A graphical non-parametric hydrologic alteration test using flow duration curves

ABSTRACT

Utilizing annual flow duration curves (FDCs), the modified Mood’s median test (MMMT) was applied to quantiles of the median annual FDCs at 122 disturbed sites in the conterminous US. A simple graphical tool based on the MMMT was combined with a false discovery rate multiple comparison procedure to illustrate the field significance of hydrologic alteration over a wide range of streamflow conditions. Hydrologic disturbance was mostly caused by dams, although other forms of alteration were explored. In addition, 249 minimally regulated Hydro-Climatic Data Network (HCDN) sites were investigated to assess regional climatic drivers of hydrologic alteration. Results indicate that dams can have varying effects on the hydrologic regime, but generally impact low flows more often than high flows in the US. At HCDN sites, we observe significant changes to hydrologic regimes in many regions, especially to low and median flows in the upper midwestern and eastern US.

KEYWORDS:

• hydrologic alteration
• flow duration curve
• streamflow data
• non-parametric hypothesis tests
• median
• field significance
• false discovery rate

Editor S. Archfield; Associate Editor I. Prosdocimi

Editor S. Archfield; Associate Editor I. Prosdocimi

Acknowledgements

The authors acknowledge the support received from the Fulbright Foreign Student Program and the SUNY College of Environmental Science and Forestry in Syracuse, NY. The authors would also like to acknowledge the two anonymous reviewers as well as Drs. Ilaria Prosdocimi and Stephen Shaw for their excellent suggestions which greatly improved this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.