A Reach is an element with one or more inflow and only one outflow. Inflow comes from other elements in the Basin Model. If there is more than one inflow, all inflow is added together before computing the outflow. Outflow is computed using one of the several available methods for simulating open channel flow. Optionally, it may include a method for representing interactions with the subsurface. The Reach Element can be used to model rivers and streams.