The resolution of the calculation of the hydraulic variables at the node can be done in two ways:

• equality of the elevations (default mode)
• equality of the hydraulic heads

In the case of equality of heads, it is possible to define a head loss at the entrance of the node (for upstreams reaches arriving at this node) and at the exit of the node (for the diversion reaches downstream). It is possible to have for the same node reaches arriving at or leaving this node with different modes (elevation for some and head for others). In this case of a head loss, a Borda type equation (proportional to the speed squared) is used.

Remark: In the case where the flow at a node is in supercritical regime on one or more of the reaches arriving or leaving this node, the calculation mode will be automatically switched to "equality of head" mode, even if the "equality of elevations" mode had been chosen here. This is indeed more physically realistic. For calculations in torrential regime to be authorized, the corresponding option must be activated in the permanent calculation parameters.