Hydrodynamic analysis of the impact of changes from precipitation extremes to surface water flooding in future climates

Climate change has resulted in significantly more frequent precipitation extremes in many parts of the world. Latest research based on UK Climate Projections has suggested that short-term precipitation is projected to increase by 20% to 45% across the UK, providing more specific information compared to previous official guidance that used a single value for the whole UK. The impact of precipitation increase to surface water flooding has been evaluated based on statistical methods to some extent. However, most existing studies are not able to capture the physical process of flood dynamics although it is critical to understand the flooding process interacting complex built-environment during those highly transient extreme events to quantify the actual risk. This work investigates and quantifies impact of the change of rainfall on the spatial pattern of surface water flooding using a 2D hydrodynamic model to simulate designed rainfall events with climate change uplifts.  Flood depth and extent maps are produced in six cities/catchments across the UK against rainfall of different return periods to demonstrate potential change of surface water flood risk in future climate. The results translate the latest UK Climate Projections into intuitional flood risk changes and can be valuable to policy-makers and stakeholders to update policy and practice on surface water flood risk management, as well as providing new methodologies and tools.