Within this project, an interactive simulation tool for risk assessment and real time prediction of floods in complex environmental settings, like urban environments, shall be developed. Floods and impact of floods on infrastructure will be predicted within a multiscale framework reaching from the river down to the scale of the built infrastructure, such as railway, subway, tunnels, waste water channels, buildings, and building infrastructure. For this, several aspects such as efficient parallel algorithms and data structures, multisscale geometric modeling, real-time grid generation and adaptation, coupling of 2D (shallow water) and 3D (Navier-Stokes) fluid codes, and interactive visual data exploration have to be addressed. By combining expertise in computer science and hydromechanics a risk analysis framework will be provided for civil engineers, architects, planners, insurance analysts, and politicians on the level of fully detailed building information models (BIM). The user of that framework will become a part of the system or the iteration loop, allowing him or her to interactively explore and evaluate various scenarios and, thus, enabling decision makers to decide on a new level of information detail and accuracy.