Once objects are created, they must generally be linked before they can function together as a model. Links come in three flavors:

• Flow Routing Links are gotten by mousing the palette button with the red R and dragging the mouse from an upstream water object to a downstream water object. When properly calibrated such a link will lag and perhaps attenuate the flow of water between the two nodes. Routing links always go from outflow or diversion to inflow.

• Instantaneous Transfer Links are gotten by mousing the palette button with the red L and then dragging the mouse from an upstream water object to a downstream water object. Such a link transfers water instantly between the two nodes. It is appropriate for models where the flow routing time is less than the time step and for screening models. Instantaneous Transfer Links always go from outflow or diversion to inflow.

• Information Links are gotten in the same way as are Instantaneous Transfer Links. The only difference is that one of the nodes is a table. These links are used to feed time series data from a table into the model and to collect output data from the model (depending on the direction of the arrow).

The following graphic loop shows the process for creating an Instantaneous Transfer Link from a table into a water node.

Here we have created a table with a single slot and desire to feed the value of that slot as a separate inflow into the Canals diversion structure. The instantaneous transfer link is selected on the palette. That means that clicking the left mouse button over any node and dragging the mouse to another node will create a link. Notice also that when we select the table slot, those slots in the reservoir which are not of type flow are greyed out. Had we run the link the other way (from the diversion to the table), the inflow to the Canal diversion would have been recorded in the table for each step of the simulation.