Rational Method Runoff Coefficient Tables for Storm Water ...
Oct 27, 2010 · Rational Method Runoff Coefficients. One of the parameters in the Rational Method equation ( Q = CiA ) is the runoff coefficient, C. The other parameters are A, the area of a watershed; i, the design rainfall intensity for a storm of specified recurrence interval and duration equal to the watershed time of concentration; and Q, the peak storm water runoff rate due to a .