A model for overland flow and associated processes within the Hydroinformatics Modelling System

This paper presents a numerical model suitable for a broad range of surface flow problems such as overland flow, wetting and drying processes, varying flow conditions and shock waves. It is based on solution of two-dimensional fully dynamic shallow water equations using a cell-centred finite-volume method. Numerical fluxes are computed with a Harten, Lax and van Leer approximate Riemann solver with a contact wave restored. The scheme is second-order accurate in space, and a total variation diminishing method is used to avoid spurious oscillations in the solution. For extending the model to rainfall-runoff applications, infiltration is considered as a constant runoff coefficient and by the Green–Ampt model. The model is implemented in the Hydroinformatics Modelling System, an object-oriented framework that enables the implementation and simulation of single and multiple processes in different spatial and temporal resolutions, as well as their interactions. The capabilities of the model are shown by comparison with analytical solutions and experimental data of a flash flood and a surface runoff experiment. Finally, a real rainfall-runoff event in a small alpine catchment is investigated. Overall, good agreement of numerical and analytical results, as well as measurements, has been obtained.