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

城市地区的洪水风险管理已成为国家政府和地方当局的一个关键问题，因为它具有政治和经济影响，并且由于气候变化和城市密集化而日益紧迫。虽然使用二维水动力学模型的城市洪水分析现在可以对地表洪水风险进行现实的评估，但越来越明显的是，由于许多原因，地下区域也很重要，应该在这些分析中考虑。基于地下水渗透的洪水风险管理的绿色基础设施（如洼地或绿色空间）日益得到推广，但其性能和对城市地下水位的影响知之甚少，可能产生重大后果。这些后果可能是积极的，但地下水位上升和地表沃茨不受控制的渗透也可能破坏水管网、地下室和地下运输网络。因此，更好地代表水文过程的渗透和土壤水分含量，确定地表-地下水的相互作用，是分析和设计最佳的洪水风险预防措施，并验证洪水衰减功能的有效性的关键。因此，该项目旨在基于现代数值技术开发一个完全耦合的地表-地下模型，以解决现有解决方案的主要问题，并在可能的气候情景下应用该模型，考虑土壤湿度的变化和GI或其他洪水风险预防措施的存在。编程和数学技能和经验方面的难度很高，非常苛刻，但是，该项目的完成将产生重大影响。它将在城市地区产生更准确和可靠的洪水模型，这些地区的洪水影响通常更严重。此外，它将有可能评估洪水风险缓解功能，如GI的有效性，通过使用一个模型，模拟非饱和流过程明确。

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.