An Artificial Friction Approach Reflecting Building Resistance for Flood Propagation Simulation on Coarse Grids

The building resistance is very important for flood propagation simulation in urban area. For high-resolution DEM, the buildings can be accurately reflected. However, such resistance cannot be well evaluated on coarse grids. To solve such problem, a novel artificial friction approach incorporated into a 2D shallow water flow (SWF) model is proposed in this work to represent the building effects in an efficient way. In this approach, the building effects on water flow resistance are computed in the form of the friction by considering the terrain slope, unit discharge and building layouts in the study area, respectively. An idealized urban area that suffer from a flash flood is taken the test case to verify. The results show that the new approach has a Nash-Sutcliffe efficiency coefficient (NSE) of 0.99 for the water depth comparing with a high-resolution DEM simulation, which indicates a very good agreement with the reliable terrain data. Furthermore, the new approach could accelerate the computation 118 times, comparing with that on the high-resolution grid generating similar accuracy, illustrating the approach could significantly improve the computational efficiency. The artificial friction approach is therefore a reliable and efficient method reflecting the building effects for flood process simulation.