Discussion of “Numerical and Experimental Study on Two Dimensional Flood Flows with and without Structures” by Mirei Shige-eda and Juichiro Akiyama

The paper by the authors is helpful because it deals with experimental setup in such an accurate way as to allow numerical simulation. The expansion of flood waves in flat areas caused by levee overtopping or failure is deeply influenced by the presence of structures, such as scattered or grouped buildings, roads, or railway embankments. The impact of a 2D flood current against single or bunched obstacles has been widely investigated experimentally as well as numerically in past years, as well as within the framework of an EU project ~IMPACT, Investigation of Flood Processes and Uncertainties!. The discussers applied a first order upwind numerical solver ~Roe scheme! to investigate a lower order of accuracy solver could give comparable results to the one developed by the au-