HEC-HMS Warnings - Troubleshooting

[KaylaTX]

I am having a few 'WARNINGS' pop up when I run my HEC-HMS model. I just started using this program, and don't know if these warnings actually affect the outcome enough to try fixing. Any help is greatly appreciated! As you can see, I'm using Muskingum as my reach method.

WARNING: Error in routing for TRUNK R-5;
Muskingum routing is unstable with the given parameters.

WARNING 41166: Control specifications time step exceeds Muskingum K for reach "TRUNK R-11"

I understand what this is saying, but don't know if it changes my outflow.

WARNING 41784: Simulation time interval is greater than 0.29 * lag for subbasin "Subbasin R-8b"; reduce simulation time interval.

Thanks in advance

 

[rshimota]

Decrease your calculation time step. Sounds like your basin R-8b time of concentration is shorter than your model time step. If your model time step is too large HMS may not model peak flow events accurately. total hydrograph volume should stay the same.

Same concept with the reach TRUNK R-11. Decrease mode ltime step. the drawback is your outut file size will increase.

I hope this helps.