Dam-Break Wave Propagation in Alpine Valley with HEC-RAS 2D: Experimental Cancano Test Case

Flood modeling by numerical solution of the two-dimensional (2D) shallow-water equations is ordinary practice. HEC-RAS 2D was recently released along with a suite of test cases showing the very good performance of the code in many practical situations. However, validation test cases aimed at demonstrating the capability of the software to deal with dam-break floods on very steep and irregular bathymetries are very limited. This paper tests HEC-RAS 2D against the discharge hydrographs measured in a historical physical model built in Froude similitude to analyze the consequences of the hypothetical collapse of the Cancano I dam (northern Italy) and the propagation of the resulting dam-break wave along the 15-km reach of the downstream alpine valley. The experimental hydrographs and the measured extent of the flooded areas are well reproduced by the numerical simulations. Moreover, the results obtained with HEC-RAS 2D are in very good agreement with those obtained using TELEMAC 2D, which confirms the suitability of the HEC-RAS 2D software for dam-break flood studies in steep alpine valleys. The data of the test case are made available to the scientific community for validation purposes.