The iFlow Modelling Framework v2.4. A modular idealised process-based model for flow and transport in estuaries

Abstract. The iFlow modelling framework allows for a systematic analysis of the water motion and sediment transport processes in estuaries and tidal rivers and the sensitivity of these processes to model parameters. iFlow has a modular structure, making the model easily extendible. This allows one to use iFlow to construct anything from very simple to rather complex models. The iFlow core is designed to make it easy to include, exclude or change model components, called modules. The core automatically ensures modules are called in the correct order, inserting iteration loops over groups of modules that are mutually dependent. The iFlow core also ensures a smooth coupling of modules using analytical and numerical solution methods or modules that use different computational grids. iFlow includes a range of modules for computing the hydrodynamics and suspended sediment dynamics in estuaries and tidal rivers. These modules employ perturbation methods, which allow for distinguishing the effect of individual forcing terms in the equations of motion and transport. Also included are several modules for computing turbulence and salinity. These modules are supported by auxiliary modules, including a module that facilitates sensitivity studies. Additional to an explanation of the model functionality, we present two case studies, demonstrating how iFlow facilitates the analysis of model results, the understanding of the underlying physics and the testing of parameter sensitivity. A comparison of the model results to measurements show a good qualitative agreement.