Extension of 2D Shallow Water Models to Hydrological Modelling

In this paper we discuss some critical aspects that should be considered in order to extend and apply a numerical model based on the 2D shallow water equations(2D-SWE) to distributed hydrological modelling. We also detail the physical processes, numerical methods and High Performance Computing(HPC) techniques that have been implemented in the freely available software Iber, to enable its application to rainfall-runoff transformation and propagation at the catchment scale.The original version of Iber is coded in Fortran and it implements an unstructured finite volume solver for the 2D depth-averaged shallowwater equations to model open channel flow in rivers and is therefore representative of many 2D free surface flow models. Hydrological processes as infiltration, evapotranspiration, percolation and groundwater flow were implemented in the last version of the software. Specific numerical schemes for the discretization of the 2D-SWE in surface runoff applications were also included in the solver. A HPC version of the solver (Iber+) coded in C++ and parallelized for CPU using OpenMP and for GPU using Nvidia CUDA was also developed. After describing briefly those implementations, we present the validation of the model in two laboratory configurations, and its application to three real catchments.