This research article presents the integration of participatory modeling and system dynamics as a novel methodology for the consolidation of social dynamic models for the subsequent evaluation and prioritization of green projects in Colombian post-conflict communities. First, through participatory work carried out with a community, the citizen factors were identified, evaluated, and systematized in relation to the problems and needs of the region. Second, based on the results obtained, a simulation model based on system dynamics—which facilitates decision-making with regard to the evaluation of green projects—was calibrated. The proposed methodology lead to the conclusion that, with the participation of the community, and with a model based on the dynamics of the variables—such as supply and demand—for natural water and land resources, it is possible to warn decision-makers about variables that can lead to the maximization of investments, and thus to prioritize and select the most appropriate environmental, social, or economic initiatives that meet the needs or expectations of the involved community. In the future, the model could be used to facilitate the management, administration, and control of water and land resources by creating alerts called reserve margins.