Abstract
A recent study employed a broken power-law (BPL) distribution for understanding the scaling frequency of bankfull discharge in snowmelt-dominated basins. This study, grounded from those findings, investigated the ability of a BPL function to describe the distribution of daily flows above the mean annual flow in 1217 sites across the conterminous U.S. (CONUS). The hydrologic regime in all the sites is unregulated and spans a wide range in drainage areas (2–120,000 km²) and elevation (0–3000 m). Available daily flow records in all sites varied between 15 and 108 years. Comparing the performance of BPL distribution and the traditionally used lognormal distribution, we found that BPL provides stronger fit in ~80% of the sites. Thus the BPL function provides a suitable tool to model daily flows in most areas of the CONUS. The potential for developing a model for predicting the frequency distribution of daily flows in ungauged sites was analyzed. We found that such model is possible using drainage area, mean basin elevation, and mean annual precipitation as predicting variables for any site located above 600 m across the CONUS. We also found strong continental-wide correlations between 3 of the 4 parameters that describe the BPL and basin characteristics. Our results indicate that the BPL function provides a robust alternative to traditional functions such as the lognormal to model the statistical variation of daily flows above the mean annual in most basins of the CONUS.
Keywords
Stream flow distribution,
Ungauged basins,
Broken power law,
Daily flows,
Statistical description of flow distribution
Citation
Segura, Catalina; Lazzati, Davide; Sankarasubramanian, Arumugam. 2013. The use of broken power-laws to describe the distributions of daily flow above the mean annual flow across the conterminous U.S. Journal of Hydrology 505:35–46.