Hydraulic parameter estimations of a 2D model validated with sedimentological findings in the point bar environment

There have been a number of flume tests of flow round bends with idealized geometry and recently hydraulic simulations of such experiment. However, studies of hydraulic models in natural river bend are rather limited because of greater complexity of the flow characteristics and lack of detailed data. In this article, we study how 2D hydraulic model and raster-based hydraulic parameter calculations predict flow characteristics on the natural point bar environment. We will compare calculations of various hydraulic parameters (velocity, bed shear stress and stream power) by the 2D model and the associated sedimentology of the point bars. As a result of comparison, the usability of the 2D model for flow-form-product relationship predictions will be evaluated in natural river bend environment. The study shows that the 2D model can be generally utilized to predict the flood-generated flow-form-product relationship in coarse-grained and structurally complex point bar environments with sand-dominated bedload. For example, point bar sections submerged in water depths greater than 50 cm showed a relatively good match laterally between the model and sedimentological estimations. Furthermore, this approach allows us to estimate flood processes on a local scale in similar point bar environments with similar to 1:50 width-length ratio. The flow direction estimates of the 2D model coincided relatively well with the sedimentological estimations on the bar head. However, flow directions on the downstream section could not be modelled because the 2D model cannot handle the helicoidal flow of the river bend. Copyright (C) 2010 John Wiley & Sons, Ltd.