Macroinvertebrate response to flow changes in a subalpine stream: predictions from two-dimensional hydrodynamic models

River Research and Applications
By:  and 



Two-dimensional hydrodynamic models are being used increasingly as alternatives to traditional one-dimensional instream flow methodologies for assessing adequacy of flow and associated faunal habitat. Two-dimensional modelling of habitat has focused primarily on fishes, but fish-based assessments may not model benthic macroinvertebrate habitat effectively. We extend two-dimensional techniques to a macroinvertebrate assemblage in a high-elevation stream in the Sierra Nevada (Dana Fork of the Tuolumne River, Yosemite National Park, CA, USA). This stream frequently flows at less than 0.03?m3?s?1 in late summer and is representative of a common water abstraction scenario: maximum water abstraction coinciding with seasonally low flows. We used two-dimensional modelling to predict invertebrate responses to reduced flows that might result from increased abstraction. We collected site-specific field data on the macroinvertebrate assemblage, bed topography and flow conditions and then coupled a two-dimensional hydrodynamic model with macroinvertebrate indices to evaluate habitat across a range of low flows. Macroinvertebrate indices were calculated for the wetted area at each flow. A surrogate flow record based on an adjacent watershed was used to evaluate frequency and duration of low flow events. Using surrogate historical records, we estimated that flow should fall below 0.071?m3?s?1 at least 1?day in 82 of 95?years and below 0.028?m3?s?1 in 48 of 95?years. Invertebrate metric means indicated minor losses in response to modelled discharge reductions, but wetted area decreased substantially. Responses of invertebrates to water abstraction will likely be a function of changing habitat quantity rather than quality.
Publication type Article
Publication Subtype Journal Article
Title Macroinvertebrate response to flow changes in a subalpine stream: predictions from two-dimensional hydrodynamic models
Series title River Research and Applications
DOI 10.1002/rra.1607
Volume 29
Issue 3
Year Published 2013
Language English
Publisher Wiley
Publisher location Hoboken, NJ
Contributing office(s) Fort Collins Science Center
Description 14 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title River Research and Applications
First page 366
Last page 379
Country United States
State California
Other Geospatial Sierra Nevada;Tuolumne River;Yosemite National Park;Dana Fork
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