This lecture presents a flood protection project for the Mebre-Sorge rivers in Lausanne, focusing on the design and implementation of retention basins, diversion galleries, and control structures to mitigate the risk of flooding in urban and rural areas. The instructor explains the project's organization, funding, and the importance of collaboration between municipalities. The lecture covers the hydraulic modeling, statistical analysis of extreme events, and the construction of retention basins to manage peak flows. The case study showcases the successful implementation of flood protection measures, highlighting the critical role of infrastructure in safeguarding communities and valuable assets from the devastating impacts of flooding.