Understanding and modelling surface-subsurface flow interactions in urban areas during floods

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Management of flood risk in urban areas has become a key issue for national governments and local authorities due to its political and economic implications and increasing urgency due to climate change and urban densification. While urban flood analysis using 2D hydrodynamic models now enables realistic assessment of surface flood risk, it is becoming increasingly obvious that the sub-surface domain is also important for a number of reasons and should be accounted in these analyses. Green Infrastructure (GI) for flood risk management based on infiltration to the groundwater (e.g. swales or green space) is increasingly promoted, but its performance and impact on the urban water table is poorly understood and can have major consequences. These consequences may be positive, but higher water tables and uncontrolled infiltration of surface waters can also damage water pipe networks, basements and underground transport networks. Hence, better representation of the hydrological processes of infiltration and soil moisture content which determine the surface-groundwater interactions, is key to analysing and designing the best flood risk prevention measures and verifying the effectiveness of flood attenuation features. Therefore, the project aims to develop a fully coupled surface-subsurface model based on modern numerical techniques in order to address the main issues of the existing solutions, and apply the model under possible climatic scenarios, considering changes in soil moisture and the presence of GI or other flood risk prevention measures.The difficulty in terms of programming and mathematical skills and experience is high and very demanding, however, accomplishment of this project will have a significant impact. It will produce more accurate and reliable flood models in urban areas where the effects of flooding are generally more severe. Furthermore, it will be possible to assess the effectiveness of flood risk mitigation features such as GI by using a model that simulates the unsaturated flow process explicitly.