REBEKA––a software tool for planning urban drainage on the basis of predicted impacts on receiving waters

Modern methodologies for planning and design of urban drainage systems are based on the idea of minimising the receiving water pollution. However, in order to implement this concept of ambient water quality standards in practice, there is a need for simple tools that can establish a clear cause––effect relation between the drainage measures and the impact on the receiving water ecosystem. REBEKA is a software tool that has been developed to provide such a tool for a particular type of receiving waters––small, alpine and pre-alpine streams. The software has been launched among Swiss practitioners in the summer of 2000 and it is already widely applied. In this paper we outline the background of the methodology.