I have successfully run the HEC RAS model for a particular stretch of river and its working fine with no instability or errors, but the propagation seems to take place only in the north bank of the river whereas there is a major tributary on the south bank but flow does not take place. please anyone help me out on what may be wrong. I have added 3 no.s of 2D flow areas on both sides of the river by lateral structures and given the same specifications. Thanking in advance.