Hello, I’m modelling a very simple river reach which functions fine under steady flow conditions, but when I try to use unsteady flow using a simplified hydrograph the water surface elevations are huge and unrealistic, even though the flows in the hydrograph are the same order of magitude or even less than the steady flow values I entered before. In the summary output tables there are negative flow rates at certain cross sections. Could anyone help me understand why this is happening?
Thanks in advance.