Scaling of Flow Duration Curves Across the Contiguous United States

Abstract:

The scaling method has been used extensively in vadose zone hydrology to analyze the spatial variability of the soil hydraulic properties. This method relies on the similar media concept of Miller and Miller (1955) and coalesces a set of functional relationships into a single reference curve using so-called scaling factors that relate the hydraulic properties at a given location to the mean properties at an arbitrary reference point. In this talk, we will adapt the scaling method to surface hydrology and characterize the spatial variability of the flow duration curve (FDC) across the contiguous United States. Scaling factors are derived numerically by fitting closed-form parametric expressions of the FDC (Vrugt and Sadegh, 2013; Sadegh et al., 2015) to multi-year discharge data of the MOPEX data set. Results show that the FDC scaling factor exhibits a strong geographic trend with spatial patterns similar to those observed in the US soil and precipitation maps. Spatio-temporal kriging of the scaling factor can be used to predict the FDC of an ungauged watershed.