Hello everyone.
I am currently half way through a masters based on the above title. I am using HEC RAS to model erosion / deposition effects of placing a sharp crested weir on a mountain stream with a slope of less than 5%.
I have most of my input data sorted out and have run some steady state models with Q5, Q25, Q50, Q75, Q95 and QMEAN and calibrating my “n” using Jarrets equation for each cross section based on bank full flow produces stage profiles that look respectable.
My question is, would this constitute adequate calibration as other than a rating curve at the weir location I have no stage-flow data for any other location?
I started out with a typical figure for n from Chow (1959) but this gave clearly incorrect water levels.
Also I have encountered several errors msgs in trying to the sediment model but through this site I have managed to get through them so far until encountering this:
Sediment Transport Analysis Version 4.1.0 Jan 2010
SLOPE CONVEYANCE STARTING METHOD HAS BEEN
CHOOSEN
HOWEVER, THE SLOPE HAS NOT BEEN DEFINED
I am running a model from 1/Jan/2010 to 31/Jan/2010 with hourly quasi steady flow data so that’s 721 iterations.
The model freezes at 1/721 simulations once it gets to the downstream cross section and proceeds no further.
I have searched the User manual and Hyd Ref manual for “Slope Conveyance” but it is not listed. Would anyone have any idea on this and how to solve it?
Oh and I should add that I specified a Normal Depth downstream boundary condition and set the friction slope to 0.04 and saved my flow data. This has not helped.
For some reason when I go back into the flow data boundary condition and click on normal depth again the 0.04 is gone and the box is blank . Is this normal or could it be the issue?
Many thanks in advance for any advice offered.