This chapter discusses how to use projects and scenarios to manage multiple models, such as models for existing and post-development condition.

To the user, a project may represent a specific type of work which consists of multiple hydrologic models. Each model in a project is a scenario. In VO, a scenario is an independent drainage net-work. A common practice for a modelling project is to create a project with multiple scenarios. At the beginning of the project, a base scenario is usually created first for the base scenario (existing condition). After that, new scenarios (post-development) are created by modifying the base sce-nario.