The 12th International Conference on Scour and Erosion (ICSE 2025)

Rock scour downstream of high-head dams and in unlined channels and stilling basins of dam spillways is a more and more frequently occurring phenomenon. Climate change and related regulatory requirements generate more frequent functioning of dam spillways, and sometimes triggers a first main spillage of spillways that have been constructed decades ago but were never used, or only used for minor discharges. Hence, unlined rock masses downstream of those structures experience greater hydraulic stress by action of hydrodynamic pressures at the water rock interface. Sound prediction of incidences involving rock scour during such flood events thus is becoming more pertinent and necessary, especially for cases where the scour hole may potentially regress towards the dam or spillway foundations. This paper firstly presents the background and main principles and methods of rocsc@r, an innovative cloud-based digital platform to compute scour of unprotected bedrock downstream of high-head dams and in unlined plunge pools and spillways. Second, the paper presents the application of this novel cloud-based digital platform to different situations of rock scour at hydraulic structures. A first case concerns the 3D numerical reproduction of observed scour after a major flood event at unlined bedrock downstream of the main spillway of an existing dam. Another application proposes 3D scour potential for a dam containing a bottom outlet with downstream lining and baffle blocks, together with a crest spillway and bridge piers in the downstream bedrock of the river channel. For these cases, well-known computational methods are compared, such as Erodibility Index Method and Comprehensive Fracture Mechanics Method, and the latest advances and innovations in fluid-solid coupling techniques and related 2D and 3D graphical outputs are presented.