Abstract:
Determination of the erodibility parameters, such as critical shear stress and erodibility coefficient,
are necessary before estimating the annual bank erosion (or bank retreat) at river reaches. However, in many
cases, the river site is inaccessible making it difficult to assess the soil parameters either by in situ tests or by
laboratory experiments. In this study, Genetic Algorithm (GA)-based optimisation technique was used to estimate the erodibility parameters of middle reaches of the Brahmaputra River in India. Two approaches were
followed. At first, erodibility parameters were estimated using daily stage records at a selected site. Secondly,
based on the annual observed bank erosions (bank retreat) from satellite images, erodibility parameters were
estimated in three different river reaches. All these results were compared with that from a previous study using
in situ jet tests. Annual bank erosions (bank retreat) were estimated using the median values of the erodibility
parameters. The results agree well with the average observed annual bank erosion of these river reaches. In
addition, the effects of measurement errors and optimisation algorithms on the parameter estimation were
analysed. Sensitivity analysis of the parameters in GA was evaluated and it was found that GA can be utilised in
the data-scarce regions to estimate the average erodibility parameters
