Near-Bank Flow and Flood Induced Bank Erosion Processes Revealed by Application of Advanced Acoustic Techniques on a Mega-River
Abstract
Bank erosion processes are a key component of river morphodynamics, controlling rates of channel shift and ultimately governing floodplain system dynamics and sedimentology. Near-bank flow fields and the interactions of turbulent fluid flows in the near-bank zone with mechanisms of bank failure and erosion styles are presently poorly understood. Recent research has suggested that bank erosion and the type of failure mechanism can play an important role in protecting the bank toe from further erosion, notably through increased near-bank roughness and the resultant reduction in near-bank flow velocity and shear stress. An improved understanding of these interactive near-bank processes is essential if we are to improve our ability to predict bank erosion and channel morphodynamics. In this study we present a series of high-resolution multibeam sonar repeat near-bank surveys and acoustic Doppler profiles (acquired as part of the NERC funded STELAR-S2S project: www.stelar-s2s.org), from the monsoonal Mekong River in SE Asia. These data are the first to simultaneously capture detailed bank topography and near-bank flow processes of a mega-river during high flow conditions. Data is presented from a range of channel morphologies and includes a variety of geotechnical bank failure styles. The results show how systematic quantification of bank roughness over bank lengths of several channel widths can be used to quantify hydraulic roughness and how such information can be used to parameterise bank erosion models. Furthermore, the evolution and role of slumped material at the bank toe is also examined during the monsoonal flood. The methods, estimates of error and implications of the results for the morphodynamic function of large river systems will be discussed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMEP41E..07L
- Keywords:
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- 1895 HYDROLOGY Instruments and techniques: monitoring;
- 1815 HYDROLOGY Erosion;
- 1825 HYDROLOGY Geomorphology: fluvial;
- 9320 GEOGRAPHIC LOCATION Asia