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Random Field Approach Based Analysis of Bed Form Heights in Curved River Sections

Author(s): Jochen Aberle; Stephan Niewerth; Petra Faulhaber

Linked Author(s): Jochen Aberle

Keywords: Random field approach; Dunes; Morphology; Elbe River; River bends

Abstract: This paper presents results of a study carried out to investigate the relationship between bed form heights and river curvature in an 11 km long regulated and curved river reach of the Elbe River in Germany. The analyzed bed topography data were collected between 2004 and 2011 with a high spatial resolution of 2 x 2 m for a range of flow rates from low flows to floods on behalf of the Federal Waterways Engineering and Research Institute (BAW), Germany. Applying the random field approach, i. e. treating the wavy bed surface as a random field of bed elevations, bed form heights along the river reach are analyzed by means of the standard deviation of bed elevations. A method for the determination of the standard deviation as a function of river station is proposed which is based on subdividing the river reach under investigation in segments with constant lengths exceeding the maximum dune length. The method is tested by analyzing bed topography data in a relatively straight 3 km long sub-section by comparing the results from the random field approach analysis with the results from a zero-crossings analysis of the same data. Due to the difficulties of generating representative longitudinal profiles for the zero-crossings analysis in curved river sections, the proposed method is then used to investigate the dependency between the surrogate bed form height measure “standard deviation” on river curvature and discharge along the total river reach under investigation. The results show a clear dependency of the standard deviation from both river planform and discharge, hence confirming that statistical analyses may be used for the characterization and prediction of flow-dependent sand bed roughness. The results are critically discussed and the potential of the random field approach for the analysis of fluvial morphology is highlighted


Year: 2013

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