Effect of bank stabilization on bend scour in anabranches of braided rivers

Bank stabilization along migrating river bends leads to deeper outer bend s cour, narrower channels and, sometimes, sharper bends. Four mechanisms are identified for these morphological responses: (1) prevention of bank sedime nt supply, (2) narrowing due to retarded point-bar growth, (3) bend deforma tion due to local prevention of channel migration and (4) vortices generate d by now impingement. A simplified, axisymmetrical model of water flow: sed iment transport, bank erosion and bank advance is used to study the first t wo mechanisms. Simulations using the model are compared with field data fro m a bank stabilization project along the Brahmaputra-Jamuna River in Bangla desh. The effects of bank stabilization are reproduced qualitatively but th e quantitative results are poor. The model overestimates channel width whil e underestimating bank migration rate and outer-bend scour. (C) 2000 Elsevi er Science Ltd. All rights reserved.