Natural-resource management that concerns multiple agents with a variety of interests can be facilitated by integrated assessment methods which include modelling and/or stakeholder participation. Integrated assessment methods are increasingly used for scenario approaches that enable policy-makers to explore possible futures and assess potential consequences of different policy or management strategies. The paper proposes a conceptual and operational framework to illustrate a scenario exercise, based on a previously developed model, by building on recently published progress on the participatory and model-based assessment approach. This framework focuses on information flows in two key operational phases, problem specification and adaptation of model outputs, where scientists and stakeholders interact. In both phases, transformation steps convert narrative information into a quantitative form (and vice-versa), thereby enabling scientists to apply computer models and decision-makers to get confident in model predictions. On the basis of four case studies aimed at solving complex water-resource management problems, we illustrate the difficulties, constraints and questions of each step of the proposed framework and present original solutions. This framework, which can be applied to all naturalresource management issues, clearly defines the step(s) at which each partner should be involved in a scenario exercise and his/her contribution. Consequently, by having greater foresight and transparency, the framework determines the nature of interactions between scientists and non-scientists. A posteriori, it also describes how a scenario exercise was conducted.