The influence of land cover roughness on the results of high resolution tsunami inundation modeling

In this paper a local case study is presented in which detailed inundation simulations have been performed to support damage analysis and risk assessment related to the 2004 tsunami in Phang Nga and Phuket, Thailand. Besides tsunami sources, bathymetry and topography, bottom roughness induced by vegetation and built environment is considered to influence inundation characteristics, such as water depths or flow velocities and therefore attracts major attention in this work. Plenty of information available on the 2004 tsunami event, high-resolution satellite imagery and extensive field measurements to derive land cover information and forest stand parameters facilitated the generation of topographic datasets, land cover maps and site-specific Manning values for the most prominent land cover classes in the study areas. The numerical models ComMIT and Mike 21 FM were used to hindcast the observed tsunami inundation and to draw conclusions on the influence of land cover on inundation patterns. Results show a strong influence of dense vegetation on flow velocities, which were reduced by up to 50% by mangroves, while the inundation extent is influenced only to a lesser extent. In urban areas, the disregard of buildings in the model led to a significant overestimation of the inundation extent. Hence different approaches to consider buildings were used and analyzed in the model. The case study highlights the importance and quantifies the effects of considering land cover roughness in inundation simulations used for local risk assessment

Integrated flood risk management – progress from the FLOODsite project

FLOODsite is the largest ever EC research project on flood risk management, with an EC grant to the budget of nearly €10 Million complemented by supporting national funds. The project, which started in 2004, is scheduled to complete in February 2009, and has involved over 200 researchers from 13 countries including many of Europe’s leading institutes and universities. The project is interdisciplinary integrating expertise from across the physical, environmental and social sciences, as well as spatial planning and management. FLOODsite is an ambitious project and aims to maintain the world-leading position of Europe in knowledge and practice for flood risk management. The tools and techniques developed through FLOODsite have been drawn together through the use of pilot studies, enabling direct feedback to flood risk managers and river, estuary and coastal stakeholders. For example, within the UK, the Thames Estuary 2100 team has proved a valuable pilot site – supporting more targeted research and better practice. The use of the pilot sites and collaboration with executive agencies in several countries will help ensure that FLOODsite results are of real value, practicable and usable. This paper describes some of the outcomes of FLOODsite in terms of contribution to knowledge on sources, pathways and receptors of flood risk and support for integrated methods of flood risk management

Failure modes and mechanisms for flood defence structures

In order to undertake a flood risk analysis, the performance of different flood defence structures under varying load conditions needs to be represented. This paper reports on work undertaken through the FLOODsite Project (Task 4) in bringing together available information on failure modes for a number of representative flood defence structure types, to support the development and implementation of system wide models for flood risk assessment. The work comprised a review of structures and failure modes which have occurred in the past, and an investigation of limit state equations and associated uncertainties for both the models and the input parameters. Summaries of all failure modes were combined to create a single reference document; it is hoped that this will be maintained and updated into the future as knowledge on different failure mechanisms evolves. Additional research into selected failure modes and embankment processes was also undertaken and is summarised in this paper, including recommendations as to areas where future research should be focussed

Advances in flood risk management from the FLOODsite project

The future management of flood risk will not come from a single technical solution or policy but from a range of responses which are tuned to the specific circumstances at a local or regional scale, taking account of national governance structures and public attitudes towards flood risks. This diversity of approach is recognised by the embodiment of the subsidiarity principle in the European Directive on the assessment and management of flood risks. This paper covers some of the main areas of innovation achieved within the European funded research project FLOODsite. These innovations will facilitate the implementation of the European Directive actions of flood risk assessments, risk mapping and the preparation of flood risk management plans. FLOODsite does not propose a single integrated methodology for flood risk management; rather it provides a set of linked methods which support integrated flood risk management. We also compare FLOODsite against the ambitions set for the EC Sixth Framework Programme Integrated Projects