The objective of this research is to explore the relatively new approach, cellular automata (CA), to model the competitive growths and then try to explain the succession process of two underwater species Chara aspera (C. aspera) and Potamogeton pectinatus (P. pectinatus) in a eutrophicated lake, the Netherlands. CA constitutes a mathematical system that simulates the dynamics of spatial–temporal patterns in discrete steps according to prescribed local evolution rules. It consists of three main components: a set of cells, cell properties or states, and local evolution rules. Comparing to conventional aggregated-based ecological models formulated by partial differential equations (PDE), CA has more flexibility to implement the individual property differences and local interactions, especially with the facilitation of the object-oriented programming (OOP) techniques. The model results are seen to be both qualitatively and quantitatively in agreement with field observations. Namely, CA is not only applicable to ecohydraulics modelling, but also in some aspects more efficient than PDE based models.