Simulation of the great flood of December 1870 in Rome

The inundation of the town of Rome during the great Tiber River flood of December 1870 is simulated by a depth-integrated two-dimensional varied flow model, using a constant inflow equal to the peak discharge of the flood. The model fits satisfactorily to the observed water elevations, both in the river and in the flooded areas. The development of the model is an important step in a research programme aimed at the reconstruction of the stage-discharge relationship of the Ripetta gauge in the nineteenth century, before that extensive work, undertaken in order to protect Rome from inundation, led to the present configuration of the riverbed. The use of the model allows some further insight into the behaviour of the flood in the flooded areas of the town. As an example, the peak river levels of the greatest historical flood, that of 1598, were used to simulate the flow, resulting in an estimated peak discharge of 4070 m(3)/s.