Jonathan Simm

Multiscale modelling in real-time flood forecasting systems: From sand grain to dike failure and inundation

Abstract Severe events around the globe have highlighted the threat to life, infrastructure and the environment posed by flooding. Flood forecasting systems are a vital component of broader flood risk management activities. These systems are becoming increasingly more sophisticated as their importance in reducing life loss and economic damages is realized. Part of this increase in complexity is focused on the ability to predict and warn of failures in dykes, levees and embankments. A new European ICT project, UrbanFlood for Environmental Services and Climate Change Adaptation, has recently been commissioned and is introduced in this presentation. The primary objective of the Urban Flood project is to develop early warning systems that will monitor flood protection systems in real-time, identify vulnerable locations, model the failure and predict dike collapse and subsequent inundation. In combination with the damage assessment, Urban Flood will serve as an advanced decision support system, mitigating the impact of seasonal and catastrophic floods. Modeling is one of the key tasks in the project. The models will be required to simulate the behavior of the material properties of the layered dikes (sand, clay, peat, grass or concrete cover, metal frame, dam gates, etc.), during extreme hydraulic loading events. In earthen dikes, extra challenge is posed by the non-linear elastic plastic properties of the deformable clay. A realistic simulation of the dike will model the free-surface water dynamics; convective and diffusive transfer of water inside the porous materials; dynamic response of clay to the water pressure; structural mechanics, deformation and actual dike breakdown and flood. The models shall cover a wide range of scales from a sand grain to a flooded city. The time scales will range from seconds (for water penetrating the soil) to hours (for dike collapse dynamics and ocean tides). Eventually, the models will predict the influence of seasonal and global changes on the stability of flood defense systems. Full 3D transient simulation of dike failure with subsequent inundation will require significant computing resources. The project started three months ago, and we will present the plan for developing the modeling cascade for the system. This work is supported by the UrbanFlood European Union project N 248767, theme ICT-2009.6.4

A new risk-based design approach for hydraulic engineering

Hydraulic structures providing flood and coastal protection facilitate economic development as well as living areas and often converge with other infrastructure. There is a need for general guidance for analysing risks of hydraulic structures. This paper analyses two actual hydraulic engineering projects in the UK in which acceptable risk levels are incorporated in the design using a new risk-based design approach, taking consciously into account the influence of stakeholders, the legal framework as set by the Government, design-elements from different design-disciplines and funding.

A Questionnaire Survey to Establish the Perceptions of Uk Specifiers Concerning the Key Material Attributes of Timber for Use in Marine and Fresh Water Engineering

Abstract Engineers have a key role in making informed decisions on the type of materials to be used in the schemes they design and construct. Currently, in England and Wales, it is believed that some ?500m per year is invested in flood and coastal defence engineering. There is a lack of centralised data in the UK holding information on timber for usage in fluvial and, particularly coastal engineering. A questionnaire survey of engineers was carried out. The survey identified the key material properties of timber required by engineers for different end uses. In addition, the survey identified that there was a lack of reliable technical information to support the use of lesser known hardwood species that did not have an established track record of use in marine and fluvial engineering in the UK.

NEW GUIDANCE TO ADDRESS THE CHALLENGES OF USING CONCRETE IN MARITIME ENGINEERING

Concrete is extensively used as one of the main construction materials in the maritime environment. At least 15% (by value) of these works includes concrete in various forms (sea walls and wave walls, concrete armour units, caissons, etc.). Despite the long history of capital investment in concrete maritime structures, it is generally recognised that there was a gap in structured guidance documents available with regard to the use of concrete in maritime structures. There remains a need to address unsolved challenges and to provide engineers with up-to-date guidance. KEY CHALLENGES FOR MARITIME CONCRETE The key challenges associated to the use of concrete in the maritime environment will be addressed are being addressed, in particular: - Designing for target performance of concrete elements. - Ensuring durable concrete material providing appropriate performance during the service life of the structure - Providing strength to concrete, without using conventional reinforcing steel - Designing with mass concrete - Mitigation of chloride-related corrosion of reinforcing steel - Delivering concrete resistant to attrition - Extent to which non-reinforced concrete armour units may be used to structurally respond to hydraulic loads - Appropriate testing of concrete for the maritime environment – in particular long term resistance to attrition, resilience to impacts, resistance to chloride attack, including laboratory testing and pilots - Repairing of maritime concrete structures