Author(s): Federico Foria; Luca Terrile; Gabriele Avancini; Emanuele Moschetti; Gabriele Miceli

Linked Author(s): Federico Foria, Luca Terrile

Keywords: Flood; Risk; Survey; River; Railway

Abstract: In countries with complex geomorphological contexts, it’s common to have an infrastructure in proximity or on rivers. The strategic value of transportation systems along the rivers is still fundamental for commercial, emergency, and touristic purposes. These are highly exposed to the erosion effect of the rivers and climate change. The Brescia-Parma railway is a railway line between Lombardia and Emilia-Romagna regions in Italy. After the town of Casalmaggiore, the railway line crosses the Po river with a steel bridge (from ch. 20+750 to ch. 21+855) on 16 piles of which 4 on the riverbed and 12 on the floodplain (Work Package 1). The piles on the river undergo a severe erosion phenomenon with a documented evolution from 1992. To assess the characteristics of the riverbed with a centimetric precision, ETS Srl has implemented and deployed a marine Unmanned Surface Vehicle (USV) for the bathymetric survey of 35000 sqm in two days. The optimized dimension of the vehicle and the cutting-edge multibeam echosounder allow the seabed mapping even in sheltered and complex contexts. The post-processed survey is automatically implemented in the software GeoHECRAS to refine lidar and open DTM data for the hydraulic modelling. Other interferences, such as the near road bridge SP343R, were drawn directly in the software. A hydrologic analysis was carried to obtain the hydrograph laws and bi-dimensional modelling (Unsteady model) was implement in GeoHECRAS. The analysis allows a comprehensive and extensive understanding of the flood evolution and erosion effects for different return periods. For the mitigation of the erosion near the piles, an intervention with sack gabions was designed following the morphology from the high precision bathymetric survey and the results of the analysis. Thanks to such data, detailed quantity take-off, and cost estimation were possible even in the early stage of the design. Nowadays, in most cases, this operation is not possible even in the design for the construction stage. From the results of the analysis, the flood development involves also the station of Mezzano Rondani (ch. 19+681) which corresponds to the right main levee of the Po river. In fact, the railway is a discontinuity of the levee. The design included a horizontal steel bulkhead with mechanical apparatus to be activated during flood events in order to close the levee and guarantee the safety of the station and the nearby urban area (Work Package 2). The design of the closing system included the reshaping of the levees, the structures, and the resolution of the station interferences. The design analyses with the aforementioned interventions show the effectiveness of the proposed solution to guarantee safety during flood events of the Po River in the area crossing the Brescia-Parma railway.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022685

Year: 2022