Rational formula - strange resulting Qp

[mecasantos]

Hi,
I'm estimating peak discharge values for two basins. One is the other's tributary. One has an area of 64 km2 and the other 0,7 km2.
For the bigger basin (Stream A) I obtain reasonable values (167 m3/s) according to other methods (SCS, Giandotti), but in the small tributary I'm getting an anormaly huge value (46 m3/s). Can someone help me find what am I doing wrong? I believe the error is related to the Rainfall Intensity because in the SCS method I obtained good discharge values (4 m3/s).
I've uploaded a small .doc file with the calculations.
Thanks and apologize my weak English.
Pedro Santos

 

[cvg]

first of all, your rainfall intensity for the small area looks a bit high
secondly, using rational method for a 64 square kilometers area is not appropriate and should not be done. Suggest a better method would be to use regression equation based on similar large watersheds
thirdly, your basin may produce more runoff during a 24-hour or longer storm.