled experiment failure of the levee was achieved. The LiveDijk Eemshaven case is representative of an operational levee. Sensors were installed to monitor the levee during at least two years in order to get a better understanding of the normal behavior of levees.
OpenMI testen LSM : KPP 2015 Hydraulica Schematisaties - Zoet
Het Landelijk SOBEK Model (LSM) is ontwikkeld in het kader van het project Deltamodel en het Nationaal Hydrologisch Instrumentarium sinds medio 2010. Het is nu mogelijk om de meerdere SOBEK modellen via OpenMI (Open Modelling Interface) te koppelen. Hierdoor kan het LSM in principe worden opgebouwd als een OpenMI-koppeling van de losse modellen van de waterbeheerders (zowel RWS als de waterschappen). In dat geval is het niet nodig om bij aanpassingen in een regionaal model dezelfde aanpassingen ook in LSM over te nemen, maar hoeft er alleen een nieuw regionaal model in OpenMI gehangen te worden en de uitwisselingslocaties van dit nieuwe model met de andere modellen aangepast te worden. Het beheer van LSM wordt daardoor in principe eenvoudiger, omdat het beheer van de individuele modellen bij de verantwoordelijke waterbeheerder kan blijven liggen, en alleen de koppelingen tussen de verschillende modellen goed beheerd moeten worden. Dit rapport doet verslag van testen of de koppeling via OpenMI in de praktijk toepasbaar en hanteerbaar is.
GRADE 2012 : procedure to derive the design hydrograph
GRADE (Generator of Rainfall and Discharge Extremes) is a new methodology to provide a better physical basis for the estimation of the design discharge of the main Dutch rivers compared to the present method based on frequency analysis of extreme discharge values. This report proposes a procedure to derive the shape of the design discharge hydrograph and the accompanying uncertainty width using the synthetic GRADE discharge series for the river Meuse at Borgharen. The focus is placed on the derivation of a design hydrograph for the failure mechanisms overflow and overtopping.
Updating levee reliability with performance observations
Flood defenses are crucial elements in flood risk mitigation in developed countries, especially in deltaic areas. In The Netherlands, the VNK2 project is analyzing the reliability of all primary flood defenses as part of a nationwide flood risk analysis. In this project, as in most other reliability analyses of flood defenses, prior probabilities of relevant parameters such as ground conditions use to be based on sparse site investigation data and/or expert judgment. What is largely neglected is the observed performance during extreme events such as excessive seepage or sand boils. Using this information and thereby reducing uncertainties contributes to identifying weak spots or to increasing reliability where positive signs of performance are observed. Ultimately, this contributes to focusing investments in flood defenses where they are needed the most. This paper proposes a methodology based on Bayesian Inference for updating uncertainties and focuses on the failure mechanisms uplift and piping. Attention is paid to the system reliability effects in this failure mode, too. The methodology is applied to a case study in The Netherlands, the prior probabilities stem from the VNK2 project. The results suggest that depending on the observation, the probability of failure can either increase or decrease by about a factor 10. The findings clearly contradict the common perception, at least in The Netherlands, that if a structure survives an extreme (load) event its reliability always increases. That is only true unless bad performance-related observations have been made.