The choice of alternative techniques in urban stormwater drainage (infiltration and detention systems), in the course of a project, is most often made with a poor understanding of site constraints, and the possibilities afforded by these techniques. This gives rise to extra costs and also subsequent malfunctioning. To arrive at feasible choices, we have formalised the decision-making process, taking account of the multiple criteria and the large number of partners involved. At present, we are developing a decision-making tool for alternative techniques in urban stormwater management at the preliminary study stage. The first phase makes it possible to eliminate solutions which are unworkable (elimination phase). It is aimed at the designer. Work on the next phase (the decision-making phase), which is more complex, is in progress. It will make it possible, in collaboration with all the partners involved, to choose a stormwater drainage strategy which will best suit the objectives and the wishes of the partners. It uses multi-criteria methods.
