As part of a joint effort between academia and practice, we propose a novel approach to digital terrain modelling for climate adaptation planning. In contrast to existing workflows, it allows designers to merely describe desired drainage patterns for a given site and use genetic solvers for their subsequent optimization. Leveraging algorithmic strategies opens the possibility to analyse multiple proposed site layouts and identify the most resilient ones. By validating the method on three typical residential development projects, this paper puts renewed emphasis on the importance of terrain modelling in the context of flood protection – a domain often dominated by technical, hardscape solutions.