simulated data varied largely

[Bimsara Chathuranga]

when i calibrated using swat cup and i cheked my objective function, there were impossible values, then i cjecked what is the reason and i found this one. my simulated data varied largely for only one month, the i checked my  rainfall data there is no problem. what is the reasin and how i solve this problem

here i attached my objective functions values and sim data