Author(s): Erik Pasche
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Abstract: Research Activities in the last decades have considerably improved our understanding about the dominating processes in natural rivers. They lead to the development of new improved mathematical methods for the hydraulic calculation of the flow in natural rivers with vegetation and compound channels (Pasche/Rouve 1985). Despite this improved knowledge the engineers still sustain in the application of traditional less reliable methods. Especially the resistance is high to give up the Manning’s formula and to apply the more physically based Darcy-Weisbach formula. They argue that the quality of the calculation is only a matter of how well the empirical parameters are calibrated. Thus simple flow formulas with only one parameter are advantageous compared to a multi-parameter approach. But this statement is only true if the flow situation with calibration data correspond to the flood events of interest. Uncertainties exist if the calibrated model is applied in a prognostic sense what is quite often the case for extreme flood events. It is the objective of this paper, to discuss the need for a more physically based hydraulic modeling of floods. The refined methods of flood modeling are explained and based on case studies with 1-dimensional and 2-dimensional flow models the benefits are demonstrated.
Year: 2007