The feedback artificial neural network model (FBANNM) was applied to the pr
ediction of the water-stages in a tidal river. The difference between a fee
d forward artificial neural network model and a FBANNM was investigated. A
simple genetic algorithm (SGA) was then incorporated into a FBANNM to help
search for the optimal network structure, especially the unit numbers of an
input layer and a hidden layer. It was concluded that the FBANNM was a use
ful tool in the short-term prediction of the water-stages that had a strong
autocorrelation due to tidal motion. The optimal network structure of the
FBANNM was effectively determined by the SGA incorporating the fitness defi
ned by Akaike's Information Criterion.