Sluice Gate Non-Convergence

HEC Users,

I am using HEC-RAS to model flow through a bridge opening which has a free outfall at the downstream end and is submerged at the upstream end. I am using Pressure/Weir Flow for the Bridge Modeling Approach. The program returns the following warning:

"The sluice gate calculations do not converge during the pressure flow only calculation."

First of all, can someone tell me how the program returns the resultant profile through the bridge when it encounters this error? Secondly, does anyone have any suggestions as to how I may troubleshoot this problem? Thanks.

Nick Emery

I am having the exact same problem. I am trying to calculate to a high water mark at this bridge, and it is very close to the low steel. So, the values are all over the place, sometime above the low steel, forcing the calculations into the pressure flow equations. I don't have an answer for your problem, but I do know that the problem lies somewhere in the calculated upstream water surface elevation and the low steel being too close in elevation. The only thing that I have found written about this said that if this is the case then you shouldn't use the pressure flow option. So, I used the Energy Only option for High Flow Method in the Bridge Modeling Approach Editor. Fortunately, I no longer received the error that you spoke about. Unfortunately, though, the water surface elevation was not changed. So, I am still having a problem with the calibration.

Hope this helps,
Susan K. Tatalovich
Fuller, Mossbarger, Scott and May Engineers, Inc.