Biological relevance of streamflow metrics: Regional and national perspectives

Freshwater Science
By: , and 



Protecting the health of streams and rivers requires identifying ecologically significant attributes of the natural flow regime. Streamflow regimes are routinely quantified using a plethora of hydrologic metrics (HMs), most of which have unknown relevance to biological communities. At regional and national scales, we evaluated which of 509 commonly used HMs were associated with biological indicators of fish and invertebrate community integrity. We quantified alteration of each HM by using statistical models to predict site-specific natural baseline values for each of 728 sites across the USA where streamflow monitoring data were available concurrent with assessments of invertebrate or fish community integrity. We then ranked HMs according to their individual association with biological integrity based on random forest models that included HMs and other relevant covariates, such as land cover and stream chemistry. HMs were generally the most important predictors of biological integrity relative to the covariates. At a national scale, the most influential HMs were measures of depleted high flows, homogenization of flows, and erratic flows. Unique combinations of biologically relevant HMs were apparent among regions. We discuss the implications of our findings to the challenge of selecting HMs for streamflow research and management.
Publication type Article
Publication Subtype Journal Article
Title Biological relevance of streamflow metrics: Regional and national perspectives
Series title Freshwater Science
DOI 10.1086/694913
Volume 36
Issue 4
Year Published 2017
Language English
Publisher University of Chicago Press
Contributing office(s) National Water Quality Assessment Program
Description 14 p.
First page 927
Last page 940
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