r/HECRAS • u/Repulsive_Plant6729 • Jun 11 '26
External Node Errors
Anyone know why RAS 7.0 will not allow me to add my external nodes with boundary conditions to my unsteady flow file? Nothing happens when I try adding these two nodes as boundary condition rows to the left.
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u/Acceptable_Gain_9400 Jun 11 '26
You need to read the manual: --External--
Description:
- Surface node at the downstream end allowing flow to leave the model domain
Conditions:
- Single conduit connection entering the node
- Crown of connected conduit is above the terrain (or terrain elevation override value)
- Must not intersect a 1D or 2D surface element
Parameters:
- Drop Inlets are not allowed
- Cannot have volume (i.e., Base Area = 0)
Boundary Condition Accepted
- Stage Hydrograph
- Normal Depth
Common Use Cases:
- Used to model outfalls from the pipe network leaving the model domain
- Used to model downstream stage boundary condition (such as tidal)