Alluvial river beds display different kinds of bed forms. One of these possible bed forms is called ‘alternate bars’. Alternate bars have adopted their name from the fact that the bar and pool occur alternately at the left and the right bank. The pool can decrease the strength of the bank, which can result in bank failure. The bars also cause hindrance to navigation and can block a water intake, if a bar is deposited in front of an irrigation canal. Furthermore, non-migrating alternate bars are considered to be a possible cause of meandering.
The properties of alternate bars can be predicted by linear theories. In those theories the behaviour of an alternate bar (amplification rate and migration rate) is assumed not to depend on the bar height. In reality however, the behaviour is dependent on the bar height, and is therefore non-linear. By applying Delft3D-FLOW one can investigate the behaviour of bars in a non-linear way.