The paper describes and demonstrates an integrated cellular automata evolutionary-based approach for evaluating future scenarios including the expansion of urban drainage networks. The approach can be used to derive a drainage network layout based on future land use scenarios. Two techniques are used to derive the layout of the system: one using agent-based modelling and the other using similar principles built as a set of raster operations within ArcGIS. The tools and models are applied to a case study in Birmingham, UK. The results show that both techniques perform well for carrying out a scoping analysis at an urban scale. The case study shows that the application of the proposed approach for simulating urban growth processes and the consequent expansion of the drainage networks can achieve promising results. The interconnected drainage model for Birmingham shows that future developments will contribute further to flooding problems if no improvements are made to the existing drainage system. The same approach can be used to identify those drainage system elements that require immediate attention and which need to be replaced in order to improve the overall system performance.