Computation stops during computation of initial conditions

Typical Problem 1: Computation Stops During Computation of Initial Conditions

Possible Causes and Solutions

1. Adverse slopes or scour holes in channel profile invert can cause problems.

o In these situations smooth the channel profile invert.

2. Review input data reported by the program in the output file.

o Look for errors.

3. Review river reach for likely trouble spots.

o Bridges
Take them out.

o Steep reaches
Try raising "Mannings n". Also try sub/super critical flow options in boundary conditions.

o Sudden changes between cross-section geometry. Make the distance between interpolated cross-sections smaller.

4. Change downstream boundary condition.

o Beware of channel control (loop rating) for small slopes. This can cause problems, especially for flat slopes.

o Add another (artificial cross-section downstream) to give a steeper slope, but be aware that this can affect the results.

o Temporarily, try a different boundary condition.

5. Check initial flow.

o Is headwater level at dam(s) giving a reasonable outflow?

o Must have flow through the dam. Cannot start-up model "dry."

o Error tolerance in DAMBRK (default) is 100 cfs.

o Some initial flows are unfortunate choices given channel, bridge or dam characteristics. For example, if flow is just about to overtop a bridge, dam, overbank, etc., DAMBRK will have difficulty.