Number 22/Measurement & inference/Hydrology
The Smoothing Fraction
The quantity
The ratio of event size to antecedent storage capacity. Below one, an event is absorbed and produces no response; above it, the response scales with the excess.
01Why it matters
It explains why identical rainfall produces floods in one catchment and nothing in another, and it is estimable from soil and storage data.
02Expected value
Runoff should be negligible below a fraction of one and rise steeply above.
03How it would be measured
Paired rainfall and runoff records with antecedent moisture estimates.
04What would refute it
Proportional response at all ratios would remove the threshold.