Connecting Event-Based Scaling of Flood Peaks to Regional Flood Frequency Relationships

Abstract

AbstractRegional flood frequency (RFF) equations are statistical characterizations that, in their simplest form, show how peak discharge quantiles scale with drainage area. They remain separated from the physical processes that occur during flood-generating rainfall-runoff events. A physical understanding of RFF equations is a long-standing unsolved problem in hydrology. This study addresses this problem using a scaling framework. Two hypotheses are introduced that collectively state that scaling slopes of event peak discharges are on average equivalent to the mean scaling slope of annual peak quantiles; the later quantity refers to an average taken over a set of exceedance probabilities under consideration. To test these hypotheses, a nested mixed-effects linear (NMEL) model was developed that characterizes event-to-event variability in scaling relationships between stream discharge peaks and drainage area. The model leads to scaling relationships for event peak discharge quantiles and annual peak quanti...