HECRAS - Energy Grade Line Discrepancy

[tatraxle]

I am having trouble with a model in determining the appropriate value for the energy grade slope. HEC-RAS calculates the energy grade slope by simply solving for S using Manning's equation. However, if I check this value against the energy grade slope that I manually determine by calculating slope between the energy elevation between two cross sections, I get a significant difference. I don't understand why there is a difference and which method is correct. I would assume that since it is a built in function of Hec-Ras, it would be accurate, but it doesn't make sense to me. I am ultimately calculating bed shear stress in the cross sections and since the eg slope is a variable in this calculation, my shear stress calcs are affected by the discrepancy. I would appreciate any assistance to enlighten me on the matter. Thanks.

 

[gbam]

Hmm, Double check the units in which the energy grade is being reported. Maybe double check the computation by hand to verify the result.