SSA 2013 strange results

[JRL_SD]

I created a simple test model in SSA 2013 to compare/analyze the results of the three link routing methods, Hydrodynamic, Kinematic Wave, and Steady Flow, and got strange results from all 3 methods, although the results using hydrodynamic were the most accurate of the 3.  I've attached a .zip file with the SSA model and a spreadsheet with my results.  Listed below are my questions for results from each routing method:

Hydrodynamic:

1.        If peak flow in Inlet-01 is 1.54, why is the peak flow in Link-01 1.91?  How could it increase?
2.        If the peak flow in Link-01 is 1.91, how can the peak flow in Link-03 be 1.66?  It shouldn’t drop.
3.        If the peak flow in Link-03 is 1.66, how can the peak flow in Link-04 be 1.62? It shouldn’t drop.
4.        If peak flow in Inlet-03 is 1.54, why is the peak flow in Link-05 1.84?  How could it increase?
5.        If the peak flow in Link-06 is 3.07, how can the peak flow in Link-07 be 3.02?  It shouldn’t drop.
6.        If the peak flow at Jun-01 is 2.02, how can the peak flow in Jun-02 be 2.02?  It shouldn’t drop.
7.        If the peak flow at Jun-03 is 3.31, how can the peak flow in Jun-04 be 3.07?  It shouldn’t drop.

Kinematic Wave:

1.        If peak flow in Inlet-01 is 1.54, why is the peak flow in Link-01 5.55?  How could it increase?
2.        If the peak flow in Link-01 is 5.55, how can the peak flow in Link-03 be 4.55?  It shouldn’t drop.
3.        If the peak flow in Link-03 is 4.55, how can the peak flow in Link-04 be 3.94? It shouldn’t drop.
4.        If peak flow in Inlet-03 is 1.54, why is the peak flow in Link-05 5.55?  How could it increase?
5.        If the peak flow in Link-06 is 7.59, how can the peak flow in Link-07 be 6.88?  It shouldn’t drop.
6.        If the peak flow at Jun-01 is 5.66, how can the peak flow in Jun-02 be 4.55?  It shouldn’t drop.
7.        If the peak flow at Jun-03 is 8.99, how can the peak flow in Jun-04 be 7.59?  It shouldn’t drop.
8.        If the sum of peak runoff from all 3 basins is 3.78, how can the peak inflow at Out-01 be 6.88?  How could it increase?

Steady Flow:

1.        If peak flow in Inlet-01 is 1.54, why is the peak flow in Link-01 7.20?  How could it increase?
2.        If peak flow in Inlet-03 is 1.54, why is the peak flow in Link-05 7.20?  How could it increase?
3.        If the peak flow at Jun-03 is 14.52, how can the peak flow in Jun-04 be 10.50?  It shouldn’t drop.
4.        If the sum of peak runoff from all 3 basins is 3.78, how can the peak inflow at Out-01 be 10.50?  How could it increase?

[MattAndersonPE]

JRL_SD 

The SSA Rational Method in 2013 routes the triangular hydrograph in 10 second intervals.  For such a tiny-model - this time step it too large, and you will recieve odd variations, like an increase in the pipes peak flow because of the large 10second time step.   SSA routes the flow based on the conservation of mass and momentum and is sensitive to the time step used.

There are service packs for SSA 2014 and 2015 that incude dropping the time step down to make a much more reasonable model.

[JRL_SD]

Thanks Matt.  I ran the model in 2015, and got realistic results.  Crazy how spurious the results from 2013 are...there should be a service pack for 2013 to fix this issue.

[armando_fayadb]

Did you ran just using rational method? did you change the time steps? for i installed the ssa 2015 service pack one but for rational method i can´t change the time steps and i´m still getting the same results.