Modelling interactions of flow and river bedforms

Background Bedforms in rivers interact with the flow, impacting, among other factors, the flow resistance. Since bedforms can produce tree-dimensional effects in the flow, simulations considering bedforms still require high‑performance computing.Methods Based on laboratory channel experiments on bedform development, numerical experiments were performed using a 2D depth-averaged model and a 3D flow model to compare simulation times and characteristics.Results The development of bedforms was not attained with 2D modelling with the morphological simulations performed here. Regarding the hydraulic simulations with the initial flat bed and with the developed bedforms, the later generates an increased energy loss observed by a marginal increment in the backwater effect. Finally, the time required for 3D modelling of hydraulic processes is at least one order of magnitude larger.Conclusions In the case analyzed here the dunes produce effects along the entire water column, and 3D effects are relevant, in such cases details of the hydraulic processes are not captured by a 2D model. However, 3D simulations of river morphology still require significant computation effort, limiting its applicability in practical problems.