The paper proposes a technique for automating the creation of, and data collection from, an exhaustive set of flood mitigation scenarios modeled in EPA SWMM5, as well as a flood mitigation strategic planning framework that leverages the exhaustive model scope. Using the proposed method, models are generated for each logical combination of a smaller set of independent flood mitigation alternatives, at each possible level of implementation (i.e. at every practical level of investment). Cost estimates and flood risk reduction values are calculated for each flood mitigation implementation phase and organized into all possible sequences of implementation. The exhaustive set of progressive implementation scenarios is then leveraged as a decision-making tool to provide flexibility in long term planning: because each phase of investment can be implemented and function independently, large flood mitigation capital improvement programs can be constructed progressively, without having to commit (politically and financially) to the cost of the fully implemented program. Strategic planning is then flexible to favor short-term cost-effectiveness of each phase, or to optimize performance given a specific annual budget, while being able to stop investing in the program after every phase.