[Mike_H]

Dear all

I'm a fairly new user of HEC-RAS, and I've built several steady-state models. However, I'm currently working on an unsteady model of a watercourse with 5 tributaries. Some of the survey data is less than perfect. The model has stability problems, with errors ranging from having exceeded the maximum number of iterations, to matrix errors.

The problem I'm having is that I've no idea where to begin to debug these errors. I've seen the page on the HEC-RAS website regarding the possible sources of error, and I had some success in trying to build the model up successively, reach by reach, by altering theta, adding cross-sections, altering the downstream boundary, but eventually, HEC-RAS defeated me. Any success I have had seems to be haphazard, to the extent that I wouldn't have any confidence in the final modelled ouput.

I've tried to look at the output log, but I don't even know where to begin to spot where the error is. Does anyone have any tips? (The HEC-RAS website suggests patience is important)

Thanks in advance

Michael