High Performance Computing in Eco-Hydraulics: High-Resolution and long-Term Numerical Modelling

The study of aquatic habitats necessitates a holistic analysis, considering the relationship between hydraulics and biota under both normal and extreme conditions. Various approaches have been proposed to characterize the physical habitat based on geomorphologic, hydrologic, or hydraulic criteria. Currently, there are various numerical hydrodynamic tools integrating the biological requirements of one or several target species, typically fishes, but not exclusively, enabling the modelling of the weight-usable area (WUA). However, one of the primary limitations of these eco-hydraulic tools is typically related to computational cost, especially in 2D and 3D modelling. Simulating flow properties in natural conditions, large river stretches, or domain discretization with millions of elements usually demands a high computational effort. The application of high-performance computing (HPC) techniques, particularly general-purpose computing on graphics processing units (GPGPU) instead of traditional central processing unit (CPU) computing, allows for overcoming this limitation. A GPU-based hydraulic code, a parallelized version of Iber, functions as a fully-integrated GPU-parallelized tool for conducting high-resolution and long-term eco-hydraulic numerical modelling. The benefits of using this GPU-parallelized tool include: (i) speed-ups of two orders of magnitude in computational time compared to traditional computing, (ii) the utilization of a specific boundary condition called ‘stepped discharge’ for the application of the Instream Flow Incremental Methodology (IFIM) within a unique model that significantly reduces computational time, and (iii) the capability to simulate high-resolution and long-term scenarios in extensive river stretches, and even entire rivers, within a suitable timeframe.