Understand Flow Network devices vs​. topography

Once a model has been populated with segments and nodes, you need to consider flow and flow direction. All of the nodes and segments up to this point should be thought of as empty pipes. They are all connected, but there is nothing moving through them. Since there is nothing inside these pipes, the concept of direction is meaningless. To determine directionality, something needs to be moving through these pipes. To do that, you need injection and delivery devices in the model.

There are several different types of devices that can exist within a Flow Network model and perform different functions, but all attach to either segments or nodes, and provide state information rather than topographical information. The first and most important device type is a device that provides flow.