Final answer:
The C in the Peak Flowrate formula stands for Runoff coefficient, which represents the fraction of rainfall that becomes runoff.
Step-by-step explanation:
In the Peak Flowrate formula, Qp = C · i · A, the C stands for Runoff coefficient.
The runoff coefficient is a dimensionless value that represents the fraction of rainfall that becomes runoff. It takes into account various factors such as soil type, vegetation cover, and slope of the land.
By multiplying the runoff coefficient with the intensity (i) and the area (A) of the catchment, you can calculate the peak flowrate (Qp) of a stream or river during a rainfall event.