Presentation given by Drs Malcolm Whitworth and Robert Inkpen (Centre for Applied Geosciences, University of Portsmouth) at UPEN workshop - Climate change and the Solent: Opportunities and Vulnerabilities.

1. Mapping and modelling climate change impacts: Flood hazard, vulnerability and community resilience.Climate Change and the Solent: Vulnerabilities and Opportunities15 September 2011 Dr. Malcolm Whitworth, Dr Rob Inkpenand Dr Richard Teeuw Centre for Applied Geosciences

2. Context Environment Agency estimate that of the 5.2 million homes in England at risk of flooding. Of these 2.8 million are at risk due to surface water alone (55%) Pitt Review, 2008

3. Context Environment Agency estimate that of the 5.2 million homes in England at risk of flooding. Of these 2.8 million are at risk due to surface water alone (55%) Flooding in urban areas is not only a key priority for UK cities but also for cities globally where 50% of global population now live in urban areas. Pitt Review, 2008

4. Context Environment Agency estimate that of the 5.2 million homes in England at risk of flooding. Of these 2.8 million are at risk due to surface water alone (55%) Flooding in urban areas is not only a key priority for UK cities but also for cities globally where 50% of global population now live in urban areas. Portsmouth city chosen as a research site due to its susceptibility to surface water and coastal flooding. Pitt Review, 2008

5. Context Floods are a dynamic process that vary in time and space. How does flood water behave in urban environments and how can we better predict it ? What new tools and datasets are required in order to better model urban flows? How can modelling be used to better prepare and manage flood events. Pitt Review, 2008

6. Cellular automata Flood modelling capability has been developed using a Cellular Automata (CA) approach. CA is based upon a grid structure (raster) composed of individual cells, where each cell has a neighbourhood. A cell can communicate with its neighbours and change state according to simple rules. Illustration of a cellular automata neighbourhood

7. Flood modelling CA is used to model floods by allowing water to migrate from one cell to its neighbours. Water flow controlled by topography, which is defined using a LiDAR height dataset. Illustration of how water propagates in a cellular automata model from seed cell to neighbouring cells during each iteration.

8. Size of the cells in the grid is termed resolution/granularity. Data has 1m cell size and so buildings and roads are visible. Flood model will replicate water movement between buildings LiDAR data of Portsmouth (from Channel Coast Observatory)

9. Coastal inundation Simulates flood eventsfrom single or multiple breach points. Model can simulate flood extent and water depth during flood event. Input parameters can be altered for sensitivity analysis. Maximum flood extent model showing water depth (25,000 iterations of model)

10. Coastal inundation Models provide basis for risk assessment. Simulation of flood scenarios. Low frequency but high consequence event. Maximum flood extent and associated flood risk (25,000 iterations of model)

11. Surface water flooding Cellular Automata (CA) based flood modelling for central Southsea. Simulation of surface water flow in urban environments. Identifies areas of water accumulation and provides basis for risk assessment. Models provide an input for surface water management during flood events.

12. Fluvial flooding Cellular Automata (CA) based flood modelling for Southampton. Identifies areas of water accumulation and provides basis for risk assessment.

13. Vulnerability and community resilience What is vulnerability ? Can we define it? Can we measure it? STATIC Population characteristics Building characteristics Physical networks/infrastructure DYNAMIC What people do and why they do it. Can we model, can we predict, can we ‘nudge’?

14. Conceptual model of place vulnerability

15. Social vulnerability Selected list of social vulnerability variables that can be used. Can these sources of ‘weakness’ also be sources of strength in crisis?

18. Vulnerability index derived by combining the census data associated with the indicators mentioned above. No standard set of indicators nor a standard way to weight or combine them What is appropriate – place specific?

20. Urban centre flooding Result of 1.5m coastal flood

22. Vulnerability and coastal flooding on Canvey Island, Essex

23. A B Adding road network you can assess how a 1.5m coastal flooding (A) and a 0.5m urban flash flood will affect the ability to evacuate differentparts of the island

24. Route A: the B1014 – normally 7 minutes Route B: the A130 – normally 10 minutes and 1 mile more Predicting the impact of the ‘shadow’ effect on the evacuation choices of a less vulnerable ward

25. Summary Models need to consider floods are dynamic systems subject to uncertainty Model inputs such as rainfall location duration and extent. Water outflow rates through drainage. Role of open natural ground as water store and sinks. Adaptation of urban areas to cope with increased water flows from climate change. Streets used as catchment basins Diversion of water to parkland/open ground for storage and infiltration. Vulnerability both static and dynamic can be quantified at a variety of scales to aid prediction of likely impacts of climate change. BUT people are predictably unpredictable !!