ABSTRACT
Secondary flows in curved channels cause bed scouring around outer banks. It is supposed that making slope of outer banks gentler is one of useful measures for mitigating scouring and bank erosion in curved and meandering channels. Therefore flow structures and bed variations around the gently sloped outer banks have to be understood to design slope of outer banks in actual rivers. However most of models proposed in curved channels were applied for the channels having a vertical wall. In this paper, applicability of the quasi-three-dimensional calculation model (the bottom velocity computation (BVC) method) is discussed for the experiments on flows and bed variations in curved channels with gently sloped outer banks (1V:2H and 1V:3H). From the comparison between calculation and experiment results, it is found that the BVC method reproduces vertical distributions of horizontal velocities and scouring depth around the gently sloped outer banks and provides a proper design of curved channels with gently sloped outer banks.
