Effetti dei percorso fluviale arginato sul controllo dei deflussi di piena: Risultati di una modellazione applicata ad un caso di studio nella Pianura Padana

Abstract

In the present paper an analysis of the characteristics of flood wave propagation in rivers with composite cross section is presented. In particular the lower section of the River Taro is described. The river is a right-hand side affluent of the River Po (Northern Italy), joining the latter 257 km upstream from its mouth. Along the final 31 km long stretch, the River Taro flows within a single main channel surrounded by flood ways, which were embanked to prevent inundation in the outer plain. Events of extensive inundation were recorded with particular frequency throughout the 19th Century. The channel pattern is typical of single channel type forms, changing from transitional to meandering, with bankfull cross-sections approximately 500 m2. Features of flood routing are analyzed as shown using a simplified parabolic (convection-diffusion) mathematical modelling scheme, with variable parameters. The celerity function shows a rapid decrease as soon as the flood way is occupied by the flow. Attenuation in wave propagation and diffusion of higher discharges produce an increase in residence times and sensible attenuation of peak discharges.