Fact sheet

Modelling of risk to people and property

FRMRC2 has produced:  Numerical assessment of flood risk to people (children and adults) and property (vehicles and buildings) in urban areas, using an integrated two-dimensional model.

Intended readership and users:  Policy makers, planners and flood risk managers are the main intended readership, as well as consulting engineers involved in flood risk management.

Where to find more information: www.floodrisk.org.uk

Summary

Flash flooding is one of the most dangerous types of disasters frequently occurring. This is due to:

 The short timescales involved;  The limited opportunity for issuing warnings;  The high average mortality levels.

Flash also frequently cause large loss or damage to property, including damage to vehicles as in the case of the 2004 flood.

Flash floods particularly lead to increased risk to the safety of people and damage to property and vehicle mobility in densely populated urban areas. In flood risk management, it is important to be able to assess the degree of safety to people and the mobility of vehicles during flash floods using numerical models for such urban areas.

In the current study, an assessment algorithm to determine the hazard degree of people safety and vehicle mobility has been integrated into an existing two-dimensional (2D) hydrodynamic model capable of simulating flash floods. Fully and partially submerged vehicles in a flume

This work has potential application in hazard modelling, which is required to be undertaken under the European Floods Directive. For example it could be used to inform meaningful thresholds for categories expressing hazard from velocity.

www.floodrisk.org.uk EPSRC Grant: EP/FP202511/1 Fact sheet

The developed model has been applied to Simulations for the Malpasset dam-failure three real case studies; the Glasgow and flood showed that the method for the Boscastle floods in the UK and the assessment of people safety was applicable, Malpasset dam-failure flood in France. and some local people living below the dam were predicted to be swept away, which Simulations for the Boscastle flood indicated corresponded well with the report findings. that vehicles in the car park would be flushed away by the high flow velocities, which indirectly testified the predictive accuracy of Stability analysis based on mechanics theory

the incipient formula for vehicles.

Hazard degree for vehicles in the Incipient velocities of prototype vehicles (Xia et al.2010) Simulated results for the Glasgow flood showed that children would be in danger on the flooded streets in this small urban area.

Instability curves for a child and an adult in floodwaters (Keller 1992) Hazard degrees for children in the predicted Glasgow flood

Other sources of information

Xia JQ, Falconer RA and Lin BL (2011). Modelling of Risk in Urban Areas. Proceedings of the Institution of Civil Engineers, Water Management 164, Issue WM1: 1-16 (doi: 10.1680/wama.2011.164.1.1). Xia JQ, Fang YT, Lin B L and Falconer RA (2011). Formula of incipient velocity for flooded vehicles. Natural Hazards (DOI 10.1007/s11069-010-9639-x). Xia JQ, Falconer RA, Lin BL and Tan GM (2010). Modelling floods routing on initially dry beds with the refined treatment of wetting and drying. International Journal of River Basin Management 8(3-4): 225-243.

Research Team

Cardiff University: Prof. Roger A. Falconer, Prof. Binliang Lin and Dr. Junqiang Xia http://hrc.engineering.cf.ac.uk/

FRMRC is an interdisciplinary research consortium made up of partners from universities, government bodies and practitioners supported by: . Engineering and Physical Sciences Research Council . Department of Environment, Food and Rural Affairs/ Joint Research Programme . Water Industry Research . Office of Public Works Dublin . Northern Ireland Rivers Agency Data were provided by the Environment Agency and the Ordnance Survey.

www.floodrisk.org.uk EPSRC Grant: EP/FP202511/1