Modelling complex rating curves with hydraulic scale models and computational fluid dynamics

Abstract

The Flom-Q research project aims to revise the framework for flood-estimation methods in Norway. Accurate rating curves are important for estimating flood discharges that are crucial input for any flood assessment task. As part of the Flom-Q project, this thesis aims to provide proof-of-concept for hydraulic scale modelling and computational fluid dynamics (CFD) modelling methods applied to rating curves for gauging stations with complex flow and complex geometries. Two case studies are explored. In the first case study the rating curve for an ogee-weir crest influenced by tail-water submergence is modelled with CFD. In the second and more extensive case study, a gauging station with complex geometry is modelled using a hybrid modelling approach, combining both a hydraulic scale model and CFD modelling. The case studies demonstrate how scale modelling and CFD modelling methods can be used to analyse flow and provide synthetic stage-discharge data for cases where complex flow is important and simpler methods cannot be used.