Differential evolution is a successful approach to solve optimization problems. The way it performs the creation of the individual allows a spontaneous self-adaptability to the function. In this paper, a new method based on differential evolution paradigm has been developed. An innovative feature has been added: the variable length of the genotype, so this approach can be applied in predicting special time series. This approach has been tested over rainfall data for real-time prediction of changing water levels on an artificial basin. This way, a floods prediction system can be obtained.