Output Breach Hydrograph deep below baseflow before the peak.

[Kinagoto]

I trust this Post finds you well.

I need you insights on the following issues I am facing with a dam breach run. The configuration shown is below.

WarmUp1
I ran a Warm Up long enough (72 hours) in order to establish initial conditions with a downstream discharge of 8900 cfs (4,100 + 3,800).
NoBreach:
• Dam # 2 with a 3,800 cfs (From_Maltby_No_2) spillway discharge at the top of dam
• Dam # 3 with a 4,100 cfs From_Maltby_No_3) spillway discharge at the top of dam
• Dam # 1 no set to fail
• A Discharge of 5,100 cfs (BC_1_Inflow) coming from the north tributary
• BC_Downstream is a Stage Hydrograph set to 3 ft.
For example one of the Breach Plan is defined as following:
• Dam # 2 with a 3,800 cfs (From_Maltby_No_2) spillway discharge at the top of dam

• Dam # 3 with a Breach Hydrograph obtained from HEC-RAS 1D run with a minimum discharge of 4,100 cfs and a pick of 17,850 cfs.
• Dam # 1 set to fail. For Dam # 1 failure, the Trigger Failure is set to Water Surface Elevation Starting at 138.5, which is just a little bit above the peak water level upstream of Dam # 1 under NoBreach Conditions.
• A Discharge of 5,100 cfs (BC_1_Inflow) coming from the north tributary
• BC_Downstream is a Stage Hydrograph set to 3 ft.
I used the output warmup file as an initial condition for the Breach 3 and 1 run.
I cannot explain why the output Breach Hydrograph, before the peak, deep below the base flow of 8900 cfs (4,100 + 3,800). Please, help me understand what is happening.

Thank you very much for your help, once again.

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