The representation of floodplain flow resistance in a 2D channel-floodplain modelling

TASSI PA; VIONNET CA; MARTIN VIDE JP

Tempe, Arizona, USA

Simposio; 3rd International Symposium on Environmental Hydraulics – ISEH 2001; 2001

Arizona State University & IAHR – International Association of Hydraulic of Engineering and Research

Numerical two-dimensional (2D) free surface flow models of river-floodplain systems enable a complex representation of the topography and the geomorphology of the alluvial system. These model’s capabilities triggered an increasing research activity in the last decade, notably in the UK. Many 2D applications showed the feasibility of the approach to capture the inundation extent of a given flood, among other relevant aspects. However, the lack of proper distributed data for calibration and validation still hampers further application of this type of models. In this work, a comparison against data taken from the scale model of the Besos River (Spain) is presented. The scale model was built to study the environmental recovery of the river by introducing artificial wetlands in some parts of the floodplains. The scale model comprised a reach of 1400m of the River Besos, and the artificial wetlands were distributed evenly alongside the sinuous plan form of the river. This experimental facility provided an excellent set of data of the flow resistance of the vegetated floodplains, measured across seventeen different sections. A finite element model based upon the long-wave approximation is constructed over the scale model geometry in order to: i) quantify the effect of flexible floodplain vegetation on the flow resistance, ii) evaluate the accuracy of the 2D-finite element code by comparing simulated and measured flow parameters at several cross sections. This technical communication will present some preliminary results towards these objectives.